Cisco Security Appliance Command Line Configuration

Cisco Security Appliance Command Line
Configuration Guide
For the Cisco ASA 5500 Series and Cisco PIX 500 Series
Software Version 8.0
Americas Headquarters
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
USA
http://www.cisco.com
Tel: 408 526-4000
800 553-NETS (6387)
Fax: 408 527-0883
Customer Order Number: N/A, Online only
Text Part Number: OL-12172-04
THE SPECIFICATIONS AND INFORMATION REGARDING THE PRODUCTS IN THIS MANUAL ARE SUBJECT TO CHANGE WITHOUT NOTICE. ALL
STATEMENTS, INFORMATION, AND RECOMMENDATIONS IN THIS MANUAL ARE BELIEVED TO BE ACCURATE BUT ARE PRESENTED WITHOUT
WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. USERS MUST TAKE FULL RESPONSIBILITY FOR THEIR APPLICATION OF ANY PRODUCTS.
THE SOFTWARE LICENSE AND LIMITED WARRANTY FOR THE ACCOMPANYING PRODUCT ARE SET FORTH IN THE INFORMATION PACKET THAT
SHIPPED WITH THE PRODUCT AND ARE INCORPORATED HEREIN BY THIS REFERENCE. IF YOU ARE UNABLE TO LOCATE THE SOFTWARE LICENSE
OR LIMITED WARRANTY, CONTACT YOUR CISCO REPRESENTATIVE FOR A COPY.
The Cisco implementation of TCP header compression is an adaptation of a program developed by the University of California, Berkeley (UCB) as part of UCB’s public
domain version of the UNIX operating system. All rights reserved. Copyright © 1981, Regents of the University of California.
NOTWITHSTANDING ANY OTHER WARRANTY HEREIN, ALL DOCUMENT FILES AND SOFTWARE OF THESE SUPPLIERS ARE PROVIDED “AS IS” WITH
ALL FAULTS. CISCO AND THE ABOVE-NAMED SUPPLIERS DISCLAIM ALL WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT
LIMITATION, THOSE OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OR ARISING FROM A COURSE OF
DEALING, USAGE, OR TRADE PRACTICE.
IN NO EVENT SHALL CISCO OR ITS SUPPLIERS BE LIABLE FOR ANY INDIRECT, SPECIAL, CONSEQUENTIAL, OR INCIDENTAL DAMAGES, INCLUDING,
WITHOUT LIMITATION, LOST PROFITS OR LOSS OR DAMAGE TO DATA ARISING OUT OF THE USE OR INABILITY TO USE THIS MANUAL, EVEN IF CISCO
OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
CCDE, CCENT, CCSI, Cisco Eos, Cisco HealthPresence, Cisco IronPort, the Cisco logo, Cisco Nurse Connect, Cisco Pulse, Cisco SensorBase, Cisco StackPower,
Cisco StadiumVision, Cisco TelePresence, Cisco Unified Computing System, Cisco WebEx, DCE, Flip Channels, Flip for Good, Flip Mino, Flipshare (Design), Flip Ultra,
Flip Video, Flip Video (Design), Instant Broadband, and Welcome to the Human Network are trademarks; Changing the Way We Work, Live, Play, and Learn, Cisco Capital,
Cisco Capital (Design), Cisco:Financed (Stylized), Cisco Store, Flip Gift Card, and One Million Acts of Green are service marks; and Access Registrar, Aironet, AllTouch,
AsyncOS, Bringing the Meeting To You, Catalyst, CCDA, CCDP, CCIE, CCIP, CCNA, CCNP, CCSP, CCVP, Cisco, the Cisco Certified Internetwork Expert logo,
Cisco IOS, Cisco Lumin, Cisco Nexus, Cisco Press, Cisco Systems, Cisco Systems Capital, the Cisco Systems logo, Cisco Unity, Collaboration Without Limitation,
Continuum, EtherFast, EtherSwitch, Event Center, Explorer, Follow Me Browsing, GainMaker, iLYNX, IOS, iPhone, IronPort, the IronPort logo, Laser Link, LightStream,
Linksys, MeetingPlace, MeetingPlace Chime Sound, MGX, Networkers, Networking Academy, PCNow, PIX, PowerKEY, PowerPanels, PowerTV, PowerTV (Design),
PowerVu, Prisma, ProConnect, ROSA, SenderBase, SMARTnet, Spectrum Expert, StackWise, WebEx, and the WebEx logo are registered trademarks of Cisco Systems, Inc.
and/or its affiliates in the United States and certain other countries.
All other trademarks mentioned in this document or website are the property of their respective owners. The use of the word partner does not imply a partnership relationship
between Cisco and any other company. (0910R)
Cisco Security Appliance Command Line Configuration Guide
Copyright © 2009 Cisco Systems, Inc. All rights reserved.
CONTENTS
About This Guide
xli
Document Objectives
Audience
xli
xli
Related Documentation
xlii
Document Conventions
xlii
Obtaining Documentation, Obtaining Support, and Security Guidelines
PART
Getting Started and General Information
1
CHAPTER
xlii
1
Introduction to the Security Appliance
Supported Platform Models
1-1
SSM and SSC Support Per Model
VPN Specifications
1-1
1-2
1-3
New Features 1-3
New Features in Version 8.0(5)
New Features in Version 8.0(4)
New Features in Version 8.0(3)
New Features in Version 8.0(2)
1-3
1-4
1-8
1-9
Firewall Functional Overview 1-14
Security Policy Overview 1-15
Permitting or Denying Traffic with Access Lists 1-15
Applying NAT 1-15
Protecting from IP Fragments 1-15
Using AAA for Through Traffic 1-15
Applying HTTP, HTTPS, or FTP Filtering 1-16
Applying Application Inspection 1-16
Sending Traffic to the Advanced Inspection and Prevention Security Services Module
Sending Traffic to the Content Security and Control Security Services Module 1-16
Applying QoS Policies 1-16
Applying Connection Limits and TCP Normalization 1-16
Enabling Threat Detection 1-17
Firewall Mode Overview 1-17
Stateful Inspection Overview 1-17
VPN Functional Overview
1-16
1-18
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
iii
Contents
Security Context Overview
CHAPTER
2
Getting Started
1-19
2-1
Getting Started with Your Platform Model
2-1
Factory Default Configurations 2-1
Restoring the Factory Default Configuration
ASA 5505 Default Configuration 2-2
ASA 5510 and Higher Default Configuration
PIX 515/515E Default Configuration 2-4
Accessing the Command-Line Interface
2-2
2-3
2-4
Setting Transparent or Routed Firewall Mode
2-5
Working with the Configuration 2-6
Saving Configuration Changes 2-6
Saving Configuration Changes in Single Context Mode 2-7
Saving Configuration Changes in Multiple Context Mode 2-7
Copying the Startup Configuration to the Running Configuration 2-8
Viewing the Configuration 2-8
Clearing and Removing Configuration Settings 2-9
Creating Text Configuration Files Offline 2-9
CHAPTER
3
Managing Feature Licenses
3-1
Supported Feature Licenses Per Model
3-1
Information About Feature Licenses 3-9
Preinstalled License 3-10
VPN Flex and Evaluation Licenses 3-10
How the Temporary License Timer Works
How Multiple Licenses Interact 3-11
Failover and Temporary Licenses 3-11
Guidelines and Limitations
3-10
3-12
Viewing Your Current License
Obtaining an Activation Key
Entering a New Activation Key
3-12
3-14
3-15
Upgrading the License for a Failover Pair 3-16
Upgrading the License for a Failover (No Reload Required) 3-16
Upgrading the License for a Failover (Reload Required) 3-17
Feature History for Licensing
3-18
Cisco Security Appliance Command Line Configuration Guide
iv
OL-12172-04
Contents
CHAPTER
4
Enabling Multiple Context Mode
4-1
Security Context Overview 4-1
Common Uses for Security Contexts 4-2
Unsupported Features 4-2
Context Configuration Files 4-2
Context Configurations 4-2
System Configuration 4-3
Admin Context Configuration 4-3
How the Security Appliance Classifies Packets 4-3
Valid Classifier Criteria 4-3
Invalid Classifier Criteria 4-4
Classification Examples 4-5
Cascading Security Contexts 4-8
Management Access to Security Contexts 4-9
System Administrator Access 4-9
Context Administrator Access 4-10
Enabling or Disabling Multiple Context Mode 4-10
Backing Up the Single Mode Configuration 4-10
Enabling Multiple Context Mode 4-10
Restoring Single Context Mode 4-11
CHAPTER
5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security
Appliance 5-1
Interface Overview 5-1
Understanding ASA 5505 Ports and Interfaces 5-2
Maximum Active VLAN Interfaces for Your License 5-2
Default Interface Configuration 5-4
VLAN MAC Addresses 5-4
Power Over Ethernet 5-4
Monitoring Traffic Using SPAN 5-4
Security Level Overview 5-5
Configuring VLAN Interfaces
5-5
Configuring Switch Ports as Access Ports
5-9
Configuring a Switch Port as a Trunk Port
5-11
Allowing Communication Between VLAN Interfaces on the Same Security Level
CHAPTER
6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring and Enabling RJ-45 Interfaces
RJ-45 Interface Overview 6-2
5-13
6-1
6-1
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
v
Contents
Default State of Physical Interfaces
Connector Types 6-2
Auto-MDI/MDIX Feature 6-2
Configuring the RJ-45 Interface 6-2
6-2
Configuring and Enabling Fiber Interfaces 6-3
Default State of Physical Interfaces 6-3
Configuring the Fiber Interface 6-4
Configuring a Redundant Interface 6-4
Redundant Interface Overview 6-5
Default State of Redundant Interfaces 6-5
Redundant Interfaces and Failover Guidelines
Redundant Interface MAC Address 6-5
Physical Interface Guidelines 6-5
Adding a Redundant Interface 6-6
Changing the Active Interface 6-7
6-5
Configuring VLAN Subinterfaces and 802.1Q Trunking 6-7
Subinterface Overview 6-7
Default State of Subinterfaces 6-7
Maximum Subinterfaces 6-8
Preventing Untagged Packets on the Physical Interface
Adding a Subinterface 6-8
CHAPTER
7
Adding and Managing Security Contexts
Configuring Resource Management 7-1
Classes and Class Members Overview
Resource Limits 7-2
Default Class 7-3
Class Members 7-4
Configuring a Class 7-4
Configuring a Security Context
6-8
7-1
7-1
7-7
Automatically Assigning MAC Addresses to Context Interfaces
Information About MAC Addresses 7-11
Default MAC Address 7-11
Interaction with Manual MAC Addresses 7-11
Failover MAC Addresses 7-12
MAC Address Format 7-12
Enabling Auto-Generation of MAC Addresses 7-12
Viewing Assigned MAC Addresses 7-13
Viewing MAC Addresses in the System Configuration
7-11
7-13
Cisco Security Appliance Command Line Configuration Guide
vi
OL-12172-04
Contents
Viewing MAC Addresses Within a Context
7-14
Changing Between Contexts and the System Execution Space
Managing Security Contexts 7-15
Removing a Security Context 7-15
Changing the Admin Context 7-16
Changing the Security Context URL 7-16
Reloading a Security Context 7-17
Reloading by Clearing the Configuration 7-17
Reloading by Removing and Re-adding the Context
Monitoring Security Contexts 7-18
Viewing Context Information 7-18
Viewing Resource Allocation 7-19
Viewing Resource Usage 7-22
Monitoring SYN Attacks in Contexts 7-23
CHAPTER
8
Configuring Interface Parameters
Security Level Overview
7-14
7-18
8-1
8-1
Configuring Interface Parameters 8-2
Interface Parameters Overview 8-2
Default State of Interfaces 8-3
Default Security Level 8-3
Multiple Context Mode Guidelines
Configuring the Interface 8-3
8-3
Allowing Communication Between Interfaces on the Same Security Level
CHAPTER
9
Configuring Basic Settings
9-1
Changing the Login Password
Changing the Enable Password
Setting the Hostname
9-1
9-1
9-2
Setting the Domain Name
9-2
Setting the Date and Time 9-2
Setting the Time Zone and Daylight Saving Time Date Range
Setting the Date and Time Using an NTP Server 9-4
Setting the Date and Time Manually 9-4
Setting the Management IP Address for a Transparent Firewall
CHAPTER
10
Configuring IP Routing
8-7
9-3
9-5
10-1
How Routing Behaves Within the ASA Security Appliance
10-1
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
vii
Contents
Egress Interface Selection Process
Next Hop Selection Process 10-2
10-1
Configuring Static and Default Routes 10-2
Configuring a Static Route 10-3
Configuring a Default Static Route 10-4
Configuring Static Route Tracking 10-5
Defining Route Maps
10-7
Configuring OSPF 10-8
OSPF Overview 10-9
Enabling OSPF 10-10
Redistributing Routes Into OSPF 10-10
Configuring OSPF Interface Parameters 10-12
Configuring OSPF Area Parameters 10-14
Configuring OSPF NSSA 10-15
Configuring Route Summarization Between OSPF Areas 10-16
Configuring Route Summarization When Redistributing Routes into OSPF
Defining Static OSPF Neighbors 10-17
Generating a Default Route 10-17
Configuring Route Calculation Timers 10-18
Logging Neighbors Going Up or Down 10-18
Displaying OSPF Update Packet Pacing 10-19
Monitoring OSPF 10-19
Restarting the OSPF Process 10-20
10-16
Configuring RIP 10-20
Enabling and Configuring RIP 10-21
Redistributing Routes into the RIP Routing Process 10-22
Configuring RIP Send/Receive Version on an Interface 10-23
Enabling RIP Authentication 10-23
Monitoring RIP 10-24
Configuring EIGRP 10-24
EIGRP Routing Overview 10-25
Enabling and Configuring EIGRP Routing 10-26
Enabling and Configuring EIGRP Stub Routing 10-27
Enabling EIGRP Authentication 10-27
Defining an EIGRP Neighbor 10-28
Redistributing Routes Into EIGRP 10-29
Configuring the EIGRP Hello Interval and Hold Time 10-30
Disabling Automatic Route Summarization 10-30
Configuring Summary Aggregate Addresses 10-31
Cisco Security Appliance Command Line Configuration Guide
viii
OL-12172-04
Contents
Disabling EIGRP Split Horizon 10-31
Changing the Interface Delay Value 10-32
Monitoring EIGRP 10-32
Disabling Neighbor Change and Warning Message Logging
10-32
The Routing Table 10-33
Displaying the Routing Table 10-33
How the Routing Table is Populated 10-33
Backup Routes 10-35
How Forwarding Decisions are Made 10-35
Dynamic Routing and Failover
CHAPTER
11
10-36
Configuring DHCP, DDNS, and WCCP Services
11-1
Configuring a DHCP Server 11-1
Enabling the DHCP Server 11-2
Configuring DHCP Options 11-3
Using Cisco IP Phones with a DHCP Server
11-4
Configuring DHCP Relay Services
11-5
Configuring Dynamic DNS 11-6
Example 1: Client Updates Both A and PTR RRs for Static IP Addresses 11-7
Example 2: Client Updates Both A and PTR RRs; DHCP Server Honors Client Update Request; FQDN
Provided Through Configuration 11-7
Example 3: Client Includes FQDN Option Instructing Server Not to Update Either RR; Server Overrides
Client and Updates Both RRs. 11-8
Example 4: Client Asks Server To Perform Both Updates; Server Configured to Update PTR RR Only;
Honors Client Request and Updates Both A and PTR RR 11-9
Example 5: Client Updates A RR; Server Updates PTR RR 11-9
Configuring Web Cache Services Using WCCP 11-9
WCCP Feature Support 11-10
WCCP Interaction With Other Features 11-10
Enabling WCCP Redirection 11-11
CHAPTER
12
Configuring Multicast Routing
Multicast Routing Overview
Enabling Multicast Routing
12-1
12-1
12-2
Configuring IGMP Features 12-2
Disabling IGMP on an Interface 12-3
Configuring Group Membership 12-3
Configuring a Statically Joined Group 12-3
Controlling Access to Multicast Groups 12-3
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
ix
Contents
Limiting the Number of IGMP States on an Interface 12-4
Modifying the Query Interval and Query Timeout 12-4
Changing the Query Response Time 12-5
Changing the IGMP Version 12-5
Configuring Stub Multicast Routing
Configuring a Static Multicast Route
12-5
12-6
Configuring PIM Features 12-6
Disabling PIM on an Interface 12-6
Configuring a Static Rendezvous Point Address 12-7
Configuring the Designated Router Priority 12-7
Filtering PIM Register Messages 12-7
Configuring PIM Message Intervals 12-8
Configuring a Multicast Boundary 12-8
Filtering PIM Neighbors 12-8
Supporting Mixed Bidirectional/Sparse-Mode PIM Networks
For More Information about Multicast Routing
CHAPTER
13
Configuring IPv6
12-9
12-10
13-1
IPv6-enabled Commands
13-1
Configuring IPv6 13-2
Configuring IPv6 on an Interface 13-3
Configuring a Dual IP Stack on an Interface 13-4
Enforcing the Use of Modified EUI-64 Interface IDs in IPv6 Addresses
Configuring IPv6 Duplicate Address Detection 13-4
Configuring IPv6 Default and Static Routes 13-5
Configuring IPv6 Access Lists 13-6
Configuring IPv6 Neighbor Discovery 13-7
Configuring Neighbor Solicitation Messages 13-7
Configuring Router Advertisement Messages 13-9
Configuring a Static IPv6 Neighbor 13-11
13-4
Verifying the IPv6 Configuration 13-11
The show ipv6 interface Command 13-11
The show ipv6 route Command 13-12
CHAPTER
14
Configuring AAA Servers and the Local Database
14-1
AAA Overview 14-1
About Authentication 14-2
About Authorization 14-2
About Accounting 14-2
Cisco Security Appliance Command Line Configuration Guide
x
OL-12172-04
Contents
AAA Server and Local Database Support 14-3
Summary of Support 14-3
RADIUS Server Support 14-4
Authentication Methods 14-4
Attribute Support 14-4
RADIUS Authorization Functions 14-5
TACACS+ Server Support 14-5
RSA/SDI Server Support 14-5
RSA/SDI Version Support 14-5
Two-step Authentication Process 14-5
SDI Primary and Replica Servers 14-5
NT Server Support 14-6
Kerberos Server Support 14-6
LDAP Server Support 14-6
SSO Support for Clientless SSL VPN with HTTP Forms
Local Database Support 14-6
User Profiles 14-7
Fallback Support 14-7
Configuring the Local Database
14-6
14-7
Identifying AAA Server Groups and Servers
14-9
Configuring an LDAP Server 14-12
Authentication with LDAP 14-13
Authorization with LDAP for VPN 14-14
LDAP Attribute Mapping 14-15
Using Certificates and User Login Credentials
Using User Login Credentials 14-16
Using certificates 14-17
14-16
Supporting a Zone Labs Integrity Server 14-17
Overview of Integrity Server and Security Appliance Interaction
Configuring Integrity Server Support 14-18
CHAPTER
15
Configuring Failover
14-18
15-1
Understanding Failover 15-1
Failover System Requirements 15-2
Hardware Requirements 15-2
Software Requirements 15-2
License Requirements 15-3
The Failover and Stateful Failover Links
Failover Link 15-3
15-3
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xi
Contents
Stateful Failover Link 15-5
Active/Active and Active/Standby Failover 15-6
Active/Standby Failover 15-7
Active/Active Failover 15-11
Determining Which Type of Failover to Use 15-15
Stateless (Regular) and Stateful Failover 15-16
Stateless (Regular) Failover 15-16
Stateful Failover 15-16
Failover Health Monitoring 15-18
Unit Health Monitoring 15-18
Interface Monitoring 15-18
Failover Feature/Platform Matrix 15-19
Failover Times by Platform 15-20
Configuring Failover 15-20
Failover Configuration Limitations 15-20
Configuring Active/Standby Failover 15-21
Prerequisites 15-21
Configuring Cable-Based Active/Standby Failover (PIX 500 Series Security Appliance
Only) 15-21
Configuring LAN-Based Active/Standby Failover 15-23
Configuring Optional Active/Standby Failover Settings 15-26
Configuring Active/Active Failover 15-29
Prerequisites 15-29
Configuring Cable-Based Active/Active Failover (PIX 500 series security appliance) 15-29
Configuring LAN-Based Active/Active Failover 15-31
Configuring Optional Active/Active Failover Settings 15-35
Configuring Unit Health Monitoring 15-41
Configuring Failover Communication Authentication/Encryption 15-41
Verifying the Failover Configuration 15-42
Using the show failover Command 15-42
Viewing Monitored Interfaces 15-50
Displaying the Failover Commands in the Running Configuration 15-50
Testing the Failover Functionality 15-51
Controlling and Monitoring Failover 15-51
Forcing Failover 15-51
Disabling Failover 15-52
Restoring a Failed Unit or Failover Group
Monitoring Failover 15-53
Failover System Messages 15-53
Debug Messages 15-53
15-52
Cisco Security Appliance Command Line Configuration Guide
xii
OL-12172-04
Contents
SNMP
15-53
Remote Command Execution 15-53
Changing Command Modes 15-54
Security Considerations 15-55
Limitations of Remote Command Execution
15-55
Auto Update Server Support in Failover Configurations
Auto Update Process Overview 15-56
Monitoring the Auto Update Process 15-57
CHAPTER
16
Using Modular Policy Framework
15-56
16-1
Information About Modular Policy Framework 16-1
Modular Policy Framework Supported Features 16-1
Modular Policy Framework Configuration Overview 16-2
Default Global Policy 16-3
Identifying Traffic (Layer 3/4 Class Map) 16-4
Default Class Maps 16-4
Maximum Class Maps 16-5
Creating a Layer 3/4 Class Map for Through Traffic 16-5
Creating a Layer 3/4 Class Map for Management Traffic 16-7
Configuring Special Actions for Application Inspections (Inspection Policy Map)
Inspection Policy Map Overview 16-9
Defining Actions in an Inspection Policy Map 16-9
Identifying Traffic in an Inspection Class Map 16-12
Creating a Regular Expression 16-13
Creating a Regular Expression Class Map 16-16
16-8
Defining Actions (Layer 3/4 Policy Map) 16-16
Information About Layer 3/4 Policy Maps 16-17
Policy Map Guidelines 16-17
Hierarchical Policy Maps 16-17
Feature Directionality 16-18
Feature Matching Guidelines Within a Policy Map 16-18
Order in Which Multiple Feature Actions are Applied 16-19
Incompatibility of Certain Feature Actions 16-20
Feature Matching Guidelines for Multiple Policy Maps 16-21
Default Layer 3/4 Policy Map 16-21
Adding a Layer 3/4 Policy Map 16-22
Applying Actions to an Interface (Service Policy)
16-23
Modular Policy Framework Examples 16-24
Applying Inspection and QoS Policing to HTTP Traffic
16-25
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xiii
Contents
Applying Inspection to HTTP Traffic Globally 16-25
Applying Inspection and Connection Limits to HTTP Traffic to Specific Servers
Applying Inspection to HTTP Traffic with NAT 16-27
PART
Configuring the Firewall
2
CHAPTER
17
Firewall Mode Overview
17-1
Routed Mode Overview 17-1
IP Routing Support 17-1
How Data Moves Through the Security Appliance in Routed Firewall Mode
An Inside User Visits a Web Server 17-2
An Outside User Visits a Web Server on the DMZ 17-3
An Inside User Visits a Web Server on the DMZ 17-4
An Outside User Attempts to Access an Inside Host 17-5
A DMZ User Attempts to Access an Inside Host 17-6
Transparent Mode Overview 17-7
Transparent Firewall Network 17-7
Allowing Layer 3 Traffic 17-7
Allowed MAC Addresses 17-7
Passing Traffic Not Allowed in Routed Mode 17-8
MAC Address vs. Route Lookups 17-8
Using the Transparent Firewall in Your Network 17-9
Transparent Firewall Guidelines 17-9
Unsupported Features in Transparent Mode 17-10
How Data Moves Through the Transparent Firewall 17-11
An Inside User Visits a Web Server 17-12
An Inside User Visits a Web Server Using NAT 17-13
An Outside User Visits a Web Server on the Inside Network
An Outside User Attempts to Access an Inside Host 17-15
CHAPTER
16-26
18
Identifying Traffic with Access Lists
17-1
17-14
18-1
Access List Overview 18-1
Access List Types 18-2
Access Control Entry Order 18-2
Access Control Implicit Deny 18-3
IP Addresses Used for Access Lists When You Use NAT
18-3
Adding an Extended Access List 18-5
Extended Access List Overview 18-5
Allowing Broadcast and Multicast Traffic through the Transparent Firewall
18-6
Cisco Security Appliance Command Line Configuration Guide
xiv
OL-12172-04
Contents
Adding an Extended ACE
18-7
Adding an EtherType Access List 18-8
EtherType Access List Overview 18-8
Supported EtherTypes 18-9
Implicit Permit of IP and ARPs Only 18-9
Implicit and Explicit Deny ACE at the End of an Access List 18-9
IPv6 Unsupported 18-9
Using Extended and EtherType Access Lists on the Same Interface
Allowing MPLS 18-10
Adding an EtherType ACE 18-10
Adding a Standard Access List
18-11
Adding a Webtype Access List
18-11
18-9
Simplifying Access Lists with Object Grouping 18-12
How Object Grouping Works 18-13
Adding Object Groups 18-13
Adding a Protocol Object Group 18-14
Adding a Network Object Group 18-14
Adding a Service Object Group 18-15
Adding an ICMP Type Object Group 18-16
Nesting Object Groups 18-16
Using Object Groups with an Access List 18-17
Displaying Object Groups 18-18
Removing Object Groups 18-19
Adding Remarks to Access Lists
18-19
Scheduling Extended Access List Activation 18-19
Adding a Time Range 18-19
Applying the Time Range to an ACE 18-20
Logging Access List Activity 18-21
Access List Logging Overview 18-21
Configuring Logging for an Access Control Entry
Managing Deny Flows 18-23
CHAPTER
19
Configuring NAT
18-22
19-1
NAT Overview 19-1
Introduction to NAT 19-1
NAT in Routed Mode 19-2
NAT in Transparent Mode 19-3
NAT Control 19-5
NAT Types 19-6
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xv
Contents
Dynamic NAT 19-6
PAT 19-8
Static NAT 19-9
Static PAT 19-9
Bypassing NAT When NAT Control is Enabled 19-10
Policy NAT 19-11
NAT and Same Security Level Interfaces 19-15
Order of NAT Commands Used to Match Real Addresses 19-16
Mapped Address Guidelines 19-16
DNS and NAT 19-17
Configuring NAT Control
19-18
Using Dynamic NAT and PAT 19-19
Dynamic NAT and PAT Implementation 19-19
Configuring Dynamic NAT or PAT 19-25
Using Static NAT
19-28
Using Static PAT
19-29
Bypassing NAT 19-32
Configuring Identity NAT 19-32
Configuring Static Identity NAT 19-33
Configuring NAT Exemption 19-35
NAT Examples 19-36
Overlapping Networks 19-36
Redirecting Ports 19-38
CHAPTER
20
Permitting or Denying Network Access
20-1
Inbound and Outbound Access List Overview
Applying an Access List to an Interface
CHAPTER
21
Applying AAA for Network Access
AAA Performance
20-1
20-2
21-1
21-1
Configuring Authentication for Network Access 21-1
Authentication Overview 21-2
One-Time Authentication 21-2
Applications Required to Receive an Authentication Challenge
Security Appliance Authentication Prompts 21-2
Static PAT and HTTP 21-3
Enabling Network Access Authentication 21-3
Enabling Secure Authentication of Web Clients 21-5
21-2
Cisco Security Appliance Command Line Configuration Guide
xvi
OL-12172-04
Contents
Authenticating Directly with the Security Appliance 21-6
Enabling Direct Authentication Using HTTP and HTTPS
Enabling Direct Authentication Using Telnet 21-7
21-6
Configuring Authorization for Network Access 21-8
Configuring TACACS+ Authorization 21-8
Configuring RADIUS Authorization 21-10
Configuring a RADIUS Server to Send Downloadable Access Control Lists 21-10
Configuring a RADIUS Server to Download Per-User Access Control List Names 21-14
Configuring Accounting for Network Access
21-14
Using MAC Addresses to Exempt Traffic from Authentication and Authorization
CHAPTER
22
Applying Filtering Services
Filtering Overview
21-16
22-1
22-1
Filtering ActiveX Objects 22-2
ActiveX Filtering Overview 22-2
Enabling ActiveX Filtering 22-2
Filtering Java Applets
22-3
Filtering URLs and FTP Requests with an External Server
URL Filtering Overview 22-4
Identifying the Filtering Server 22-4
Buffering the Content Server Response 22-6
Caching Server Addresses 22-6
Filtering HTTP URLs 22-7
Configuring HTTP Filtering 22-7
Enabling Filtering of Long HTTP URLs 22-7
Truncating Long HTTP URLs 22-7
Exempting Traffic from Filtering 22-8
Filtering HTTPS URLs 22-8
Filtering FTP Requests 22-9
22-4
Viewing Filtering Statistics and Configuration 22-9
Viewing Filtering Server Statistics 22-10
Viewing Buffer Configuration and Statistics 22-11
Viewing Caching Statistics 22-11
Viewing Filtering Performance Statistics 22-11
Viewing Filtering Configuration 22-12
CHAPTER
23
Managing the AIP SSM and CSC SSM
Managing the AIP SSM
23-1
23-1
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xvii
Contents
AIP SSM Overview 23-1
How the AIP SSM Works with the Adaptive Security Appliance
Operating Modes 23-3
Using Virtual Sensors 23-3
AIP SSM Procedure Overview 23-4
Sessioning to the AIP SSM 23-5
Configuring the Security Policy on the AIP SSM 23-6
Assigning Virtual Sensors to Security Contexts 23-6
Diverting Traffic to the AIP SSM 23-8
Managing the CSC SSM 23-9
About the CSC SSM 23-10
Getting Started with the CSC SSM 23-12
Determining What Traffic to Scan 23-13
Limiting Connections Through the CSC SSM
Diverting Traffic to the CSC SSM 23-16
Checking SSM Status
24
23-15
23-18
Transferring an Image onto an SSM
CHAPTER
23-2
Preventing Network Attacks
23-19
24-1
Configuring Threat Detection 24-1
Configuring Basic Threat Detection 24-1
Basic Threat Detection Overview 24-2
Configuring Basic Threat Detection 24-2
Managing Basic Threat Statistics 24-4
Configuring Scanning Threat Detection 24-5
Enabling Scanning Threat Detection 24-5
Managing Shunned Hosts 24-6
Viewing Attackers and Targets 24-7
Configuring and Viewing Threat Statistics 24-7
Configuring Threat Statistics 24-7
Viewing Threat Statistics 24-8
Configuring TCP Normalization 24-12
TCP Normalization Overview 24-12
Enabling the TCP Normalizer 24-12
Configuring Connection Limits and Timeouts 24-17
Connection Limit Overview 24-17
TCP Intercept Overview 24-18
Disabling TCP Intercept for Management Packets for Clientless SSL Compatibility
Dead Connection Detection (DCD) Overview 24-18
24-18
Cisco Security Appliance Command Line Configuration Guide
xviii
OL-12172-04
Contents
TCP Sequence Randomization Overview 24-18
Enabling Connection Limits and Timeouts 24-19
Preventing IP Spoofing
24-21
Configuring the Fragment Size
24-22
Blocking Unwanted Connections
24-22
Configuring IP Audit for Basic IPS Support
CHAPTER
25
Configuring QoS
24-23
25-1
QoS Overview 25-1
Supported QoS Features 25-2
What is a Token Bucket? 25-2
Policing Overview 25-3
Priority Queueing Overview 25-3
Traffic Shaping Overview 25-4
How QoS Features Interact 25-4
DSCP and DiffServ Preservation 25-5
Creating the Standard Priority Queue for an Interface 25-5
Determining the Queue and TX Ring Limits 25-6
Configuring the Priority Queue 25-7
Identifying Traffic for QoS Using Class Maps
Creating a QoS Class Map 25-8
QoS Class Map Examples 25-8
25-8
Creating a Policy for Standard Priority Queueing and/or Policing
25-9
Creating a Policy for Traffic Shaping and Hierarchical Priority Queueing
25-11
Viewing QoS Statistics 25-13
Viewing QoS Police Statistics 25-13
Viewing QoS Standard Priority Statistics 25-14
Viewing QoS Shaping Statistics 25-14
Viewing QoS Standard Priority Queue Statistics 25-15
CHAPTER
26
Configuring Application Layer Protocol Inspection
Inspection Engine Overview 26-2
When to Use Application Protocol Inspection
Inspection Limitations 26-2
Default Inspection Policy 26-3
Configuring Application Inspection
CTIQBE Inspection 26-10
CTIQBE Inspection Overview
26-1
26-2
26-5
26-10
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xix
Contents
Limitations and Restrictions 26-10
Verifying and Monitoring CTIQBE Inspection
26-10
DCERPC Inspection 26-12
DCERPC Overview 26-12
Configuring a DCERPC Inspection Policy Map for Additional Inspection Control
DNS Inspection 26-14
How DNS Application Inspection Works 26-14
How DNS Rewrite Works 26-15
Configuring DNS Rewrite 26-16
Using the Static Command for DNS Rewrite 26-16
Using the Alias Command for DNS Rewrite 26-17
Configuring DNS Rewrite with Two NAT Zones 26-17
DNS Rewrite with Three NAT Zones 26-18
Configuring DNS Rewrite with Three NAT Zones 26-20
Verifying and Monitoring DNS Inspection 26-21
Configuring a DNS Inspection Policy Map for Additional Inspection Control
26-21
ESMTP Inspection 26-24
Configuring an ESMTP Inspection Policy Map for Additional Inspection Control
FTP Inspection 26-27
FTP Inspection Overview 26-28
Using the strict Option 26-28
Configuring an FTP Inspection Policy Map for Additional Inspection Control
Verifying and Monitoring FTP Inspection 26-32
GTP Inspection 26-33
GTP Inspection Overview 26-33
Configuring a GTP Inspection Policy Map for Additional Inspection Control
Verifying and Monitoring GTP Inspection 26-38
H.323 Inspection 26-39
H.323 Inspection Overview 26-39
How H.323 Works 26-40
Limitations and Restrictions 26-41
Configuring an H.323 Inspection Policy Map for Additional Inspection Control
Configuring H.323 and H.225 Timeout Values 26-44
Verifying and Monitoring H.323 Inspection 26-44
Monitoring H.225 Sessions 26-44
Monitoring H.245 Sessions 26-45
Monitoring H.323 RAS Sessions 26-45
HTTP Inspection 26-46
HTTP Inspection Overview
26-13
26-25
26-29
26-34
26-41
26-46
Cisco Security Appliance Command Line Configuration Guide
xx
OL-12172-04
Contents
Configuring an HTTP Inspection Policy Map for Additional Inspection Control
26-46
Instant Messaging Inspection 26-50
IM Inspection Overview 26-50
Configuring an Instant Messaging Inspection Policy Map for Additional Inspection Control
ICMP Inspection
26-53
ICMP Error Inspection
ILS Inspection
26-54
26-54
MGCP Inspection 26-55
MGCP Inspection Overview 26-55
Configuring an MGCP Inspection Policy Map for Additional Inspection Control
Configuring MGCP Timeout Values 26-58
Verifying and Monitoring MGCP Inspection 26-58
MMP Inspection 26-59
Configuring MMP Inspection for a TLS Proxy
26-57
26-60
NetBIOS Inspection 26-61
Configuring a NetBIOS Inspection Policy Map for Additional Inspection Control
PPTP Inspection
26-61
26-63
RADIUS Accounting Inspection 26-63
Configuring a RADIUS Inspection Policy Map for Additional Inspection Control
RSH Inspection
26-50
26-64
26-64
RTSP Inspection 26-65
RTSP Inspection Overview 26-65
Using RealPlayer 26-65
Restrictions and Limitations 26-66
Configuring an RTSP Inspection Policy Map for Additional Inspection Control 26-66
Configuring a SIP Inspection Policy Map for Additional Inspection Control 26-66
SIP Inspection 26-68
SIP Inspection Overview 26-69
SIP Instant Messaging 26-69
Configuring a SIP Inspection Policy Map for Additional Inspection Control
Configuring SIP Timeout Values 26-74
Verifying and Monitoring SIP Inspection 26-74
26-70
Skinny (SCCP) Inspection 26-75
SCCP Inspection Overview 26-75
Supporting Cisco IP Phones 26-75
Restrictions and Limitations 26-76
Verifying and Monitoring SCCP Inspection 26-76
Configuring a Skinny (SCCP) Inspection Policy Map for Additional Inspection Control
26-77
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxi
Contents
SMTP and Extended SMTP Inspection
SNMP Inspection
26-78
26-80
SQL*Net Inspection
26-80
Sun RPC Inspection 26-81
Sun RPC Inspection Overview 26-81
Managing Sun RPC Services 26-81
Verifying and Monitoring Sun RPC Inspection
TFTP Inspection
XDMCP Inspection
CHAPTER
27
26-82
26-83
26-84
Configuring Cisco Unified Communications Proxy Features
27-1
Overview of the Adaptive Security Appliance in Cisco Unified Communications
TLS Proxy Applications in Cisco Unified Communications 27-3
Licensing for Cisco Unified Communications Proxy Features
27-1
27-4
Phone Proxy 27-5
About the Phone Proxy 27-5
Phone Proxy Limitations and Restrictions 27-7
Phone Proxy Configuration 27-8
Configuration Prerequisites 27-9
Requirements to Support the 7960 and 7940 IP Phones 27-11
Addressing Requirements for IP Phones on Multiple Interfaces 27-11
Supported Cisco UCM and IP Phones for the Phone Proxy 27-12
End-User Phone Provisioning 27-13
Configuring the Phone Proxy in a Non-secure Cisco UCM Cluster 27-13
Importing Certificates from the Cisco UCM 27-17
Configuring the Phone Proxy in a Mixed-mode Cisco UCM Cluster 27-19
Phone Proxy Configuration for Cisco IP Communicator 27-24
Configuring Linksys Routers for UDP Port Forwarding 27-24
About Rate Limiting TFTP Requests 27-25
About ICMP Traffic Destined for the Media Termination Address 27-26
Troubleshooting the Phone Proxy 27-26
Debugging Information from the Security Appliance 27-26
Debugging Information from IP Phones 27-30
IP Phone Registration Failure 27-31
Media Termination Address Errors 27-40
Audio Problems with IP Phones 27-40
Saving SAST Keys 27-41
TLS Proxy for Encrypted Voice Inspection
Overview 27-43
27-42
Cisco Security Appliance Command Line Configuration Guide
xxii
OL-12172-04
Contents
Configuring TLS Proxy 27-43
Debugging TLS Proxy 27-47
CTL Client 27-50
Cisco Unified Mobility and MMP Inspection Engine 27-52
Mobility Proxy Overview 27-52
Mobility Proxy Deployment Scenarios 27-53
Establishing Trust Relationships for Cisco UMA Deployments 27-56
Configuring the Security Appliance for Cisco Unified Mobility 27-57
Debugging for Cisco Unified Mobility 27-58
Cisco Unified Presence 27-59
Architecture for Cisco Unified Presence 27-59
Establishing a Trust Relationship in the Presence Federation 27-61
About the Security Certificate Exchange Between Cisco UP and the Security Appliance
Configuring the Presence Federation Proxy for Cisco Unified Presence 27-62
Debugging the Security Appliance for Cisco Unified Presence 27-64
27-62
Sample Configurations for Cisco Unified Communications Proxy Features 27-65
Phone Proxy Sample Configurations 27-65
Example 1: Nonsecure Cisco UCM cluster, Cisco UCM and TFTP Server on Publisher 27-65
Example 2: Mixed-mode Cisco UCM cluster, Cisco UCM and TFTP Server on Publisher 27-66
Example 3: Mixed-mode Cisco UCM cluster, Cisco UCM and TFTP Server on Different
Servers 27-68
Example 4: Mixed-mode Cisco UCM cluster, Primary Cisco UCM, Secondary and TFTP Server on
Different Servers 27-69
Example 5: LSC Provisioning in Mixed-mode Cisco UCM cluster; Cisco UCM and TFTP Server on
Publisher 27-71
Example 6: VLAN Transversal 27-73
Cisco Unified Mobility Sample Configurations 27-75
Example 1: Cisco UMC/Cisco UMA Architecture – Security Appliance as Firewall with TLS Proxy
and MMP Inspection 27-75
Example 2: Cisco UMC/Cisco UMA Architecture – Security Appliance as TLS Proxy Only 27-76
Cisco Unified Presence Sample Configuration 27-78
CHAPTER
28
Configuring ARP Inspection and Bridging Parameters for Transparent Mode
28-1
Configuring ARP Inspection 28-1
ARP Inspection Overview 28-1
Adding a Static ARP Entry 28-2
Enabling ARP Inspection 28-2
Customizing the MAC Address Table 28-3
MAC Address Table Overview 28-3
Adding a Static MAC Address 28-3
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxiii
Contents
Setting the MAC Address Timeout 28-4
Disabling MAC Address Learning 28-4
Viewing the MAC Address Table 28-4
PART
Configuring VPN
3
CHAPTER
29
Configuring IPsec and ISAKMP
Tunneling Overview
IPsec Overview
29-1
29-1
29-2
Configuring ISAKMP 29-2
ISAKMP Overview 29-2
Configuring ISAKMP Policies 29-5
Enabling ISAKMP on the Outside Interface 29-6
Disabling ISAKMP in Aggressive Mode 29-6
Determining an ID Method for ISAKMP Peers 29-6
Enabling IPsec over NAT-T 29-7
Using NAT-T 29-7
Enabling IPsec over TCP 29-8
Waiting for Active Sessions to Terminate Before Rebooting
Alerting Peers Before Disconnecting 29-9
29-8
Configuring Certificate Group Matching 29-9
Creating a Certificate Group Matching Rule and Policy 29-9
Using the Tunnel-group-map default-group Command 29-11
Configuring IPsec 29-11
Understanding IPsec Tunnels 29-11
Understanding Transform Sets 29-12
Defining Crypto Maps 29-12
Applying Crypto Maps to Interfaces 29-19
Using Interface Access Lists 29-19
Changing IPsec SA Lifetimes 29-21
Creating a Basic IPsec Configuration 29-22
Using Dynamic Crypto Maps 29-23
Providing Site-to-Site Redundancy 29-26
Viewing an IPsec Configuration 29-26
Clearing Security Associations
29-26
Clearing Crypto Map Configurations
Supporting the Nokia VPN Client
29-27
29-27
Cisco Security Appliance Command Line Configuration Guide
xxiv
OL-12172-04
Contents
CHAPTER
30
Configuring L2TP over IPSec
30-1
L2TP Overview 30-1
IPSec Transport and Tunnel Modes
30-2
Configuring L2TP over IPSec Connections 30-3
Tunnel Group Switching 30-5
Apple iPhone and MAC OS X Compatibility 30-6
Viewing L2TP over IPSec Connection Information
Using L2TP Debug Commands 30-8
Enabling IPSec Debug 30-9
Getting Additional Information 30-9
CHAPTER
31
Setting General IPSec VPN Parameters
31-1
Configuring VPNs in Single, Routed Mode
Configuring IPSec to Bypass ACLs
30-6
31-1
31-1
Permitting Intra-Interface Traffic 31-2
NAT Considerations for Intra-Interface Traffic
Setting Maximum Active IPSec VPN Sessions
31-3
31-3
Using Client Update to Ensure Acceptable Client Revision Levels
31-4
Understanding Load Balancing 31-6
Implementing Load Balancing 31-6
Prerequisites 31-7
Eligible Platforms 31-7
Eligible Clients 31-7
VPN Load-Balancing Cluster Configurations 31-7
Some Typical Mixed Cluster Scenarios 31-8
Scenario 1: Mixed Cluster with No WebVPN Connections 31-8
Scenario 2: Mixed Cluster Handling WebVPN Connections 31-8
Configuring Load Balancing 31-9
Configuring the Public and Private Interfaces for Load Balancing 31-9
Configuring the Load Balancing Cluster Attributes 31-10
Enabling Redirection Using a Fully-qualified Domain Name 31-11
Viewing Load Balancing 31-12
Configuring VPN Session Limits
CHAPTER
32
31-13
Configuring Connection Profiles, Group Policies, and Users
Overview of Connection Profiles, Group Policies, and Users
Connection Profiles 32-2
General Connection Profile Connection Parameters
32-1
32-1
32-3
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxv
Contents
IPSec Tunnel-Group Connection Parameters 32-4
Connection Profile Connection Parameters for Clientless SSL VPN Sessions
32-5
Configuring Connection Profiles 32-6
Maximum Connection Profiles 32-6
Default IPSec Remote Access Connection Profile Configuration 32-7
Configuring IPSec Tunnel-Group General Attributes 32-7
Configuring IPSec Remote-Access Connection Profiles 32-8
Specifying a Name and Type for the IPSec Remote Access Connection Profile 32-8
Configuring IPSec Remote-Access Connection Profile General Attributes 32-8
Enabling IPv6 VPN Access 32-12
Configuring IPSec Remote-Access Connection Profile IPSec Attributes 32-13
Configuring IPSec Remote-Access Connection Profile PPP Attributes 32-15
Configuring LAN-to-LAN Connection Profiles 32-16
Default LAN-to-LAN Connection Profile Configuration 32-16
Specifying a Name and Type for a LAN-to-LAN Connection Profile 32-16
Configuring LAN-to-LAN Connection Profile General Attributes 32-17
Configuring LAN-to-LAN IPSec Attributes 32-17
Configuring Connection Profiles for Clientless SSL VPN Sessions 32-19
Specifying a Connection Profile Name and Type for Clientless SSL VPN Sessions 32-19
Configuring General Tunnel-Group Attributes for Clientless SSL VPN Sessions 32-20
Configuring Tunnel-Group Attributes for Clientless SSL VPN Sessions 32-23
Customizing Login Windows for Users of Clientless SSL VPN sessions 32-27
Configuring Microsoft Active Directory Settings for Password Management 32-27
Using Active Directory to Force the User to Change Password at Next Logon 32-28
Using Active Directory to Specify Maximum Password Age 32-30
Using Active Directory to Override an Account Disabled AAA Indicator 32-31
Using Active Directory to Enforce Minimum Password Length 32-32
Using Active Directory to Enforce Password Complexity 32-33
Configuring the Connection Profile for RADIUS/SDI Message Support for the AnyConnect
Client 32-34
AnyConnect Client and RADIUS/SDI Server Interaction 32-34
Configuring the Security Appliance to Support RADIUS/SDI Messages 32-35
Group Policies 32-36
Default Group Policy 32-37
Configuring Group Policies 32-38
Configuring an External Group Policy
Configuring an Internal Group Policy
Configuring Group Policy Attributes
Configuring WINS and DNS Servers
Configuring VPN-Specific Attributes
32-38
32-39
32-40
32-40
32-41
Cisco Security Appliance Command Line Configuration Guide
xxvi
OL-12172-04
Contents
Configuring Security Attributes 32-44
Configuring the Banner Message 32-46
Configuring IPSec-UDP Attributes 32-46
Configuring Split-Tunneling Attributes 32-47
Configuring Domain Attributes for Tunneling 32-48
Configuring Attributes for VPN Hardware Clients 32-50
Configuring Backup Server Attributes 32-53
Configuring Microsoft Internet Explorer Client Parameters 32-54
Configuring Network Admission Control Parameters 32-56
Configuring Address Pools 32-60
Configuring Firewall Policies 32-60
Configuring Client Access Rules 32-63
Configuring Group-Policy Attributes for Clientless SSL VPN Sessions
Configuring User Attributes 32-75
Viewing the Username Configuration 32-76
Configuring Attributes for Specific Users 32-76
Setting a User Password and Privilege Level 32-76
Configuring User Attributes 32-77
Configuring VPN User Attributes 32-77
Configuring Clientless SSL VPN Access for Specific Users
CHAPTER
33
Configuring IP Addresses for VPNs
34
Configuring Remote Access IPSec VPNs
Summary of the Configuration
Configuring Interfaces
32-81
33-1
Configuring an IP Address Assignment Method
Configuring Local IP Address Pools 33-2
Configuring AAA Addressing 33-2
Configuring DHCP Addressing 33-3
CHAPTER
33-1
34-1
34-1
34-2
Configuring ISAKMP Policy and Enabling ISAKMP on the Outside Interface
Configuring an Address Pool
Adding a User
32-65
34-3
34-4
34-4
Creating a Transform Set
Defining a Tunnel Group
34-4
34-5
Creating a Dynamic Crypto Map
34-6
Creating a Crypto Map Entry to Use the Dynamic Crypto Map
34-7
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxvii
Contents
CHAPTER
35
Configuring Network Admission Control
Overview
35-1
35-1
Uses, Requirements, and Limitations
35-2
Viewing the NAC Policies on the Security Appliance
Adding, Accessing, or Removing a NAC Policy
35-2
35-4
Configuring a NAC Policy 35-4
Specifying the Access Control Server Group 35-5
Setting the Query-for-Posture-Changes Timer 35-5
Setting the Revalidation Timer 35-6
Configuring the Default ACL for NAC 35-6
Configuring Exemptions from NAC 35-7
Assigning a NAC Policy to a Group Policy
35-8
Changing Global NAC Framework Settings 35-8
Changing Clientless Authentication Settings 35-8
Enabling and Disabling Clientless Authentication 35-8
Changing the Login Credentials Used for Clientless Authentication
Changing NAC Framework Session Attributes 35-10
CHAPTER
36
Configuring Easy VPN Services on the ASA 5505
36-1
Specifying the Client/Server Role of the Cisco ASA 5505
Specifying the Primary and Secondary Servers
Specifying the Mode 36-3
NEM with Multiple Interfaces
Comparing Tunneling Options
36-2
36-4
36-4
36-5
Specifying the Tunnel Group or Trustpoint
Specifying the Tunnel Group 36-7
Specifying the Trustpoint 36-7
Configuring Split Tunneling
36-1
36-3
Configuring Automatic Xauth Authentication
Configuring IPSec Over TCP
35-9
36-6
36-8
Configuring Device Pass-Through
36-8
Configuring Remote Management
36-9
Guidelines for Configuring the Easy VPN Server 36-9
Group Policy and User Attributes Pushed to the Client
Authentication Options 36-12
36-10
Cisco Security Appliance Command Line Configuration Guide
xxviii
OL-12172-04
Contents
CHAPTER
37
Configuring the PPPoE Client
PPPoE Client Overview
37-1
37-1
Configuring the PPPoE Client Username and Password
Enabling PPPoE
37-3
Using PPPoE with a Fixed IP Address
37-3
Monitoring and Debugging the PPPoE Client
CHAPTER
38
37-2
Clearing the Configuration
37-5
Using Related Commands
37-5
Configuring LAN-to-LAN IPsec VPNs
Summary of the Configuration
Configuring Interfaces
37-4
38-1
38-1
38-2
Configuring ISAKMP Policy and Enabling ISAKMP on the Outside Interface
Creating a Transform Set
Configuring an ACL
38-4
38-4
Defining a Tunnel Group
38-5
Creating a Crypto Map and Applying It To an Interface
Applying Crypto Maps to Interfaces 38-7
CHAPTER
39
38-2
Configuring Clientless SSL VPN
38-6
39-1
Getting Started 39-1
Observing Clientless SSL VPN Security Precautions 39-2
Understanding Features Not Supported in Clientless SSL VPN 39-3
Using SSL to Access the Central Site 39-3
Using HTTPS for Clientless SSL VPN Sessions 39-3
Configuring Clientless SSL VPN and ASDM Ports 39-4
Configuring Support for Proxy Servers 39-4
Configuring SSL/TLS Encryption Protocols 39-6
Authenticating with Digital Certificates 39-6
Enabling Cookies on Browsers for Clientless SSL VPN 39-7
Managing Passwords 39-7
Using Single Sign-on with Clientless SSL VPN 39-8
Configuring SSO with HTTP Basic or NTLM Authentication 39-9
Configuring SSO Authentication Using SiteMinder 39-10
Configuring SSO Authentication Using SAML Browser Post Profile
Configuring SSO with the HTTP Form Protocol 39-15
Authenticating with Digital Certificates 39-21
39-12
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxix
Contents
Creating and Applying Clientless SSL VPN Resources 39-21
Assigning Users to Group Policies 39-21
Using the Security Appliance Authentication Server
Using a RADIUS Server 39-21
39-21
Configuring Connection Profile Attributes for Clientless SSL VPN
39-22
Configuring Group Policy and User Attributes for Clientless SSL VPN
39-22
Configuring Browser Access to Client-Server Plug-ins 39-24
Introduction to Browser Plug-Ins 39-24
Plug-in Requirements and Restrictions 39-25
Preparing the Security Appliance for a Plug-in 39-25
Installing Plug-ins Redistributed By Cisco 39-26
Providing Access to Third-Party Plug-ins 39-28
Example: Providing Access to a Citrix Java Presentation Server
Viewing the Plug-ins Installed on the Security Appliance 39-29
39-28
Configuring Application Access 39-30
Configuring Smart Tunnel Access 39-30
About Smart Tunnels 39-30
Why Smart Tunnels? 39-31
Smart Tunnel Requirements, Restrictions, and Limitations 39-31
Adding Applications to Be Eligible for Smart Tunnel Access 39-32
Assigning a Smart Tunnel List 39-35
Configuring Smart Tunnel Auto Sign-on 39-36
Automating Smart Tunnel Access 39-37
Enabling and Disabling Smart Tunnel Access 39-38
Configuring Port Forwarding 39-38
About Port Forwarding 39-39
Why Port Forwarding? 39-39
Port Forwarding Requirements and Restrictions 39-39
Configuring DNS for Port Forwarding 39-40
Adding Applications to Be Eligible for Port Forwarding 39-41
Assigning a Port Forwarding List 39-42
Automating Port Forwarding 39-43
Enabling and Disabling Port Forwarding 39-43
Application Access User Notes 39-44
Using Application Access on Vista 39-44
Closing Application Access to Prevent hosts File Errors 39-44
Recovering from hosts File Errors When Using Application Access 39-44
Configuring File Access 39-47
Adding Support for File Access
39-48
Cisco Security Appliance Command Line Configuration Guide
xxx
OL-12172-04
Contents
Ensuring Clock Accuracy for SharePoint Access
Using Clientless SSL VPN with PDAs
39-49
39-50
Using E-Mail over Clientless SSL VPN 39-50
Configuring E-mail Proxies 39-50
E-mail Proxy Certificate Authentication 39-51
Configuring Web E-mail: MS Outlook Web Access 39-51
Optimizing Clientless SSL VPN Performance 39-52
Configuring Caching 39-52
Configuring Content Transformation 39-52
Configuring a Certificate for Signing Rewritten Java Content 39-53
Disabling Content Rewrite 39-53
Using Proxy Bypass 39-53
Configuring Application Profile Customization Framework 39-54
APCF Syntax 39-54
APCF Example 39-56
Clientless SSL VPN End User Setup 39-56
Defining the End User Interface 39-56
Viewing the Clientless SSL VPN Home Page 39-57
Viewing the Clientless SSL VPN Application Access Panel 39-57
Viewing the Floating Toolbar 39-58
Customizing Clientless SSL VPN Pages 39-59
How Customization Works 39-59
Exporting a Customization Template 39-60
Editing the Customization Template 39-60
Importing a Customization Object 39-66
Applying Customizations to Connection Profiles, Group Policies and Users
Login Screen Advanced Customization 39-67
Customizing Help 39-71
Customizing a Help File Provided By Cisco 39-72
Creating Help Files for Languages Not Provided by Cisco 39-73
Importing a Help File to Flash Memory 39-73
Exporting a Previously Imported Help File from Flash Memory 39-74
Requiring Usernames and Passwords 39-74
Communicating Security Tips 39-75
Configuring Remote Systems to Use Clientless SSL VPN Features 39-75
Translating the Language of User Messages 39-79
Understanding Language Translation 39-80
Creating Translation Tables 39-81
Referencing the Language in a Customization Object 39-82
39-66
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxxi
Contents
Changing a Group Policy or User Attributes to Use the Customization Object
Capturing Data 39-84
Creating a Capture File 39-84
Using a Browser to Display Capture Data
CHAPTER
40
39-84
39-85
Configuring AnyConnect VPN Client Connections
40-1
Installing the AnyConnect SSL VPN Client 40-2
Remote PC System Requirements 40-2
Installing the AnyConnect Client 40-2
Enabling AnyConnect Client Connections
Enabling Permanent Client Installation
Configuring DTLS
40-3
40-5
40-5
Prompting Remote Users
40-6
Enabling AnyConnect Client Profile Downloads
Enabling Additional AnyConnect Client Features
Enabling Start Before Logon 40-9
40-6
40-8
Translating Languages for AnyConnect User Messages
Understanding Language Translation 40-10
Creating Translation Tables 40-10
Configuring Advanced SSL VPN Features 40-12
Enabling Rekey 40-12
Enabling and Adjusting Dead Peer Detection
Enabling Keepalive 40-13
Using Compression 40-14
Adjusting MTU Size 40-14
Viewing SSL VPN Sessions 40-15
Logging Off SVC Sessions 40-15
Updating SSL VPN Client Images 40-16
CHAPTER
41
Configuring Certificates
40-9
40-12
41-1
Public Key Cryptography 41-1
About Public Key Cryptography 41-1
Certificate Scalability 41-2
About Key Pairs 41-2
About Trustpoints 41-3
About Revocation Checking 41-3
About CRLs 41-3
About OCSP 41-4
Cisco Security Appliance Command Line Configuration Guide
xxxii
OL-12172-04
Contents
Supported CA Servers
41-5
Certificate Configuration 41-5
Preparing for Certificates 41-5
Configuring Key Pairs 41-6
Generating Key Pairs 41-6
Removing Key Pairs 41-7
Configuring Trustpoints 41-7
Obtaining Certificates 41-9
Obtaining Certificates with SCEP 41-9
Obtaining Certificates Manually 41-11
Using Extended Keys for Certificates 41-13
Configuring CRLs for a Trustpoint 41-13
Exporting and Importing Trustpoints 41-15
Exporting a Trustpoint Configuration 41-15
Importing a Trustpoint Configuration 41-16
Configuring CA Certificate Map Rules 41-16
The Local CA 41-17
Configuring the Local CA Server 41-18
The Default Local CA Server 41-19
Customizing the Local CA Server 41-20
Certificate Characteristics 41-21
Defining Storage for Local CA Files 41-23
Default Flash Memory Data Storage 41-23
Setting up External Local CA File Storage 41-24
CRL Storage 41-24
CRL Downloading 41-25
Enrolling Local CA Users 41-25
Setting Up Enrollment Parameters 41-27
Enrollment Requirements 41-27
Starting and Stopping the Local CA Server 41-28
Enabling the Local CA Server 41-28
Debugging the Local CA Server 41-29
Disabling the Local CA Server 41-29
Managing the Local CA User Database 41-29
Adding and Enrolling Users 41-30
Renewing Users 41-31
Revoking Certificates and Removing or Restoring Users
Revocation Checking 41-32
Displaying Local CA Server Information 41-32
Display Local CA Configuration 41-33
41-31
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxxiii
Contents
Display Certificate Database 41-33
Display the Local CA Certificate 41-34
Display the CRL 41-34
Display the User Database 41-34
Local CA Server Maintenance and Backup Procedures 41-35
Maintaining the Local CA User Database 41-35
Maintaining the Local CA Certificate Database 41-36
Local CA Certificate Rollover 41-36
Archiving the Local CA Server Certificate and Keypair 41-36
Deleting the Local CA Server 41-37
PART
System Administration
4
CHAPTER
42
Managing System Access
Allowing Telnet Access
42-1
42-1
Allowing SSH Access 42-2
Configuring SSH Access 42-2
Using an SSH Client 42-3
Allowing HTTPS Access for ASDM 42-3
Enabling HTTPS Access 42-4
Accessing ASDM from Your PC 42-4
Managing the Security Appliance on a Different Interface from the VPN Tunnel Termination
Interface 42-5
Configuring AAA for System Administrators 42-5
Configuring Authentication for CLI and ASDM Access 42-5
Configuring Authentication To Access Privileged EXEC Mode (the enable Command)
Configuring Authentication for the enable Command 42-6
Authenticating Users Using the Login Command 42-7
Limiting User CLI and ASDM Access with Management Authorization 42-7
Configuring Command Authorization 42-8
Command Authorization Overview 42-9
Configuring Local Command Authorization 42-11
Configuring TACACS+ Command Authorization 42-14
Configuring Command Accounting 42-18
Viewing the Current Logged-In User 42-18
Recovering from a Lockout 42-19
Configuring a Login Banner
42-6
42-20
Cisco Security Appliance Command Line Configuration Guide
xxxiv
OL-12172-04
Contents
CHAPTER
43
Managing Software and Configurations
Viewing Files in Flash Memory
43-1
43-1
Retrieving Files from Flash Memory
43-2
Removing Files from Flash Memory
43-2
Downloading Software or Configuration Files to Flash Memory 43-2
Downloading a File to a Specific Location 43-3
Downloading a File to the Startup or Running Configuration 43-3
Configuring the Application Image and ASDM Image to Boot
Configuring the File to Boot as the Startup Configuration
43-4
43-5
Performing Zero Downtime Upgrades for Failover Pairs 43-5
Upgrading an Active/Standby Failover Configuration 43-6
Upgrading and Active/Active Failover Configuration 43-7
Backing Up Configuration Files 43-8
Backing up the Single Mode Configuration or Multiple Mode System Configuration
Backing Up a Context Configuration in Flash Memory 43-8
Backing Up a Context Configuration within a Context 43-9
Copying the Configuration from the Terminal Display 43-9
Backing Up Additional Files Using the Export and Import Commands 43-9
Using a Script to Back Up and Restore Files 43-10
Prerequisites 43-10
Running the Script 43-10
Sample Script 43-11
43-8
Configuring Auto Update Support 43-19
Configuring Communication with an Auto Update Server 43-20
Configuring Client Updates as an Auto Update Server 43-21
Viewing Auto Update Status 43-22
CHAPTER
44
Monitoring the Security Appliance
44-1
Using SNMP 44-1
SNMP Overview 44-1
Enabling SNMP 44-4
Configuring and Managing Logs 44-5
Logging Overview 44-6
Logging in Multiple Context Mode 44-6
Analyzing Syslogs 44-6
Enabling and Disabling Logging 44-7
Enabling Logging to All Configured Output Destinations 44-7
Disabling Logging to All Configured Output Destinations 44-7
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxxv
Contents
Viewing the Log Configuration 44-7
Configuring Log Output Destinations 44-8
Sending System Log Messages to a Syslog Server 44-8
Sending System Log Messages to the Console Port 44-10
Sending System Log Messages to an E-mail Address 44-10
Sending System Log Messages to ASDM 44-11
Sending System Log Messages to a Telnet or SSH Session 44-13
Sending System Log Messages to the Log Buffer 44-14
Filtering System Log Messages 44-16
Message Filtering Overview 44-17
Filtering System Log Messages by Class 44-17
Filtering System Log Messages with Custom Message Lists 44-18
Customizing the Log Configuration 44-19
Configuring the Logging Queue 44-20
Including the Date and Time in System Log Messages 44-20
Including the Device ID in System Log Messages 44-20
Generating System Log Messages in EMBLEM Format 44-21
Disabling a System Log Message 44-22
Changing the Severity Level of a System Log Message 44-22
Limiting the Rate of System Log Message Generation 44-23
Changing the Amount of Internal Flash Memory Available for Logs 44-23
Understanding System Log Messages 44-24
System Log Message Format 44-24
Severity Levels 44-25
CHAPTER
45
Troubleshooting the Security Appliance
45-1
Testing Your Configuration 45-1
Enabling ICMP Debug Messages and System Log Messages
Pinging Security Appliance Interfaces 45-2
Pinging Through the Security Appliance 45-4
Disabling the Test Configuration 45-5
Traceroute 45-6
Packet Tracer 45-6
Reloading the Security Appliance
45-1
45-6
Performing Password Recovery 45-6
Recovering Passwords for the ASA 5500 Series Adaptive Security Appliance
Recovering Passwords for the PIX 500 Series Security Appliance 45-8
Disabling Password Recovery 45-9
Resetting the Password on the SSM Hardware Module 45-10
45-7
Cisco Security Appliance Command Line Configuration Guide
xxxvi
OL-12172-04
Contents
Using the ROM Monitor to Load a Software Image
Erasing the Flash File System
45-10
45-12
Other Troubleshooting Tools 45-12
Viewing Debug Messages 45-12
Capturing Packets 45-12
Viewing the Crash Dump 45-13
Common Problems
PART
Reference
5
APPENDIX
45-13
A
Sample Configurations
A-1
Example 1: Multiple Mode Firewall With Outside Access A-1
System Configuration for Example 1 A-3
Admin Context Configuration for Example 1 A-4
Customer A Context Configuration for Example 1 A-4
Customer B Context Configuration for Example 1 A-5
Customer C Context Configuration for Example 1 A-5
Example 2: Single Mode Firewall Using Same Security Level
A-6
Example 3: Shared Resources for Multiple Contexts A-8
System Configuration for Example 3 A-9
Admin Context Configuration for Example 3 A-10
Department 1 Context Configuration for Example 3 A-11
Department 2 Context Configuration for Example 3 A-12
Example 4: Multiple Mode, Transparent Firewall with Outside Access
System Configuration for Example 4 A-14
Admin Context Configuration for Example 4 A-15
Customer A Context Configuration for Example 4 A-16
Customer B Context Configuration for Example 4 A-16
Customer C Context Configuration for Example 4 A-17
Example 5: Single Mode, Transparent Firewall with NAT
Example 6: IPv6 Configuration
A-13
A-18
A-19
Example 7: Dual ISP Support Using Static Route Tracking
A-20
Example 8: Multicast Routing A-21
For PIM Sparse Mode A-22
For PIM bidir Mode A-23
Example 9: LAN-Based Active/Standby Failover (Routed Mode)
Primary Unit Configuration for Example 9 A-24
Secondary Unit Configuration for Example 9 A-25
A-24
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxxvii
Contents
Example 10: LAN-Based Active/Active Failover (Routed Mode) A-25
Primary Unit Configuration for Example 10 A-26
Primary System Configuration for Example 10 A-26
Primary admin Context Configuration for Example 10 A-27
Primary ctx1 Context Configuration for Example 10 A-28
Secondary Unit Configuration for Example 10 A-28
Example 11: LAN-Based Active/Standby Failover (Transparent Mode)
Primary Unit Configuration for Example 11 A-29
Secondary Unit Configuration for Example 11 A-30
A-28
Example 12: LAN-Based Active/Active Failover (Transparent Mode) A-30
Primary Unit Configuration for Example 12 A-31
Primary System Configuration for Example 12 A-31
Primary admin Context Configuration for Example 12 A-32
Primary ctx1 Context Configuration for Example 12 A-33
Secondary Unit Configuration for Example 12 A-33
Example 13: Cable-Based Active/Standby Failover (Routed Mode)
A-34
Example 14: Cable-Based Active/Standby Failover (Transparent Mode)
Example 15: ASA 5505 Base License
A-35
A-36
Example 16: ASA 5505 Security Plus License with Failover and Dual-ISP Backup
Primary Unit Configuration for Example 16 A-38
Secondary Unit Configuration for Example 16 A-40
A-38
Example 17: AIP SSM in Multiple Context Mode A-40
System Configuration for Example 17 A-41
Context 1 Configuration for Example 17 A-42
Context 2 Configuration for Example 17 A-42
Context 3 Configuration for Example 17 A-43
APPENDIX
B
Using the Command-Line Interface
B-1
Firewall Mode and Security Context Mode
Command Modes and Prompts
Syntax Formatting
B-3
Command-Line Editing
B-3
Command Completion
B-4
B-4
Filtering show Command Output
Command Output Paging
Adding Comments
B-2
B-3
Abbreviating Commands
Command Help
B-1
B-4
B-6
B-7
Cisco Security Appliance Command Line Configuration Guide
xxxviii
OL-12172-04
Contents
Text Configuration Files B-7
How Commands Correspond with Lines in the Text File B-7
Command-Specific Configuration Mode Commands B-7
Automatic Text Entries B-8
Line Order B-8
Commands Not Included in the Text Configuration B-8
Passwords B-8
Multiple Security Context Files B-8
Supported Character Sets B-9
APPENDIX
C
Addresses, Protocols, and Ports
C-1
IPv4 Addresses and Subnet Masks C-1
Classes C-1
Private Networks C-2
Subnet Masks C-2
Determining the Subnet Mask C-3
Determining the Address to Use with the Subnet Mask
C-3
IPv6 Addresses C-5
IPv6 Address Format C-5
IPv6 Address Types C-6
Unicast Addresses C-6
Multicast Address C-8
Anycast Address C-9
Required Addresses C-10
IPv6 Address Prefixes C-10
Protocols and Applications
TCP and UDP Ports
C-11
Local Ports and Protocols
ICMP Types
APPENDIX
D
C-11
C-14
C-15
Configuring an External Server for Authorization and Authentication
Understanding Policy Enforcement of Permissions and Attributes
D-1
D-2
Configuring an External LDAP Server D-3
Organizing the Security Appliance for LDAP Operations D-3
Searching the Hierarchy D-4
Binding the Security Appliance to the LDAP Server D-5
Login DN Example for Active Directory D-5
Defining the Security Appliance LDAP Configuration D-5
Supported Cisco Attributes for LDAP Authorization D-6
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xxxix
Contents
Cisco-AV-Pair Attribute Syntax D-12
Active Directory/LDAP VPN Remote Access Authorization Use Cases
User-Based Attributes Policy Enforcement D-15
Placing LDAP users in a specific Group-Policy D-17
Enforcing Static IP Address Assignment for AnyConnect Tunnels
Enforcing Dial-in Allow or Deny Access D-22
Enforcing Logon Hours and Time-of-Day Rules D-25
D-14
D-19
Configuring an External RADIUS Server D-27
Reviewing the RADIUS Configuration Procedure D-27
Security Appliance RADIUS Authorization Attributes D-27
Configuring an External TACACS+ Server
APPENDIX
E
D-35
Configuring the Security Appliance for Use with MARS E-1
Taskflow for Configuring MARS to Monitor Security Appliances E-1
Enabling Administrative Access to MARS on the Security Appliance E-2
Adding a Security Appliance to Monitor E-3
Adding Security Contexts E-4
Adding Discovered Contexts E-4
Editing Discovered Contexts E-5
Setting the Logging Severity Level for System Log Messages E-5
System Log Messages That Are Processed by MARS E-5
Configuring Specific Features E-7
GLOSSARY
INDEX
Cisco Security Appliance Command Line Configuration Guide
xl
OL-12172-04
About This Guide
This preface introduces the Cisco Security Appliance Command Line Configuration Guide, and includes
the following sections:
•
Document Objectives, page xli
•
Audience, page xli
•
Related Documentation, page xlii
•
Document Conventions, page xlii
•
Obtaining Documentation, Obtaining Support, and Security Guidelines, page xlii
Document Objectives
The purpose of this guide is to help you configure the security appliance using the command-line
interface. This guide does not cover every feature, but describes only the most common configuration
scenarios.
You can also configure and monitor the security appliance by using ASDM, a GUI application. ASDM
includes configuration wizards to guide you through some common configuration scenarios, and online
Help for less common scenarios. For more information, see:
http://www.cisco.com/en/US/products/ps6121/tsd_products_support_series_home.html
For software Versions 8.0(4) and below, this guide applies to the Cisco PIX 500 series security
appliances (PIX 515E, PIX 525, and PIX 535). The PIX security appliance is not supported in Version
8.0(5) and above.
For all software versions, this guide applies to the Cisco ASA 5500 series security appliances
(ASA 5505, ASA 5510, ASA 5520, ASA 5540, and ASA 5550). The ASA 5580 is not supported in
Version 8.0.
Throughout this guide, the term “security appliance” applies generically to all supported models, unless
specified otherwise.
Note
The PIX 501, PIX 506E, and PIX 520 security appliances are not supported.
Audience
This guide is for network managers who perform any of the following tasks:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
xli
About This Guide
•
Manage network security
•
Install and configure firewalls/security appliances
•
Configure VPNs
•
Configure intrusion detection software
Related Documentation
For more information, refer to Navigating the Cisco ASA 5500 Series Documentation:
http://www.cisco.com/en/US/docs/security/asa/roadmap/asaroadmap.html
Document Conventions
Command descriptions use these conventions:
•
Braces ({ }) indicate a required choice.
•
Square brackets ([ ]) indicate optional elements.
•
Vertical bars ( | ) separate alternative, mutually exclusive elements.
•
Boldface indicates commands and keywords that are entered literally as shown.
•
Italics indicate arguments for which you supply values.
Examples use these conventions:
Note
•
Examples depict screen displays and the command line in screen font.
•
Information you need to enter in examples is shown in boldface screen font.
•
Variables for which you must supply a value are shown in italic screen font.
Means reader take note. Notes contain helpful suggestions or references to material not covered in the
manual.
Obtaining Documentation, Obtaining Support, and Security
Guidelines
For information on obtaining documentation, obtaining support, providing documentation feedback,
security guidelines, and also recommended aliases and general Cisco documents, see the monthly
What’s New in Cisco Product Documentation, which also lists all new and revised Cisco technical
documentation, at:
http://www.cisco.com/en/US/docs/general/whatsnew/whatsnew.html
Cisco Security Appliance Command Line Configuration Guide
xlii
OL-12172-04
PA R T
1
Getting Started and General Information
CH A P T E R
1
Introduction to the Security Appliance
The security appliance combines advanced stateful firewall and VPN concentrator functionality in one
device, and for some models, an integrated intrusion prevention module called the AIP SSM or an
integrated content security and control module called the CSC SSM. The security appliance includes
many advanced features, such as multiple security contexts (similar to virtualized firewalls), transparent
(Layer 2) firewall or routed (Layer 3) firewall operation, advanced inspection engines, IPSec and
clientless SSL support, and many more features. See the “Supported Feature Licenses Per Model”
section on page 3-1 for a list of supported platforms and features. For a list of new features, see the
Cisco ASA 5500 Series Release Notes or the Cisco PIX Security Appliance Release Notes.
This chapter includes the following sections:
•
Supported Platform Models, page 1-1
•
SSM and SSC Support Per Model, page 1-2
•
VPN Specifications, page 1-3
•
New Features, page 1-3
•
Firewall Functional Overview, page 1-14
•
VPN Functional Overview, page 1-18
•
Security Context Overview, page 1-19
Supported Platform Models
Software Version 8.0 is supported on the following platform models:
•
ASA 5505
•
ASA 5510
•
ASA 5520
•
ASA 5540
•
ASA 5550
•
PIX 515/515E
•
PIX 525
•
PIX 535
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-1
Chapter 1
Introduction to the Security Appliance
SSM and SSC Support Per Model
Note
The Cisco PIX 501 and PIX 506E security appliances are not supported in any version; all other PIX
models are supported in Version 8.0(4) and earlier only.
The ASA 5580 is not supported in Version 8.0.
For information about licenses and features supported on each platform, see Chapter 3, “Managing
Feature Licenses.”
SSM and SSC Support Per Model
Table 1-1 shows the SSMs supported by each platform:
Table 1-1
SSM Support
Platform
SSM Models
ASA 5505
No support
ASA 5510
AIP SSM 10
AIP SSM 20
CSC SSM 10
CSC SSM 20
4GE SSM
ASA 5520
AIP SSM 10
AIP SSM 20
CSC SSM 10
CSC SSM 20
4GE SSM
ASA 5540
AIP SSM 10
AIP SSM 20
CSC SSM 101
CSC SSM 201
4GE SSM
ASA 5550
No support (the 4GE SSM is built-in and not user-removable)
1. The CSC SSM licenses support up to 1000 users while the Cisco ASA 5540 Series appliance can support significantly more
users. If you deploy CSC SSM with an ASA 5540 adaptive security appliance, be sure to configure the security appliance to
send the CSC SSM only the traffic that should be scanned.
Cisco Security Appliance Command Line Configuration Guide
1-2
OL-12172-04
Chapter 1
Introduction to the Security Appliance
VPN Specifications
VPN Specifications
See the Cisco ASA 5500 Series VPN Compatibility Reference at
http://cisco.cisco.com/en/US/docs/security/asa/compatibility/asa-vpn-compatibility.html.
New Features
This section lists the features added for each maintenance release, and includes the following topics:
•
New Features in Version 8.0(5), page 1-3
•
New Features in Version 8.0(4), page 1-4
•
New Features in Version 8.0(3), page 1-8
•
New Features in Version 8.0(2), page 1-9
New Features in Version 8.0(5)
Table 1-2 lists the new features for Version 8.0(5).
Hi
Note
Table 1-2
Version 8.0(5) is not supported on the PIX security appliance.
New Features for ASA Version 8.0(5)
Feature
Description
Remote Access Features
Scalable Solutions for
Waiting-to-Resume
VPN Sessions
An administrator can now keep track of the number of users in the active state and can look at the
statistics. The sessions that have been inactive for the longest time are marked as idle (and are
automatically logged off) so that license capacity is not reached and new users can log in
The following ASDM screen was modified: Monitoring > VPN > VPN Statistics > Sessions.
Application Inspection Features
Enabling Call Set up
Between H.323
Endpoints
You can enable call setup between H.323 endpoints when the Gatekeeper is inside the network. The
security appliance includes options to open pinholes for calls based on the
RegistrationRequest/RegistrationConfirm (RRQ/RCF) messages.
Because these RRQ/RCF messages are sent to and from the Gatekeeper, the calling endpoint's IP
address is unknown and the security appliance opens a pinhole through source IP address/port 0/0.
By default, this option is disabled.
The following commands were introduced: ras-enhancement enable, show
running-configuration ras-enhancement, clear configure ras-enhancement.
The following ASDM screen was modified: Configuration > Firewall > Objects > Inspect Maps >
H.323 > Details > State Checking.
Interface Features
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-3
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-2
New Features for ASA Version 8.0(5) (continued)
Feature
Description
In multiple context
mode, auto-generated
MAC addresses now use
a user-configurable
prefix, and other
enhancements
The MAC address format was changed to use a prefix, to use a fixed starting value (A2), and to use
a different scheme for the primary and secondary unit MAC addresses in a failover pair.
The MAC addresess are also now persistent accross reloads.
The command parser now checks if auto-generation is enabled; if you want to also manually assign
a MAC address, you cannot start the manual MAC address with A2.
The following command was modified: mac-address auto prefix prefix.
The following ASDM screen was modified: Configuration > Context Management > Security
Contexts.
High Availablility Features
To distinguish between link up/down transitions during normal operation from link up/down
No notifications when
interfaces are brought up transitions during failover, no link up/link down traps are sent during a failover. Also, no related
or brought down during syslog messages are sent.
a switchover event
Routing Features
DHCP RFC
compatibility (rfc3011,
rfc3527) to resolve
routing issues
This enhancement introduces security appliance support for DHCP RFCs 3011 (The IPv4 Subnet
Selection Option) and 3527 (Link Selection Sub-option for the Relay Agent Information Option).
For each DHCP server that is configured using the dhcp-server command, you can now configure
the security appliance to send the subnet-selection option, and the link-selection option or neither.
The following ASDM screen was modified: Remote Access VPN > Network Access > IPsec
connection profiles > Add/Edit.
New Features in Version 8.0(4)
Table 1-3 lists the new features for Version 8.0(4).
Table 1-3
Feature
New Features for ASA and PIX Version 8.0(4)
Description
Unified Communications Features1
Phone Proxy
Phone Proxy functionality is supported. ASA Phone Proxy provides similar features to those of the
Metreos Cisco Unified Phone Proxy with additional support for SIP inspection and enhanced
security. The ASA Phone Proxy has the following key features:
•
Secures remote IP phones by forcing the phones to encrypt signaling and media
•
Performs certificate-based authentication with remote IP phones
•
Terminates TLS signaling from IP phones and initiates TCP and TLS to Cisco Unified Mobility
Advantage servers
•
Terminates SRTP and initiates RTP/SRTP to the called party
In ASDM, see Configuration > Firewall > Advanced > Encrypted Traffic Inspection > Phone Proxy.
Cisco Security Appliance Command Line Configuration Guide
1-4
OL-12172-04
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-3
New Features for ASA and PIX Version 8.0(4) (continued)
Feature
Description
Mobility Proxy
Secure connectivity (mobility proxy) between Cisco Unified Mobility Advantage clients and
servers is supported.
Cisco Unified Mobility Advantage solutions include the Cisco Unified Mobile Communicator, an
easy-to-use software application for mobile handsets that extends enterprise communications
applications and services to mobile phones and smart phones and the Cisco Unified Mobility
Advantage server. The mobility solution streamlines the communication experience, enabling
real-time collaboration across the enterprise.
The ASA in this solution delivers inspection for the MMP (formerly called OLWP) protocol, the
proprietary protocol between Cisco Unified Mobile Communicator and Cisco Unified Mobility
Advantage. The ASA also acts as a TLS proxy, terminating and reoriginating the TLS signaling
between the Cisco Unified Mobile Communicator and Cisco Unified Mobility Advantage.
In ASDM, see Configuration > Firewall > Advanced > Encrypted Traffic Inspection > TLS Proxy.
Presence Federation
Proxy
Secure connectivity (presence federation proxy) between Cisco Unified Presence servers and
Cisco/Microsoft Presence servers is supported. With the Presence solution, businesses can securely
connect their Cisco Unified Presence clients back to their enterprise networks, or share Presence
information between Presence servers in different enterprises.
The ASA delivers functionality to enable Presence for Internet and intra-enterprise
communications. An SSL-enabled Cisco Unified Presence client can establish an SSL connection
to the Presence Server. The ASA enables SSL connectivity between server to server
communication including third-party Presence servers communicating with Cisco Unified
Presence servers. Enterprises share Presence information, and can use IM applications. The ASA
inspects SIP messages between the servers.
In ASDM, see Configuration > Firewall > Service Policy Rules > Add/Edit Service Policy Rule >
Rule Actions > Protocol Inspection or Configuration > Firewall > Advanced > Encrypted Traffic
Inspection > TLS Proxy > Add > Client Configuration.
Remote Access Features
Auto Sign-On with
Smart Tunnels for IE1
This feature lets you enable the replacement of logon credentials for WININET connections. Most
Microsoft applications use WININET, including Internet Explorer. Mozilla Firefox does not, so it
is not supported by this feature. It also supports HTTP-based authentication, therefore form-based
authentication does not work with this feature.
Credentials are statically associated to destination hosts, not services, so if initial credentials are
wrong, they cannot be dynamically corrected during runtime. Also, because of the association with
destinations hosts, providing support for an auto sign-on enabled host may not be desirable if you
want to deny access to some of the services on that host.
To configure a group auto sign-on for smart tunnels, you create a global list of auto sign-on sites,
then assign the list to group policies or user names. This feature is not supported with Dynamic
Access Policy.
In ASDM, see Firewall > Advanced > ACL Manager.
Entrust Certificate
Provisioning1
ASDM includes a link to the Entrust website to apply for temporary (test) or discounted permanent
SSL identity certificates for your ASA.
In ASDM, see Configuration > Remote Access VPN > Certificate Management > Identity
Certificates. Click Enroll ASA SSL VPN head-end with Entrust.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-5
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-3
New Features for ASA and PIX Version 8.0(4) (continued)
Feature
Description
Extended Time for User You can configure the security appliance to give remote users more time to enter their credentials
Reauthentication on IKE on a Phase 1 SA rekey. Previously, when reauthenticate-on-rekey was configured for IKE tunnels
Rekey
and a phase 1 rekey occurred, the security appliance prompted the user to authenticate and only
gave the user approximately 2 minutes to enter their credentials. If the user did not enter their
credentials in that 2 minute window, the tunnel would be terminated. With this new feature enabled,
users now have more time to enter credentials before the tunnel drops. The total amount of time is
the difference between the new Phase 1 SA being established, when the rekey actually takes place,
and the old Phase 1 SA expiring. With default Phase 1 rekey times set, the difference is roughly 3
hours, or about 15% of the rekey interval.
In ASDM, see Configuration > Device Management > Certificate Management > Identity
Certificates.
Persistent IPsec
Tunneled Flows
With the persistent IPsec tunneled flows feature enabled, the security appliance preserves and
resumes stateful (TCP) tunneled flows after the tunnel drops, then recovers. All other flows are
dropped when the tunnel drops and must reestablish when a new tunnel comes up. Preserving the
TCP flows allows some older or sensitive applications to keep working through a short-lived tunnel
drop. This feature supports IPsec LAN-to-LAN tunnels and Network Extension Mode tunnels from
a Hardware Client. It does not support IPsec or AnyConnect/SSL VPN remote access tunnels. See
the [no] sysopt connection preserve-vpn-flows command. This option is disabled by default.
In ASDM, see Configuration > Remote Access VPN > Network (Client) Access > Advanced >
IPsec > System Options. Check the Preserve stateful VPN flows when the tunnel drops for
Network Extension Mode (NEM) checkbox to enable persistent IPsec tunneled flows.
Show Active Directory
Groups
The CLI command show ad-groups was added to list the active directory groups. ASDM Dynamic
Access Policy uses this command to present the administrator with a list of MS AD groups that can
be used to define the VPN policy.
In ASDM, see Configuration > Remote Access VPN > Clientless SSL VPN Access > Dynamic
Access Policies > Add/Edit DAP > Add/Edit AAA Attribute.
Smart Tunnel over Mac
OS1
Smart tunnels now support Mac OS.
In ASDM, see Configuration > Remote Access VPN > Clientless SSL VPN Access > Portal >
Smart Tunnels.
Firewall Features
QoS Traffic Shaping
If you have a device that transmits packets at a high speed, such as the security appliance with Fast
Ethernet, and it is connected to a low speed device such as a cable modem, then the cable modem
is a bottleneck at which packets are frequently dropped. To manage networks with differing line
speeds, you can configure the security appliance to transmit packets at a fixed slower rate. See the
shape command. See also the crypto ipsec security-association replay command, which lets you
configure the IPSec anti-replay window size. One side-effect of priority queueing is packet
re-ordering. For IPSec packets, out-of-order packets that are not within the anti-replay window
generate warning syslog messages. These warnings become false alarms in the case of priority
queueing. This new command avoids possible false alarms.
In ASDM, see Configuration > Firewall > Security Policy > Service Policy Rules > Add/Edit
Service Policy Rule > Rule Actions > QoS. Note that the only traffic class supported for traffic
shaping is class-default, which matches all traffic.
Cisco Security Appliance Command Line Configuration Guide
1-6
OL-12172-04
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-3
New Features for ASA and PIX Version 8.0(4) (continued)
Feature
Description
TCP Normalization
Enhancements
You can now configure TCP normalization actions for certain packet types. Previously, the default
actions for these kinds of packets was to drop the packet. Now you can set the TCP normalizer to
allow the packets.
•
TCP invalid ACK check (the invalid-ack command)
•
TCP packet sequence past window check (the seq-past-window command)
•
TCP SYN-ACK with data check (the synack-data command)
You can also set the TCP out-of-order packet buffer timeout (the queue command timeout
keyword). Previously, the timeout was 4 seconds. You can now set the timeout to another value.
The default action for packets that exceed MSS has changed from drop to allow (the exceed-mss
command).
The following non-configurable actions have changed from drop to clear for these packet types:
•
Bad option length in TCP
•
TCP Window scale on non-SYN
•
Bad TCP window scale value
•
Bad TCP SACK ALLOW option
In ASDM, see Configuration > Firewall > Objects > TCP Maps.
TCP Intercept statistics
You can enable collection for TCP Intercept statistics using the threat-detection statistics
tcp-intercept command, and view them using the show threat-detection statistics command.
In ASDM 6.1(5) and later, see Configuration > Firewall > Threat Detection. This command was
not supported in ASDM 6.1(3).
Threat detection shun
timeout
You can now configure the shun timeout for threat detection using the threat-detection
scanning-threat shun duration command.
In ASDM 6.1(5) and later, see Configuration > Firewall > Threat Detection. This command was
not supported in ASDM 6.1(3).
Timeout for SIP
Provisional Media
You can now configure the timeout for SIP provisional media using the timeout
sip-provisional-media command.
In ASDM, see Configuration > Firewall > Advanced > Global Timeouts.
Platform Features
Native VLAN support
for the ASA 5505
You can now include the native VLAN in an ASA 5505 trunk port using the switchport trunk
native vlan command.
In ASDM, see Configuration > Device Setup > Interfaces > Switch Ports > Edit dialog.
SNMP support for
unnamed interfaces
Previously, SNMP only provided information about interfaces that were configured using the
nameif command. For example, SNMP only sent traps and performed walks on the IF MIB and IP
MIB for interfaces that were named. Because the ASA 5505 has both unnamed switch ports and
named VLAN interfaces, SNMP was enhanced to show information about all physical interfaces
and logical interfaces; a nameif command is no longer required to display the interfaces using
SNMP. These changes affect all models, and not just the ASA 5505.
1. This feature is not supported on the PIX security appliance.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-7
Chapter 1
Introduction to the Security Appliance
New Features
New Features in Version 8.0(3)
Table 1-4 lists the new features for Version 8.0(3).
Table 1-4
New Features for ASA and PIX Version 8.0(3)
Feature
Description
AnyConnect RSA SoftID API
Integration
Provides support for AnyConnect VPN clients to communicate directly with RSA SoftID
for obtaining user token codes. It also provides the ability to specify SoftID message
support for a connection profile (tunnel group), and the ability to configure SDI messages
on the security appliance that match SDI messages received through a RADIUS proxy.
This feature ensures the prompts displayed to the remote client user are appropriate for
the action required during authentication and the AnyConnect client responds
successfully to authentication challenges.
IP Address Reuse Delay
Delays the reuse of an IP address after it has been returned to the IP address pool.
Increasing the delay prevents problems the security appliance may experience when an
IP address is returned to the pool and reassigned quickly.
In ASDM, see Configure > Remote Access VPN > Network (Client) Access > Address
Assignment > Assignment Policy.
WAAS Inspection
Added support for Wide Area Application Services (WAAS) inspection. WAAS gives
branch and remote offices LAN-like access to WAN and MAN services. See the inspect
waas command.
In ASDM, see Configuration > Firewall > Service Policy Rules > Add/Edit Service
Policy Rule > Rule Actions > Protocol Inspection.
DNS Guard Enhancement
Added an option to enable or disable DNS guard. When enabled, this feature allows only
one DNS response back from a DNS request.
In ASDM, see Configuration > Firewall > Objects > Inspect maps > DNS.
Fully Qualified Domain Name
Support Enhancement
Added option in the redirect-fqdn command to send either the fully qualified domain
name (FQDN) or the IP address to the client in a VPN load balancing cluster.
In ASDM, see Configuration > Device Management >High Availability > VPN Load
Balancing or Configuration > Remote Access VPN >Load Balancing.
Clientless SSL VPN Caching
Static Content Enhancement
Added a new command to allow clientless SSL VPN users to cache the static content,
cache-static-content enable.
In ASDM, see Configuration > Remote Access VPN > Clientless SSL VPN Access >
Advanced > Content Cache.
DHCP Client Enhancements
Added two new items for the DHCP client. The first option configures DHCP Option 61
to send either the MAC or the string "cisco-<MAC>-<interface>-<hostname>", where <
> represents the corresponding values as the client identifier. The second option either
sets or clears the broadcast flag for DHCP discover when the DHCP request has the
broadcast flag enabled.
In ASDM, see Configuration > Device Management > DHCP > DHCP Server; then click
on Advanced button.
ASDM Banner
When you start ASDM, new banner text appears in a dialog box with the option to
continue or disconnect. See the banner asdm command.
In ASDM, see Configuration > Properties > Device Administration > Banner.
Cisco Security Appliance Command Line Configuration Guide
1-8
OL-12172-04
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-4
New Features for ASA and PIX Version 8.0(3) (continued)
Feature
Description
ESMTP Enhancement
Addedan option for Extended Simple Mail Transfer Protocol (ESMTP) inspection to
work over Transport Layer Security (TLS).
In ASDM, see Configuration > Firewall > Objects > Inspect Map > ESMTP.
Smart Card Removal
Enhancement
Added option in the VPN group policy to specify whether tunnels stay connected or not
when the Smart Card is removed. Previously, the tunnels were always disconnected. See
the smartcard-removal-disconnect command.
In ASDM, see Configuration > Remote Access VPN > Network (Client) Access > Group
Policies > Add/Edit Internal/External Group Policies > More Options.
New Features in Version 8.0(2)
Table 1-5 lists the new features for Version 8.0(2).
Note
Table 1-5
There was no ASA or PIX 8.0(1) release.
New Features for ASA and PIX Version 8.0(2)
ASA Feature Type
Feature
Description
Routing
EIGRP routing
The security appliance supports EIGRP or EIGRP stub routing.
High Availability
Remote command
execution in Failover
pairs
You can execute commands on the peer unit in a failover pair without having
to connect directly to the peer. This works for both Active/Standby and
Active/Active failover.
CSM configuration
rollback support
Adds support for the Cisco Security Manager configuration rollback feature
in failover configurations.
Failover pair Auto
Update support
You can use an Auto Update server to update the platform image and
configuration in failover pairs.
Stateful Failover for SIP
signaling
SIP media and signaling connections are replicated to the standby unit.
Redundant interfaces
A logical redundant interface pairs an active and a standby physical interface.
When the active interface fails, the standby interface becomes active and
starts passing traffic. You can configure a redundant interface to increase the
security appliance reliability. This feature is separate from device-level
failover, but you can configure redundant interfaces as well as failover if
desired. You can configure up to eight redundant interface pairs.
Password reset
You can reset the password on the SSM hardware module.
General Features
SSMs
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-9
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-5
New Features for ASA and PIX Version 8.0(2) (continued)
ASA Feature Type
VPN Features
Feature
Description
1
Authentication
Enhancements
Combined certificate and An administrator requires a username and password in addition to a
username/password
certificate for login to SSL VPN connections.
login
Internal domain
username/password
Provides a password for access to internal resources for users who log in with
credentials other than a domain username and password, for example, with a
one-time password. This is a password in addition to the one a user enters
when logging in.
Generic LDAP support
This includes OpenLDAP and Novell LDAP. Expands LDAP support
available for authentication and authorization.
Onscreen keyboard
The security appliance includes an onscreen keyboard option for the login
page and subsequent authentication requests for internal resources. This
provides additional protection against software-based keystroke loggers by
requiring a user to use a mouse to click characters in an onscreen keyboard
for authentication, rather than entering the characters on a physical keyboard.
SAML SSO verified with The security appliance supports Security Assertion Markup Language
RSA Access Manager
(SAML) protocol for Single Sign On (SSO) with RSA Access Manager
(Cleartrust and Federated Identity Manager).
Certificates
Cisco Secure
Desktop
NTLMv2
Version 8.0(2) adds support for NTLMv2 authentication for Windows-based
clients.
Local certificate
authority
Provides a certificate authority on the security appliance for use with SSL
VPN connections, both browser- and client-based.
OCSP CRL
Provides OCSP revocation checking for SSL VPN.
Host Scan
As a condition for the completion of a Cisco AnyConnect or clientless SSL
VPN connection, the remote computer scans for a greatly expanded
collection of antivirus and antispyware applications, firewalls, operating
systems, and associated updates. It also scans for any registry entries,
filenames, and process names that you specify. It sends the scan results to the
security appliance. The security appliance uses both the user login credentials
and the computer scan results to assign a Dynamic Access Policy (DAP).
With an Advanced Endpoint Assessment License, you can enhance Host Scan
by configuring an attempt to update noncompliant computers to meet version
requirements.
Cisco can provide timely updates to the list of applications and versions that
Host Scan supports in a package that is separate from Cisco Secure Desktop.
Simplified prelogin
assessment and periodic
checks
Cisco Secure Desktop now simplifies the configuration of prelogin and
periodic checks to perform on remote Microsoft Windows computers. Cisco
Secure Desktop lets you add, modify, remove, and place conditions on
endpoint checking criteria using a simplified, graphical view of the checks.
As you use this graphical view to configure sequences of checks, link them
to branches, deny logins, and assign endpoint profiles, Cisco Secure Desktop
Manager records the changes to an XML file. You can configure the security
appliance to use returned results in combination with many other types of
data, such as the connection type and multiple group settings, to generate and
apply a DAP to the session.
Cisco Security Appliance Command Line Configuration Guide
1-10
OL-12172-04
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-5
New Features for ASA and PIX Version 8.0(2) (continued)
ASA Feature Type
Feature
Description
Access Policies
Dynamic access policies
(DAP)
VPN gateways operate in dynamic environments. Multiple variables can
affect each VPN connection, for example, intranet configurations that
frequently change, the various roles each user may inhabit within an
organization, and logins from remote access sites with different
configurations and levels of security. The task of authorizing users is much
more complicated in a VPN environment than it is in a network with a static
configuration.
Dynamic Access Policies (DAP) on the security appliance let you configure
authorization that addresses these many variables. You create a dynamic
access policy by setting a collection of access control attributes that you
associate with a specific user tunnel or session. These attributes address
issues of multiple group membership and endpoint security. That is, the
security appliance grants access to a particular user for a particular session
based on the policies you define. It generates a DAP at the time the user
connects by selecting and/or aggregating attributes from one or more DAP
records. It selects these DAP records based on the endpoint security
information of the remote device and the AAA authorization information for
the authenticated user. It then applies the DAP record to the user tunnel or
session.
Platform
Enhancements
Administrator
differentiation
Lets you differentiate regular remote access users and administrative users
under the same database, either RADIUS or LDAP. You can create and
restrict access to the console via various methods (TELNET and SSH, for
example) to administrators only. It is based on the IETF RADIUS
service-type attribute.
VLAN support for
remote access VPN
connections
Provides support for mapping (tagging) of client traffic at the group or user
level. This feature is compatible with clientless as well as IPsec and SSL
tunnel-based connections.
VPN load balancing for
the ASA 5510
Extends load balancing support to ASA 5510 adaptive security appliances
that have a Security Plus license.
Crypto conditional debug Lets users debug an IPsec tunnel on the basis of predefined crypto conditions
such as the peer IP address, connection-ID of a crypto engine, and security
parameter index (SPI). By limiting debug messages to specific IPSec
operations and reducing the amount of debug output, you can better
troubleshoot the security appliance with a large number of tunnels.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-11
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-5
New Features for ASA and PIX Version 8.0(2) (continued)
ASA Feature Type
Feature
Description
Browser-based SSL
VPN Features
Enhanced portal design
Version 8.0(2) includes an enhanced end user interface that is more cleanly
organized and visually appealing.
Customization
Supports administrator-defined customization of all user-visible content.
Support for FTP
You can provide file access via FTP in additional to CIFS (Windows-based).
Plugin applets
Version 8.0(2) adds a framework for supporting TCP-based applications
without requiring a pre-installed client application. Java applets let users
access these applications from the browser-enabled SSL VPN portal. Initial
support is for TELNET, SSH, RDP, and VNC.
Smart tunnels
A smart tunnel is a connection between an application and a remote site,
using a browser-based SSL VPN session with the security appliance as the
pathway. Version 8.0(2) lets you identify the applications to which you want
to grant smart tunnel access, and lets you specify the path to the application
and the SHA-1 hash of its checksum to check before granting it access. Lotus
SameTime and Microsoft Outlook Express are examples of applications to
which you might want to grant smart tunnel access.
The remote host originating the smart tunnel connection must be running
Microsoft Windows Vista, Windows XP, or Windows 2000, and the browser
must be enabled with Java, Microsoft ActiveX, or both.
RSS newsfeed
Administrators can populate the clientless portal with RSS newsfeed
information, which lets company news or other information display on a user
screen.
Personal bookmark
support
Users can define their own bookmarks. These bookmarks are stored on a file
server.
Transformation
enhancements
Adds support for several complex forms of web content over clientless
connections, including Adobe flash and Java WebStart.
IPv6
Allows access to IPv6 resources over a public IPv4 connection.
Web folders
Lets browser-based SSL VPN users connecting from Windows operating
systems browse shared file systems and perform the following operations:
view folders, view folder and file properties, create, move, copy, copy from
the local host to the remote host, copy from the remote host to the local host,
and delete. Internet Explorer indicates when a web folder is accessible.
Accessing this folder launches another window, providing a view of the
shared folder, on which users can perform web folder functions, assuming the
properties of the folders and documents permit them.
Microsoft Sharepoint
enhancement
Extends Web Access support for Microsoft Sharepoint, integrating Microsoft
Office applications available on the machine with the browser to view,
change, and save documents shared on a server. Version 8.0(2) supports
Windows Sharepoint Services 2.0 in Windows Server 2003.
HTTP Proxy
PAC support
Lets you specify the URL of a proxy autoconfiguration file (PAC) to
download to the browser. Once downloaded, the PAC file uses a JavaScript
function to identify a proxy for each URL.
HTTPS Proxy
Proxy exclusion list
Lets you configure a list of URLs to exclude from the HTTP requests the
security appliance can send to an external proxy server.
Browser-based SSL
VPN Features
(continued)
Cisco Security Appliance Command Line Configuration Guide
1-12
OL-12172-04
Chapter 1
Introduction to the Security Appliance
New Features
Table 1-5
New Features for ASA and PIX Version 8.0(2) (continued)
ASA Feature Type
Feature
Description
NAC
SSL VPN tunnel support The security appliance provides NAC posture validation of endpoints that
establish AnyConnect VPN client sessions.
Support for audit
services
You can configure the security appliance to pass the IP address of the client
to an optional audit server if the client does not respond to a posture
validation request. The audit server uses the host IP address to challenge the
host directly to assess its health. For example, it might challenge the host to
determine whether its virus checking software is active and up-to-date. After
the audit server completes its interaction with the remote host, it passes a
token to the posture validation server, indicating the health of the remote host.
If the token indicates the remote host is healthy, the posture validation server
sends a network access policy to the security appliance for application to the
traffic on the tunnel.
Modular policy
framework inspect class
map
Traffic can match one of multiple match commands in an inspect class map;
formerly, traffic had to match all match commands in a class map to match
the class map.
AIC for encrypted
streams and AIC Arch
changes
Provides HTTP inspection into TLS, which allows AIC/MPF inspection in
WebVPN HTTP and HTTPS streams.
Firewall Features
Application
Inspection
TLS Proxy for SCCP and Enables inspection of encrypted traffic. Implementations include SSL
SIP2
encrypted VoIP signaling, namely Skinny and SIP, interacting with the Cisco
CallManager.
Access Lists
SIP enhancements for
CCM
Improves interoperability with CCM 5.0 and 6.x with respect to signaling
pinholes.
Full RTSP PAT support
Provides TCP fragment reassembly support, a scalable parsing routine on
RTSP, and security enhancements that protect RTSP traffic.
Enhanced service object
group
Lets you configure a service object group that contains a mix of TCP services,
UDP services, ICMP-type services, and any protocol. It removes the need for
a specific ICMP-type object group and protocol object group. The enhanced
service object group also specifies both source and destination services. The
access list CLI now supports this behavior.
Ability to rename access Lets you rename an access list.
list
Live access list hit counts Includes the hit count for ACEs from multiple access lists. The hit count value
represents how many times traffic hits a particular access rule.
Attack Prevention
Set connection limits for For a Layer 3/4 management class map, you can specify the set connection
management traffic to the command.
adaptive security
appliance
Threat detection
You can enable basic threat detection and scanning threat detection to
monitor attacks such as DoS attacks and scanning attacks. For scanning
attacks, you can automatically shun attacking hosts. You can also enable scan
threat statistics to monitor both valid and invalid traffic for hosts, ports,
protocols, and access lists.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-13
Chapter 1
Introduction to the Security Appliance
Firewall Functional Overview
Table 1-5
New Features for ASA and PIX Version 8.0(2) (continued)
ASA Feature Type
Feature
Description
NAT
Transparent firewall NAT You can configure NAT for a transparent firewall.
support
IPS
Virtual IPS sensors with
the AIP SSM
The AIP SSM running IPS software Version 6.0 and above can run multiple
virtual sensors, which means you can configure multiple security policies on
the AIP SSM. You can assign each context or single mode adaptive security
appliance to one or more virtual sensors, or you can assign multiple security
contexts to the same virtual sensor. See the IPS documentation for more
information about virtual sensors, including the maximum number of sensors
supported.
Logging
Secure logging
You can enable secure connections to the syslog server using SSL or TLS
with TCP, and encrypted system log message content. Not supported on the
PIX series adaptive security appliance.
IPv6
IPv6 support for SIP
The SIP inspection engine supports IPv6 addresses. IPv6 addresses can be
used in URLs, in the Via header field, and SDP fields.
1. Clientless SSL VPN features are not supported on the PIX security appliance.
2. TLS proxy is not supported on the PIX security appliance.
Firewall Functional Overview
Firewalls protect inside networks from unauthorized access by users on an outside network. A firewall
can also protect inside networks from each other, for example, by keeping a human resources network
separate from a user network. If you have network resources that need to be available to an outside user,
such as a web or FTP server, you can place these resources on a separate network behind the firewall,
called a demilitarized zone (DMZ). The firewall allows limited access to the DMZ, but because the DMZ
only includes the public servers, an attack there only affects the servers and does not affect the other
inside networks. You can also control when inside users access outside networks (for example, access to
the Internet), by allowing only certain addresses out, by requiring authentication or authorization, or by
coordinating with an external URL filtering server.
When discussing networks connected to a firewall, the outside network is in front of the firewall, the
inside network is protected and behind the firewall, and a DMZ, while behind the firewall, allows limited
access to outside users. Because the security appliance lets you configure many interfaces with varied
security policies, including many inside interfaces, many DMZs, and even many outside interfaces if
desired, these terms are used in a general sense only.
This section includes the following topics:
•
Security Policy Overview, page 1-15
•
Firewall Mode Overview, page 1-17
•
Stateful Inspection Overview, page 1-17
Cisco Security Appliance Command Line Configuration Guide
1-14
OL-12172-04
Chapter 1
Introduction to the Security Appliance
Firewall Functional Overview
Security Policy Overview
A security policy determines which traffic is allowed to pass through the firewall to access another
network. By default, the security appliance allows traffic to flow freely from an inside network (higher
security level) to an outside network (lower security level). You can apply actions to traffic to customize
the security policy. This section includes the following topics:
•
Permitting or Denying Traffic with Access Lists, page 1-15
•
Applying NAT, page 1-15
•
Protecting from IP Fragments, page 1-15
•
Using AAA for Through Traffic, page 1-15
•
Applying HTTP, HTTPS, or FTP Filtering, page 1-16
•
Applying Application Inspection, page 1-16
•
Sending Traffic to the Advanced Inspection and Prevention Security Services Module, page 1-16
•
Sending Traffic to the Content Security and Control Security Services Module, page 1-16
•
Applying QoS Policies, page 1-16
•
Applying Connection Limits and TCP Normalization, page 1-16
Permitting or Denying Traffic with Access Lists
You can apply an access list to limit traffic from inside to outside, or allow traffic from outside to inside.
For transparent firewall mode, you can also apply an EtherType access list to allow non-IP traffic.
Applying NAT
Some of the benefits of NAT include the following:
•
You can use private addresses on your inside networks. Private addresses are not routable on the
Internet.
•
NAT hides the local addresses from other networks, so attackers cannot learn the real address of a
host.
•
NAT can resolve IP routing problems by supporting overlapping IP addresses.
Protecting from IP Fragments
The security appliance provides IP fragment protection. This feature performs full reassembly of all
ICMP error messages and virtual reassembly of the remaining IP fragments that are routed through the
security appliance. Fragments that fail the security check are dropped and logged. Virtual reassembly
cannot be disabled.
Using AAA for Through Traffic
You can require authentication and/or authorization for certain types of traffic, for example, for HTTP.
The security appliance also sends accounting information to a RADIUS or TACACS+ server.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-15
Chapter 1
Introduction to the Security Appliance
Firewall Functional Overview
Applying HTTP, HTTPS, or FTP Filtering
Although you can use access lists to prevent outbound access to specific websites or FTP servers,
configuring and managing web usage this way is not practical because of the size and dynamic nature of
the Internet. We recommend that you use the security appliance in conjunction with a separate server
running one of the following Internet filtering products:
•
Websense Enterprise
•
Secure Computing SmartFilter
Applying Application Inspection
Inspection engines are required for services that embed IP addressing information in the user data packet
or that open secondary channels on dynamically assigned ports. These protocols require the security
appliance to do a deep packet inspection.
Sending Traffic to the Advanced Inspection and Prevention Security Services Module
If your model supports the AIP SSM for intrusion prevention, then you can send traffic to the AIP SSM
for inspection. The AIP SSM is an intrusion prevention services module that monitors and performs
real-time analysis of network traffic by looking for anomalies and misuse based on an extensive,
embedded signature library. When the system detects unauthorized activity, it can terminate the specific
connection, permanently block the attacking host, log the incident, and send an alert to the device
manager. Other legitimate connections continue to operate independently without interruption. For more
information, see Configuring the Cisco Intrusion Prevention System Sensor Using the Command Line
Interface.
Sending Traffic to the Content Security and Control Security Services Module
If your model supports it, the CSC SSM provides protection against viruses, spyware, spam, and other
unwanted traffic. It accomplishes this by scanning the FTP, HTTP, POP3, and SMTP traffic that you
configure the adaptive security appliance to send to it.
Applying QoS Policies
Some network traffic, such as voice and streaming video, cannot tolerate long latency times. QoS is a
network feature that lets you give priority to these types of traffic. QoS refers to the capability of a
network to provide better service to selected network traffic.
Applying Connection Limits and TCP Normalization
You can limit TCP and UDP connections and embryonic connections. Limiting the number of
connections and embryonic connections protects you from a DoS attack. The security appliance uses the
embryonic limit to trigger TCP Intercept, which protects inside systems from a DoS attack perpetrated
by flooding an interface with TCP SYN packets. An embryonic connection is a connection request that
has not finished the necessary handshake between source and destination.
TCP normalization is a feature consisting of advanced TCP connection settings designed to drop packets
that do not appear normal.
Cisco Security Appliance Command Line Configuration Guide
1-16
OL-12172-04
Chapter 1
Introduction to the Security Appliance
Firewall Functional Overview
Enabling Threat Detection
You can configure scanning threat detection and basic threat detection, and also how to use statistics to
analyze threats.
Basic threat detection detects activity that might be related to an attack, such as a DoS attack, and
automatically sends a system log message.
A typical scanning attack consists of a host that tests the accessibility of every IP address in a subnet (by
scanning through many hosts in the subnet or sweeping through many ports in a host or subnet). The
scanning threat detection feature determines when a host is performing a scan. Unlike IPS scan detection
that is based on traffic signatures, the security appliance scanning threat detection feature maintains an
extensive database that contains host statistics that can be analyzed for scanning activity.
The host database tracks suspicious activity such as connections with no return activity, access of closed
service ports, vulnerable TCP behaviors such as non-random IPID, and many more behaviors.
You can configure the security appliance to send system log messages about an attacker or you can
automatically shun the host.
Firewall Mode Overview
The security appliance runs in two different firewall modes:
•
Routed
•
Transparent
In routed mode, the security appliance is considered to be a router hop in the network.
In transparent mode, the security appliance acts like a “bump in the wire,” or a “stealth firewall,” and is
not considered a router hop. The security appliance connects to the same network on its inside and
outside interfaces.
You might use a transparent firewall to simplify your network configuration. Transparent mode is also
useful if you want the firewall to be invisible to attackers. You can also use a transparent firewall for
traffic that would otherwise be blocked in routed mode. For example, a transparent firewall can allow
multicast streams using an EtherType access list.
Stateful Inspection Overview
All traffic that goes through the security appliance is inspected using the Adaptive Security Algorithm
and either allowed through or dropped. A simple packet filter can check for the correct source address,
destination address, and ports, but it does not check that the packet sequence or flags are correct. A filter
also checks every packet against the filter, which can be a slow process.
A stateful firewall like the security appliance, however, takes into consideration the state of a packet:
•
Is this a new connection?
If it is a new connection, the security appliance has to check the packet against access lists and
perform other tasks to determine if the packet is allowed or denied. To perform this check, the first
packet of the session goes through the “session management path,” and depending on the type of
traffic, it might also pass through the “control plane path.”
The session management path is responsible for the following tasks:
– Performing the access list checks
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-17
Chapter 1
Introduction to the Security Appliance
VPN Functional Overview
– Performing route lookups
– Allocating NAT translations (xlates)
– Establishing sessions in the “fast path”
Note
The session management path and the fast path make up the “accelerated security path.”
Some packets that require Layer 7 inspection (the packet payload must be inspected or altered) are
passed on to the control plane path. Layer 7 inspection engines are required for protocols that have
two or more channels: a data channel, which uses well-known port numbers, and a control channel,
which uses different port numbers for each session. These protocols include FTP, H.323, and SNMP.
•
Is this an established connection?
If the connection is already established, the security appliance does not need to re-check packets;
most matching packets can go through the fast path in both directions. The fast path is responsible
for the following tasks:
– IP checksum verification
– Session lookup
– TCP sequence number check
– NAT translations based on existing sessions
– Layer 3 and Layer 4 header adjustments
For UDP or other connectionless protocols, the security appliance creates connection state
information so that it can also use the fast path.
Data packets for protocols that require Layer 7 inspection can also go through the fast path.
Some established session packets must continue to go through the session management path or the
control plane path. Packets that go through the session management path include HTTP packets that
require inspection or content filtering. Packets that go through the control plane path include the
control packets for protocols that require Layer 7 inspection.
VPN Functional Overview
A VPN is a secure connection across a TCP/IP network (such as the Internet) that appears as a private
connection. This secure connection is called a tunnel. The security appliance uses tunneling protocols to
negotiate security parameters, create and manage tunnels, encapsulate packets, transmit or receive them
through the tunnel, and unencapsulate them. The security appliance functions as a bidirectional tunnel
endpoint: it can receive plain packets, encapsulate them, and send them to the other end of the tunnel
where they are unencapsulated and sent to their final destination. It can also receive encapsulated
packets, unencapsulate them, and send them to their final destination. The security appliance invokes
various standard protocols to accomplish these functions.
The security appliance performs the following functions:
•
Establishes tunnels
•
Negotiates tunnel parameters
•
Authenticates users
•
Assigns user addresses
•
Encrypts and decrypts data
Cisco Security Appliance Command Line Configuration Guide
1-18
OL-12172-04
Chapter 1
Introduction to the Security Appliance
Security Context Overview
•
Manages security keys
•
Manages data transfer across the tunnel
•
Manages data transfer inbound and outbound as a tunnel endpoint or router
The security appliance invokes various standard protocols to accomplish these functions.
Security Context Overview
You can partition a single security appliance into multiple virtual devices, known as security contexts.
Each context is an independent device, with its own security policy, interfaces, and administrators.
Multiple contexts are similar to having multiple standalone devices. Many features are supported in
multiple context mode, including routing tables, firewall features, IPS, and management. Some features
are not supported, including VPN and dynamic routing protocols.
In multiple context mode, the security appliance includes a configuration for each context that identifies
the security policy, interfaces, and almost all the options you can configure on a standalone device. The
system administrator adds and manages contexts by configuring them in the system configuration,
which, like a single mode configuration, is the startup configuration. The system configuration identifies
basic settings for the security appliance. The system configuration does not include any network
interfaces or network settings for itself; rather, when the system needs to access network resources (such
as downloading the contexts from the server), it uses one of the contexts that is designated as the admin
context.
The admin context is just like any other context, except that when a user logs into the admin context,
then that user has system administrator rights and can access the system and all other contexts.
Note
You can run all your contexts in routed mode or transparent mode; you cannot run some contexts in one
mode and others in another.
Multiple context mode supports static routing only. For more information about multiple context mode,
see Chapter 4, “Enabling Multiple Context Mode.”
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
1-19
Chapter 1
Introduction to the Security Appliance
Security Context Overview
Cisco Security Appliance Command Line Configuration Guide
1-20
OL-12172-04
CH A P T E R
2
Getting Started
This chapter describes how to access the command-line interface, configure the firewall mode, and work
with the configuration. This chapter includes the following sections:
•
Getting Started with Your Platform Model, page 2-1
•
Factory Default Configurations, page 2-1
•
Accessing the Command-Line Interface, page 2-4
•
Setting Transparent or Routed Firewall Mode, page 2-5
•
Working with the Configuration, page 2-6
Getting Started with Your Platform Model
This guide applies to multiple security appliance platforms and models: the PIX 500 series security
appliances and the ASA 5500 series adaptive security appliances. There are some hardware differences
between the PIX and the ASA security appliance. Moreover, the ASA 5505 includes a built-in switch,
and requires some special configuration. For these hardware-based differences, the platforms or models
supported are noted directly in each section.
Some models do not support all features covered in this guide. For example, the ASA 5505 adaptive
security appliance does not support security contexts. This guide might not list each supported model
when discussing a feature. To determine the features that are supported for your model before you start
your configuration, see the “Supported Feature Licenses Per Model” section on page 3-1 for a detailed
list of the features supported for each model.
Factory Default Configurations
The factory default configuration is the configuration applied by Cisco to new security appliances. The
factory default configuration is supported on all models except for the PIX 525 and PIX 535 security
appliances.
For the PIX 515/515E and the ASA 5510 and higher security appliances, the factory default
configuration configures an interface for management so you can connect to it using ASDM, with which
you can then complete your configuration.
For the ASA 5505 adaptive security appliance, the factory default configuration configures interfaces
and NAT so that the security appliance is ready to use in your network immediately.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
2-1
Chapter 2
Getting Started
Factory Default Configurations
The factory default configuration is available only for routed firewall mode and single context mode. See
Chapter 4, “Enabling Multiple Context Mode,” for more information about multiple context mode. See
the “Setting Transparent or Routed Firewall Mode” section on page 2-5 for more information about
routed and transparent firewall mode.
This section includes the following topics:
•
Restoring the Factory Default Configuration, page 2-2
•
ASA 5505 Default Configuration, page 2-2
•
ASA 5510 and Higher Default Configuration, page 2-3
•
PIX 515/515E Default Configuration, page 2-4
Restoring the Factory Default Configuration
To restore the factory default configuration, enter the following command:
hostname(config)# configure factory-default [ip_address [mask]]
If you specify the ip_address, then you set the inside or management interface IP address, depending on
your model, instead of using the default IP address of 192.168.1.1. The http command uses the subnet
you specify. Similarly, the dhcpd address command range consists of addresses within the subnet that
you specify.
After you restore the factory default configuration, save it to internal Flash memory using the write
memory command. The write memory command saves the running configuration to the default location
for the startup configuration, even if you previously configured the boot config command to set a
different location; when the configuration was cleared, this path was also cleared.
Note
This command also clears the boot system command, if present, along with the rest of the configuration.
The boot system command lets you boot from a specific image, including an image on the external Flash
memory card. The next time you reload the security appliance after restoring the factory configuration,
it boots from the first image in internal Flash memory; if you do not have an image in internal Flash
memory, the security appliance does not boot.
To configure additional settings that are useful for a full configuration, see the setup command.
ASA 5505 Default Configuration
The default factory configuration for the ASA 5505 adaptive security appliance configures the
following:
•
An inside VLAN 1 interface that includes the Ethernet 0/1 through 0/7 switch ports. If you did not
set the IP address in the configure factory-default command, then the VLAN 1 IP address and mask
are 192.168.1.1 and 255.255.255.0.
•
An outside VLAN 2 interface that includes the Ethernet 0/0 switch port. VLAN 2 derives its IP
address using DHCP.
•
The default route is also derived from DHCP.
•
All inside IP addresses are translated when accessing the outside using interface PAT.
•
By default, inside users can access the outside, and outside users are prevented from accessing the
inside.
Cisco Security Appliance Command Line Configuration Guide
2-2
OL-12172-04
Chapter 2
Getting Started
Factory Default Configurations
•
The DHCP server is enabled on the security appliance, so a PC connecting to the VLAN 1 interface
receives an address between 192.168.1.2 and 192.168.1.254.
•
The HTTP server is enabled for ASDM and is accessible to users on the 192.168.1.0 network.
The configuration consists of the following commands:
interface Ethernet 0/0
switchport access vlan 2
no shutdown
interface Ethernet 0/1
switchport access vlan 1
no shutdown
interface Ethernet 0/2
switchport access vlan 1
no shutdown
interface Ethernet 0/3
switchport access vlan 1
no shutdown
interface Ethernet 0/4
switchport access vlan 1
no shutdown
interface Ethernet 0/5
switchport access vlan 1
no shutdown
interface Ethernet 0/6
switchport access vlan 1
no shutdown
interface Ethernet 0/7
switchport access vlan 1
no shutdown
interface vlan2
nameif outside
no shutdown
ip address dhcp setroute
interface vlan1
nameif inside
ip address 192.168.1.1 255.255.255.0
security-level 100
no shutdown
global (outside) 1 interface
nat (inside) 1 0 0
http server enable
http 192.168.1.0 255.255.255.0 inside
dhcpd address 192.168.1.2-192.168.1.254 inside
dhcpd auto_config outside
dhcpd enable inside
logging asdm informational
ASA 5510 and Higher Default Configuration
The default factory configuration for the ASA 5510 and higher adaptive security appliance configures
the following:
•
The management interface, Management 0/0. If you did not set the IP address in the configure
factory-default command, then the IP address and mask are 192.168.1.1 and 255.255.255.0.
•
The DHCP server is enabled on the security appliance, so a PC connecting to the interface receives
an address between 192.168.1.2 and 192.168.1.254.
•
The HTTP server is enabled for ASDM and is accessible to users on the 192.168.1.0 network.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
2-3
Chapter 2
Getting Started
Accessing the Command-Line Interface
The configuration consists of the following commands:
interface management 0/0
ip address 192.168.1.1 255.255.255.0
nameif management
security-level 100
no shutdown
asdm logging informational 100
asdm history enable
http server enable
http 192.168.1.0 255.255.255.0 management
dhcpd address 192.168.1.2-192.168.1.254 management
dhcpd lease 3600
dhcpd ping_timeout 750
dhcpd enable management
PIX 515/515E Default Configuration
The default factory configuration for the PIX 515/515E security appliance configures the following:
•
The inside Ethernet1 interface. If you did not set the IP address in the configure factory-default
command, then the IP address and mask are 192.168.1.1 and 255.255.255.0.
•
The DHCP server is enabled on the security appliance, so a PC connecting to the interface receives
an address between 192.168.1.2 and 192.168.1.254.
•
The HTTP server is enabled for ASDM and is accessible to users on the 192.168.1.0 network.
The configuration consists of the following commands:
interface ethernet 1
ip address 192.168.1.1 255.255.255.0
nameif management
security-level 100
no shutdown
asdm logging informational 100
asdm history enable
http server enable
http 192.168.1.0 255.255.255.0 management
dhcpd address 192.168.1.2-192.168.1.254 management
dhcpd lease 3600
dhcpd ping_timeout 750
dhcpd enable management
Accessing the Command-Line Interface
For initial configuration, access the command-line interface directly from the console port. Later, you
can configure remote access using Telnet or SSH according to Chapter 42, “Managing System Access.”
If your system is already in multiple context mode, then accessing the console port places you in the
system execution space. See Chapter 4, “Enabling Multiple Context Mode,” for more information about
multiple context mode.
Note
If you want to use ASDM to configure the security appliance instead of the command-line interface, you
can connect to the default management address of 192.168.1.1 (if your security appliance includes a
factory default configuration. See the “Factory Default Configurations” section on page 2-1.). On the
Cisco Security Appliance Command Line Configuration Guide
2-4
OL-12172-04
Chapter 2
Getting Started
Setting Transparent or Routed Firewall Mode
ASA 5510 and higher adaptive security appliances, the interface to which you connect with ASDM is
Management 0/0. For the ASA 5505 adaptive security appliance, the switch port to which you connect
with ASDM is any port, except for Ethernet 0/0. For the PIX 515/515E security appliance, the interface
to which you connect with ASDM is Ethernet 1. If you do not have a factory default configuration, follow
the steps in this section to access the command-line interface. You can then configure the minimum
parameters to access ASDM by entering the setup command.
To access the command-line interface, perform the following steps:
Step 1
Connect a PC to the console port using the provided console cable, and connect to the console using a
terminal emulator set for 9600 baud, 8 data bits, no parity, 1 stop bit, no flow control.
See the hardware guide that came with your security appliance for more information about the console
cable.
Step 2
Press the Enter key to see the following prompt:
hostname>
This prompt indicates that you are in user EXEC mode.
Step 3
To access privileged EXEC mode, enter the following command:
hostname> enable
The following prompt appears:
Password:
Step 4
Enter the enable password at the prompt.
By default, the password is blank, and you can press the Enter key to continue. See the “Changing the
Enable Password” section on page 9-1 to change the enable password.
The prompt changes to:
hostname#
To exit privileged mode, enter the disable, exit, or quit command.
Step 5
To access global configuration mode, enter the following command:
hostname# configure terminal
The prompt changes to the following:
hostname(config)#
To exit global configuration mode, enter the exit, quit, or end command.
Setting Transparent or Routed Firewall Mode
You can set the security appliance to run in routed firewall mode (the default) or transparent firewall
mode.
For multiple context mode, you can use only one firewall mode for all contexts. You must set the mode
in the system execution space.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
2-5
Chapter 2
Getting Started
Working with the Configuration
When you change modes, the security appliance clears the configuration because many commands are
not supported for both modes. If you already have a populated configuration, be sure to back up your
configuration before changing the mode; you can use this backup for reference when creating your new
configuration. See the “Backing Up Configuration Files” section on page 43-8. For multiple context
mode, the system configuration is erased. This action removes any contexts from running. If you then
re-add a context that has an existing configuration that was created for the wrong mode, the context
configuration will not work correctly. Be sure to recreate your context configurations for the correct
mode before you re-add them, or add new contexts with new paths for the new configurations.
If you download a text configuration to the security appliance that changes the mode with the
firewall transparent command, be sure to put the command at the top of the configuration; the security
appliance changes the mode as soon as it reads the command and then continues reading the
configuration you downloaded. If the command is later in the configuration, the security appliance clears
all the preceding lines in the configuration. See the “Downloading Software or Configuration Files to
Flash Memory” section on page 43-2 for information about downloading text files.
•
To set the mode to transparent, enter the following command in the system execution space:
hostname(config)# firewall transparent
This command also appears in each context configuration for informational purposes only; you
cannot enter this command in a context.
•
To set the mode to routed, enter the following command in the system execution space:
hostname(config)# no firewall transparent
Working with the Configuration
This section describes how to work with the configuration. The security appliance loads the
configuration from a text file, called the startup configuration. This file resides by default as a hidden
file in internal Flash memory. You can, however, specify a different path for the startup configuration.
(For more information, see Chapter 43, “Managing Software and Configurations.”)
When you enter a command, the change is made only to the running configuration in memory. You must
manually save the running configuration to the startup configuration for your changes to remain after a
reboot.
The information in this section applies to both single and multiple security contexts, except where noted.
Additional information about contexts is in Chapter 4, “Enabling Multiple Context Mode.”
This section includes the following topics:
•
Saving Configuration Changes, page 2-6
•
Copying the Startup Configuration to the Running Configuration, page 2-8
•
Viewing the Configuration, page 2-8
•
Clearing and Removing Configuration Settings, page 2-9
•
Creating Text Configuration Files Offline, page 2-9
Saving Configuration Changes
This section describes how to save your configuration, and includes the following topics:
•
Saving Configuration Changes in Single Context Mode, page 2-7
Cisco Security Appliance Command Line Configuration Guide
2-6
OL-12172-04
Chapter 2
Getting Started
Working with the Configuration
•
Saving Configuration Changes in Multiple Context Mode, page 2-7
Saving Configuration Changes in Single Context Mode
To save the running configuration to the startup configuration, enter the following command:
hostname# write memory
Note
The copy running-config startup-config command is equivalent to the write memory command.
Saving Configuration Changes in Multiple Context Mode
You can save each context (and system) configuration separately, or you can save all context
configurations at the same time. This section includes the following topics:
•
Saving Each Context and System Separately, page 2-7
•
Saving All Context Configurations at the Same Time, page 2-7
Saving Each Context and System Separately
To save the system or context configuration, enter the following command within the system or context:
hostname# write memory
Note
The copy running-config startup-config command is equivalent to the write memory command.
For multiple context mode, context startup configurations can reside on external servers. In this case, the
security appliance saves the configuration back to the server you identified in the context URL, except
for an HTTP or HTTPS URL, which do not let you save the configuration to the server.
Saving All Context Configurations at the Same Time
To save all context configurations at the same time, as well as the system configuration, enter the
following command in the system execution space:
hostname# write memory all [/noconfirm]
If you do not enter the /noconfirm keyword, you see the following prompt:
Are you sure [Y/N]:
After you enter Y, the security appliance saves the system configuration and each context. Context
startup configurations can reside on external servers. In this case, the security appliance saves the
configuration back to the server you identified in the context URL, except for an HTTP or HTTPS URL,
which do not let you save the configuration to the server.
After the security appliance saves each context, the following message appears:
‘Saving context ‘b’ ... ( 1/3 contexts saved ) ’
Sometimes, a context is not saved because of an error. See the following information for errors:
•
For contexts that are not saved because of low memory, the following message appears:
The context 'context a' could not be saved due to Unavailability of resources
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
2-7
Chapter 2
Getting Started
Working with the Configuration
•
For contexts that are not saved because the remote destination is unreachable, the following message
appears:
The context 'context a' could not be saved due to non-reachability of destination
•
For contexts that are not saved because the context is locked, the following message appears:
Unable to save the configuration for the following contexts as these contexts are
locked.
context ‘a’ , context ‘x’ , context ‘z’ .
A context is only locked if another user is already saving the configuration or in the process of
deleting the context.
•
For contexts that are not saved because the startup configuration is read-only (for example, on an
HTTP server), the following message report is printed at the end of all other messages:
Unable to save the configuration for the following contexts as these contexts have
read-only config-urls:
context ‘a’ , context ‘b’ , context ‘c’ .
•
For contexts that are not saved because of bad sectors in the Flash memory, the following message
appears:
The context 'context a' could not be saved due to Unknown errors
Copying the Startup Configuration to the Running Configuration
Copy a new startup configuration to the running configuration using one of these options:
•
To merge the startup configuration with the running configuration, enter the following command:
hostname(config)# copy startup-config running-config
A merge adds any new commands from the new configuration to the running configuration. If the
configurations are the same, no changes occur. If commands conflict or if commands affect the
running of the context, then the effect of the merge depends on the command. You might get errors,
or you might have unexpected results.
•
To load the startup configuration and discard the running configuration, restart the security
appliance by entering the following command:
hostname# reload
Alternatively, you can use the following commands to load the startup configuration and discard the
running configuration without requiring a reboot:
hostname/contexta(config)# clear configure all
hostname/contexta(config)# copy startup-config running-config
Viewing the Configuration
The following commands let you view the running and startup configurations.
•
To view the running configuration, enter the following command:
hostname# show running-config
Cisco Security Appliance Command Line Configuration Guide
2-8
OL-12172-04
Chapter 2
Getting Started
Working with the Configuration
•
To view the running configuration of a specific command, enter the following command:
hostname# show running-config command
•
To view the startup configuration, enter the following command:
hostname# show startup-config
Clearing and Removing Configuration Settings
To erase settings, enter one of the following commands.
•
To clear all the configuration for a specified command, enter the following command:
hostname(config)# clear configure configurationcommand [level2configurationcommand]
This command clears all the current configuration for the specified configuration command. If you
only want to clear the configuration for a specific version of the command, you can enter a value for
level2configurationcommand.
For example, to clear the configuration for all aaa commands, enter the following command:
hostname(config)# clear configure aaa
To clear the configuration for only aaa authentication commands, enter the following command:
hostname(config)# clear configure aaa authentication
•
To disable the specific parameters or options of a command, enter the following command:
hostname(config)# no configurationcommand [level2configurationcommand] qualifier
In this case, you use the no command to remove the specific configuration identified by qualifier.
For example, to remove a specific nat command, enter enough of the command to identify it
uniquely as follows:
hostname(config)# no nat (inside) 1
•
To erase the startup configuration, enter the following command:
hostname(config)# write erase
•
To erase the running configuration, enter the following command:
hostname(config)# clear configure all
Note
In multiple context mode, if you enter clear configure all from the system configuration, you
also remove all contexts and stop them from running.
Creating Text Configuration Files Offline
This guide describes how to use the CLI to configure the security appliance; when you save commands,
the changes are written to a text file. Instead of using the CLI, however, you can edit a text file directly
on your PC and paste a configuration at the configuration mode command-line prompt in its entirety, or
line by line. Alternatively, you can download a text file to the security appliance internal Flash memory.
See Chapter 43, “Managing Software and Configurations,” for information on downloading the
configuration file to the security appliance.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
2-9
Chapter 2
Getting Started
Working with the Configuration
In most cases, commands described in this guide are preceded by a CLI prompt. The prompt in the
following example is “hostname(config)#”:
hostname(config)# context a
In the text configuration file you are not prompted to enter commands, so the prompt is omitted as
follows:
context a
For additional information about formatting the file, see Appendix B, “Using the Command-Line
Interface.”
Cisco Security Appliance Command Line Configuration Guide
2-10
OL-12172-04
CH A P T E R
3
Managing Feature Licenses
A license specifies the options that are enabled on a given security appliance. It is represented by an
activation key which is a 160-bit (5 32-bit words or 20 bytes) value. This value encodes the serial number
(an 11 character string) and the enabled features.
This chapter describes how to obtain an activation key and activate it. It also describes the available
licenses for each model. This chapter includes the following sections:
This document includes the following sections:
•
Supported Feature Licenses Per Model, page 3-1
•
Information About Feature Licenses, page 3-9
•
Guidelines and Limitations, page 3-12
•
Viewing Your Current License, page 3-12
•
Obtaining an Activation Key, page 3-14
•
Entering a New Activation Key, page 3-15
•
Upgrading the License for a Failover Pair, page 3-16
•
Feature History for Licensing, page 3-18
Supported Feature Licenses Per Model
This section lists the feature licenses available for each model:
•
ASA 5505, Table 3-1 on page 3-2
•
ASA 5510, Table 3-2 on page 3-3
•
ASA 5520, Table 3-3 on page 3-4
•
ASA 5540, Table 3-4 on page 3-5
•
ASA 5550, Table 3-5 on page 3-6
•
PIX 515/515E, Table 3-6 on page 3-7
•
PIX 525. Table 3-7 on page 3-8
•
PIX 535, Table 3-8 on page 3-9
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-1
Chapter 3
Managing Feature Licenses
Supported Feature Licenses Per Model
Note
The ASA 5580 is not supported in Version 8.0; for ASA 5580 information, see the licensing
documentation for Version 8.1 or later.
The PIX 500 series security appliance does not support temporary licenses.
Items that are in italics are separate, optional licenses with which that you can replace the Base or
Security Plus license. You can mix and match licenses, for example, the 10 security context license plus
the Strong Encryption license; or the 500 SSL VPN license plus the GTP/GPRS license; or all four
licenses together.
Table 3-1
ASA 5505 Adaptive Security Appliance License Features
ASA 5505
Base License
Users, concurrent
1
10
2
Optional licenses:
50
Security Contexts
Security Plus
102
Unlimited
Optional licenses:
50
Unlimited
No support
No support
25 combined IPSec and SSL VPN
25 combined IPSec and SSL VPN
Max. IPSec Sessions
10
25
Max. SSL VPN
Sessions
2
VPN Sessions
3
Optional licenses:
10
2
25
Optional licenses:
10
25
VPN Load Balancing
No support
No support
Advanced Endpoint
Assessment
None
Unified Communications
Proxy Sessions4
2
Failover
No support
Active/Standby (no stateful failover)
GTP/GPRS
No support
No support
Maximum VLANs/Zones
3 (2 regular zones and 1 restricted zone that
can only communicate with 1 other zone)
20
Maximum VLAN Trunks
No support
8 trunks
Optional license: Enabled
Optional license: 24
None
2
Optional license: Enabled
Optional license: 24
Concurrent Firewall Conns 10 K
25 K
Max. Physical Interfaces
Unlimited, assigned to VLANs/zones
Unlimited, assigned to VLANs/zones
Encryption
Base (DES)
Base (DES)
Minimum RAM
256 MB (default)
Optional license:
Strong (3DES/AES)
Optional license:
Strong (3DES/AES)
256 MB (default)
1. In routed mode, hosts on the inside (Business and Home VLANs) count towards the limit only when they communicate with the outside (Internet VLAN).
Internet hosts are not counted towards the limit. Hosts that initiate traffic between Business and Home are also not counted towards the limit. The interface
associated with the default route is considered to be the Internet interface. If there is no default route, hosts on all interfaces are counted toward the limit.
In transparent mode, the interface with the lowest number of hosts is counted towards the host limit. See the show local-host command to view the host
limits.
2. For a 10-user license, the max. DHCP clients is 32. For 50 users, the max. is 128. For unlimited users, the max. is 250, which is the max. for other models.
3. Although the maximum IPSec and SSL VPN sessions add up to more than the maximum VPN sessions, the combined sessions should not exceed the VPN
session limit. If you exceed the maximum VPN sessions, you can overload the security appliance, so be sure to size your network appropriately. When
determining the session makeup of the combined limit, the number of SSL VPN sessions cannot exceed the number of licensed SSL VPN sessions on the
security appliance (which is 2 by default).
4. Phone Proxy, Mobility Proxy, Presence Federation Proxy, and TLS Proxy are all licensed under the UC Proxy umbrella, and can be mixed and matched.
For example, if you configure a phone with a primary and backup Cisco Unified Communications Manager, there are 2 TLS/SRTP connections, and 2
UC Proxy sessions are used. This license was introduced in Version 8.0(4). In prior versions, TLS proxy for SIP and Skinny inspection was included in
the Base License.
Cisco Security Appliance Command Line Configuration Guide
3-2
OL-12172-04
Chapter 3
Managing Feature Licenses
Supported Feature Licenses Per Model
Table 3-2
ASA 5510 Adaptive Security Appliance License Features
ASA 5510
Base License
Security Plus
Users, concurrent
Unlimited
Unlimited
Security Contexts
No support
2
Optional licenses:
5
VPN Sessions
1
250 combined IPSec and SSL VPN
250 combined IPSec and SSL VPN
Max. IPSec Sessions
250
250
Max. SSL VPN
Sessions
2
Optional licenses:
10
25
50
2
100
250
10
2
Optional VPN Flex license: 250
VPN Load Balancing
No support
Advanced Endpoint
Assessment
None
Unified Communications
2
Proxy Sessions3 (introduced
in 8.0(4))
25
50
100
250
Optional VPN Flex license: 250
Supported
Optional license: Enabled
Optional licenses
24
Optional licenses:
50
None
2
100
Optional license: Enabled
Optional licenses
24
50
100
Failover
No support
Active/Standby or Active/Active4
GTP/GPRS
No support
No support
Max. VLANs
50
100
Concurrent Firewall Conns
50 K
130 K
Max. Physical Interfaces
Unlimited
Unlimited
Encryption
Base (DES)
Min. RAM
256 MB (default)
Optional license:
Strong (3DES/AES)
Base (DES)
Optional license:
Strong (3DES/AES)
256 MB (default)
1. Although the maximum IPSec and SSL VPN sessions add up to more than the maximum VPN sessions, the combined sessions should not exceed the VPN
session limit. If you exceed the maximum VPN sessions, you can overload the security appliance, so be sure to size your network appropriately. When
determining the session makeup of the combined limit, the number of SSL VPN sessions cannot exceed the number of licensed SSL VPN sessions on the
security appliance (which is 2 by default).
2. Available in Version 8.0(4) and later.
3. Phone Proxy, Mobility Proxy, Presence Federation Proxy, and TLS Proxy are all licensed under the UC Proxy umbrella, and can be mixed and matched.
For example, if you configure a phone with a primary and backup Cisco Unified Communications Manager, there are 2 TLS/SRTP connections, and 2
UC Proxy sessions are used. This license was introduced in Version 8.0(4). In prior versions, TLS proxy for SIP and Skinny inspection was included in
the Base License.
4. You cannot use Active/Active failover and VPN; if you want to use VPN, use Active/Standby failover.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-3
Chapter 3
Managing Feature Licenses
Supported Feature Licenses Per Model
Table 3-3
ASA 5520 Adaptive Security Appliance License Features
ASA 5520
Base License
Users, concurrent
Unlimited
Security Contexts
2
Optional licenses:
5
VPN Sessions
1
Unlimited
10
20
750 combined IPSec and SSL VPN
Max. IPSec Sessions
750
Max. SSL VPN
Sessions
2
Optional licenses:
10
25
50
100
Optional VPN Flex licenses:
VPN Load Balancing
Supported
Advanced Endpoint
Assessment
None
Unified Communications
Proxy Sessions3
2
250
2
500
250
750
750
Optional license: Enabled
Optional licenses
24
50
100
Failover
Active/Standby or Active/Active
GTP/GPRS
None
Max. VLANs
150
250
500
750
1000
4
Optional license: Enabled
Concurrent Firewall Conns 280 K
Max. Physical Interfaces
Unlimited
Encryption
Base (DES)
Min. RAM
512 MB (default)
Optional license: Strong (3DES/AES)
1. Although the maximum IPSec and SSL VPN sessions add up to more than the maximum VPN sessions, the combined sessions should not exceed the VPN
session limit. If you exceed the maximum VPN sessions, you can overload the security appliance, so be sure to size your network appropriately. When
determining the session makeup of the combined limit, the number of SSL VPN sessions cannot exceed the number of licensed SSL VPN sessions on the
security appliance (which is 2 by default).
2. Available in Version 8.0(4) and later.
3. Phone Proxy, Mobility Proxy, Presence Federation Proxy, and TLS Proxy are all licensed under the UC Proxy umbrella, and can be mixed and matched.
For example, if you configure a phone with a primary and backup Cisco Unified Communications Manager, there are 2 TLS/SRTP connections, and 2
UC Proxy sessions are used. This license was introduced in Version 8.0(4). In prior versions, TLS proxy for SIP and Skinny inspection was included in
the Base License.
4. You cannot use Active/Active failover and VPN; if you want to use VPN, use Active/Standby failover.
Cisco Security Appliance Command Line Configuration Guide
3-4
OL-12172-04
Chapter 3
Managing Feature Licenses
Supported Feature Licenses Per Model
Table 3-4
ASA 5540 Adaptive Security Appliance License Features
ASA 5540
Base License
Users, concurrent
Unlimited
Security Contexts
2
Optional licenses:
5
VPN Sessions
1
Unlimited
10
20
50
5000 combined IPSec and SSL VPN
Max. IPSec Sessions
5000
Max. SSL VPN
Sessions
2
Optional licenses:
10
25
50
100
Optional VPN Flex Licenses:
VPN Load Balancing
Supported
Advanced Endpoint
Assessment
None
Unified Communications
Proxy Sessions3
2
Failover
Active/Standby or Active/Active4
GTP/GPRS
None
Max. VLANs
200
Concurrent Firewall Conns
400 K
Max. Physical Interfaces
Unlimited
Encryption
Base (DES)
Min. RAM
1 GB (default)
250
2
500
250
750
1000
2500
750
1000
2500
1000
2000
Optional license: Enabled
Optional licenses
24
50
100
250
500
750
Optional license: Enabled
Optional license: Strong (3DES/AES)
1. Although the maximum IPSec and SSL VPN sessions add up to more than the maximum VPN sessions, the combined sessions should not exceed the VPN
session limit. If you exceed the maximum VPN sessions, you can overload the security appliance, so be sure to size your network appropriately. When
determining the session makeup of the combined limit, the number of SSL VPN sessions cannot exceed the number of licensed SSL VPN sessions on the
security appliance (which is 2 by default). This license was introduced in Version 8.0(4). In prior versions, TLS proxy for SIP and Skinny inspection was
included in the Base License.
2. Available in Version 8.0(4) and later.
3. Phone Proxy, Mobility Proxy, Presence Federation Proxy, and TLS Proxy are all licensed under the UC Proxy umbrella, and can be mixed and matched.
For example, if you configure a phone with a primary and backup Cisco Unified Communications Manager, there are 2 TLS/SRTP connections, and 2
UC Proxy sessions are used. Prior to 8.0(4), only TLS Proxy was available.
4. You cannot use Active/Active failover and VPN; if you want to use VPN, use Active/Standby failover.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-5
Chapter 3
Managing Feature Licenses
Supported Feature Licenses Per Model
Table 3-5
ASA 5550 Adaptive Security Appliance License Features
ASA 5550
Base License
Users, concurrent
Unlimited
Security Contexts
2
Optional licenses:
5
VPN Sessions
1
10
20
50
5000 combined IPSec and SSL VPN
Max. IPSec Sessions
5000
Max. SSL VPN
Sessions
2
Optional licenses:
10
25
50
100
Optional VPN Flex licenses:
VPN Load Balancing
Supported
Advanced Endpoint
Assessment
None
Unified Communications
Proxy Sessions3
2
Failover
Active/Standby or Active/Active4
GTP/GPRS
None
Max. VLANs
250
250
2
500
250
750
1000
2500
5000
750
1000
2500
5000
1000
2000
3000
Optional license: Enabled
Optional licenses
24
50
100
250
500
750
Optional license: Enabled
Concurrent Firewall Conns 650 K
Max. Physical Interfaces
Unlimited
Encryption
Base (DES)
Min. RAM
4 GB (default)
Optional license: Strong (3DES/AES)
1. Although the maximum IPSec and SSL VPN sessions add up to more than the maximum VPN sessions, the combined sessions should not exceed the VPN
session limit. If you exceed the maximum VPN sessions, you can overload the security appliance, so be sure to size your network appropriately. When
determining the session makeup of the combined limit, the number of SSL VPN sessions cannot exceed the number of licensed SSL VPN sessions on the
security appliance (which is 2 by default). This license was introduced in Version 8.0(4). In prior versions, TLS proxy for SIP and Skinny inspection was
included in the Base License.
2. Available in Version 8.0(4) and later.
3. Phone Proxy, Mobility Proxy, Presence Federation Proxy, and TLS Proxy are all licensed under the UC Proxy umbrella, and can be mixed and matched.
For example, if you configure a phone with a primary and backup Cisco Unified Communications Manager, there are 2 TLS/SRTP connections, and 2 UC
Proxy sessions are used.
4. You cannot use Active/Active failover and VPN; if you want to use VPN, use Active/Standby failover.
Cisco Security Appliance Command Line Configuration Guide
3-6
OL-12172-04
Chapter 3
Managing Feature Licenses
Supported Feature Licenses Per Model
Table 3-6
PIX 515/515E Security Appliance License Features
PIX 515/515E
R (Restricted)
UR (Unrestricted)
FO (Failover)1
FO-AA (Failover
Active/Active)1
Advanced
Endpoint
Assessment
No support
No support
No support
No support
Encryption
None Optional licenses: None Optional licenses: None Optional licenses: None Optional licenses:
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Failover
No support
Active/Standby
Active/Active
Active/Standby
Active/Standby
Active/Active
Firewall Conns,
concurrent
48 K
130 K
130 K
130 K
GTP/GPRS
None Optional license:
Enabled
None Optional license:
Enabled
None Optional license:
Enabled
None Optional license:
Enabled
IPSec Sessions
2000
2000
2000
2000
Physical
Interfaces, max.
3
6
6
6
RAM, min.
64 MB (default)
128 MB
128 MB
128 MB
Security
Contexts
No support
2 Optional license: 5
2 Optional license: 5
2 Optional license: 5
SSL VPN
Sessions
No support
No support
No support
No support
Unified
No support
Communications
Proxy Sessions
No support
No support
No support
Users,
concurrent
Unlimited
Unlimited
Unlimited
Unlimited
VLANs, max.
10
25
25
25
VPN Load
Balancing
No support
No support
No support
No support
1. This license can only be used in a failover pair with another unit with a UR license. Both units must be the same model.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-7
Chapter 3
Managing Feature Licenses
Supported Feature Licenses Per Model
Table 3-7
PIX 525 Security Appliance License Features
PIX 525
R (Restricted)
UR (Unrestricted)
FO (Failover)1
FO-AA (Failover
Active/Active)1
Advanced
Endpoint
Assessment
No support
No support
No support
No support
Encryption
None Optional licenses: None Optional licenses: None Optional licenses: None Optional licenses:
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Failover
No support
Active/Standby
Active/Active
Active/Standby
Active/Standby
Active/Active
Firewall Conns,
concurrent
140 K
280 K
280 K
280 K
GTP/GPRS
None Optional license:
Enabled
None Optional license:
Enabled
None Optional license:
Enabled
None Optional license:
Enabled
IPSec Sessions
2000
2000
2000
2000
Physical
Interfaces, max.
6
10
10
10
RAM, min.
128 MB (default)
256 MB
256 MB
256 MB
Security
Contexts
No support
2 Optional licenses:
2 Optional licenses:
2 Optional licenses:
SSL VPN
Sessions
No support
No support
No support
No support
Unified
No support
Communications
Proxy Sessions
No support
No support
No support
Users,
concurrent
Unlimited
Unlimited
Unlimited
Unlimited
VLANs, max.
25
100
100
100
VPN Load
Balancing
No support
No support
No support
No support
5
10 20
50
5
10 20
50
5
10
20
50
1. This license can only be used in a failover pair with another unit with a UR license. Both units must be the same model.
Cisco Security Appliance Command Line Configuration Guide
3-8
OL-12172-04
Chapter 3
Managing Feature Licenses
Information About Feature Licenses
Table 3-8
PIX 535 Security Appliance License Features
PIX 535
R (Restricted)
UR (Unrestricted)
FO (Failover)1
FO-AA (Failover
Active/Active)1
Advanced
Endpoint
Assessment
No support
No support
No support
No support
Encryption
None Optional licenses: None Optional licenses: None Optional licenses: None Optional licenses:
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Base
(DES)
Strong
(3DES/
AES)
Failover
No support
Active/Standby
Active/Active
Active/Standby
Active/Standby
Active/Active
Firewall Conns,
concurrent
250 K
500 K
500 K
500 K
GTP/GPRS
None Optional license:
Enabled
None Optional license:
Enabled
None Optional license:
Enabled
None Optional license:
Enabled
IPSec Sessions
2000
2000
2000
2000
Physical
Interfaces, max.
8
14
14
14
RAM, min.
512 MB (default)
1024 MB
1024 MB
1024 MB
Security
Contexts
No support
2 Optional licenses:
2 Optional licenses:
2 Optional licenses:
SSL VPN
Sessions
No support
No support
No support
No support
Unified
No support
Communications
Proxy Sessions
No support
No support
No support
Users,
concurrent
Unlimited
Unlimited
Unlimited
Unlimited
VLANs, max.
50
150
150
150
VPN Load
Balancing
No support
No support
No support
No support
5
10 20
50
5
10 20
50
5
10
20
50
1. This license can only be used in a failover pair with another unit with a UR license. Both units must be the same model.
Information About Feature Licenses
A license specifies the options that are enabled on a given security appliance. It is represented by an
activation key which is a 160-bit (5 32-bit words or 20 bytes) value. This value encodes the serial number
(an 11 character string) and the enabled features.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-9
Chapter 3
Managing Feature Licenses
Information About Feature Licenses
This section includes the following topics:
•
Preinstalled License, page 3-10
•
VPN Flex and Evaluation Licenses, page 3-10
Preinstalled License
By default, your security appliance ships with a license already installed. This license might be the Base
License, to which you want to add more licenses, or it might already have all of your licenses installed,
depending on what you ordered and what your vendor installed for you. See the “Viewing Your Current
License” section on page 3-12 section to determine which licenses you have installed.
VPN Flex and Evaluation Licenses
Note
The PIX 500 series security appliance does not support temporary licenses.
In addition to permanent licenses, you can purchase a temporary VPN Flex license or receive an
evaluation license that has a time-limit. For example, you might buy a VPN Flex license to handle
short-term surges in the number of concurrent SSL VPN users.
This section includes the following topics:
•
How the Temporary License Timer Works, page 3-10
•
How Multiple Licenses Interact, page 3-11
•
Failover and Temporary Licenses, page 3-11
How the Temporary License Timer Works
Note
•
The timer for the temporary license starts counting down when you activate it on the security
appliance.
•
If you stop using the temporary license before it times out, for example you activate a permanent
license or a different temporary license, then the timer halts. The timer only starts again when you
reactivate the temporary license.
•
If the temporary license is active, and you shut down the security appliance, then the timer continues
to count down. If you intend to leave the security appliance in a shut down state for an extended
period of time, then you should activate the permanent license before you shut down to preserve the
temporary license.
•
When a temporary license expires, the next time you reload the security appliance, the permanent
license is used; you are not forced to perform a reload immediately when the license expires.
We suggest you do not change the system clock after you install the temporary license. If you set the
clock to be a later date, then if you reload, the security appliance checks the system clock against the
original installation time, and assumes that more time has passed than has actually been used. If you set
the clock back, and the actual running time is greater than the time between the original installation time
and the system clock, then the license immediately expires after a reload.
Cisco Security Appliance Command Line Configuration Guide
3-10
OL-12172-04
Chapter 3
Managing Feature Licenses
Information About Feature Licenses
How Multiple Licenses Interact
•
When you activate a temporary license, then features from both permanent and temporary licenses
combine to form the running license. The security appliance uses the highest value from each license
for each feature, and displays any resolved conflicts between the licenses when you enter a
temporary activation key. In the rare circumstance that a temporary license has lower capability than
the permanent license, the permanent license values are used.
•
When you activate a permanent license, it overwrites the currently-running permanent and
temporary licenses and becomes the running license.
Note
If the permanent license is a downgrade from the temporary license, then you need to reload
the security appliance to disable the temporary license and restore the permanent license.
Until you reload, the temporary license continues to count down.
Interim release 8.0(4.16) includes an enhancement so that you do not need to reload the
security appliance after reactivating the already installed permanent license; this
enhancement stops the temporary license from continuing to count down with no disruption
of traffic.
•
To reenable the features of the temporary license if you later activate a permanent license, simply
reenter the temporary activation key. For a license upgrade, you do not need to reload.
•
To switch to a different temporary license, enter the new activation key; the new license is used
instead of the old temporary license and combines with the permanent license to create a new
running license. The security appliance can have multiple temporary licenses installed; but only one
is active at any given time.
See the following figure for examples of permanent and VPN Flex activation keys, and how they interact.
Permanent and VPN Flex Activation Keys
Permanent Key
1.
Base + 10 SSL conns
VPN Flex Key
+
Merged Key
2.
Base + 25 SSL conns
Base + 10 SSL conns
+
Base + 10 SSL conns
+
Base + 10 SSL conns + +
50 contexts
50 contexts
=
Base + 10 SSL conns
Merged Key
=
VPN Flex Key
25 SSL conns
Base + 25 SSL conns
Permanent Key
Evaluation Key
Merged Key
4.
=
Permanent Key
Permanent Key
3.
25 SSL conns
Merged Key
Base + 10 SSL conns +
50 contexts
New Merged Key
=
Base + 25 SSL conns
251137
Figure 3-1
Failover and Temporary Licenses
Because the temporary license continues to count down for as long as it is activated on a failover unit,
we do not recommend using a temporary license in a failover situation, except in an emergency where
the temporary license is activated only for a short period of time. In this case, one unit can use the
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-11
Chapter 3
Managing Feature Licenses
Guidelines and Limitations
permanent license and the other unit can use the temporary license if the features are equivalent between
the permanent and temporary licenses. This functionality is useful if the hardware fails on a unit, and
you need to replace it for a short period of time until the replacement unit arrives.
Guidelines and Limitations
See the following guidelines for activation keys.
Context Mode Guidelines
In multiple context mode, apply the activation key in the system execution space.
Firewall Mode Guidelines
Activation keys are available in both routed and transparent mode.
Failover Guidelines
Because the temporary license continues to count down for as long as it is activated on a failover unit,
we do not recommend using a temporary license in a failover situation, except in an emergency where
the temporary license is activated only for a short period of time. In this case, one unit can use the
permanent license and the other unit can use the temporary license if the features are equivalent between
the permanent and temporary licenses. This functionality is useful if the hardware fails on a unit, and
you need to replace it for a short period of time until the replacement unit arrives.
Additional Guidelines and Limitations
•
The activation key is not stored in your configuration file; it is stored as a hidden file in Flash
memory.
•
The activation key is tied to the serial number of the device. Feature licenses cannot be transferred
between devices (except in the case of a hardware failure). If you have to replace your device due
to a hardware failure, contact the Cisco Licensing Team to have your existing license transferred to
the new serial number. The Cisco Licensing Team will ask for the Product Authorization Key
reference number and existing serial number.
•
Once purchased, you cannot return a license for a refund or for an upgraded license.
•
You cannot add two separate licenses for the same feature together; for example, if you purchase a
25-session SSL VPN license, and later purchase a 50-session license, you cannot use 75 sessions;
you can use a maximum of 50 sessions.
Viewing Your Current License
This section describes how to view your current license, and for temporary activation keys, how much
time the license has left.
Cisco Security Appliance Command Line Configuration Guide
3-12
OL-12172-04
Chapter 3
Managing Feature Licenses
Viewing Your Current License
Detailed Steps
Command
Purpose
show activation-key detail
Shows the installed licenses, including information about temporary
licenses.
Example:
hostname# show activation-key detail
Examples
The following is sample output from the show activation-key detail command that shows a permanent
activation license, an active temporary license, the merged running license, and also the activation keys
for inactive temporary licenses:
hostname# show activation-key detail
Serial Number:
JMX0916L0Z4
Permanent Flash Activation Key: 0xf412675d 0x48a446bc 0x8c532580 0xb000b8c4 0xcc21f48e
Licensed features for this platform:
Maximum Physical Interfaces : Unlimited
Maximum VLANs
: 200
Inside Hosts
: Unlimited
Failover
: Active/Active
VPN-DES
: Enabled
VPN-3DES-AES
: Enabled
Security Contexts
: 2
GTP/GPRS
: Disabled
VPN Peers
: 5000
WebVPN Peers
: 2
AnyConnect for Mobile
: Disabled
AnyConnect for Linksys phone : Disabled
Advanced Endpoint Assessment : Disabled
UC Proxy Sessions:
: 2
Temporary Flash Activation Key: 0xcb0367ce 0x700dd51d 0xd57b98e3 0x6ebcf553 0x0b058aac
Licensed features for this platform:
Maximum Physical Interfaces : Unlimited
Maximum VLANs
: 200
Inside Hosts
: Unlimited
Failover
: Active/Active
VPN-DES
: Enabled
VPN-3DES-AES
: Disabled
Security Contexts
: 2
GTP/GPRS
: Disabled
VPN Peers
: 5000
WebVPN Peers
: 500
AnyConnect for Mobile
: Disabled
AnyConnect for Linksys phone : Disabled
Advanced Endpoint Assessment : Disabled
UC Proxy Sessions:
: 2
This is a time-based license that will expire in 27 day(s).
Running Activation Key: 0xcb0367ce 0x700dd51d 0xd57b98e3 0x6ebcf553 0x0b058aac
Licensed features for this platform:
Maximum Physical Interfaces : Unlimited
Maximum VLANs
: 200
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-13
Chapter 3
Managing Feature Licenses
Obtaining an Activation Key
Inside Hosts
Failover
VPN-DES
VPN-3DES-AES
Security Contexts
GTP/GPRS
VPN Peers
WebVPN Peers
AnyConnect for Mobile
AnyConnect for Linksys phone
Advanced Endpoint Assessment
UC Proxy Sessions:
:
:
:
:
:
:
:
:
:
:
:
:
Unlimited
Active/Active
Enabled
Enabled
2
Disabled
5000
500
Disabled
Disabled
Disabled
2
This platform has an ASA 5540 VPN Premium license.
This is a time-based license that will expire in 27 day(s).
The flash activation key is the SAME as the running key.
Non-active temporary keys:
Time left
-----------------------------------------------------------------0x2a53d6
0xfc087bfe 0x691b94fb 0x73dc8bf3 0xcc028ca2 28 day(s)
0xa13a46c2 0x7c10ec8d 0xad8a2257 0x5ec0ab7f 0x86221397 27 day(s)
Obtaining an Activation Key
To obtain an activation key, you need a Product Authorization Key, which you can purchase from your
Cisco account representative. You need to purchase a separate Product Activation Key for each feature
license. For example, if you have the Base License, you can purchase separate keys for Advanced
Endpoint Assessment and for additional SSL VPN sessions.
Note
For a failover pair, you need separate activation keys for each unit. Make sure the licenses included in
the keys are the same for both units.
After obtaining the Product Authorization Keys, register them on Cisco.com by performing the
following steps:
Step 1
Obtain the serial number for your security appliance by entering the following command:
hostname# show activation-key
Step 2
Access one of the following URLs.
•
Use the following website if you are a registered user of Cisco.com:
http://www.cisco.com/go/license
•
Use the following website if you are not a registered user of Cisco.com:
http://www.cisco.com/go/license/public
Step 3
Enter the following information, when prompted:
•
Product Authorization Key (if you have multiple keys, enter one of the keys first. You have to enter
each key as a separate process.)
•
The serial number of your security appliance
Cisco Security Appliance Command Line Configuration Guide
3-14
OL-12172-04
Chapter 3
Managing Feature Licenses
Entering a New Activation Key
•
Your email address
An activation key is automatically generated and sent to the email address that you provide. This key
includes all features you have registered so far for permanent licenses. For VPN Flex licenses, each
license has a separate activation key.
Step 4
If you have additional Product Authorization Keys, repeat Step 3 for each Product Authorization Key.
After you enter all of the Product Authorization Keys, the final activation key provided includes all of
the permanent features you registered.
Entering a New Activation Key
Before entering the activation key, ensure that the image in Flash memory and the running image are the
same. You can do this by reloading the security appliance before entering the new activation key.
Prerequisites
•
If you are already in multiple context mode, enter the activation key in the system execution space.
•
Some licenses require you to reload the security appliance after you activate them. Table 3-9 lists
the licenses that require reloading.
Table 3-9
License Reloading Requirements
Model
License Action Requiring Reload
ASA 5505 and ASA 5510
Changing between the Base and Security Plus
license.
PIX 500 series
Changing between R, UR, FO, and FO-AA
licenses.
All models
Changing the Encryption license.
All models
Downgrading any license (for example, going
from 10 contexts to 2 contexts).
Note
If a temporary license expires, and the
permanent license is a downgrade, then
you do not need to immediately reload the
security appliance; the next time you
reload, the permanent license is restored.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-15
Chapter 3
Managing Feature Licenses
Upgrading the License for a Failover Pair
Detailed Steps
Step 1
Command
Purpose
activation-key key
Applies an activation key to the security appliance. The key is a
five-element hexadecimal string with one space between each
element. The leading 0x specifier is optional; all values are
assumed to be hexadecimal.
Example:
hostname(config)# activation-key
0xd11b3d48 0xa80a4c0a 0x48e0fd1c
0xb0443480 0x843fc490
Step 2
reload
Example:
hostname(config)# reload
You can enter one permanent key, and multiple temporary keys.
The last temporary key entered is the active one. See the “VPN
Flex and Evaluation Licenses” section on page 3-10 for more
information. To change the running activation key, enter the
activation-key command with a new key value.
(Might be required.) Reloads the security appliance. Some
licenses require you to reload the security appliance after entering
the new activation key. See Table 3-9 on page 3-15 for a list of
licenses that need reloading. If you need to reload, you will see
the following message:
WARNING: The running activation key was not updated with
the requested key. The flash activation key was updated
with the requested key, and will become active after the
next reload.
Upgrading the License for a Failover Pair
If you need to upgrade the license on a failover pair, you might have some amount of downtime
depending on whether the license requires a reload. See Table 3-9 on page 3-15 for more information
about licenses requiring a reload. This section includes the following topics:
•
Upgrading the License for a Failover (No Reload Required), page 3-16
•
Upgrading the License for a Failover (Reload Required), page 3-17
Upgrading the License for a Failover (No Reload Required)
Use the following procedure if your new license does not require you to reload. See Table 3-9 on
page 3-15 for more information about licenses requiring a reload. This procedure ensures that there is
no downtime.
Detailed Steps
Command
Purpose
On the active unit:
Step 1
no failover
Example:
active(config)# no failover
Disables failover on the active unit. The standby unit remains in
standby mode.
Cisco Security Appliance Command Line Configuration Guide
3-16
OL-12172-04
Chapter 3
Managing Feature Licenses
Upgrading the License for a Failover Pair
Step 2
Command
Purpose
activation-key key
Installs the new license on the active unit.
Example:
active(config)# activation-key 0xd11b3d48
0xa80a4c0a 0x48e0fd1c 0xb0443480
0x843fc490
On the standby unit:
Step 3
activation-key key
Installs the new license on the standby unit.
Example:
standby(config)# activation-key 0xc125727f
0x903de1ee 0x8c838928 0x92dc84d4
0x003a2ba0
On the active unit:
Step 4
Reenables failover.
failover
Example:
active(config)# failover
Upgrading the License for a Failover (Reload Required)
Use the following procedure if your new license requires you to reload. See Table 3-9 on page 3-15 for
more information about licenses requiring a reload. Reloading the failover pair causes a loss of
connectivity during the reload.
Detailed Steps
Command
Purpose
On the active unit:
Step 1
no failover
Example:
active(config)# no failover
Step 2
Disables failover on the active unit. The standby unit remains in
standby mode.
activation-key key
Installs the new license on the active unit.
Example:
active(config)# activation-key 0xd11b3d48
0xa80a4c0a 0x48e0fd1c 0xb0443480
0x843fc490
If you need to reload, you will see the following message:
WARNING: The running activation key was not updated with
the requested key. The flash activation key was updated
with the requested key, and will become active after the
next reload.
If you do not need to reload, then follow the “Upgrading the
License for a Failover (No Reload Required)” section on
page 3-16 instead of this procedure.
On the standby unit:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-17
Chapter 3
Managing Feature Licenses
Feature History for Licensing
Step 3
Command
Purpose
activation-key key
Installs the new license on the standby unit.
Example:
standby(config)# activation-key 0xc125727f
0x903de1ee 0x8c838928 0x92dc84d4
0x003a2ba0
Step 4
Reloads the standby unit.
reload
Example:
standby(config)# reload
On the active unit:
Step 5
Reloads the active unit. When you are prompted to save the
configuration before reloading, answer No. This means that when
the active unit comes back up, failover will still be enabled.
reload
Example:
active(config)# reload
Feature History for Licensing
Table 3-10 lists the release history for this feature.
Table 3-10
Feature History for Licensing
Feature Name
Releases
Feature Information
Increased Connections and VLANs
7.0(5)
Increased the following limits:
•
ASA5510 Base license connections from 32000 to
5000; VLANs from 0 to 10.
•
ASA5510 Security Plus license connections from
64000 to 130000; VLANs from 10 to 25.
•
ASA5520 connections from 130000 to 280000; VLANs
from 25 to 100.
•
ASA5540 connections from 280000 to 400000; VLANs
from 100 to 200.
SSL VPN Licenses for the ASA 5500 series
7.1(1)
SSL VPN licenses were introduced. This feature is not
supported on the Cisco PIX 500 series.
Increased SSL VPN Licenses
7.2(1)
A 5000-user SSL VPN license was introduced for the ASA
5550 and above.
Cisco Security Appliance Command Line Configuration Guide
3-18
OL-12172-04
Chapter 3
Managing Feature Licenses
Feature History for Licensing
Table 3-10
Feature History for Licensing (continued)
Feature Name
Releases
Feature Information
Increased VLANs
7.2(2)
The maximum number of VLANs for the Security Plus
License on the ASA 5505 was increased from 5 (3 fully
functional; 1 failover; one restricted to a backup interface)
to 20 fully functional interfaces. In addition, the number of
trunk ports was increased from 1 to 8. Now there are 20
fully functional interfaces, you do not need to use the
backup interface command to cripple a backup ISP
interface; you can use a fully-functional interface for it. The
backup interface command is still useful for an Easy VPN
configuration.
VLAN limits were also increased for the ASA 5510 (from
10 to 50 for the Base License, and from 25 to 100 for the
Security Plus License), the ASA 5520 (from 100 to 150),
the ASA 5550 (from 200 to 250).
Gigabit Ethernet Support for the ASA 5510
7.2(3)
The ASA 5510 now has the Security Plus License to enable
GE (Gigabit Ethernet) for port 0 and 1. If you upgrade the
license from Base to Security Plus, the capacity of the
external Ethernet0/0 and Ethernet0/1 ports increases from
the original FE (Fast Ethernet) (100 Mbps) to GE (1000
Mbps). The interface names will remain Ethernet 0/0 and
Ethernet 0/1. Use the speed command to change the speed
on the interface and use the show interface command to see
what speed is currently configured for each interface.
Advanced Endpoint Assessment License for the 8.0(2)
ASA 5500 series
The Advanced Endpoint Assessment License was
introduced. As a condition for the completion of a Cisco
AnyConnect or clientless SSL VPN connections, the remote
computer scans for a greatly expanded collection of
antivirus and antispyware applications, firewalls, operating
systems, and associated updates. It also scans for any
registry entries, filenames, and process names that you
specify. It sends the scan results to the adaptive security
appliance. The security appliance uses both the user login
credentials and the computer scan results to assign a
Dynamic Access Policy (DAP).
With an Advanced Endpoint Assessment License, you can
enhance Host Scan by configuring an attempt to update
noncompliant computers to meet version requirements.
We provide timely updates to the list of applications and
versions that Host Scan supports in a package that is
separate from Cisco Secure Desktop.
This feature is not supported on the PIX 500 series.
VPN Load Balancing for the ASA 5510
8.0(2)
VPN load balancing is now supported on the ASA 5510
Security Plus License.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
3-19
Chapter 3
Managing Feature Licenses
Feature History for Licensing
Table 3-10
Feature History for Licensing (continued)
Feature Name
Releases
Feature Information
VPN Flex and Temporary Licenses for the ASA 8.0(4)
5500 series
Support for temporary licenses was introduced. This feature
is not supported on the PIX 500 series.
Unified Communications Proxy Sessions
license for the ASA 5500 series
The UC Proxy sessions license was introduced. This feature
is not available in Version 8.1. This feature is not supported
on the PIX 500 series.
8.0(4)
Cisco Security Appliance Command Line Configuration Guide
3-20
OL-12172-04
CH A P T E R
4
Enabling Multiple Context Mode
This chapter describes how to use security contexts and enable multiple context mode. This chapter
includes the following sections:
•
Security Context Overview, page 4-1
•
Enabling or Disabling Multiple Context Mode, page 4-10
Security Context Overview
You can partition a single security appliance into multiple virtual devices, known as security contexts.
Each context is an independent device, with its own security policy, interfaces, and administrators.
Multiple contexts are similar to having multiple standalone devices. Many features are supported in
multiple context mode, including routing tables, firewall features, IPS, and management. Some features
are not supported, including VPN and dynamic routing protocols.
Note
When the security appliance is configured for security contexts (also called firewall multmode) or
Active/Active stateful failover, IPSec or SSL VPN cannot be enabled. Therefore, these features are
unavailable.
This section provides an overview of security contexts, and includes the following topics:
•
Common Uses for Security Contexts, page 4-2
•
Unsupported Features, page 4-2
•
Context Configuration Files, page 4-2
•
How the Security Appliance Classifies Packets, page 4-3
•
Cascading Security Contexts, page 4-8
•
Management Access to Security Contexts, page 4-9
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
4-1
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
Common Uses for Security Contexts
You might want to use multiple security contexts in the following situations:
•
You are a service provider and want to sell security services to many customers. By enabling
multiple security contexts on the security appliance, you can implement a cost-effective,
space-saving solution that keeps all customer traffic separate and secure, and also eases
configuration.
•
You are a large enterprise or a college campus and want to keep departments completely separate.
•
You are an enterprise that wants to provide distinct security policies to different departments.
•
You have any network that requires more than one security appliance.
Unsupported Features
Multiple context mode does not support the following features:
•
Dynamic routing protocols
Security contexts support only static routes. You cannot enable OSPF, RIP, or EIGRP in multiple
context mode.
•
VPN
•
Multicast routing. Multicast bridging is supported.
•
Threat Detection
•
QoS
•
Phone Proxy
Context Configuration Files
This section describes how the security appliance implements multiple context mode configurations and
includes the following sections:
•
Context Configurations, page 4-2
•
System Configuration, page 4-3
•
Admin Context Configuration, page 4-3
Context Configurations
The security appliance includes a configuration for each context that identifies the security policy,
interfaces, and almost all the options you can configure on a standalone device. You can store context
configurations on the internal Flash memory or the external Flash memory card, or you can download
them from a TFTP, FTP, or HTTP(S) server.
Cisco Security Appliance Command Line Configuration Guide
4-2
OL-12172-04
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
System Configuration
The system administrator adds and manages contexts by configuring each context configuration location,
allocated interfaces, and other context operating parameters in the system configuration, which, like a
single mode configuration, is the startup configuration. The system configuration identifies basic
settings for the security appliance. The system configuration does not include any network interfaces or
network settings for itself; rather, when the system needs to access network resources (such as
downloading the contexts from the server), it uses one of the contexts that is designated as the admin
context. The system configuration does include a specialized failover interface for failover traffic only.
Admin Context Configuration
The admin context is just like any other context, except that when a user logs in to the admin context,
then that user has system administrator rights and can access the system and all other contexts. The
admin context is not restricted in any way, and can be used as a regular context. However, because
logging into the admin context grants you administrator privileges over all contexts, you might need to
restrict access to the admin context to appropriate users. The admin context must reside on Flash
memory, and not remotely.
If your system is already in multiple context mode, or if you convert from single mode, the admin context
is created automatically as a file on the internal Flash memory called admin.cfg. This context is named
“admin.” If you do not want to use admin.cfg as the admin context, you can change the admin context.
How the Security Appliance Classifies Packets
Each packet that enters the security appliance must be classified, so that the security appliance can
determine to which context to send a packet. This section includes the following topics:
Note
•
Valid Classifier Criteria, page 4-3
•
Invalid Classifier Criteria, page 4-4
•
Classification Examples, page 4-5
If the destination MAC address is a multicast or broadcast MAC address, the packet is duplicated and
delivered to each context.
Valid Classifier Criteria
This section describes the criteria used by the classifier, and includes the following topics:
•
Unique Interfaces, page 4-3
•
Unique MAC Addresses, page 4-4
•
NAT Configuration, page 4-4
Unique Interfaces
If only one context is associated with the ingress interface, the security appliance classifies the packet
into that context. In transparent firewall mode, unique interfaces for contexts are required, so this method
is used to classify packets at all times.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
4-3
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
Unique MAC Addresses
If multiple contexts share an interface, then the classifier uses the interface MAC address. The security
appliance lets you assign a different MAC address in each context to the same shared interface, whether
it is a shared physical interface or a shared subinterface. By default, shared interfaces do not have unique
MAC addresses; the interface uses the physical interface burned-in MAC address in every context. An
upstream router cannot route directly to a context without unique MAC addresses. You can set the MAC
addresses manually when you configure each interface (see the “Configuring Interface Parameters”
section on page 8-2), or you can automatically generate MAC addresses (see the “Automatically
Assigning MAC Addresses to Context Interfaces” section on page 7-11).
NAT Configuration
If you do not have unique MAC addresses, then the classifier intercepts the packet and performs a
destination IP address lookup. All other fields are ignored; only the destination IP address is used. To
use the destination address for classification, the classifier must have knowledge about the subnets
located behind each security context. The classifier relies on the NAT configuration to determine the
subnets in each context. The classifier matches the destination IP address to either a static command or
a global command. In the case of the global command, the classifier does not need a matching nat
command or an active NAT session to classify the packet. Whether the packet can communicate with the
destination IP address after classification depends on how you configure NAT and NAT control.
For example, the classifier gains knowledge about subnets 10.10.10.0, 10.20.10.0 and 10.30.10.0 when
the context administrators configure static commands in each context:
•
Context A:
static (inside,shared) 10.10.10.0 10.10.10.0 netmask 255.255.255.0
•
Context B:
static (inside,shared) 10.20.10.0 10.20.10.0 netmask 255.255.255.0
•
Context C:
static (inside,shared) 10.30.10.0 10.30.10.0 netmask 255.255.255.0
Note
For management traffic destined for an interface, the interface IP address is used for classification.
Invalid Classifier Criteria
The following configurations are not used for packet classification:
•
NAT exemption—The classifier does not use a NAT exemption configuration for classification
purposes because NAT exemption does not identify a mapped interface.
•
Routing table—If a context includes a static route that points to an external router as the next-hop
to a subnet, and a different context includes a static command for the same subnet, then the classifier
uses the static command to classify packets destined for that subnet and ignores the static route.
Cisco Security Appliance Command Line Configuration Guide
4-4
OL-12172-04
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
Classification Examples
Figure 4-1 shows multiple contexts sharing an outside interface. The classifier assigns the packet to
Context B because Context B includes the MAC address to which the router sends the packet.
Figure 4-1
Packet Classification with a Shared Interface using MAC Addresses
Internet
Packet Destination:
209.165.201.1 via MAC 000C.F142.4CDC
GE 0/0.1 (Shared Interface)
Classifier
Admin
Context
MAC 000C.F142.4CDB
Context A
GE 0/1.1
MAC 000C.F142.4CDC
Context B
GE 0/1.2
GE 0/1.3
Admin
Network
Inside
Customer A
Inside
Customer B
Host
209.165.202.129
Host
209.165.200.225
Host
209.165.201.1
153367
MAC 000C.F142.4CDA
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
4-5
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
Figure 4-2 shows multiple contexts sharing an outside interface without MAC addresses assigned. The
classifier assigns the packet to Context B because Context B includes the address translation that
matches the destination address.
Figure 4-2
Packet Classification with a Shared Interface using NAT
Internet
Packet Destination:
209.165.201.3
GE 0/0.1 (Shared Interface)
Classifier
Admin
Context
Context A
Context B
Dest Addr Translation
209.165.201.3 10.1.1.13
GE 0/1.1
GE 0/1.2
GE 0/1.3
Inside
Customer A
Inside
Customer B
Host
10.1.1.13
Host
10.1.1.13
Host
10.1.1.13
92399
Admin
Network
Note that all new incoming traffic must be classified, even from inside networks. Figure 4-3 shows a host
on the Context B inside network accessing the Internet. The classifier assigns the packet to Context B
because the ingress interface is Gigabit Ethernet 0/1.3, which is assigned to Context B.
Note
If you share an inside interface and do not use unique MAC addresses, the classifier imposes some major
restrictions. The classifier relies on the address translation configuration to classify the packet within a
context, and you must translate the destination addresses of the traffic. Because you do not usually
perform NAT on outside addresses, sending packets from inside to outside on a shared interface is not
always possible; the outside network is large, (the Web, for example), and addresses are not predictable
for an outside NAT configuration. If you share an inside interface, we suggest you use unique MAC
addresses.
Cisco Security Appliance Command Line Configuration Guide
4-6
OL-12172-04
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
Figure 4-3
Incoming Traffic from Inside Networks
Internet
GE 0/0.1
Admin
Context
Context A
Context B
Classifier
GE 0/1.1
GE 0/1.2
GE 0/1.3
Inside
Customer A
Inside
Customer B
Host
10.1.1.13
Host
10.1.1.13
Host
10.1.1.13
92395
Admin
Network
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
4-7
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
For transparent firewalls, you must use unique interfaces. Figure 4-4 shows a host on the Context B
inside network accessing the Internet. The classifier assigns the packet to Context B because the ingress
interface is Gigabit Ethernet 1/0.3, which is assigned to Context B.
Figure 4-4
Transparent Firewall Contexts
Internet
Classifier
GE 0/0.2
GE 0/0.1
GE 0/0.3
Admin
Context
Context A
Context B
GE 1/0.1
GE 1/0.2
GE 1/0.3
Inside
Customer A
Inside
Customer B
Host
10.1.1.13
Host
10.1.2.13
Host
10.1.3.13
92401
Admin
Network
Cascading Security Contexts
Placing a context directly in front of another context is called cascading contexts; the outside interface
of one context is the same interface as the inside interface of another context. You might want to cascade
contexts if you want to simplify the configuration of some contexts by configuring shared parameters in
the top context.
Note
Cascading contexts requires that you configure unique MAC addresses for each context interface.
Because of the limitations of classifying packets on shared interfaces without MAC addresses, we do not
recommend using cascading contexts without unique MAC addresses.
Cisco Security Appliance Command Line Configuration Guide
4-8
OL-12172-04
Chapter 4
Enabling Multiple Context Mode
Security Context Overview
Figure 4-5 shows a gateway context with two contexts behind the gateway.
Figure 4-5
Cascading Contexts
Internet
GE 0/0.2
Outside
Gateway
Context
Inside
GE 0/0.1
(Shared Interface)
Outside
Outside
Admin
Context
Context A
Inside
GE 1/1.43
Inside
153366
GE 1/1.8
Management Access to Security Contexts
The security appliance provides system administrator access in multiple context mode as well as access
for individual context administrators. The following sections describe logging in as a system
administrator or as a a context administrator:
•
System Administrator Access, page 4-9
•
Context Administrator Access, page 4-10
System Administrator Access
You can access the security appliance as a system administrator in two ways:
•
Access the security appliance console.
From the console, you access the system execution space, which means that any commands you enter
affect only the system configuration or the running of the system (for run-time commands).
•
Access the admin context using Telnet, SSH, or ASDM.
See Chapter 42, “Managing System Access,” to enable Telnet, SSH, and SDM access.
As the system administrator, you can access all contexts.
When you change to a context from admin or the system, your username changes to the default
“enable_15” username. If you configured command authorization in that context, you need to either
configure authorization privileges for the “enable_15” user, or you can log in as a different name for
which you provide sufficient privileges in the command authorization configuration for the context. To
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
4-9
Chapter 4
Enabling Multiple Context Mode
Enabling or Disabling Multiple Context Mode
log in with a username, enter the login command. For example, you log in to the admin context with the
username “admin.” The admin context does not have any command authorization configuration, but all
other contexts include command authorization. For convenience, each context configuration includes a
user “admin” with maximum privileges. When you change from the admin context to context A, your
username is altered, so you must log in again as “admin” by entering the login command. When you
change to context B, you must again enter the login command to log in as “admin.”
The system execution space does not support any AAA commands, but you can configure its own enable
password, as well as usernames in the local database to provide individual logins.
Context Administrator Access
You can access a context using Telnet, SSH, or ASDM. If you log in to a non-admin context, you can
only access the configuration for that context. You can provide individual logins to the context. See See
Chapter 42, “Managing System Access,” to enable Telnet, SSH, and SDM access and to configure
management authentication.
Enabling or Disabling Multiple Context Mode
Your security appliance might already be configured for multiple security contexts depending on how
you ordered it from Cisco. If you are upgrading, however, you might need to convert from single mode
to multiple mode by following the procedures in this section. ASDM does not support changing modes,
so you need to change modes using the CLI.
This section includes the following topics:
•
Backing Up the Single Mode Configuration, page 4-10
•
Enabling Multiple Context Mode, page 4-10
•
Restoring Single Context Mode, page 4-11
Backing Up the Single Mode Configuration
When you convert from single mode to multiple mode, the security appliance converts the running
configuration into two files. The original startup configuration is not saved, so if it differs from the
running configuration, you should back it up before proceeding.
Enabling Multiple Context Mode
The context mode (single or multiple) is not stored in the configuration file, even though it does endure
reboots. If you need to copy your configuration to another device, set the mode on the new device to
match using the mode command.
When you convert from single mode to multiple mode, the security appliance converts the running
configuration into two files: a new startup configuration that comprises the system configuration, and
admin.cfg that comprises the admin context (in the root directory of the internal Flash memory). The
original running configuration is saved as old_running.cfg (in the root directory of the internal Flash
memory). The original startup configuration is not saved. The security appliance automatically adds an
entry for the admin context to the system configuration with the name “admin.”
To enable multiple mode, enter the following command:
Cisco Security Appliance Command Line Configuration Guide
4-10
OL-12172-04
Chapter 4
Enabling Multiple Context Mode
Enabling or Disabling Multiple Context Mode
hostname(config)# mode multiple
You are prompted to reboot the security appliance.
Restoring Single Context Mode
If you convert from multiple mode to single mode, you might want to first copy a full startup
configuration (if available) to the security appliance; the system configuration inherited from multiple
mode is not a complete functioning configuration for a single mode device. Because the system
configuration does not have any network interfaces as part of its configuration, you must access the
security appliance from the console to perform the copy.
To copy the old running configuration to the startup configuration and to change the mode to single
mode, perform the following steps in the system execution space:
Step 1
To copy the backup version of your original running configuration to the current startup configuration,
enter the following command in the system execution space:
hostname(config)# copy flash:old_running.cfg startup-config
Step 2
To set the mode to single mode, enter the following command in the system execution space:
hostname(config)# mode single
The security appliance reboots.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
4-11
Chapter 4
Enabling Multiple Context Mode
Enabling or Disabling Multiple Context Mode
Cisco Security Appliance Command Line Configuration Guide
4-12
OL-12172-04
CH A P T E R
5
Configuring Switch Ports and VLAN Interfaces
for the Cisco ASA 5505 Adaptive Security
Appliance
This chapter describes how to configure the switch ports and VLAN interfaces of the ASA 5505 adaptive
security appliance.
Note
To configure interfaces of other models, see Chapter 6, “Configuring Ethernet Settings, Redundant
Interfaces, and Subinterfaces,” and Chapter 8, “Configuring Interface Parameters.”
The security appliance interfaces do not support jumbo frames.
This chapter includes the following sections:
•
Interface Overview, page 5-1
•
Configuring VLAN Interfaces, page 5-5
•
Configuring Switch Ports as Access Ports, page 5-9
•
Configuring a Switch Port as a Trunk Port, page 5-11
•
Allowing Communication Between VLAN Interfaces on the Same Security Level, page 5-13
Interface Overview
This section describes the ports and interfaces of the ASA 5505 adaptive security appliance, and includes
the following topics:
•
Understanding ASA 5505 Ports and Interfaces, page 5-2
•
Maximum Active VLAN Interfaces for Your License, page 5-2
•
Default Interface Configuration, page 5-4
•
VLAN MAC Addresses, page 5-4
•
Power Over Ethernet, page 5-4
•
Security Level Overview, page 5-5
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
5-1
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Interface Overview
Understanding ASA 5505 Ports and Interfaces
The ASA 5505 adaptive security appliance supports a built-in switch. There are two kinds of ports and
interfaces that you need to configure:
•
Physical switch ports—The adaptive security appliance has eight Fast Ethernet switch ports that
forward traffic at Layer 2, using the switching function in hardware. Two of these ports are PoE
ports. See the “Power Over Ethernet” section on page 5-4 for more information. You can connect
these interfaces directly to user equipment such as PCs, IP phones, or a DSL modem. Or you can
connect to another switch.
•
Logical VLAN interfaces—In routed mode, these interfaces forward traffic between VLAN
networks at Layer 3, using the configured security policy to apply firewall and VPN services. In
transparent mode, these interfaces forward traffic between the VLANs on the same network at Layer
2, using the configured security policy to apply firewall services. See the “Maximum Active VLAN
Interfaces for Your License” section for more information about the maximum VLAN interfaces.
VLAN interfaces let you divide your equipment into separate VLANs, for example, home, business,
and Internet VLANs.
To segregate the switch ports into separate VLANs, you assign each switch port to a VLAN interface.
Switch ports on the same VLAN can communicate with each other using hardware switching. But when
a switch port on VLAN 1 wants to communicate with a switch port on VLAN 2, then the adaptive
security appliance applies the security policy to the traffic and routes or bridges between the two
VLANs.
Note
Subinterfaces are not available for the ASA 5505 adaptive security appliance.
Maximum Active VLAN Interfaces for Your License
In transparent firewall mode, you can configure two active VLANs in the Base license and three active
VLANs in the Security Plus license, one of which must be for failover.
In routed mode, you can configure up to three active VLANs with the Base license, and up to 20 active
VLANs with the Security Plus license.
An active VLAN is a VLAN with a nameif command configured.
Cisco Security Appliance Command Line Configuration Guide
5-2
OL-12172-04
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Interface Overview
With the Base license, the third VLAN can only be configured to initiate traffic to one other VLAN. See
Figure 5-1 for an example network where the Home VLAN can communicate with the Internet, but
cannot initiate contact with Business.
Figure 5-1
ASA 5505 Adaptive Security Appliance with Base License
Internet
Home
153364
ASA 5505
with Base License
Business
With the Security Plus license, you can configure 20 VLAN interfaces, including a VLAN interface for
failover and a VLAN interface as a backup link to your ISP. This backup interface does not pass through
traffic unless the route through the primary interface fails. You can configure trunk ports to accomodate
multiple VLANs per port.
Note
The ASA 5505 adaptive security appliance supports Active/Standby failover, but not Stateful failover.
See Figure 5-2 for an example network.
Figure 5-2
ASA 5505 Adaptive Security Appliance with Security Plus License
Backup ISP
Primary ISP
ASA 5505
with Security Plus
License
Failover
ASA 5505
DMZ
Inside
153365
Failover Link
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
5-3
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Interface Overview
Default Interface Configuration
If your adaptive security appliance includes the default factory configuration, your interfaces are
configured as follows:
•
The outside interface (security level 0) is VLAN 2.
Ethernet0/0 is assigned to VLAN 2 and is enabled.
The VLAN 2 IP address is obtained from the DHCP server.
•
The inside interface (security level 100) is VLAN 1
Ethernet 0/1 through Ethernet 0/7 are assigned to VLAN 1 and is enabled.
VLAN 1 has IP address 192.168.1.1.
Restore the default factory configuration using the configure factory-default command.
Use the procedures in this chapter to modify the default configuration, for example, to add VLAN
interfaces.
If you do not have a factory default configuration, all switch ports are in VLAN 1, but no other
parameters are configured.
VLAN MAC Addresses
In routed firewall mode, all VLAN interfaces share a MAC address. Ensure that any connected switches
can support this scenario. If the connected switches require unique MAC addresses, you can manually
assign MAC addresses.
In transparent firewall mode, each VLAN has a unique MAC address. You can override the generated
MAC addresses if desired by manually assigning MAC addresses.
Power Over Ethernet
Ethernet 0/6 and Ethernet 0/7 support PoE for devices such as IP phones or wireless access points. If you
install a non-PoE device or do not connect to these switch ports, the adaptive security appliance does not
supply power to the switch ports.
If you shut down the switch port using the shutdown command, you disable power to the device. Power
is restored when you enter no shutdown. See the “Configuring Switch Ports as Access Ports” section on
page 5-9 for more information about shutting down a switch port.
To view the status of PoE switch ports, including the type of device connected (Cisco or IEEE 802.3af),
use the show power inline command.
Monitoring Traffic Using SPAN
If you want to monitor traffic that enters or exits one or more switch ports, you can enable SPAN, also
known as switch port monitoring. The port for which you enable SPAN (called the destination port)
receives a copy of every packet transmitted or received on a specified source port. The SPAN feature lets
you attach a sniffer to the destination port so you can monitor all traffic; without SPAN, you would have
to attach a sniffer to every port you want to monitor. You can only enable SPAN for one destination port.
Cisco Security Appliance Command Line Configuration Guide
5-4
OL-12172-04
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Configuring VLAN Interfaces
See the switchport monitor command in the Cisco Security Appliance Command Reference for more
information.
Security Level Overview
Each VLAN interface must have a security level in the range 0 to 100 (from lowest to highest). For
example, you should assign your most secure network, such as the inside business network, to level 100.
The outside network connected to the Internet can be level 0. Other networks, such as a home network
can be in between. You can assign interfaces to the same security level. See the “Allowing
Communication Between VLAN Interfaces on the Same Security Level” section on page 5-13 for more
information.
The level controls the following behavior:
•
Network access—By default, there is an implicit permit from a higher security interface to a lower
security interface (outbound). Hosts on the higher security interface can access any host on a lower
security interface. You can limit access by applying an access list to the interface.
For same security interfaces, there is an implicit permit for interfaces to access other interfaces on
the same security level or lower.
•
Inspection engines—Some application inspection engines are dependent on the security level. For
same security interfaces, inspection engines apply to traffic in either direction.
– NetBIOS inspection engine—Applied only for outbound connections.
– SQL*Net inspection engine—If a control connection for the SQL*Net (formerly OraServ) port
exists between a pair of hosts, then only an inbound data connection is permitted through the
adaptive security appliance.
•
Filtering—HTTP(S) and FTP filtering applies only for outbound connections (from a higher level
to a lower level).
For same security interfaces, you can filter traffic in either direction.
•
NAT control—When you enable NAT control, you must configure NAT for hosts on a higher security
interface (inside) when they access hosts on a lower security interface (outside).
Without NAT control, or for same security interfaces, you can choose to use NAT between any
interface, or you can choose not to use NAT. Keep in mind that configuring NAT for an outside
interface might require a special keyword.
•
established command—This command allows return connections from a lower security host to a
higher security host if there is already an established connection from the higher level host to the
lower level host.
For same security interfaces, you can configure established commands for both directions.
Configuring VLAN Interfaces
For each VLAN to pass traffic, you need to configure an interface name (the nameif command), and for
routed mode, an IP address. You should also change the security level from the default, which is 0. If
you name an interface “inside” and you do not set the security level explicitly, then the adaptive security
appliance sets the security level to 100.
For information about how many VLANs you can configure, see the “Maximum Active VLAN
Interfaces for Your License” section on page 5-2.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
5-5
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Configuring VLAN Interfaces
Note
If you are using failover, do not use this procedure to name interfaces that you are reserving for failover
communications. See Chapter 15, “Configuring Failover,” to configure the failover link.
If you change the security level of an interface, and you do not want to wait for existing connections to
time out before the new security information is used, you can clear the connections using the
clear local-host command.
To configure a VLAN interface, perform the following steps:
Step 1
To specify the VLAN ID, enter the following command:
hostname(config)# interface vlan number
Where the number is between 1 and 4090.
For example, enter the following command:
hostname(config)# interface vlan 100
To remove this VLAN interface and all associated configuration, enter the no interface vlan command.
Because this interface also includes the interface name configuration, and the name is used in other
commands, those commands are also removed.
Step 2
(Optional) For the Base license, allow this interface to be the third VLAN by limiting it from initiating
contact to one other VLAN using the following command:
hostname(config-if)# no forward interface vlan number
Where number specifies the VLAN ID to which this VLAN interface cannot initiate traffic.
With the Base license, you can only configure a third VLAN if you use this command to limit it.
For example, you have one VLAN assigned to the outside for Internet access, one VLAN assigned to an
inside business network, and a third VLAN assigned to your home network. The home network does not
need to access the business network, so you can use the no forward interface command on the home
VLAN; the business network can access the home network, but the home network cannot access the
business network.
If you already have two VLAN interfaces configured with a nameif command, be sure to enter the no
forward interface command before the nameif command on the third interface; the adaptive security
appliance does not allow three fully functioning VLAN interfaces with the Base license on the ASA 5505
adaptive security appliance.
Note
Step 3
If you upgrade to the Security Plus license, you can remove this command and achieve full
functionality for this interface. If you leave this command in place, this interface continues to be
limited even after upgrading.
To name the interface, enter the following command:
hostname(config-if)# nameif name
The name is a text string up to 48 characters, and is not case-sensitive. You can change the name by
reentering this command with a new value. Do not enter the no form, because that command causes all
commands that refer to that name to be deleted.
Step 4
To set the security level, enter the following command:
hostname(config-if)# security-level number
Cisco Security Appliance Command Line Configuration Guide
5-6
OL-12172-04
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Configuring VLAN Interfaces
Where number is an integer between 0 (lowest) and 100 (highest).
Step 5
(Routed mode only) To set the IP address, enter one of the following commands.
Note
To set an IPv6 address, see the “Configuring IPv6 on an Interface” section on page 13-3.
To set the management IP address for transparent firewall mode, see the “Setting the
Management IP Address for a Transparent Firewall” section on page 9-5. In transparent mode,
you do not set the IP address for each interface, but rather for the whole adaptive security
appliance or context.
For failover, you must set the IP address an standby address manually; DHCP and PPPoE are not
supported.
•
To set the IP address manually, enter the following command:
hostname(config-if)# ip address ip_address [mask] [standby ip_address]
The standby keyword and address is used for failover. See Chapter 15, “Configuring Failover,” for
more information.
•
To obtain an IP address from a DHCP server, enter the following command:
hostname(config-if)# ip address dhcp [setroute]
Reenter this command to reset the DHCP lease and request a new lease.
If you do not enable the interface using the no shutdown command before you enter the ip address
dhcp command, some DHCP requests might not be sent.
•
Step 6
To obtain an IP address from a PPPoE server, see Chapter 37, “Configuring the PPPoE Client.”
(Optional) To assign a private MAC address to this interface, enter the following command:
hostname(config-if)# mac-address mac_address [standby mac_address]
By default in routed mode, all VLANs use the same MAC address. In transparent mode, the VLANs use
unique MAC addresses. You might want to set unique VLANs or change the generated VLANs if your
switch requires it, or for access control purposes.
Step 7
(Optional) To set an interface to management-only mode, so that it does not allow through traffic, enter
the following command:
hostname(config-if)# management-only
Step 8
By default, VLAN interfaces are enabled. To enable the interface, if it is not already enabled, enter the
following command:
hostname(config-if)# no shutdown
To disable the interface, enter the shutdown command.
The following example configures seven VLAN interfaces, including the failover interface which is
configured separately using the failover lan command:
hostname(config)# interface vlan 100
hostname(config-if)# nameif outside
hostname(config-if)# security-level 0
hostname(config-if)# ip address 10.1.1.1 255.255.255.0
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
5-7
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Configuring VLAN Interfaces
hostname(config-if)# no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 200
nameif inside
security-level 100
ip address 10.2.1.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 201
nameif dept1
security-level 90
ip address 10.2.2.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 202
nameif dept2
security-level 90
ip address 10.2.3.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 300
nameif dmz
security-level 50
ip address 10.3.1.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 400
nameif backup-isp
security-level 50
ip address 10.1.2.1 255.255.255.0
no shutdown
hostname(config-if)# failover lan faillink vlan500
hostname(config)# failover interface ip faillink 10.4.1.1 255.255.255.0 standby 10.4.1.2
255.255.255.0
The following example configures three VLAN interfaces for the Base license. The third home interface
cannot forward traffic to the business interface.
hostname(config)# interface vlan 100
hostname(config-if)# nameif outside
hostname(config-if)# security-level 0
hostname(config-if)# ip address dhcp
hostname(config-if)# no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 200
nameif business
security-level 100
ip address 10.1.1.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 300
no forward interface vlan 200
nameif home
security-level 50
ip address 10.2.1.1 255.255.255.0
no shutdown
Cisco Security Appliance Command Line Configuration Guide
5-8
OL-12172-04
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Configuring Switch Ports as Access Ports
Configuring Switch Ports as Access Ports
By default, all switch ports are shut down. To assign a switch port to one VLAN, configure it as an access
port. To create a trunk port to carry multiple VLANs, see the “Configuring a Switch Port as a Trunk Port”
section on page 5-11.
By default, the speed and duplex for switch ports are set to auto-negotiate. The default auto-negotiation
setting also includes the Auto-MDI/MDIX feature. Auto-MDI/MDIX eliminates the need for crossover
cabling by performing an internal crossover when a straight cable is detected during the auto-negotiation
phase. Either the speed or duplex must be set to auto-negotiate to enable Auto-MDI/MDIX for the
interface. If you explicitly set both the speed and duplex to a fixed value, thus disabling auto-negotiation
for both settings, then Auto-MDI/MDIX is also disabled.
Caution
The ASA 5505 adaptive security appliance does not support Spanning Tree Protocol for loop detection
in the network. Therefore you must ensure that any connection with the adaptive security appliance does
not end up in a network loop.
To configure a switch port, perform the following steps:
Step 1
To specify the switch port you want to configure, enter the following command:
hostname(config)# interface ethernet0/port
Where port is 0 through 7. For example, enter the following command:
hostname(config)# interface ethernet0/1
Step 2
To assign this switch port to a VLAN, enter the following command:
hostname(config-if)# switchport access vlan number
Where number is the VLAN ID, between 1 and 4090.
Note
Step 3
You might assign multiple switch ports to the primary or backup VLANs if the Internet access device
includes Layer 2 redundancy.
(Optional) To prevent the switch port from communicating with other protected switch ports on the same
VLAN, enter the following command:
hostname(config-if)# switchport protected
You might want to prevent switch ports from communicating with each other if the devices on those
switch ports are primarily accessed from other VLANs, you do not need to allow intra-VLAN access,
and you want to isolate the devices from each other in case of infection or other security breach. For
example, if you have a DMZ that hosts three web servers, you can isolate the web servers from each other
if you apply the switchport protected command to each switch port. The inside and outside networks
can both communicate with all three web servers, and vice versa, but the web servers cannot
communicate with each other.
Step 4
(Optional) To set the speed, enter the following command:
hostname(config-if)# speed {auto | 10 | 100}
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
5-9
Chapter 5
Configuring Switch Ports as Access Ports
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
The auto setting is the default. If you set the speed to anything other than auto on PoE ports Ethernet
0/6 or 0/7, then Cisco IP phones and Cisco wireless access points that do not support IEEE 802.3af will
not be detected and supplied with power.
Step 5
(Optional) To set the duplex, enter the following command:
hostname(config-if)# duplex {auto | full | half}
The auto setting is the default. If you set the duplex to anything other than auto on PoE ports Ethernet
0/6 or 0/7, then Cisco IP phones and Cisco wireless access points that do not support IEEE 802.3af will
not be detected and supplied with power.
Step 6
To enable the switch port, if it is not already enabled, enter the following command:
hostname(config-if)# no shutdown
To disable the switch port, enter the shutdown command.
The following example configures five VLAN interfaces, including the failover interface which is
configured using the failover lan command:
hostname(config)# interface vlan 100
hostname(config-if)# nameif outside
hostname(config-if)# security-level 0
hostname(config-if)# ip address 10.1.1.1 255.255.255.0
hostname(config-if)# no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 200
nameif inside
security-level 100
ip address 10.2.1.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 300
nameif dmz
security-level 50
ip address 10.3.1.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 400
nameif backup-isp
security-level 50
ip address 10.1.2.1 255.255.255.0
no shutdown
hostname(config-if)# failover lan faillink vlan500
hostname(config)# failover interface ip faillink 10.4.1.1 255.255.255.0 standby 10.4.1.2
255.255.255.0
hostname(config)# interface ethernet 0/0
hostname(config-if)# switchport access vlan 100
hostname(config-if)# no shutdown
hostname(config-if)# interface ethernet 0/1
hostname(config-if)# switchport access vlan 200
hostname(config-if)# no shutdown
hostname(config-if)# interface ethernet 0/2
hostname(config-if)# switchport access vlan 300
hostname(config-if)# no shutdown
hostname(config-if)# interface ethernet 0/3
Cisco Security Appliance Command Line Configuration Guide
5-10
OL-12172-04
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Configuring a Switch Port as a Trunk Port
hostname(config-if)# switchport access vlan 400
hostname(config-if)# no shutdown
hostname(config-if)# interface ethernet 0/4
hostname(config-if)# switchport access vlan 500
hostname(config-if)# no shutdown
Configuring a Switch Port as a Trunk Port
By default, all switch ports are shut down. This procedure tells how to create a trunk port that can carry
multiple VLANs using 802.1Q tagging. Trunk mode is available only with the Security Plus license.
To create an access port, where an interface is assigned to only one VLAN, see the “Configuring Switch
Ports as Access Ports” section on page 5-9.
By default, the speed and duplex for switch ports are set to auto-negotiate. The default auto-negotiation
setting also includes the Auto-MDI/MDIX feature. Auto-MDI/MDIX eliminates the need for crossover
cabling by performing an internal crossover when a straight cable is detected during the auto-negotiation
phase. Either the speed or duplex must be set to auto-negotiate to enable Auto-MDI/MDIX for the
interface. If you explicitly set both the speed and duplex to a fixed value, thus disabling auto-negotiation
for both settings, then Auto-MDI/MDIX is also disabled.
To configure a trunk port, perform the following steps:
Step 1
To specify the switch port you want to configure, enter the following command:
hostname(config)# interface ethernet0/port
Where port is 0 through 7. For example, enter the following command:
hostname(config)# interface ethernet0/1
Step 2
To assign VLANs to this trunk, enter one or more of the following commands.
•
To assign native VLANs, enter the following command:
hostname(config-if)# switchport trunk native vlan vlan_id
where the vlan_id is a single VLAN ID between 1 and 4090.
Packets on the native VLAN are not modified when sent over the trunk. For example, if a port has
VLANs 2, 3 and 4 assigned to it, and VLAN 2 is the native VLAN, then packets on VLAN 2 that
egress the port are not modified with an 802.1Q header. Frames which ingress (enter) this port and
have no 802.1Q header are put into VLAN 2.
Each port can only have one native VLAN, but every port can have either the same or a different
native VLAN.
•
To assign VLANs, enter the following command:
hostname(config-if)# switchport trunk allowed vlan vlan_range
where the vlan_range (with VLANs between 1 and 4090) can be identified in one of the following
ways:
A single number (n)
A range (n-x)
Separate numbers and ranges by commas, for example:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
5-11
Chapter 5
Configuring a Switch Port as a Trunk Port
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
5,7-10,13,45-100
You can enter spaces instead of commas, but the command is saved to the configuration with
commas.
You can include the native VLAN in this command, but it is not required; the native VLAN is passed
whether it is included in this command or not.
This switch port cannot pass traffic until you assign at least one VLAN to it, native or non-native.
Step 3
To make this switch port a trunk port, enter the following command:
hostname(config-if)# switchport mode trunk
To restore this port to access mode, enter the switchport mode access command.
Step 4
(Optional) To prevent the switch port from communicating with other protected switch ports on the same
VLAN, enter the following command:
hostname(config-if)# switchport protected
You might want to prevent switch ports from communicating with each other if the devices on those
switch ports are primarily accessed from other VLANs, you do not need to allow intra-VLAN access,
and you want to isolate the devices from each other in case of infection or other security breach. For
example, if you have a DMZ that hosts three web servers, you can isolate the web servers from each other
if you apply the switchport protected command to each switch port. The inside and outside networks
can both communicate with all three web servers, and vice versa, but the web servers cannot
communicate with each other.
Step 5
(Optional) To set the speed, enter the following command:
hostname(config-if)# speed {auto | 10 | 100}
The auto setting is the default.
Step 6
(Optional) To set the duplex, enter the following command:
hostname(config-if)# duplex {auto | full | half}
The auto setting is the default.
Step 7
To enable the switch port, if it is not already enabled, enter the following command:
hostname(config-if)# no shutdown
To disable the switch port, enter the shutdown command.
The following example configures seven VLAN interfaces, including the failover interface which is
configured using the failover lan command. VLANs 200, 201, and 202 are trunked on Ethernet 0/1.
hostname(config)# interface vlan 100
hostname(config-if)# nameif outside
hostname(config-if)# security-level 0
hostname(config-if)# ip address 10.1.1.1 255.255.255.0
hostname(config-if)# no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 200
nameif inside
security-level 100
ip address 10.2.1.1 255.255.255.0
no shutdown
hostname(config-if)# interface vlan 201
hostname(config-if)# nameif dept1
Cisco Security Appliance Command Line Configuration Guide
5-12
OL-12172-04
Chapter 5
Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Allowing Communication Between VLAN Interfaces on the Same Security Level
hostname(config-if)# security-level 90
hostname(config-if)# ip address 10.2.2.1 255.255.255.0
hostname(config-if)# no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 202
nameif dept2
security-level 90
ip address 10.2.3.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 300
nameif dmz
security-level 50
ip address 10.3.1.1 255.255.255.0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface vlan 400
nameif backup-isp
security-level 50
ip address 10.1.2.1 255.255.255.0
no shutdown
hostname(config-if)# failover lan faillink vlan500
hostname(config)# failover interface ip faillink 10.4.1.1 255.255.255.0 standby 10.4.1.2
255.255.255.0
hostname(config)# interface ethernet 0/0
hostname(config-if)# switchport access vlan 100
hostname(config-if)# no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface ethernet 0/1
switchport mode trunk
switchport trunk allowed vlan 200-202
switchport trunk native vlan 5
no shutdown
hostname(config-if)# interface ethernet 0/2
hostname(config-if)# switchport access vlan 300
hostname(config-if)# no shutdown
hostname(config-if)# interface ethernet 0/3
hostname(config-if)# switchport access vlan 400
hostname(config-if)# no shutdown
hostname(config-if)# interface ethernet 0/4
hostname(config-if)# switchport access vlan 500
hostname(config-if)# no shutdown
Allowing Communication Between VLAN Interfaces on the
Same Security Level
By default, interfaces on the same security level cannot communicate with each other. Allowing
communication between same security interfaces lets traffic flow freely between all same security
interfaces without access lists.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
5-13
Chapter 5 Configuring Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance
Allowing Communication Between VLAN Interfaces on the Same Security Level
Note
If you enable NAT control, you do not need to configure NAT between same security level interfaces.
See the “NAT and Same Security Level Interfaces” section on page 19-15 for more information on NAT
and same security level interfaces.
If you enable same security interface communication, you can still configure interfaces at different
security levels as usual.
To enable interfaces on the same security level so that they can communicate with each other, enter the
following command:
hostname(config)# same-security-traffic permit inter-interface
To disable this setting, use the no form of this command.
Cisco Security Appliance Command Line Configuration Guide
5-14
OL-12172-04
CH A P T E R
6
Configuring Ethernet Settings, Redundant
Interfaces, and Subinterfaces
This chapter describes how to configure and enable physical Ethernet interfaces, how to create redundant
interface pairs, and how to add subinterfaces. If you have both fiber and copper Ethernet ports (for
example, on the 4GE SSM for the ASA 5510 and higher series adaptive security appliance), this chapter
describes how to configure the interface media type.
Note
•
In single context mode, complete the procedures in this chapter and then continue your interface
configuration in Chapter 8, “Configuring Interface Parameters.”
•
In multiple context mode, complete the procedures in this chapter in the system execution space,
then assign interfaces and subinterfaces to contexts according to Chapter 7, “Adding and Managing
Security Contexts,” and finally configure the interface parameters within each context according to
Chapter 8, “Configuring Interface Parameters.”
To configure interfaces for the ASA 5505 adaptive security appliance, see Chapter 5, “Configuring
Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance.”
The security appliance interfaces do not support jumbo frames.
This chapter includes the following sections:
•
Configuring and Enabling RJ-45 Interfaces, page 6-1
•
Configuring and Enabling Fiber Interfaces, page 6-3
•
Configuring a Redundant Interface, page 6-4
•
Configuring VLAN Subinterfaces and 802.1Q Trunking, page 6-7
Configuring and Enabling RJ-45 Interfaces
This section describes how to configure Ethernet settings for physical interfaces with an RJ-45
connector, and how to enable the interface. It includes the following topics:
•
RJ-45 Interface Overview, page 6-2
•
Configuring the RJ-45 Interface, page 6-2
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
6-1
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring and Enabling RJ-45 Interfaces
RJ-45 Interface Overview
This section describes the RJ-45 interface, and includes the following topics:
•
Default State of Physical Interfaces, page 6-2
•
Connector Types, page 6-2
•
Auto-MDI/MDIX Feature, page 6-2
Default State of Physical Interfaces
By default, all physical interfaces are shut down. You must enable the physical interface before any
traffic can pass through it (either alone or as part of a redundant interface pair), or through a subinterface.
For multiple context mode, if you allocate an interface (physical, redundant, or subinterface) to a
context, the interfaces are enabled by default in the context. However, before traffic can pass through the
context interface, you must first enable the physical interface in the system configuration according to
this procedure.
By default, the speed and duplex for copper (RJ-45) interfaces are set to auto-negotiate.
Connector Types
The ASA 5550 adaptive security appliance and the 4GE SSM for the ASA 5510 and higher adaptive
security appliance include two connector types: copper RJ-45 and fiber SFP. RJ-45 is the default. If you
want to configure the security appliance to use the fiber SFP connectors, see the “Configuring and
Enabling Fiber Interfaces” section on page 6-3.
Auto-MDI/MDIX Feature
For RJ-45 interfaces on the ASA 5500 series adaptive security appliance, the default auto-negotiation
setting also includes the Auto-MDI/MDIX feature. Auto-MDI/MDIX eliminates the need for crossover
cabling by performing an internal crossover when a straight cable is detected during the auto-negotiation
phase. Either the speed or duplex must be set to auto-negotiate to enable Auto-MDI/MDIX for the
interface. If you explicitly set both the speed and duplex to a fixed value, thus disabling auto-negotiation
for both settings, then Auto-MDI/MDIX is also disabled. For Gigabit Ethernet, when the speed and
duplex are set to 1000 and full, then the interface always auto-negotiates; therefore Auto-MDI/MDIX is
always enabled and you cannot disable it.
Configuring the RJ-45 Interface
To enable the interface, or to set a specific speed and duplex, perform the following steps:
Step 1
To specify the interface you want to configure, enter the following command:
hostname(config)# interface physical_interface
hostname(config-if)#
where the physical_interface ID includes the type, slot, and port number as type[slot/]port.
The physical interface types include the following:
•
ethernet
Cisco Security Appliance Command Line Configuration Guide
6-2
OL-12172-04
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring and Enabling Fiber Interfaces
•
gigabitethernet
•
management (ASA 5500 only)
For the PIX 500 series security appliance, enter the type followed by the port number, for example,
ethernet0.
For the ASA 5500 series adaptive security appliance, enter the type followed by slot/port, for example,
gigabitethernet0/1 or ethernet 0/1.
The ASA 5500 management interface is a Fast Ethernet interface designed for management traffic only,
and is specified as management0/0. You can, however, use it for through traffic if desired (see the
management-only command). In transparent firewall mode, you can use the management interface (for
management purposes) in addition to the two interfaces allowed for through traffic. You can also add
subinterfaces to the management interface to provide management in each security context for multiple
context mode.
Step 2
(Optional) To set the speed, enter the following command:
hostname(config-if)# speed {auto | 10 | 100 | 1000 | nonegotiate}
The auto setting is the default. The speed nonegotiate command disables link negotiation.
Step 3
(Optional) To set the duplex, enter the following command:
hostname(config-if)# duplex {auto | full | half}
The auto setting is the default.
Step 4
To enable the interface, enter the following command:
hostname(config-if)# no shutdown
To disable the interface, enter the shutdown command. If you enter the shutdown command, you also
shut down all subinterfaces. If you shut down an interface in the system execution space, then that
interface is shut down in all contexts that share it.
Configuring and Enabling Fiber Interfaces
This section describes how to configure Ethernet settings for physical interfaces, and how to enable the
interface. By default, the connectors used on the 4GE SSM or for built-in interfaces in slot 1 on the ASA
5550 adaptive security appliance are the RJ-45 connectors. To use the fiber SFP connectors, you must
set the media type to SFP. The fiber interface has a fixed speed and does not support duplex, but you can
set the interface to negotiate link parameters (the default) or not to negotiate.
This section includes the following topics:
•
Default State of Physical Interfaces, page 6-3
•
Configuring the Fiber Interface, page 6-4
Default State of Physical Interfaces
By default, all physical interfaces are shut down. You must enable the physical interface before any
traffic can pass through it (either alone or as part of a redundant interface pair), or through a subinterface.
For multiple context mode, if you allocate an interface (physical, redundant, or subinterface) to a
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
6-3
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring a Redundant Interface
context, the interfaces are enabled by default in the context. However, before traffic can pass through the
context interface, you must first enable the physical interface in the system configuration according to
this procedure.
Configuring the Fiber Interface
To enable the interface, set the media type, or to set negotiation settings, perform the following steps:
Step 1
To specify the interface you want to configure, enter the following command:
hostname(config)# interface gigabitethernet 1/port
hostname(config-if)#
The fiber interfaces are available in slot 1 only.
Step 2
To set the media type to SFP, enter the following command:
hostname(config-if)# media-type sfp
To restore the default RJ-45, enter the media-type rj45 command.
Step 3
(Optional) To disable link negotiation, enter the following command:
hostname(config-if)# speed nonegotiate
The default is no speed nonegotiate, which sets the speed to 1000 Mbps and enables link negotiation
for flow-control parameters and remote fault information. The speed nonegotiate command disables
link negotiation.
Step 4
To enable the interface, enter the following command:
hostname(config-if)# no shutdown
To disable the interface, enter the shutdown command. If you enter the shutdown command, you also
shut down all subinterfaces. If you shut down an interface in the system execution space, then that
interface is shut down in all contexts that share it.
Configuring a Redundant Interface
A logical redundant interface pairs an active and a standby physical interface. When the active interface
fails, the standby interface becomes active and starts passing traffic. You can configure a redundant
interface to increase the security appliance reliability. This feature is separate from device-level failover,
but you can configure redundant interfaces as well as failover if desired. You can configure up to 8
redundant interface pairs.
All security appliance configuration refers to the logical redundant interface instead of the member
physical interfaces.
This section describes how to configure redundant interfaces, and includes the following topics:
•
Redundant Interface Overview, page 6-5
•
Adding a Redundant Interface, page 6-6
•
Changing the Active Interface, page 6-7
Cisco Security Appliance Command Line Configuration Guide
6-4
OL-12172-04
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring a Redundant Interface
Redundant Interface Overview
This section includes overview information about redundant interfaces, and includes the following
topics:
•
Default State of Redundant Interfaces, page 6-5
•
Redundant Interfaces and Failover Guidelines, page 6-5
•
Redundant Interface MAC Address, page 6-5
•
Physical Interface Guidelines, page 6-5
Default State of Redundant Interfaces
When you add a redundant interface, it is enabled by default. However, the member interfaces must also
be enabled to pass traffic.
Redundant Interfaces and Failover Guidelines
Follow these guidelines when adding member interfaces:
•
If you want to use a redundant interface for the failover or state link, then you must configure the
redundant interface as part of the basic configuration on the secondary unit in addition to the primary
unit.
•
If you use a redundant interface for the failover or state link, you must put a switch or hub between
the two units; you cannot connect them directly. Without the switch or hub, you could have the active
port on the primary unit connected directly to the standby port on the secondary unit.
•
You can monitor redundant interfaces for failover using the monitor-interface command; be sure
to reference the logical redundant interface name.
•
When the active interface fails over to the standby interface, this activity does not cause the
redundant interface to appear to be failed when being monitored for device-level failover. Only when
both physical interfaces fail does the redundant interface appear to be failed.
•
Redundant interface delay values are configurable, but by default the unit will inherit the default
delay values based on the physical type of its member interfaces.
Redundant Interface MAC Address
The redundant interface uses the MAC address of the first physical interface that you add. If you change
the order of the member interfaces in the configuration, then the MAC address changes to match the
MAC address of the interface that is now listed first. Alternatively, you can assign a MAC address to the
redundant interface, which is used regardless of the member interface MAC addresses (see the
“Configuring Interface Parameters” section on page 8-2 or the “Automatically Assigning MAC
Addresses to Context Interfaces” section on page 7-11). When the active interface fails over to the
standby, the same MAC address is maintained so that traffic is not disrupted.
Physical Interface Guidelines
Follow these guidelines when adding member interfaces:
•
Both member interfaces must be of the same physical type. For example, both must be Ethernet.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
6-5
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring a Redundant Interface
•
Caution
You cannot add a physical interface to the redundant interface if you configured a name for it. You
must first remove the name using the no nameif command.
If you are using a physical interface already in your configuration, removing the name will clear any
configuration that refers to the interface.
•
The only configuration available to physical interfaces that are part of a redundant interface pair are
physical parameters (set in the “Configuring and Enabling RJ-45 Interfaces” section on page 6-1 or
the “Configuring and Enabling Fiber Interfaces” section on page 6-3), the description command,
and the shutdown command. You can also enter run-time commands like default and help.
•
If you shut down the active interface, then the standby interface becomes active.
Adding a Redundant Interface
You can configure up to 8 redundant interface pairs. To configure a redundant interface, perform the
following steps:
Step 1
To add the logical redundant interface, enter the following command:
hostname(config)# interface redundant number
hostname(config-if)#
where the number argument is an integer between 1 and 8.
Step 2
To add the first member interface to the redundant interface, enter the following command:
hostname(config-if)# member-interface physical_interface
See the “Configuring and Enabling RJ-45 Interfaces” section for a description of the physical interface
ID.
After you add the interface, any configuration for it (such as an IP address) is removed.
Step 3
To add the second member interface to the redundant interface, enter the following command:
hostname(config-if)# member-interface physical_interface
Make sure the second interface is the same physical type as the first interface.
To remove a member interface, enter the no member-interface physical_interface command. You
cannot remove both member interfaces from the redundant interface; the redundant interface requires at
least one member interface.
Step 4
To enable the interface (if you previously disabled it), enter the following command:
hostname(config-if)# no shutdown
By default, the interface is enabled. To disable the interface, enter the shutdown command. If you enter
the shutdown command, you also shut down all subinterfaces. If you shut down an interface in the
system execution space, then that interface is shut down in all contexts that share it.
The following example creates two redundant interfaces:
hostname(config)# interface redundant 1
hostname(config-if)# member-interface gigabitethernet 0/0
hostname(config-if)# member-interface gigabitethernet 0/1
Cisco Security Appliance Command Line Configuration Guide
6-6
OL-12172-04
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring VLAN Subinterfaces and 802.1Q Trunking
hostname(config-if)# interface redundant 2
hostname(config-if)# member-interface gigabitethernet 0/2
hostname(config-if)# member-interface gigabitethernet 0/3
Changing the Active Interface
By default, the active interface is the first interface listed in the configuration, if it is available. To view
which interface is active, enter the following command:
hostname# show interface redundantnumber detail | grep Member
For example:
hostname# show interface redundant1 detail | grep Member
Members GigabitEthernet0/3(Active), GigabitEthernet0/2
To change the active interface, enter the following command:
hostname# redundant-interface redundantnumber active-member physical_interface
where the redundantnumber argument is the redundant interface ID, such as redundant1.
The physical_interface is the member interface ID that you want to be active.
Configuring VLAN Subinterfaces and 802.1Q Trunking
This section describes how to configure a subinterface, and includes the following topics:
•
Subinterface Overview, page 6-7
•
Adding a Subinterface, page 6-8
Subinterface Overview
Subinterfaces let you divide a physical or redundant interface into multiple logical interfaces that are
tagged with different VLAN IDs. An interface with one or more VLAN subinterfaces is automatically
configured as an 802.1Q trunk. Because VLANs allow you to keep traffic separate on a given physical
interface, you can increase the number of interfaces available to your network without adding additional
physical interfaces or security appliances. This feature is particularly useful in multiple context mode so
that you can assign unique interfaces to each context.
This section includes the following topics:
•
Default State of Subinterfaces, page 6-7
•
Maximum Subinterfaces, page 6-8
•
Preventing Untagged Packets on the Physical Interface, page 6-8
Default State of Subinterfaces
When you add a subinterface, it is enabled by default. However, the physical or redundant interface must
also be enabled to pass traffic (see the “Configuring and Enabling RJ-45 Interfaces” section on page 6-1,
the “Configuring and Enabling Fiber Interfaces” section on page 6-3, or the “Configuring a Redundant
Interface” section on page 6-4).
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
6-7
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring VLAN Subinterfaces and 802.1Q Trunking
Maximum Subinterfaces
To determine how many subinterfaces are allowed for your platform, see the “Supported Feature
Licenses Per Model” section on page 3-1.
Preventing Untagged Packets on the Physical Interface
If you use subinterfaces, you typically do not also want the physical interface to pass traffic, because the
physical interface passes untagged packets. This property is also true for the active physical interface in
a redundant interface pair. Because the physical or redundant interface must be enabled for the
subinterface to pass traffic, ensure that the physical or redundant interface does not pass traffic by
leaving out the nameif command. If you want to let the physical or redundant interface pass untagged
packets, you can configure the nameif command as usual. See the “Configuring Interface Parameters”
section on page 8-1 for more information about completing the interface configuration.
Adding a Subinterface
To add a subinterface and assign a VLAN to it, perform the following steps:
Step 1
To specify the new subinterface, enter the following command:
hostname(config)# interface {physical_interface | redundant number}.subinterface
hostname(config-subif)#
See the “Configuring and Enabling RJ-45 Interfaces” section for a description of the physical interface
ID.
The redundant number argument is the redundant interface ID, such as redundant 1.
The subinterface ID is an integer between 1 and 4294967293.
The following command adds a subinterface to a Gigabit Ethernet interface:
hostname(config)# interface gigabitethernet 0/1.100
The following command adds a subinterface to a redundant interface:
hostname(config)# interface redundant 1.100
Step 2
To specify the VLAN for the subinterface, enter the following command:
hostname(config-subif)# vlan vlan_id
The vlan_id is an integer between 1 and 4094. Some VLAN IDs might be reserved on connected
switches, so check the switch documentation for more information.
You can only assign a single VLAN to a subinterface, and you cannot assign the same VLAN to multiple
subinterfaces. You cannot assign a VLAN to the physical interface. Each subinterface must have a
VLAN ID before it can pass traffic. To change a VLAN ID, you do not need to remove the old VLAN
ID with the no option; you can enter the vlan command with a different VLAN ID, and the security
appliance changes the old ID.
Step 3
To enable the subinterface (if you previously disabled it), enter the following command:
hostname(config-subif)# no shutdown
Cisco Security Appliance Command Line Configuration Guide
6-8
OL-12172-04
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring VLAN Subinterfaces and 802.1Q Trunking
By default, the subinterface is enabled. To disable the interface, enter the shutdown command. If you
shut down an interface in the system execution space, then that interface is shut down in all contexts that
share it.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
6-9
Chapter 6
Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces
Configuring VLAN Subinterfaces and 802.1Q Trunking
Cisco Security Appliance Command Line Configuration Guide
6-10
OL-12172-04
CH A P T E R
7
Adding and Managing Security Contexts
This chapter describes how to configure multiple security contexts on the security appliance, and
includes the following sections:
•
Configuring Resource Management, page 7-1
•
Configuring a Security Context, page 7-7
•
Automatically Assigning MAC Addresses to Context Interfaces, page 7-11
•
Changing Between Contexts and the System Execution Space, page 7-14
•
Managing Security Contexts, page 7-15
For information about how contexts work and how to enable multiple context mode, see Chapter 4,
“Enabling Multiple Context Mode.”
Configuring Resource Management
By default, all security contexts have unlimited access to the resources of the security appliance, except
where maximum limits per context are enforced. However, if you find that one or more contexts use too
many resources, and they cause other contexts to be denied connections, for example, then you can
configure resource management to limit the use of resources per context.
This section includes the following topics:
•
Classes and Class Members Overview, page 7-1
•
Configuring a Class, page 7-4
Classes and Class Members Overview
The security appliance manages resources by assigning contexts to resource classes. Each context uses
the resource limits set by the class. This section includes the following topics:
•
Resource Limits, page 7-2
•
Default Class, page 7-3
•
Class Members, page 7-4
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-1
Chapter 7
Adding and Managing Security Contexts
Configuring Resource Management
Resource Limits
When you create a class, the security appliance does not set aside a portion of the resources for each
context assigned to the class; rather, the security appliance sets the maximum limit for a context. If you
oversubscribe resources, or allow some resources to be unlimited, a few contexts can “use up” those
resources, potentially affecting service to other contexts.
You can set the limit for individual resources, as a percentage (if there is a hard system limit) or as an
absolute value.
You can oversubscribe the security appliance by assigning more than 100 percent of a resource across
all contexts. For example, you can set the Bronze class to limit connections to 20 percent per context,
and then assign 10 contexts to the class for a total of 200 percent. If contexts concurrently use more than
the system limit, then each context gets less than the 20 percent you intended. (See Figure 7-1.)
Figure 7-1
Resource Oversubscription
Total Number of System Connections = 999,900
Max. 20%
(199,800)
Maximum connections
allowed.
16%
(159,984)
Connections in use.
12%
(119,988)
4%
(39,996)
1
2
3
4
5
6
Contexts in Class
7
8
9
10
104895
Connections denied
because system limit
was reached.
8%
(79,992)
If you assign an absolute value to a resource across all contexts that exceeds the practical limit of the
security appliance, then the performance of the security appliance might be impaired.
The security appliance lets you assign unlimited access to one or more resources in a class, instead of a
percentage or absolute number. When a resource is unlimited, contexts can use as much of the resource
as the system has available or that is practically available. For example, Context A, B, and C are in the
Silver Class, which limits each class member to 1 percent of the connections, for a total of 3 percent; but
the three contexts are currently only using 2 percent combined. Gold Class has unlimited access to
connections. The contexts in the Gold Class can use more than the 97 percent of “unassigned”
connections; they can also use the 1 percent of connections not currently in use by Context A, B, and C,
even if that means that Context A, B, and C are unable to reach their 3 percent combined limit. (See
Figure 7-2.) Setting unlimited access is similar to oversubscribing the security appliance, except that you
have less control over how much you oversubscribe the system.
Cisco Security Appliance Command Line Configuration Guide
7-2
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Configuring Resource Management
Figure 7-2
Unlimited Resources
50% 43%
5%
Maximum connections
allowed.
4%
Connections in use.
3%
Connections denied
because system limit
was reached.
2%
A
B
C
Contexts Silver Class
1
2
3
Contexts Gold Class
153211
1%
Default Class
All contexts belong to the default class if they are not assigned to another class; you do not have to
actively assign a context to the default class.
If a context belongs to a class other than the default class, those class settings always override the default
class settings. However, if the other class has any settings that are not defined, then the member context
uses the default class for those limits. For example, if you create a class with a 2 percent limit for all
concurrent connections, but no other limits, then all other limits are inherited from the default class.
Conversely, if you create a class with a limit for all resources, the class uses no settings from the default
class.
By default, the default class provides unlimited access to resources for all contexts, except for the
following limits, which are by default set to the maximum allowed per context:
•
Telnet sessions—5 sessions.
•
SSH sessions—5 sessions.
•
IPSec sessions—5 sessions.
•
MAC addresses—65,535 entries.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-3
Chapter 7
Adding and Managing Security Contexts
Configuring Resource Management
Figure 7-3 shows the relationship between the default class and other classes. Contexts A and C belong
to classes with some limits set; other limits are inherited from the default class. Context B inherits no
limits from default because all limits are set in its class, the Gold class. Context D was not assigned to
a class, and is by default a member of the default class.
Figure 7-3
Class
Bronze
(Some
Limits
Set)
Context A
Resource Classes
Default Class
Context D
Class Silver
(Some Limits
Set)
Class Gold
(All Limits
Set)
Context B
104689
Context C
Class Members
To use the settings of a class, assign the context to the class when you define the context. All contexts
belong to the default class if they are not assigned to another class; you do not have to actively assign a
context to default. You can only assign a context to one resource class. The exception to this rule is that
limits that are undefined in the member class are inherited from the default class; so in effect, a context
could be a member of default plus another class.
Configuring a Class
To configure a class in the system configuration, perform the following steps. You can change the value
of a particular resource limit by reentering the command with a new value.
Step 1
To specify the class name and enter the class configuration mode, enter the following command in the
system execution space:
hostname(config)# class name
The name is a string up to 20 characters long. To set the limits for the default class, enter default for the
name.
Step 2
To set the resource limits, see the following options:
•
To set all resource limits (shown in Table 7-1) to be unlimited, enter the following command:
hostname(config-resmgmt)# limit-resource all 0
Cisco Security Appliance Command Line Configuration Guide
7-4
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Configuring Resource Management
For example, you might want to create a class that includes the admin context that has no limitations.
The default class has all resources set to unlimited by default.
•
To set a particular resource limit, enter the following command:
hostname(config-resmgmt)# limit-resource [rate] resource_name number[%]
For this particular resource, the limit overrides the limit set for all. Enter the rate argument to set
the rate per second for certain resources. For resources that do not have a system limit, you cannot
set the percentage (%) between 1 and 100; you can only set an absolute value. See Table 7-1 for
resources for which you can set the rate per second and which to not have a system limit.
Table 7-1 lists the resource types and the limits. See also the show resource types command.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-5
Chapter 7
Adding and Managing Security Contexts
Configuring Resource Management
Table 7-1
Resource Names and Limits
Rate or
Resource Name Concurrent
Minimum and
Maximum Number
per Context
System Limit1
mac-addresses Concurrent
N/A
65,535
conns
N/A
Concurrent connections: TCP or UDP connections between any two
hosts, including connections between one
See the “Supported
host and multiple other hosts.
Feature Licenses Per
Model” section on
page 3-1 for the
connection limit for your
platform.
Concurrent
or Rate
Description
For transparent firewall mode, the number of
MAC addresses allowed in the MAC address
table.
Rate: N/A
inspects
Rate
N/A
N/A
Application inspections.
hosts
Concurrent
N/A
N/A
Hosts that can connect through the security
appliance.
asdm
Concurrent
1 minimum
32
ASDM management sessions.
5 maximum
ssh
Concurrent
1 minimum
Note
ASDM sessions use two HTTPS
connections: one for monitoring that
is always present, and one for making
configuration changes that is present
only when you make changes. For
example, the system limit of 32
ASDM sessions represents a limit of
64 HTTPS sessions.
100
SSH sessions.
5 maximum
syslogs
Rate
N/A
N/A
System log messages.
telnet
Concurrent
1 minimum
100
Telnet sessions.
N/A
Address translations.
5 maximum
xlates
Concurrent
N/A
1. If this column value is N/A, then you cannot set a percentage of the resource because there is no hard system limit for the resource.
For example, to set the default class limit for conns to 10 percent instead of unlimited, enter the
following commands:
hostname(config)# class default
hostname(config-class)# limit-resource conns 10%
All other resources remain at unlimited.
To add a class called gold, enter the following commands:
hostname(config)# class gold
Cisco Security Appliance Command Line Configuration Guide
7-6
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Configuring a Security Context
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
hostname(config-class)#
limit-resource
limit-resource
limit-resource
limit-resource
limit-resource
limit-resource
limit-resource
limit-resource
limit-resource
limit-resource
mac-addresses 10000
conns 15%
rate conns 1000
rate inspects 500
hosts 9000
asdm 5
ssh 5
rate syslogs 5000
telnet 5
xlates 36000
Configuring a Security Context
The security context definition in the system configuration identifies the context name, configuration file
URL, and interfaces that a context can use.
Note
If you do not have an admin context (for example, if you clear the configuration) then you must first
specify the admin context name by entering the following command:
hostname(config)# admin-context name
Although this context name does not exist yet in your configuration, you can subsequently enter the
context name command to match the specified name to continue the admin context configuration.
To add or change a context in the system configuration, perform the following steps:
Step 1
To add or modify a context, enter the following command in the system execution space:
hostname(config)# context name
The name is a string up to 32 characters long. This name is case sensitive, so you can have two contexts
named “customerA” and “CustomerA,” for example. You can use letters, digits, or hyphens, but you
cannot start or end the name with a hyphen.
“System” or “Null” (in upper or lower case letters) are reserved names, and cannot be used.
Step 2
(Optional) To add a description for this context, enter the following command:
hostname(config-ctx)# description text
Step 3
To specify the interfaces you can use in the context, enter the command appropriate for a physical
interface or for one or more subinterfaces.
•
To allocate a physical interface, enter the following command:
hostname(config-ctx)# allocate-interface physical_interface [mapped_name]
[visible | invisible]
•
To allocate one or more subinterfaces, enter the following command:
hostname(config-ctx)# allocate-interface
physical_interface.subinterface[-physical_interface.subinterface]
[mapped_name[-mapped_name]] [visible | invisible]
Note
Do not include a space between the interface type and the port number.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-7
Chapter 7
Adding and Managing Security Contexts
Configuring a Security Context
You can enter these commands multiple times to specify different ranges. If you remove an allocation
with the no form of this command, then any context commands that include this interface are removed
from the running configuration.
Transparent firewall mode allows only two interfaces to pass through traffic; however, on the ASA
adaptive security appliance, you can use the dedicated management interface, Management 0/0, (either
the physical interface or a subinterface) as a third interface for management traffic.
Note
The management interface for transparent mode does not flood a packet out the interface when that
packet is not in the MAC address table.
You can assign the same interfaces to multiple contexts in routed mode, if desired. Transparent mode
does not allow shared interfaces.
The mapped_name is an alphanumeric alias for the interface that can be used within the context instead
of the interface ID. If you do not specify a mapped name, the interface ID is used within the context. For
security purposes, you might not want the context administrator to know which interfaces are being used
by the context.
A mapped name must start with a letter, end with a letter or digit, and have as interior characters only
letters, digits, or an underscore. For example, you can use the following names:
int0
inta
int_0
For subinterfaces, you can specify a range of mapped names.
If you specify a range of subinterfaces, you can specify a matching range of mapped names. Follow these
guidelines for ranges:
•
The mapped name must consist of an alphabetic portion followed by a numeric portion. The
alphabetic portion of the mapped name must match for both ends of the range. For example, enter
the following range:
int0-int10
If you enter gigabitethernet0/1.1-gigabitethernet0/1.5 happy1-sad5, for example, the command
fails.
•
The numeric portion of the mapped name must include the same quantity of numbers as the
subinterface range. For example, both ranges include 100 interfaces:
gigabitethernet0/0.100-gigabitethernet0/0.199 int1-int100
If you enter gigabitethernet0/0.100-gigabitethernet0/0.199 int1-int15, for example, the command
fails.
Specify visible to see physical interface properties in the show interface command even if you set a
mapped name. The default invisible keyword specifies to only show the mapped name.
The following example shows gigabitethernet0/1.100, gigabitethernet0/1.200, and
gigabitethernet0/2.300 through gigabitethernet0/1.305 assigned to the context. The mapped names are
int1 through int8.
hostname(config-ctx)# allocate-interface gigabitethernet0/1.100 int1
hostname(config-ctx)# allocate-interface gigabitethernet0/1.200 int2
hostname(config-ctx)# allocate-interface gigabitethernet0/2.300-gigabitethernet0/2.305
int3-int8
Cisco Security Appliance Command Line Configuration Guide
7-8
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Configuring a Security Context
Step 4
To identify the URL from which the system downloads the context configuration, enter the following
command:
hostname(config-ctx)# config-url url
When you add a context URL, the system immediately loads the context so that it is running, if the
configuration is available.
Note
Enter the allocate-interface command(s) before you enter the config-url command. The security
appliance must assign interfaces to the context before it loads the context configuration; the context
configuration might include commands that refer to interfaces (interface, nat, global...). If you enter the
config-url command first, the security appliance loads the context configuration immediately. If the
context contains any commands that refer to interfaces, those commands fail.
See the following URL syntax:
•
disk:/[path/]filename
This URL indicates the internal Flash memory. The filename does not require a file extension,
although we recommend using “.cfg”. If the configuration file is not available, you see the following
message:
WARNING: Could not fetch the URL disk:/url
INFO: Creating context with default config
You can then change to the context, configure it at the CLI, and enter the write memory command
to write the file to Flash memory.
Note
•
The admin context file must be stored on the internal Flash memory.
ftp://[user[:password]@]server[:port]/[path/]filename[;type=xx]
The type can be one of the following keywords:
– ap—ASCII passive mode
– an—ASCII normal mode
– ip—(Default) Binary passive mode
– in—Binary normal mode
The server must be accessible from the admin context. The filename does not require a file
extension, although we recommend using “.cfg”. If the configuration file is not available, you see
the following message:
WARNING: Could not fetch the URL ftp://url
INFO: Creating context with default config
You can then change to the context, configure it at the CLI, and enter the write memory command
to write the file to the FTP server.
•
http[s]://[user[:password]@]server[:port]/[path/]filename
The server must be accessible from the admin context. The filename does not require a file
extension, although we recommend using “.cfg”. If the configuration file is not available, you see
the following message:
WARNING: Could not fetch the URL http://url
INFO: Creating context with default config
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-9
Chapter 7
Adding and Managing Security Contexts
Configuring a Security Context
If you change to the context and configure the context at the CLI, you cannot save changes back to
HTTP or HTTPS servers using the write memory command. You can, however, use the copy tftp
command to copy the running configuration to a TFTP server.
•
tftp://[user[:password]@]server[:port]/[path/]filename[;int=interface_name]
The server must be accessible from the admin context. Specify the interface name if you want to
override the route to the server address. The filename does not require a file extension, although we
recommend using “.cfg”. If the configuration file is not available, you see the following message:
WARNING: Could not fetch the URL tftp://url
INFO: Creating context with default config
You can then change to the context, configure it at the CLI, and enter the write memory command
to write the file to the TFTP server.
To change the URL, reenter the config-url command with a new URL.
See the “Changing the Security Context URL” section on page 7-16 for more information about
changing the URL.
For example, enter the following command:
hostname(config-ctx)# config-url ftp://joe:passw0rd1@10.1.1.1/configlets/test.cfg
Step 5
(Optional) To assign the context to a resource class, enter the following command:
hostname(config-ctx)# member class_name
If you do not specify a class, the context belongs to the default class. You can only assign a context to
one resource class.
For example, to assign the context to the gold class, enter the following command:
hostname(config-ctx)# member gold
Step 6
(Optional) To assign an IPS virtual sensor to this context if you have the AIP SSM installed, use the
allocate-ips command. See the “Assigning Virtual Sensors to Security Contexts” section on page 23-6
for detailed information about virtual sensors.
The following example sets the admin context to be “administrator,” creates a context called
“administrator” on the internal Flash memory, and then adds two contexts from an FTP server:
hostname(config)# admin-context administrator
hostname(config)# context administrator
hostname(config-ctx)# allocate-interface gigabitethernet0/0.1
hostname(config-ctx)# allocate-interface gigabitethernet0/1.1
hostname(config-ctx)# config-url flash:/admin.cfg
hostname(config-ctx)#
hostname(config-ctx)#
hostname(config-ctx)#
hostname(config-ctx)#
int3-int8
hostname(config-ctx)#
hostname(config-ctx)#
context test
allocate-interface gigabitethernet0/0.100 int1
allocate-interface gigabitethernet0/0.102 int2
allocate-interface gigabitethernet0/0.110-gigabitethernet0/0.115
config-url ftp://user1:passw0rd@10.1.1.1/configlets/test.cfg
member gold
hostname(config-ctx)# context sample
hostname(config-ctx)# allocate-interface gigabitethernet0/1.200 int1
hostname(config-ctx)# allocate-interface gigabitethernet0/1.212 int2
Cisco Security Appliance Command Line Configuration Guide
7-10
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Automatically Assigning MAC Addresses to Context Interfaces
hostname(config-ctx)# allocate-interface gigabitethernet0/1.230-gigabitethernet0/1.235
int3-int8
hostname(config-ctx)# config-url ftp://user1:passw0rd@10.1.1.1/configlets/sample.cfg
hostname(config-ctx)# member silver
Automatically Assigning MAC Addresses to Context Interfaces
This section tells how to configure auto-generation of MAC addresses, and includes the following
sections:
•
Information About MAC Addresses, page 7-11
•
Default MAC Address, page 7-11
•
Failover MAC Addresses, page 7-12
•
MAC Address Format, page 7-12
•
Enabling Auto-Generation of MAC Addresses, page 7-12
•
Viewing Assigned MAC Addresses, page 7-13
Information About MAC Addresses
To allow contexts to share interfaces, we suggest that you assign unique MAC addresses to each shared
context interface. The MAC address is used to classify packets within a context. If you share an interface,
but do not have unique MAC addresses for the interface in each context, then the destination IP address
is used to classify packets. The destination address is matched with the context NAT configuration, and
this method has some limitations compared to the MAC address method. See the “How the Security
Appliance Classifies Packets” section on page 4-3 for information about classifying packets.
In the rare circumstance that the generated MAC address conflicts with another private MAC address in
your network, you can manually set the MAC address for the interface within the context. See the
“Configuring the Interface” section on page 8-3 to manually set the MAC address.
Default MAC Address
By default, the physical interface uses the burned-in MAC address, and all subinterfaces of a physical
interface use the same burned-in MAC address.
All auto-generated MAC addresses start with A2. The auto-generated MAC addresses are persistent
across reloads.
Interaction with Manual MAC Addresses
If you manually assign a MAC address and also enable auto-generation, then the manually assigned
MAC address is used. If you later remove the manual MAC address, the auto-generated address is used.
Because auto-generated addresses start with A2, you cannot start manual MAC addresses with A2 if you
also want to use auto-generation.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-11
Chapter 7
Adding and Managing Security Contexts
Automatically Assigning MAC Addresses to Context Interfaces
Failover MAC Addresses
For use with failover, the security appliance generates both an active and standby MAC address for each
interface. If the active unit fails over and the standby unit becomes active, the new active unit starts using
the active MAC addresses to minimize network disruption. See the “MAC Address Format” section for
more information.
For upgrading failover units with the legacy version of the mac-address auto command before the
prefix keyword was introduced, see the mac-address auto command in the Cisco Security Appliance
Command Reference.
MAC Address Format
The security appliance generates the MAC address using the following format:
A2xx.yyzz.zzzz
Where xx.yy is a user-defined prefix, and zz.zzzz is an internal counter generated by the security
appliance. For the standby MAC address, the address is identical except that the internal counter is
increased by 1.
For an example of how the prefix is used, if you set a prefix of 77, then the security appliance converts
77 into the hexadecimal value 004D (yyxx). When used in the MAC address, the prefix is reversed (xxyy)
to match the security appliance native form:
A24D.00zz.zzzz
For a prefix of 1009 (03F1), the MAC address is:
A2F1.03zz.zzzz
Enabling Auto-Generation of MAC Addresses
You can automatically assign private MAC addresses to each context interface by entering the following
command in the system configuration:
hostname(config)# mac-address auto prefix prefix
Where the prefix is a decimal value between 0 and 65535. This prefix is converted to a 4-digit
hexadecimal number, and used as part of the MAC address. The prefix ensures that each security
appliance uses unique MAC addresses, so you can have multiple security appliances on a network
segment, for example. See the “MAC Address Format” section for more information about how the
prefix is used.
When you configure a nameif command for the interface in a context, the new MAC address is generated
immediately. If you enable this command after you configure context interfaces, then MAC addresses
are generated for all interfaces immediately after you enter the command. If you use the no mac-address
auto command, the MAC address for each interface reverts to the default MAC address. For example,
subinterfaces of GigabitEthernet 0/1 revert to using the MAC address of GigabitEthernet 0/1.
Note
For the MAC address generation method when not using a prefix (not recommended), see the
mac-address auto command in the Cisco Security Appliance Command Reference.
Cisco Security Appliance Command Line Configuration Guide
7-12
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Automatically Assigning MAC Addresses to Context Interfaces
Viewing Assigned MAC Addresses
You can view auto-generated MAC addresses within the system configuration or within the context. This
section includes the following topics:
•
Viewing MAC Addresses in the System Configuration, page 7-13
•
Viewing MAC Addresses Within a Context, page 7-14
Viewing MAC Addresses in the System Configuration
To view the assigned MAC addresses from the system execution space, enter the following command:
hostname# show running-config all context [name]
The all option is required to view the assigned MAC addresses. Although this command is
user-configurable in global configuration mode only, the mac-address auto command appears as a
read-only entry in the configuration for each context along with the assigned MAC address. Only
allocated interfaces that are configured with a nameif command within the context have a MAC address
assigned.
Note
If you manually assign a MAC address to an interface, but also have auto-generation enabled, the
auto-generated address continues to show in the configuration even though the manual MAC address is
the one that is in use. If you later remove the manual MAC address, the auto-generated one shown will
be used.
The following output from the show running-config all context admin command shows the primary
and standby MAC address assigned to the Management0/0 interface:
hostname# show running-config all context admin
context admin
allocate-interface Management0/0
mac-address auto Management0/0 a24d.0000.1440 a24d.0000.1441
config-url disk0:/admin.cfg
The following output from the show running-config all context command shows all the MAC addresses
(primary and standby) for all context interfaces. Note that because the GigabitEthernet0/0 and
GigabitEthernet0/1 main interfaces are not configured with a nameif command inside the contexts, no
MAC addresses have been generated for them.
hostname# show running-config all context
admin-context admin
context admin
allocate-interface Management0/0
mac-address auto Management0/0 a2d2.0400.125a a2d2.0400.125b
config-url disk0:/admin.cfg
!
context CTX1
allocate-interface GigabitEthernet0/0
allocate-interface GigabitEthernet0/0.1-GigabitEthernet0/0.5
mac-address auto GigabitEthernet0/0.1 a2d2.0400.11bc a2d2.0400.11bd
mac-address auto GigabitEthernet0/0.2 a2d2.0400.11c0 a2d2.0400.11c1
mac-address auto GigabitEthernet0/0.3 a2d2.0400.11c4 a2d2.0400.11c5
mac-address auto GigabitEthernet0/0.4 a2d2.0400.11c8 a2d2.0400.11c9
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-13
Chapter 7
Adding and Managing Security Contexts
Changing Between Contexts and the System Execution Space
mac-address auto GigabitEthernet0/0.5 a2d2.0400.11cc a2d2.0400.11cd
allocate-interface GigabitEthernet0/1
allocate-interface GigabitEthernet0/1.1-GigabitEthernet0/1.3
mac-address auto GigabitEthernet0/1.1 a2d2.0400.120c a2d2.0400.120d
mac-address auto GigabitEthernet0/1.2 a2d2.0400.1210 a2d2.0400.1211
mac-address auto GigabitEthernet0/1.3 a2d2.0400.1214 a2d2.0400.1215
config-url disk0:/CTX1.cfg
!
context CTX2
allocate-interface GigabitEthernet0/0
allocate-interface GigabitEthernet0/0.1-GigabitEthernet0/0.5
mac-address auto GigabitEthernet0/0.1 a2d2.0400.11ba a2d2.0400.11bb
mac-address auto GigabitEthernet0/0.2 a2d2.0400.11be a2d2.0400.11bf
mac-address auto GigabitEthernet0/0.3 a2d2.0400.11c2 a2d2.0400.11c3
mac-address auto GigabitEthernet0/0.4 a2d2.0400.11c6 a2d2.0400.11c7
mac-address auto GigabitEthernet0/0.5 a2d2.0400.11ca a2d2.0400.11cb
allocate-interface GigabitEthernet0/1
allocate-interface GigabitEthernet0/1.1-GigabitEthernet0/1.3
mac-address auto GigabitEthernet0/1.1 a2d2.0400.120a a2d2.0400.120b
mac-address auto GigabitEthernet0/1.2 a2d2.0400.120e a2d2.0400.120f
mac-address auto GigabitEthernet0/1.3 a2d2.0400.1212 a2d2.0400.1213
config-url disk0:/CTX2.cfg
!
Viewing MAC Addresses Within a Context
To view the MAC address in use by each interface within the context, enter the following command:
hostname/context# show interface | include (Interface)|(MAC)
For example:
hostname/context# show interface | include (Interface)|(MAC)
Interface GigabitEthernet1/1.1 "g1/1.1", is down, line protocol is down
MAC address a201.0101.0600, MTU 1500
Interface GigabitEthernet1/1.2 "g1/1.2", is down, line protocol is down
MAC address a201.0102.0600, MTU 1500
Interface GigabitEthernet1/1.3 "g1/1.3", is down, line protocol is down
MAC address a201.0103.0600, MTU 1500
...
Note
The show interface command shows the MAC address in use; if you manually assign a MAC address
and also have auto-generation enabled, then you can only view the unused auto-generated address from
within the system configuration.
Changing Between Contexts and the System Execution Space
If you log in to the system execution space (or the admin context using Telnet or SSH), you can change
between contexts and perform configuration and monitoring tasks within each context. The running
configuration that you edit in a configuration mode, or that is used in the copy or write commands,
depends on your location. When you are in the system execution space, the running configuration
consists only of the system configuration; when you are in a context, the running configuration consists
only of that context. For example, you cannot view all running configurations (system plus all contexts)
by entering the show running-config command. Only the current configuration displays.
Cisco Security Appliance Command Line Configuration Guide
7-14
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
To change between the system execution space and a context, or between contexts, see the following
commands:
•
To change to a context, enter the following command:
hostname# changeto context name
The prompt changes to the following:
hostname/name#
•
To change to the system execution space, enter the following command:
hostname/admin# changeto system
The prompt changes to the following:
hostname#
Managing Security Contexts
This section describes how to manage security contexts, and includes the following topics:
•
Removing a Security Context, page 7-15
•
Changing the Admin Context, page 7-16
•
Changing the Security Context URL, page 7-16
•
Reloading a Security Context, page 7-17
•
Monitoring Security Contexts, page 7-18
Removing a Security Context
You can only remove a context by editing the system configuration. You cannot remove the current
admin context, unless you remove all contexts using the clear context command.
Note
If you use failover, there is a delay between when you remove the context on the active unit and when
the context is removed on the standby unit. You might see an error message indicating that the number
of interfaces on the active and standby units are not consistent; this error is temporary and can be
ignored.
Use the following commands for removing contexts:
•
To remove a single context, enter the following command in the system execution space:
hostname(config)# no context name
All context commands are also removed.
•
To remove all contexts (including the admin context), enter the following command in the system
execution space:
hostname(config)# clear context
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-15
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Changing the Admin Context
The system configuration does not include any network interfaces or network settings for itself; rather,
when the system needs to access network resources (such as downloading the contexts from the server),
it uses one of the contexts that is designated as the admin context.
The admin context is just like any other context, except that when a user logs in to the admin context,
then that user has system administrator rights and can access the system and all other contexts. The
admin context is not restricted in any way, and can be used as a regular context. However, because
logging into the admin context grants you administrator privileges over all contexts, you might need to
restrict access to the admin context to appropriate users.
You can set any context to be the admin context, as long as the configuration file is stored in the internal
Flash memory. To set the admin context, enter the following command in the system execution space:
hostname(config)# admin-context context_name
Any remote management sessions, such as Telnet, SSH, or HTTPS, that are connected to the admin
context are terminated. You must reconnect to the new admin context.
Note
A few system commands, including ntp server, identify an interface name that belongs to the admin
context. If you change the admin context, and that interface name does not exist in the new admin
context, be sure to update any system commands that refer to the interface.
Changing the Security Context URL
You cannot change the security context URL without reloading the configuration from the new URL.
The security appliance merges the new configuration with the current running configuration. Reentering
the same URL also merges the saved configuration with the running configuration. A merge adds any
new commands from the new configuration to the running configuration. If the configurations are the
same, no changes occur. If commands conflict or if commands affect the running of the context, then the
effect of the merge depends on the command. You might get errors, or you might have unexpected
results. If the running configuration is blank (for example, if the server was unavailable and the
configuration was never downloaded), then the new configuration is used. If you do not want to merge
the configurations, you can clear the running configuration, which disrupts any communications through
the context, and then reload the configuration from the new URL.
To change the URL for a context, perform the following steps:
Step 1
If you do not want to merge the configuration, change to the context and clear its configuration by
entering the following commands. If you want to perform a merge, skip to Step 2.
hostname# changeto context name
hostname/name# configure terminal
hostname/name(config)# clear configure all
Step 2
If required, change to the system execution space by entering the following command:
hostname/name(config)# changeto system
Step 3
To enter the context configuration mode for the context you want to change, enter the following
command:
hostname(config)# context name
Cisco Security Appliance Command Line Configuration Guide
7-16
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Step 4
To enter the new URL, enter the following command:
hostname(config)# config-url new_url
The system immediately loads the context so that it is running.
Reloading a Security Context
You can reload the context in two ways:
•
Clear the running configuration and then import the startup configuration.
This action clears most attributes associated with the context, such as connections and NAT tables.
•
Remove the context from the system configuration.
This action clears additional attributes, such as memory allocation, which might be useful for
troubleshooting. However, to add the context back to the system requires you to respecify the URL
and interfaces.
This section includes the following topics:
•
Reloading by Clearing the Configuration, page 7-17
•
Reloading by Removing and Re-adding the Context, page 7-18
Reloading by Clearing the Configuration
To reload the context by clearing the context configuration, and reloading the configuration from the
URL, perform the following steps:
Step 1
To change to the context that you want to reload, enter the following command:
hostname# changeto context name
Step 2
To access configuration mode, enter the following command:
hostname/name# configure terminal
Step 3
To clear the running configuration, enter the following command:
hostname/name(config)# clear configure all
This command clears all connections.
Step 4
To reload the configuration, enter the following command:
hostname/name(config)# copy startup-config running-config
The security appliance copies the configuration from the URL specified in the system configuration. You
cannot change the URL from within a context.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-17
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Reloading by Removing and Re-adding the Context
To reload the context by removing the context and then re-adding it, perform the steps in the following
sections:
1.
“Automatically Assigning MAC Addresses to Context Interfaces” section on page 7-11
2.
“Configuring a Security Context” section on page 7-7
Monitoring Security Contexts
This section describes how to view and monitor context information, and includes the following topics:
•
Viewing Context Information, page 7-18
•
Viewing Resource Allocation, page 7-19
•
Viewing Resource Usage, page 7-22
•
Monitoring SYN Attacks in Contexts, page 7-23
Viewing Context Information
From the system execution space, you can view a list of contexts including the name, allocated
interfaces, and configuration file URL.
From the system execution space, view all contexts by entering the following command:
hostname# show context [name | detail| count]
The detail option shows additional information. See the following sample displays below for more
information.
If you want to show information for a particular context, specify the name.
The count option shows the total number of contexts.
The following is sample output from the show context command. The following sample display shows
three contexts:
hostname# show context
Context Name
*admin
Interfaces
GigabitEthernet0/1.100
GigabitEthernet0/1.101
contexta
GigabitEthernet0/1.200
GigabitEthernet0/1.201
contextb
GigabitEthernet0/1.300
GigabitEthernet0/1.301
Total active Security Contexts: 3
URL
disk0:/admin.cfg
disk0:/contexta.cfg
disk0:/contextb.cfg
Table 7-2 shows each field description.
Table 7-2
show context Fields
Field
Description
Context Name
Lists all context names. The context name with the asterisk (*) is the admin context.
Interfaces
The interfaces assigned to the context.
URL
The URL from which the security appliance loads the context configuration.
Cisco Security Appliance Command Line Configuration Guide
7-18
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
The following is sample output from the show context detail command:
hostname# show context detail
Context "admin", has been created, but initial ACL rules not complete
Config URL: disk0:/admin.cfg
Real Interfaces: Management0/0
Mapped Interfaces: Management0/0
Flags: 0x00000013, ID: 1
Context "ctx", has been created, but initial ACL rules not complete
Config URL: ctx.cfg
Real Interfaces: GigabitEthernet0/0.10, GigabitEthernet0/1.20,
GigabitEthernet0/2.30
Mapped Interfaces: int1, int2, int3
Flags: 0x00000011, ID: 2
Context "system", is a system resource
Config URL: startup-config
Real Interfaces:
Mapped Interfaces: Control0/0, GigabitEthernet0/0,
GigabitEthernet0/0.10, GigabitEthernet0/1, GigabitEthernet0/1.10,
GigabitEthernet0/1.20, GigabitEthernet0/2, GigabitEthernet0/2.30,
GigabitEthernet0/3, Management0/0, Management0/0.1
Flags: 0x00000019, ID: 257
Context "null", is a system resource
Config URL: ... null ...
Real Interfaces:
Mapped Interfaces:
Flags: 0x00000009, ID: 258
See the Cisco Security Appliance Command Reference for more information about the detail output.
The following is sample output from the show context count command:
hostname# show context count
Total active contexts: 2
Viewing Resource Allocation
From the system execution space, you can view the allocation for each resource across all classes and
class members.
To view the resource allocation, enter the following command:
hostname# show resource allocation [detail]
This command shows the resource allocation, but does not show the actual resources being used. See the
“Viewing Resource Usage” section on page 7-22 for more information about actual resource usage.
The detail argument shows additional information. See the following sample displays for more
information.
The following sample display shows the total allocation of each resource as an absolute value and as a
percentage of the available system resources:
hostname# show resource allocation
Resource
Total
Conns [rate]
35000
Inspects [rate]
35000
Syslogs [rate]
10500
Conns
305000
Hosts
78842
% of Avail
N/A
N/A
N/A
30.50%
N/A
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-19
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
SSH
Telnet
Xlates
All
35
35
91749
unlimited
35.00%
35.00%
N/A
Table 7-3 shows each field description.
Table 7-3
show resource allocation Fields
Field
Description
Resource
The name of the resource that you can limit.
Total
The total amount of the resource that is allocated across all contexts. The amount
is an absolute number of concurrent instances or instances per second. If you
specified a percentage in the class definition, the security appliance converts the
percentage to an absolute number for this display.
% of Avail
The percentage of the total system resources that is allocated across all contexts, if
the resource has a hard system limit. If a resource does not have a system limit, this
column shows N/A.
The following is sample output from the show resource allocation detail command:
hostname# show resource allocation detail
Resource Origin:
A
Value was derived from the resource 'all'
C
Value set in the definition of this class
D
Value set in default class
Resource
Class
Mmbrs Origin
Limit
Conns [rate]
default
all
CA unlimited
gold
1
C
34000
silver
1
CA
17000
bronze
0
CA
8500
All Contexts:
3
Inspects [rate]
Syslogs [rate]
Conns
Hosts
SSH
default
gold
silver
bronze
All Contexts:
all
1
1
0
3
CA
DA
CA
CA
default
gold
silver
bronze
All Contexts:
all
1
1
0
3
CA
C
CA
CA
default
gold
silver
bronze
All Contexts:
all
1
1
0
3
CA
C
CA
CA
default
gold
silver
bronze
All Contexts:
all
1
1
0
3
CA
DA
CA
CA
default
gold
all
1
C
D
unlimited
unlimited
10000
5000
unlimited
6000
3000
1500
unlimited
200000
100000
50000
unlimited
unlimited
26214
13107
5
5
Total
Total %
34000
17000
N/A
N/A
51000
N/A
10000
N/A
10000
N/A
6000
3000
N/A
N/A
9000
N/A
200000
100000
20.00%
10.00%
300000
30.00%
26214
N/A
26214
N/A
5
5.00%
Cisco Security Appliance Command Line Configuration Guide
7-20
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Telnet
Xlates
mac-addresses
silver
bronze
All Contexts:
1
0
3
CA
CA
default
gold
silver
bronze
All Contexts:
all
1
1
0
3
C
D
CA
CA
default
gold
silver
bronze
All Contexts:
all
1
1
0
3
CA
DA
CA
CA
default
gold
silver
bronze
All Contexts:
all
1
1
0
3
C
D
CA
CA
10
5
5
5
10
5
unlimited
unlimited
23040
11520
65535
65535
6553
3276
10
10.00%
20
20.00%
5
10
5.00%
10.00%
20
20.00%
23040
N/A
23040
N/A
65535
6553
100.00%
9.99%
137623
209.99%
Table 7-4 shows each field description.
Table 7-4
show resource allocation detail Fields
Field
Description
Resource
The name of the resource that you can limit.
Class
The name of each class, including the default class.
The All contexts field shows the total values across all classes.
Mmbrs
The number of contexts assigned to each class.
Origin
The origin of the resource limit, as follows:
•
A—You set this limit with the all option, instead of as an individual resource.
•
C—This limit is derived from the member class.
•
D—This limit was not defined in the member class, but was derived from the
default class. For a context assigned to the default class, the value will be “C”
instead of “D.”
The security appliance can combine “A” with “C” or “D.”
Limit
The limit of the resource per context, as an absolute number. If you specified a
percentage in the class definition, the security appliance converts the percentage to
an absolute number for this display.
Total
The total amount of the resource that is allocated across all contexts in the class.
The amount is an absolute number of concurrent instances or instances per second.
If the resource is unlimited, this display is blank.
% of Avail
The percentage of the total system resources that is allocated across all contexts in
the class. If the resource is unlimited, this display is blank. If the resource does not
have a system limit, then this column shows N/A.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-21
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Viewing Resource Usage
From the system execution space, you can view the resource usage for each context and display the
system resource usage.
From the system execution space, view the resource usage for each context by entering the following
command:
hostname# show resource usage [context context_name | top n | all | summary | system]
[resource {resource_name | all} | detail] [counter counter_name [count_threshold]]
By default, all context usage is displayed; each context is listed separately.
Enter the top n keyword to show the contexts that are the top n users of the specified resource. You must
specify a single resource type, and not resource all, with this option.
The summary option shows all context usage combined.
The system option shows all context usage combined, but shows the system limits for resources instead
of the combined context limits.
For the resource resource_name, see Table 7-1 for available resource names. See also the show resource
type command. Specify all (the default) for all types.
The detail option shows the resource usage of all resources, including those you cannot manage. For
example, you can view the number of TCP intercepts.
The counter counter_name is one of the following keywords:
•
current—Shows the active concurrent instances or the current rate of the resource.
•
denied—Shows the number of instances that were denied because they exceeded the resource limit
shown in the Limit column.
•
peak—Shows the peak concurrent instances, or the peak rate of the resource since the statistics were
last cleared, either using the clear resource usage command or because the device rebooted.
•
all—(Default) Shows all statistics.
The count_threshold sets the number above which resources are shown. The default is 1. If the usage of
the resource is below the number you set, then the resource is not shown. If you specify all for the
counter name, then the count_threshold applies to the current usage.
Note
To show all resources, set the count_threshold to 0.
The following is sample output from the show resource usage context command, which shows the
resource usage for the admin context:
hostname# show resource usage context admin
Resource
Telnet
Conns
Hosts
Current
1
44
45
Peak
1
55
56
Limit
5
N/A
N/A
Denied
0
0
0
Context
admin
admin
admin
The following is sample output from the show resource usage summary command, which shows the
resource usage for all contexts and all resources. This sample shows the limits for 6 contexts.
hostname# show resource usage summary
Resource
Syslogs [rate]
Conns
Current
1743
584
Peak
2132
763
Limit
Denied Context
N/A
0 Summary
280000(S)
0 Summary
Cisco Security Appliance Command Line Configuration Guide
7-22
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Xlates
8526
8966
N/A
0
Hosts
254
254
N/A
0
Conns [rate]
270
535
N/A
1704
Inspects [rate]
270
535
N/A
0
S = System: Combined context limits exceed the system limit; the
Summary
Summary
Summary
Summary
system limit is shown.
The following is sample output from the show resource usage summary command, which shows the
limits for 25 contexts. Because the context limit for Telnet and SSH connections is 5 per context, then
the combined limit is 125. The system limit is only 100, so the system limit is shown.
hostname# show resource usage summary
Resource
Current
Peak
Limit
Denied
Context
Telnet
1
1
100[S]
0
Summary
SSH
2
2
100[S]
0
Summary
Conns
56
90
N/A
0
Summary
Hosts
89
102
N/A
0
Summary
S = System: Combined context limits exceed the system limit; the system limit is shown.
The following is sample output from the show resource usage system command, which shows the
resource usage for all contexts, but it shows the system limit instead of the combined context limits. The
counter all 0 option is used to show resources that are not currently in use. The Denied statistics indicate
how many times the resource was denied due to the system limit, if available.
hostname# show resource usage system counter all 0
Resource
Telnet
SSH
ASDM
Syslogs [rate]
Conns
Xlates
Hosts
Conns [rate]
Inspects [rate]
Current
0
0
0
1
0
0
0
1
0
Peak
0
0
0
18
1
0
2
1
0
Limit
100
100
32
N/A
280000
N/A
N/A
N/A
N/A
Denied
0
0
0
0
0
0
0
0
0
Context
System
System
System
System
System
System
System
System
System
Monitoring SYN Attacks in Contexts
The security appliance prevents SYN attacks using TCP Intercept. TCP Intercept uses the SYN cookies
algorithm to prevent TCP SYN-flooding attacks. A SYN-flooding attack consists of a series of SYN
packets usually originating from spoofed IP addresses. The constant flood of SYN packets keeps the
server SYN queue full, which prevents it from servicing connection requests. When the embryonic
connection threshold of a connection is crossed, the security appliance acts as a proxy for the server and
generates a SYN-ACK response to the client SYN request. When the security appliance receives an ACK
back from the client, it can then authenticate the client and allow the connection to the server.
You can monitor the rate of attacks for individual contexts using the show perfmon command; you can
monitor the amount of resources being used by TCP intercept for individual contexts using the show
resource usage detail command; you can monitor the resources being used by TCP intercept for the
entire system using the show resource usage summary detail command.
The following is sample output from the show perfmon command that shows the rate of TCP intercepts
for a context called admin.
hostname/admin# show perfmon
Context:admin
PERFMON STATS:
Xlates
Current
0/s
Average
0/s
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-23
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Connections
TCP Conns
UDP Conns
URL Access
URL Server Req
WebSns Req
TCP Fixup
HTTP Fixup
FTP Fixup
AAA Authen
AAA Author
AAA Account
TCP Intercept
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
322779/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
0/s
322779/s
The following is sample output from the show resource usage detail command that shows the amount
of resources being used by TCP Intercept for individual contexts. (Sample text in italics shows the TCP
intercept information.)
hostname(config)# show resource usage detail
Resource
Current
Peak
Limit
memory
843732
847288 unlimited
chunk:channels
14
15 unlimited
chunk:fixup
15
15 unlimited
chunk:hole
1
1 unlimited
chunk:ip-users
10
10 unlimited
chunk:list-elem
21
21 unlimited
chunk:list-hdr
3
4 unlimited
chunk:route
2
2 unlimited
chunk:static
1
1 unlimited
tcp-intercepts
328787
803610 unlimited
np-statics
3
3 unlimited
statics
1
1 unlimited
ace-rules
1
1 unlimited
console-access-rul
2
2 unlimited
fixup-rules
14
15 unlimited
memory
959872
960000 unlimited
chunk:channels
15
16 unlimited
chunk:dbgtrace
1
1 unlimited
chunk:fixup
15
15 unlimited
chunk:global
1
1 unlimited
chunk:hole
2
2 unlimited
chunk:ip-users
10
10 unlimited
chunk:udp-ctrl-blk
1
1 unlimited
chunk:list-elem
24
24 unlimited
chunk:list-hdr
5
6 unlimited
chunk:nat
1
1 unlimited
chunk:route
2
2 unlimited
chunk:static
1
1 unlimited
tcp-intercept-rate
16056
16254 unlimited
globals
1
1 unlimited
np-statics
3
3 unlimited
statics
1
1 unlimited
nats
1
1 unlimited
ace-rules
2
2 unlimited
console-access-rul
2
2 unlimited
fixup-rules
14
15 unlimited
memory
232695716
232020648 unlimited
chunk:channels
17
20 unlimited
chunk:dbgtrace
3
3 unlimited
chunk:fixup
15
15 unlimited
chunk:ip-users
4
4 unlimited
chunk:list-elem
1014
1014 unlimited
chunk:list-hdr
1
1 unlimited
chunk:route
1
1 unlimited
Denied
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Context
admin
admin
admin
admin
admin
admin
admin
admin
admin
admin
admin
admin
admin
admin
admin
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
system
system
system
system
system
system
system
system
Cisco Security Appliance Command Line Configuration Guide
7-24
OL-12172-04
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
block:16384
block:2048
510
32
885
34
unlimited
unlimited
0 system
0 system
The following sample output shows the resources being used by TCP intercept for the entire system.
(Sample text in italics shows the TCP intercept information.)
hostname(config)# show resource usage summary detail
Resource
Current
Peak
Limit
memory
238421312
238434336 unlimited
chunk:channels
46
48 unlimited
chunk:dbgtrace
4
4 unlimited
chunk:fixup
45
45 unlimited
chunk:global
1
1 unlimited
chunk:hole
3
3 unlimited
chunk:ip-users
24
24 unlimited
chunk:udp-ctrl-blk
1
1 unlimited
chunk:list-elem
1059
1059 unlimited
chunk:list-hdr
10
11 unlimited
chunk:nat
1
1 unlimited
chunk:route
5
5 unlimited
chunk:static
2
2 unlimited
block:16384
510
885 unlimited
block:2048
32
35 unlimited
tcp-intercept-rate
341306
811579 unlimited
globals
1
1 unlimited
np-statics
6
6 unlimited
statics
2
2
N/A
nats
1
1
N/A
ace-rules
3
3
N/A
console-access-rul
4
4
N/A
fixup-rules
43
44
N/A
Denied
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Context
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Summary
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
7-25
Chapter 7
Adding and Managing Security Contexts
Managing Security Contexts
Cisco Security Appliance Command Line Configuration Guide
7-26
OL-12172-04
CH A P T E R
8
Configuring Interface Parameters
This chapter describes how to configure each interface (physical, redundant, or subinterface) for a name,
security level, and IP address.
Note
•
For single context mode, the procedures in this chapter continue the interface configuration started
in Chapter 6, “Configuring Ethernet Settings, Redundant Interfaces, and Subinterfaces.”
•
For multiple context mode, the procedures in Chapter 6, “Configuring Ethernet Settings, Redundant
Interfaces, and Subinterfaces,” are performed in the system execution space, while the procedures
in this chapter are performed within each security context.
To configure interfaces for the ASA 5505 adaptive security appliance, see Chapter 5, “Configuring
Switch Ports and VLAN Interfaces for the Cisco ASA 5505 Adaptive Security Appliance.”
This chapter includes the following sections:
•
Security Level Overview, page 8-1
•
Configuring Interface Parameters, page 8-2
•
Allowing Communication Between Interfaces on the Same Security Level, page 8-7
Security Level Overview
Each interface must have a security level from 0 (lowest) to 100 (highest). For example, you should
assign your most secure network, such as the inside host network, to level 100. While the outside
network connected to the Internet can be level 0. Other networks, such as DMZs can be in between. You
can assign interfaces to the same security level. See the “Allowing Communication Between Interfaces
on the Same Security Level” section on page 8-7 for more information.
The level controls the following behavior:
•
Network access—By default, there is an implicit permit from a higher security interface to a lower
security interface (outbound). Hosts on the higher security interface can access any host on a lower
security interface. You can limit access by applying an access list to the interface.
If you enable communication for same security interfaces (see the “Allowing Communication
Between Interfaces on the Same Security Level” section on page 8-7), there is an implicit permit for
interfaces to access other interfaces on the same security level or lower.
•
Inspection engines—Some application inspection engines are dependent on the security level. For
same security interfaces, inspection engines apply to traffic in either direction.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
8-1
Chapter 8
Configuring Interface Parameters
Configuring Interface Parameters
– NetBIOS inspection engine—Applied only for outbound connections.
– SQL*Net inspection engine—If a control connection for the SQL*Net (formerly OraServ) port
exists between a pair of hosts, then only an inbound data connection is permitted through the
security appliance.
•
Filtering—HTTP(S) and FTP filtering applies only for outbound connections (from a higher level
to a lower level).
If you enable communication for same security interfaces, you can filter traffic in either direction.
•
NAT control—When you enable NAT control, you must configure NAT for hosts on a higher security
interface (inside) when they access hosts on a lower security interface (outside).
Without NAT control, or for same security interfaces, you can choose to use NAT between any
interface, or you can choose not to use NAT. Keep in mind that configuring NAT for an outside
interface might require a special keyword.
•
established command—This command allows return connections from a lower security host to a
higher security host if there is already an established connection from the higher level host to the
lower level host.
If you enable communication for same security interfaces , you can configure established
commands for both directions.
Configuring Interface Parameters
Before you can complete your configuration and allow traffic through the security appliance, you need
to configure an interface name, and for routed mode, an IP address.
Note
If you are using failover, do not use this procedure to name interfaces that you are reserving for failover
and Stateful Failover communications. See Chapter 15, “Configuring Failover.” to configure the failover
and state links.
This section includes the following topics:
•
Interface Parameters Overview, page 8-2
•
Configuring the Interface, page 8-3
Interface Parameters Overview
This section describes interface parameters and includes the following topics:
•
Default State of Interfaces, page 8-3
•
Default Security Level, page 8-3
•
Multiple Context Mode Guidelines, page 8-3
Cisco Security Appliance Command Line Configuration Guide
8-2
OL-12172-04
Chapter 8
Configuring Interface Parameters
Configuring Interface Parameters
Default State of Interfaces
The default state of an interface depends on the type and the context mode.
In multiple context mode, all allocated interfaces are enabled by default, no matter what the state of the
interface is in the system execution space. However, for traffic to pass through the interface, the interface
also has to be enabled in the system execution space. If you shut down an interface in the system
execution space, then that interface is down in all contexts that share it.
In single mode or in the system execution space, interfaces have the following default states:
•
Physical interfaces—Disabled.
•
Redundant Interfaces—Enabled. However, for traffic to pass through the redundant interface, the
member physical interfaces must also be enabled.
•
Subinterfaces—Enabled. However, for traffic to pass through the subinterface, the physical interface
must also be enabled.
Default Security Level
The default security level is 0. If you name an interface “inside” and you do not set the security level
explicitly, then the security appliance sets the security level to 100.
Note
If you change the security level of an interface, and you do not want to wait for existing connections to
time out before the new security information is used, you can clear the connections using the
clear local-host command.
Multiple Context Mode Guidelines
For multiple context mode, follow these guidelines:
•
Configure the context interfaces from within each context.
•
Configure context interfaces that you already assigned to the context in the system configuration.
Other interfaces are not available.
•
Configure Ethernet settings, redundant interfaces, and subinterfaces in the system configuration. No
other configuration is available. The exception is for failover interfaces, which are configured in the
system configuration. Do not configure failover interfaces with the procedures in this chapter. See
Chapter 15, “Configuring Failover,” for more information.
Configuring the Interface
To configure an interface or subinterface, perform the following steps:
Step 1
To specify the interface you want to configure, enter the following command:
hostname(config)# interface {{redundant number| physical_interface}[.subinterface] |
mapped_name}
hostname(config-if)#
The redundant number argument is the redundant interface ID, such as redundant 1.
Append the subinterface ID to the physical or redundant interface ID separated by a period (.).
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
8-3
Chapter 8
Configuring Interface Parameters
Configuring Interface Parameters
In multiple context mode, enter the mapped_name if one was assigned using the allocate-interface
command.
The physical_interface ID includes the type, slot, and port number as type [slot/]port. The physical
interface types include the following:
•
ethernet
•
gigabitethernet
•
management (ASA 5500 only)
For the PIX 500 series security appliance, enter the type followed by the port number, for example,
ethernet 0.
For the ASA 5500 series adaptive security appliance, enter the type followed by slot/port, for example,
gigabitethernet 0/1 or ethernet 0/1.
Note
For the ASA 5550 adaptive security appliance, for maximum throughput, be sure to balance your
traffic over the two interface slots; for example, assign the inside interface to slot 1 and the
outside interface to slot 0.
The ASA 5500 management interface is a Fast Ethernet interface designed for management traffic only,
and is specified as management 0/0. You can, however, use it for through traffic if desired (see the
management-only command). In transparent firewall mode, you can use the management interface (for
management purposes) in addition to the two interfaces allowed for through traffic. You can also add
subinterfaces to the management interface to provide management in each security context for multiple
context mode.
For example, enter the following command:
hostname(config)# interface gigabitethernet 0/1.1
Step 2
To name the interface, enter the following command:
hostname(config-if)# nameif name
The name is a text string up to 48 characters, and is not case-sensitive. You can change the name by
reentering this command with a new value. Do not enter the no form, because that command causes all
commands that refer to that name to be deleted.
Step 3
To set the security level, enter the following command:
hostname(config-if)# security-level number
Where number is an integer between 0 (lowest) and 100 (highest).
Step 4
(Optional) To set an interface to management-only mode, enter the following command:
hostname(config-if)# management-only
The ASA 5510 and higher adaptive security appliance includes a dedicated management interface called
Management 0/0, which is meant to support traffic to the security appliance. However, you can configure
any interface to be a management-only interface using the management-only command. Also, for
Management 0/0, you can disable management-only mode so the interface can pass through traffic just
like any other interface.
Cisco Security Appliance Command Line Configuration Guide
8-4
OL-12172-04
Chapter 8
Configuring Interface Parameters
Configuring Interface Parameters
Note
Step 5
Transparent firewall mode allows only two interfaces to pass through traffic; however, on the
ASA 5510 and higher adaptive security appliance, you can use the Management 0/0 interface
(either the physical interface or a subinterface) as a third interface for management traffic. The
mode is not configurable in this case and must always be management-only.
To set the IP address, enter one of the following commands.
In routed firewall mode, set the IP address for all interfaces. In transparent firewall mode, do not set the
IP address for each interface, but rather set it for the whole security appliance or context. The exception
is for the Management 0/0 management-only interface, which does not pass through traffic. To set the
transparent firewall mode whole security appliance or context management IP address, see the “Setting
the Management IP Address for a Transparent Firewall” section on page 9-5. To set the IP address of the
Management 0/0 interface or subinterface, use one of the following commands.
To set an IPv6 address, see the “Configuring IPv6 on an Interface” section on page 13-3.
For use with failover, you must set the IP address and standby address manually; DHCP and PPPoE are
not supported.
•
To set the IP address manually, enter the following command:
hostname(config-if)# ip address ip_address [mask] [standby ip_address]
where the ip_address and mask arguments set the interface IP address and subnet mask.
The standby ip_address argument is used for failover. See Chapter 15, “Configuring Failover,” for
more information.
•
To obtain an IP address from a DHCP server, enter the following command:
hostname(config-if)# ip address dhcp [setroute]
where the setroute keyword lets the security appliance use the default route supplied by the DHCP
server.
Reenter this command to reset the DHCP lease and request a new lease.
If you do not enable the interface using the no shutdown command before you enter the ip address
dhcp command, some DHCP requests might not be sent.
•
To obtain an IP address from a PPPoE server, see Chapter 37, “Configuring the PPPoE Client.”
PPPoE is not supported in multiple context mode.
Step 6
(Optional) To assign a private MAC address to this interface, enter the following command:
hostname(config-if)# mac-address mac_address [standby mac_address]
The mac_address is in H.H.H format, where H is a 16-bit hexadecimal digit. For example, the
MAC address 00-0C-F1-42-4C-DE is entered as 000C.F142.4CDE.
By default, the physical interface uses the burned-in MAC address, and all subinterfaces of a physical
interface use the same burned-in MAC address. A redundant interface uses the MAC address of the first
physical interface that you add. If you change the order of the member interfaces in the configuration,
then the MAC address changes to match the MAC address of the interface that is now listed first. If you
assign a MAC address to the redundant interface using this command, then it is used regardless of the
member interface MAC addresses.
In multiple context mode, if you share an interface between contexts, you can assign a unique MAC
address to the interface in each context. This feature lets the security appliance easily classify packets
into the appropriate context. Using a shared interface without unique MAC addresses is possible, but has
some limitations. See the “How the Security Appliance Classifies Packets” section on page 4-3 for more
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
8-5
Chapter 8
Configuring Interface Parameters
Configuring Interface Parameters
information. You can assign each MAC address manually, or you can automatically generate MAC
addresses for shared interfaces in contexts. See the “Automatically Assigning MAC Addresses to
Context Interfaces” section on page 7-11 to automatically generate MAC addresses. If you automatically
generate MAC addresses, you can use the mac-address command to override the generated address. The
first two bytes of a manual MAC address cannot be A2 if you also want to use auto-generated MAC
addresses.
For single context mode, or for interfaces that are not shared in multiple context mode, you might want
to assign unique MAC addresses to subinterfaces. For example, your service provider might perform
access control based on the MAC address.
For use with failover, set the standby MAC address. If the active unit fails over and the standby unit
becomes active, the new active unit starts using the active MAC addresses to minimize network
disruption, while the old active unit uses the standby address.
Step 7
To enable the interface, if it is not already enabled, enter the following command:
hostname(config-if)# no shutdown
To disable the interface, enter the shutdown command. If you enter the shutdown command for a
physical or redundant interface, you also shut down all subinterfaces. If you shut down an interface in
the system execution space, then that interface is shut down in all contexts that share it, even though the
context configurations show the interface as enabled.
The following example configures parameters for the physical interface in single mode:
hostname(config)# interface gigabitethernet 0/1
hostname(config-if)# speed 1000
hostname(config-if)# duplex full
hostname(config-if)# nameif inside
hostname(config-if)# security-level 100
hostname(config-if)# ip address 10.1.1.1 255.255.255.0
hostname(config-if)# no shutdown
The following example configures parameters for a subinterface in single mode:
hostname(config)# interface gigabitethernet 0/1.1
hostname(config-subif)# vlan 101
hostname(config-subif)# nameif dmz1
hostname(config-subif)# security-level 50
hostname(config-subif)# ip address 10.1.2.1 255.255.255.0
hostname(config-subif)# mac-address 000C.F142.4CDE standby 020C.F142.4CDE
hostname(config-subif)# no shutdown
The following example configures interface parameters in multiple context mode for the system
configuration, and allocates the gigabitethernet 0/1.1 subinterface to contextA:
hostname(config)# interface gigabitethernet 0/1
hostname(config-if)# speed 1000
hostname(config-if)# duplex full
hostname(config-if)# no shutdown
hostname(config-if)# interface gigabitethernet 0/1.1
hostname(config-subif)# vlan 101
hostname(config-subif)# no shutdown
hostname(config-subif)# context contextA
hostname(config-ctx)# ...
hostname(config-ctx)# allocate-interface gigabitethernet 0/1.1
The following example configures parameters in multiple context mode for the context configuration:
hostname/contextA(config)# interface gigabitethernet 0/1.1
Cisco Security Appliance Command Line Configuration Guide
8-6
OL-12172-04
Chapter 8
Configuring Interface Parameters
Allowing Communication Between Interfaces on the Same Security Level
hostname/contextA(config-if)#
hostname/contextA(config-if)#
hostname/contextA(config-if)#
hostname/contextA(config-if)#
hostname/contextA(config-if)#
nameif inside
security-level 100
ip address 10.1.2.1 255.255.255.0
mac-address 030C.F142.4CDE standby 040C.F142.4CDE
no shutdown
Allowing Communication Between Interfaces on the Same
Security Level
By default, interfaces on the same security level cannot communicate with each other. Allowing
communication between same security interfaces provides the following benefits:
•
You can configure more than 101 communicating interfaces.
If you use different levels for each interface and do not assign any interfaces to the same security
level, you can configure only one interface per level (0 to 100).
•
Note
You want traffic to flow freely between all same security interfaces without access lists.
If you enable NAT control, you do not need to configure NAT between same security level interfaces.
See the “NAT and Same Security Level Interfaces” section on page 19-15 for more information on NAT
and same security level interfaces.
If you enable same security interface communication, you can still configure interfaces at different
security levels as usual.
To enable interfaces on the same security level so that they can communicate with each other, enter the
following command:
hostname(config)# same-security-traffic permit inter-interface
To disable this setting, use the no form of this command.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
8-7
Chapter 8
Configuring Interface Parameters
Allowing Communication Between Interfaces on the Same Security Level
Cisco Security Appliance Command Line Configuration Guide
8-8
OL-12172-04
CH A P T E R
9
Configuring Basic Settings
This chapter describes how to configure basic settings on your security appliance that are typically
required for a functioning configuration. This chapter includes the following sections:
•
Changing the Login Password, page 9-1
•
Changing the Enable Password, page 9-1
•
Setting the Hostname, page 9-2
•
Setting the Domain Name, page 9-2
•
Setting the Date and Time, page 9-2
•
Setting the Management IP Address for a Transparent Firewall, page 9-5
Changing the Login Password
The login password is used for Telnet and SSH connections. By default, the login password is “cisco.”
To change the password, enter the following command:
hostname(config)# {passwd | password} password
You can enter passwd or password. The password is a case-sensitive password of up to 16 alphanumeric
and special characters. You can use any character in the password except a question mark or a space.
The password is saved in the configuration in encrypted form, so you cannot view the original password
after you enter it. Use the no password command to restore the password to the default setting.
Changing the Enable Password
The enable password lets you enter privileged EXEC mode. By default, the enable password is blank. To
change the enable password, enter the following command:
hostname(config)# enable password password
The password is a case-sensitive password of up to 16 alphanumeric and special characters. You can use
any character in the password except a question mark or a space.
This command changes the password for the highest privilege level. If you configure local command
authorization, you can set enable passwords for each privilege level from 0 to 15.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
9-1
Chapter 9
Configuring Basic Settings
Setting the Hostname
The password is saved in the configuration in encrypted form, so you cannot view the original password
after you enter it. Enter the enable password command without a password to set the password to the
default, which is blank.
Setting the Hostname
When you set a hostname for the security appliance, that name appears in the command line prompt. If
you establish sessions to multiple devices, the hostname helps you keep track of where you enter
commands. The default hostname depends on your platform.
For multiple context mode, the hostname that you set in the system execution space appears in the
command line prompt for all contexts. The hostname that you optionally set within a context does not
appear in the command line, but can be used by the banner command $(hostname) token.
To specify the hostname for the security appliance or for a context, enter the following command:
hostname(config)# hostname name
This name can be up to 63 characters. A hostname must start and end with a letter or digit, and have as
interior characters only letters, digits, or a hyphen.
This name appears in the command line prompt. For example:
hostname(config)# hostname farscape
farscape(config)#
Setting the Domain Name
The security appliance appends the domain name as a suffix to unqualified names. For example, if you
set the domain name to “example.com,” and specify a syslog server by the unqualified name of “jupiter,”
then the security appliance qualifies the name to “jupiter.example.com.”
The default domain name is default.domain.invalid.
For multiple context mode, you can set the domain name for each context, as well as within the system
execution space.
To specify the domain name for the security appliance, enter the following command:
hostname(config)# domain-name name
For example, to set the domain as example.com, enter the following command:
hostname(config)# domain-name example.com
Setting the Date and Time
This section describes how to set the date and time, either manually or dynamically using an NTP server.
Time derived from an NTP server overrides any time set manually. This section also describes how to
set the time zone and daylight saving time date range.
Note
In multiple context mode, set the time in the system configuration only.
Cisco Security Appliance Command Line Configuration Guide
9-2
OL-12172-04
Chapter 9
Configuring Basic Settings
Setting the Date and Time
This section includes the following topics:
•
Setting the Time Zone and Daylight Saving Time Date Range, page 9-3
•
Setting the Date and Time Using an NTP Server, page 9-4
•
Setting the Date and Time Manually, page 9-4
Setting the Time Zone and Daylight Saving Time Date Range
By default, the time zone is UTC and the daylight saving time date range is from 2:00 a.m. on the first
Sunday in April to 2:00 a.m. on the last Sunday in October. To change the time zone and daylight saving
time date range, perform the following steps:
Step 1
To set the time zone, enter the following command in global configuration mode:
hostname(config)# clock timezone zone [-]hours [minutes]
Where zone specifies the time zone as a string, for example, PST for Pacific Standard Time.
The [-]hours value sets the number of hours of offset from UTC. For example, PST is -8 hours.
The minutes value sets the number of minutes of offset from UTC.
Step 2
To change the date range for daylight saving time from the default, enter one of the following commands.
The default recurring date range is from 2:00 a.m. on the second Sunday in March to 2:00 a.m. on the
first Sunday in November.
•
To set the start and end dates for daylight saving time as a specific date in a specific year, enter the
following command:
hostname(config)# clock summer-time zone date {day month | month day} year hh:mm {day
month | month day} year hh:mm [offset]
If you use this command, you need to reset the dates every year.
The zone value specifies the time zone as a string, for example, PDT for Pacific Daylight Time.
The day value sets the day of the month, from 1 to 31. You can enter the day and month as April 1
or as 1 April, for example, depending on your standard date format.
The month value sets the month as a string. You can enter the day and month as April 1 or as 1 April,
for example, depending on your standard date format.
The year value sets the year using four digits, for example, 2004. The year range is 1993 to 2035.
The hh:mm value sets the hour and minutes in 24-hour time.
The offset value sets the number of minutes to change the time for daylight saving time. By default,
the value is 60 minutes.
•
To specify the start and end dates for daylight saving time, in the form of a day and time of the
month, and not a specific date in a year, enter the following command.
hostname(config)# clock summer-time zone recurring [week weekday month hh:mm week
weekday month hh:mm] [offset]
This command lets you set a recurring date range that you do not need to alter yearly.
The zone value specifies the time zone as a string, for example, PDT for Pacific Daylight Time.
The week value specifies the week of the month as an integer between 1 and 4 or as the words first
or last. For example, if the day might fall in the partial fifth week, then specify last.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
9-3
Chapter 9
Configuring Basic Settings
Setting the Date and Time
The weekday value specifies the day of the week: Monday, Tuesday, Wednesday, and so on.
The month value sets the month as a string.
The hh:mm value sets the hour and minutes in 24-hour time.
The offset value sets the number of minutes to change the time for daylight saving time. By default,
the value is 60 minutes.
Setting the Date and Time Using an NTP Server
To obtain the date and time from an NTP server, perform the following steps:
Step 1
To configure authentication with an NTP server, perform the following steps:
a.
To enable authentication, enter the following command:
hostname(config)# ntp authenticate
b.
To specify an authentication key ID to be a trusted key, which is required for authentication with an
NTP server, enter the following command:
hostname(config)# ntp trusted-key key_id
Where the key_id is between 1 and 4294967295. You can enter multiple trusted keys for use with
multiple servers.
c.
To set a key to authenticate with an NTP server, enter the following command:
hostname(config)# ntp authentication-key key_id md5 key
Where key_id is the ID you set in Step 1b using the ntp trusted-key command, and key is a string
up to 32 characters in length.
Step 2
To identify an NTP server, enter the following command:
hostname(config)# ntp server ip_address [key key_id] [source interface_name] [prefer]
Where the key_id is the ID you set in Step 1b using the ntp trusted-key command.
The source interface_name identifies the outgoing interface for NTP packets if you do not want to use
the default interface in the routing table. Because the system does not include any interfaces in multiple
context mode, specify an interface name defined in the admin context.
The prefer keyword sets this NTP server as the preferred server if multiple servers have similar
accuracy. NTP uses an algorithm to determine which server is the most accurate and synchronizes to that
one. If servers are of similar accuracy, then the prefer keyword specifies which of those servers to use.
However, if a server is significantly more accurate than the preferred one, the security appliance uses the
more accurate one. For example, the security appliance uses a server of stratum 2 over a server of
stratum 3 that is preferred.
You can identify multiple servers; the security appliance uses the most accurate server.
Setting the Date and Time Manually
To set the date time manually, enter the following command:
Cisco Security Appliance Command Line Configuration Guide
9-4
OL-12172-04
Chapter 9
Configuring Basic Settings
Setting the Management IP Address for a Transparent Firewall
hostname# clock set hh:mm:ss {month day | day month} year
Where hh:mm:ss sets the hour, minutes, and seconds in 24-hour time. For example, set 20:54:00 for 8:54
pm.
The day value sets the day of the month, from 1 to 31. You can enter the day and month as april 1 or as
1 april, for example, depending on your standard date format.
The month value sets the month. Depending on your standard date format, you can enter the day and
month as april 1 or as 1 april.
The year value sets the year using four digits, for example, 2004. The year range is 1993 to 2035.
The default time zone is UTC. If you change the time zone after you enter the clock set command using
the clock timezone command, the time automatically adjusts to the new time zone.
This command sets the time in the hardware chip, and does not save the time in the configuration file.
This time endures reboots. Unlike the other clock commands, this command is a privileged EXEC
command. To reset the clock, you need to set a new time for the clock set command.
Setting the Management IP Address for a Transparent Firewall
Transparent firewall mode only
A transparent firewall does not participate in IP routing. The only IP configuration required for the
security appliance is to set the management IP address. This address is required because the security
appliance uses this address as the source address for traffic originating on the security appliance, such
as system messages or communications with AAA servers. You can also use this address for remote
management access.
For multiple context mode, set the management IP address within each context.
To set the management IP address, enter the following command:
hostname(config)# ip address ip_address [mask] [standby ip_address]
This address must be on the same subnet as the upstream and downstream routers. You cannot set the
subnet to a host subnet (255.255.255.255). This address must be IPv4; the transparent firewall does not
support IPv6.
The standby keyword and address is used for failover. See Chapter 15, “Configuring Failover,” for more
information.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
9-5
Chapter 9
Configuring Basic Settings
Setting the Management IP Address for a Transparent Firewall
Cisco Security Appliance Command Line Configuration Guide
9-6
OL-12172-04
CH A P T E R
10
Configuring IP Routing
This chapter describes how to configure IP routing on the security appliance. This chapter includes the
following sections:
•
How Routing Behaves Within the ASA Security Appliance, page 10-1
•
Configuring Static and Default Routes, page 10-2
•
Defining Route Maps, page 10-7
•
Configuring OSPF, page 10-8
•
Configuring RIP, page 10-20
•
Configuring EIGRP, page 10-24
•
The Routing Table, page 10-33
•
Dynamic Routing and Failover, page 10-36
How Routing Behaves Within the ASA Security Appliance
The ASA security appliance uses both routing table and XLATE tables for routing decisions. To handle
destination IP translated traffic, that is, untranslated traffic, ASA searches for existing XLATE, or static
translation to select the egress interface. The selection process is as follows:
Egress Interface Selection Process
1.
If destination IP translating XLATE already exists, the egress interface for the packet is determined
from the XLATE table, but not from the routing table.
2.
If destination IP translating XLATE does not exist, but a matching static translation exists, then the
egress interface is determined from the static route and an XLATE is created, and the routing table
is not used.
3.
If destination IP translating XLATE does not exist and no matching static translation exists, the
packet is not destination IP translated. The security appliance processes this packet by looking up
the route to select egress interface, then source IP translation is performed (if necessary).
For regular dynamic outbound NAT, initial outgoing packets are routed using the route table and
then creating the XLATE. Incoming return packets are forwarded using existing XLATE only. For
static NAT, destination translated incoming packets are always forwarded using existing XLATE or
static translation rules.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-1
Chapter 10
Configuring IP Routing
Configuring Static and Default Routes
Next Hop Selection Process
After selecting egress interface using any method described above, an additional route lookup is
performed to find out suitable next hop(s) that belong to previously selected egress interface. If there are
no routes in routing table that explicitly belong to selected interface, the packet is dropped with level 6
error message 110001 "no route to host", even if there is another route for a given destination network
that belongs to different egress interface. If the route that belongs to selected egress interface is found,
the packet is forwarded to corresponding next hop.
Load sharing on the security appliance is possible only for multiple next-hops available using single
egress interface. Load sharing cannot share multiple egress interfaces.
If dynamic routing is in use on security appliance and route table changes after XLATE creation, for
example route flap, then destination translated traffic is still forwarded using old XLATE, not via route
table, until XLATE times out. It may be either forwarded to wrong interface or dropped with message
110001 "no route to host" if old route was removed from the old interface and attached to another one
by routing process.
The same problem may happen when there is no route flaps on the security appliance itself, but some
routing process is flapping around it, sending source translated packets that belong to the same flow
through the security appliance using different interfaces. Destination translated return packets may be
forwarded back using the wrong egress interface.
This issue has a high probability in same security traffic configuration, where virtually any traffic may
be either source-translated or destination-translated, depending on direction of initial packet in the flow.
When this issue occurs after a route flap, it can be resolved manually by using the clear xlate
command, or automatically resolved by an XLATE timeout. XLATE timeout may be decreased if
necessary. To ensure that this rarely happens, make sure that there is no route flaps on security appliance
and around it. That is, ensure that destination translated packets that belong to the same flow are always
forwarded the same way through the security appliance.
Configuring Static and Default Routes
This section describes how to configure static and default routes on the security appliance.
Multiple context mode does not support dynamic routing, so you must use static routes for any networks
to which the security appliance is not directly connected; for example, when there is a router between a
network and the security appliance.
You might want to use static routes in single context mode in the following cases:
•
Your networks use a different router discovery protocol from RIP or OSPF.
•
Your network is small and you can easily manage static routes.
•
You do not want the traffic or CPU overhead associated with routing protocols.
The simplest option is to configure a default route to send all traffic to an upstream router, relying on the
router to route the traffic for you. However, in some cases the default gateway might not be able to reach
the destination network, so you must also configure more specific static routes. For example, if the
default gateway is outside, then the default route cannot direct traffic to any inside networks that are not
directly connected to the security appliance.
In transparent firewall mode, for traffic that originates on the security appliance and is destined for a
non-directly connected network, you need to configure either a default route or static routes so the
security appliance knows out of which interface to send traffic. Traffic that originates on the security
Cisco Security Appliance Command Line Configuration Guide
10-2
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring Static and Default Routes
appliance might include communications to a syslog server, Websense or N2H2 server, or AAA server.
If you have servers that cannot all be reached through a single default route, then you must configure
static routes.
The security appliance supports up to three equal cost routes on the same interface for load balancing.
This section includes the following topics:
•
Configuring a Static Route, page 10-3
•
Configuring a Default Static Route, page 10-4
•
Configuring Static Route Tracking, page 10-5
For information about configuring IPv6 static and default routes, see the “Configuring IPv6 Default and
Static Routes” section on page 13-5.
Configuring a Static Route
To add a static route, enter the following command:
hostname(config)# route if_name dest_ip mask gateway_ip [distance]
The dest_ip and mask is the IP address for the destination network and the gateway_ip is the address of
the next-hop router.The addresses you specify for the static route are the addresses that are in the packet
before entering the security appliance and performing NAT.
The distance is the administrative distance for the route. The default is 1 if you do not specify a value.
Administrative distance is a parameter used to compare routes among different routing protocols. The
default administrative distance for static routes is 1, giving it precedence over routes discovered by
dynamic routing protocols but not directly connect routes. The default administrative distance for routes
discovered by OSPF is 110. If a static route has the same administrative distance as a dynamic route, the
static routes take precedence. Connected routes always take precedence over static or dynamically
discovered routes.
Static routes remain in the routing table even if the specified gateway becomes unavailable. If the
specified gateway becomes unavailable, you need to remove the static route from the routing table
manually. However, static routes are removed from the routing table if the specified interface goes down.
They are reinstated when the interface comes back up.
Note
If you create a static route with an administrative distance greater than the administrative distance of the
routing protocol running on the security appliance, then a route to the specified destination discovered
by the routing protocol takes precedence over the static route. The static route is used only if the
dynamically discovered route is removed from the routing table.
The following example creates a static route that sends all traffic destined for 10.1.1.0/24 to the router
(10.1.2.45) connected to the inside interface:
hostname(config)# route inside 10.1.1.0 255.255.255.0 10.1.2.45 1
You can define up to three equal cost routes to the same destination per interface. ECMP is not supported
across multiple interfaces. With ECMP, the traffic is not necessarily divided evenly between the routes;
traffic is distributed among the specified gateways based on an algorithm that hashes the source and
destination IP addresses.
The following example shows static routes that are equal cost routes that direct traffic to three different
gateways on the outside interface. The security appliance distributes the traffic among the specified
gateways.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-3
Chapter 10
Configuring IP Routing
Configuring Static and Default Routes
hostname(config)# route outside 10.10.10.0 255.255.255.0 192.168.1.1
hostname(config)# route outside 10.10.10.0 255.255.255.0 192.168.1.2
hostname(config)# route outside 10.10.10.0 255.255.255.0 192.168.1.3
Configuring a Default Static Route
A default route identifies the gateway IP address to which the security appliance sends all IP packets for
which it does not have a learned or static route. A default static route is simply a static route with
0.0.0.0/0 as the destination IP address. Routes that identify a specific destination take precedence over
the default route.
Note
In ASA software Versions 7.0 and later, if you have two default routes configured on different interfaces
that have different metrics, the connection to the ASA firewall that is made from the higher metric
interface fails, but connections to the ASA firewall from the lower metric interface succeed as expected.
PIX software Version 6.3 supports connections from both the the higher and the lower metric interfaces.
You can define up to three equal cost default route entries per device. Defining more than one equal cost
default route entry causes the traffic sent to the default route to be distributed among the specified
gateways. When defining more than one default route, you must specify the same interface for each
entry.
If you attempt to define more than three equal cost default routes, or if you attempt to define a default
route with a different interface than a previously defined default route, you receive the message
“ERROR: Cannot add route entry, possible conflict with existing routes.”
You can define a separate default route for tunneled traffic along with the standard default route. When
you create a default route with the tunneled option, all traffic from a tunnel terminating on the security
appliance that cannot be routed using learned or static routes, is sent to this route. For traffic emerging
from a tunnel, this route overrides over any other configured or learned default routes.
The following restrictions apply to default routes with the tunneled option:
•
Do not enable unicast RPF (ip verify reverse-path) on the egress interface of tunneled route.
Enabling uRPF on the egress interface of a tunneled route causes the session to fail.
•
Do not enable TCP intercept on the egress interface of the tunneled route. Doing so causes the
session to fail.
•
Do not use the VoIP inspection engines (CTIQBE, H.323, GTP, MGCP, RTSP, SIP, SKINNY), the
DNS inspect engine, or the DCE RPC inspection engine with tunneled routes. These inspection
engines ignore the tunneled route.
You cannot define more than one default route with the tunneled option; ECMP for tunneled traffic is
not supported.
To define the default route, enter the following command:
hostname(config)# route if_name 0.0.0.0 0.0.0.0 gateway_ip [distance | tunneled]
Tip
You can enter 0 0 instead of 0.0.0.0 0.0.0.0 for the destination network address and mask, for example:
hostname(config)# route outside 0 0 192.168.1 1
Cisco Security Appliance Command Line Configuration Guide
10-4
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring Static and Default Routes
The following example shows a security appliance configured with three equal cost default routes and a
default route for tunneled traffic. Unencrypted traffic received by the security appliance for which there
is no static or learned route is distributed among the gateways with the IP addresses 192.168.2.1,
192.168.2.2, 192.168.2.3. Encrypted traffic receive by the security appliance for which there is no static
or learned route is passed to the gateway with the IP address 192.168.2.4.
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
route
route
route
route
outside
outside
outside
outside
0
0
0
0
0
0
0
0
192.168.2.1
192.168.2.2
192.168.2.3
192.168.2.4 tunneled
Configuring Static Route Tracking
One of the problems with static routes is that there is no inherent mechanism for determining if the route
is up or down. They remain in the routing table even if the next hop gateway becomes unavailable. Static
routes are only removed from the routing table if the associated interface on the security appliance goes
down.
The static route tracking feature provides a method for tracking the availability of a static route and
installing a backup route if the primary route should fail. This allows you to, for example, define a
default route to an ISP gateway and a backup default route to a secondary ISP in case the primary ISP
becomes unavailable.
The security appliance does this by associating a static route with a monitoring target that you define. It
monitors the target using ICMP echo requests. If an echo reply is not received within a specified time
period, the object is considered down and the associated route is removed from the routing table. A
previously configured backup route is used in place of the removed route.
When selecting a monitoring target, you need to make sure it can respond to ICMP echo requests. The
target can be any network object that you choose, but you should consider using:
•
the ISP gateway (for dual ISP support) address
•
the next hop gateway address (if you are concerned about the availability of the gateway)
•
a server on the target network, such as a AAA server, that the security appliance needs to
communicate with
•
a persistent network object on the destination network (a desktop or notebook computer that may be
shut down at night is not a good choice)
You can configure static route tracking for statically defined routes or default routes obtained through
DHCP or PPPoE. You can only enable PPPoE clients on multiple interface with route tracking.
To configure static route tracking, perform the following steps:
Step 1
Configure the tracked object monitoring parameters:
a.
Define the monitoring process:
hostname(config)# sla monitor sla_id
If you are configuring a new monitoring process, you are taken to SLA monitor configuration mode.
If you are changing the monitoring parameters for an unscheduled monitoring process that already
has a type defined, you are taken directly to the SLA protocol configuration mode.
b.
Specify the monitoring protocol. If you are changing the monitoring parameters for an unscheduled
monitoring process that already has a type defined, you are taken directly to SLA protocol
configuration mode and cannot change this setting.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-5
Chapter 10
Configuring IP Routing
Configuring Static and Default Routes
hostname(config-sla-monitor)# type echo protocol ipIcmpEcho target_ip interface
if_name
The target_ip is the IP address of the network object whose availability the tracking process
monitors. While this object is available, the tracking process route is installed in the routing table.
When this object becomes unavailable, the tracking process removed the route and the backup route
is used in its place.
c.
Schedule the monitoring process:
hostname(config)# sla monitor schedule sla_id [life {forever | seconds}] [start-time
{hh:mm[:ss] [month day | day month] | pending | now | after hh:mm:ss}] [ageout
seconds] [recurring]
Typically, you will use sla monitor schedule sla_id life forever start-time now for the monitoring
schedule, and allow the monitoring configuration determine how often the testing occurs. However,
you can schedule this monitoring process to begin in the future and to only occur at specified times.
Step 2
Associate a tracked static route with the SLA monitoring process by entering the following command:
hostname(config)# track track_id rtr sla_id reachability
The track_id is a tracking number you assign with this command. The sla_id is the ID number of the
SLA process you defined in Step 1.
Step 3
Define the static route to be installed in the routing table while the tracked object is reachable using one
of the following options:
•
To track a static route, enter the following command:
hostname(config)# route if_name dest_ip mask gateway_ip [admin_distance] track
track_id
You cannot use the tunneled option with the route command with static route tracking.
•
To track a default route obtained through DHCP, enter the following commands:
hostname(config)# interface phy_if
hostname(config-if)# dhcp client route track track_id
hostname(config-if)# ip addresss dhcp setroute
hostname(config-if)# exit
Note
•
You must use the setroute argument with the ip address dhcp command to obtain the
default route using DHCP.
To track a default route obtained through PPPoE, enter the following commands:
hostname(config)# interface phy_if
hostname(config-if)# pppoe client route track track_id
hostname(config-if)# ip addresss pppoe setroute
hostname(config-if)# exit
Note
Step 4
You must use the setroute argument with the ip address pppoe command to obtain the
default route using PPPoE.
Define the backup route to use when the tracked object is unavailable using one of the following options.
The administrative distance of the backup route must be greater than the administrative distance of the
tracked route. If it is not, the backup route will be installed in the routing table instead of the tracked
route.
Cisco Security Appliance Command Line Configuration Guide
10-6
OL-12172-04
Chapter 10
Configuring IP Routing
Defining Route Maps
•
To use a static route, enter the following command:
hostname(config)# route if_name dest_ip mask gateway_ip [admin_distance]
The static route must have the same destination and mask as the tracked route. If you are tracking a
default route obtained through DHCP or PPPoE, then the address and mask would be 0.0.0.0 0.0.0.0.
•
To use a default route obtained through DHCP, enter the following commands:
hostname(config)# interface phy_if
hostname(config-if)# dhcp client route track track_id
hostname(config-if)# dhcp client route distance admin_distance
hostname(config-if)# ip addresss dhcp setroute
hostname(config-if)# exit
You must use the setroute argument with the ip address dhcp command to obtain the default route
using DHCP. Make sure the administrative distance is greater than the administrative distance of the
tracked route.
•
To use a default route obtained through PPPoE, enter the following commands:
hostname(config)# interface phy_if
hostname(config-if)# pppoe client route track track_id
hostname(config-if)# pppoe client route distance admin_distance
hostname(config-if)# ip addresss pppoe setroute
hostname(config-if)# exit
You must use the setroute argument with the ip address pppoe command to obtain the default route
using PPPoE. Make sure the administrative distance is greater than the administrative distance of
the tracked route.
Defining Route Maps
Route maps are used when redistributing routes into an OSPF, RIP, or EIGRP routing process. They are
also used when generating a default route into an OSPF routing process. A route map defines which of
the routes from the specified routing protocol are allowed to be redistributed into the target routing
process.
To define a route map, perform the following steps:
Step 1
To create a route map entry, enter the following command:
hostname(config)# route-map name {permit | deny} [sequence_number]
Route map entries are read in order. You can identify the order using the sequence_number option, or
the security appliance uses the order in which you add the entries.
Step 2
Enter one or more match commands:
•
To match any routes that have a destination network that matches a standard ACL, enter the
following command:
hostname(config-route-map)# match ip address acl_id [acl_id] [...]
If you specify more than one ACL, then the route can match any of the ACLs.
•
To match any routes that have a specified metric, enter the following command:
hostname(config-route-map)# match metric metric_value
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-7
Chapter 10
Configuring IP Routing
Configuring OSPF
The metric_value can be from 0 to 4294967295.
•
To match any routes that have a next hop router address that matches a standard ACL, enter the
following command:
hostname(config-route-map)# match ip next-hop acl_id [acl_id] [...]
If you specify more than one ACL, then the route can match any of the ACLs.
•
To match any routes with the specified next hop interface, enter the following command:
hostname(config-route-map)# match interface if_name
If you specify more than one interface, then the route can match either interface.
•
To match any routes that have been advertised by routers that match a standard ACL, enter the
following command:
hostname(config-route-map)# match ip route-source acl_id [acl_id] [...]
If you specify more than one ACL, then the route can match any of the ACLs.
•
To match the route type, enter the following command:
hostname(config-route-map)# match route-type {internal | external [type-1 | type-2]}
Step 3
Enter one or more set commands.
If a route matches the match commands, then the following set commands determine the action to
perform on the route before redistributing it.
•
To set the metric, enter the following command:
hostname(config-route-map)# set metric metric_value
The metric_value can be a value between 0 and 294967295
•
To set the metric type, enter the following command:
hostname(config-route-map)# set metric-type {type-1 | type-2}
The following example shows how to redistribute routes with a hop count equal to 1 into OSPF. The
security appliance redistributes these routes as external LSAs with a metric of 5, metric type of Type 1.
hostname(config)# route-map
hostname(config-route-map)#
hostname(config-route-map)#
hostname(config-route-map)#
1-to-2 permit
match metric 1
set metric 5
set metric-type type-1
Configuring OSPF
This section describes how to configure OSPF. This section includes the following topics:
•
OSPF Overview, page 10-9
•
Enabling OSPF, page 10-10
•
Redistributing Routes Into OSPF, page 10-10
•
Configuring OSPF Interface Parameters, page 10-12
Cisco Security Appliance Command Line Configuration Guide
10-8
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring OSPF
•
Configuring OSPF Area Parameters, page 10-14
•
Configuring OSPF NSSA, page 10-15
•
Defining Static OSPF Neighbors, page 10-17
•
Configuring Route Summarization Between OSPF Areas, page 10-16
•
Configuring Route Summarization When Redistributing Routes into OSPF, page 10-16
•
Generating a Default Route, page 10-17
•
Configuring Route Calculation Timers, page 10-18
•
Logging Neighbors Going Up or Down, page 10-18
•
Displaying OSPF Update Packet Pacing, page 10-19
•
Monitoring OSPF, page 10-19
•
Restarting the OSPF Process, page 10-20
OSPF Overview
OSPF uses a link-state algorithm to build and calculate the shortest path to all known destinations. Each
router in an OSPF area contains an identical link-state database, which is a list of each of the router
usable interfaces and reachable neighbors.
The advantages of OSPF over RIP include the following:
•
OSPF link-state database updates are sent less frequently than RIP updates, and the link-state
database is updated instantly rather than gradually as stale information is timed out.
•
Routing decisions are based on cost, which is an indication of the overhead required to send packets
across a certain interface. The security appliance calculates the cost of an interface based on link
bandwidth rather than the number of hops to the destination. The cost can be configured to specify
preferred paths.
The disadvantage of shortest path first algorithms is that they require a lot of CPU cycles and memory.
The security appliance can run two processes of OSPF protocol simultaneously, on different sets of
interfaces. You might want to run two processes if you have interfaces that use the same IP addresses
(NAT allows these interfaces to coexist, but OSPF does not allow overlapping addresses). Or you might
want to run one process on the inside, and another on the outside, and redistribute a subset of routes
between the two processes. Similarly, you might need to segregate private addresses from public
addresses.
You can redistribute routes into an OSPF routing process from another OSPF routing process, a RIP
routing process, or from static and connected routes configured on OSPF-enabled interfaces.
The security appliance supports the following OSPF features:
•
Support of intra-area, interarea, and external (Type I and Type II) routes.
•
Support of a virtual link.
•
OSPF LSA flooding.
•
Authentication to OSPF packets (both password and MD5 authentication).
•
Support for configuring the security appliance as a designated router or a designated backup router.
The security appliance also can be set up as an ABR; however, the ability to configure the security
appliance as an ASBR is limited to default information only (for example, injecting a default route).
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-9
Chapter 10
Configuring IP Routing
Configuring OSPF
•
Support for stub areas and not-so-stubby-areas.
•
Area boundary router type-3 LSA filtering.
Enabling OSPF
To enable OSPF, you need to create an OSPF routing process, specify the range of IP addresses
associated with the routing process, then assign area IDs associated with that range of IP addresses.
To enable OSPF, perform the following steps:
Step 1
To create an OSPF routing process, enter the following command:
hostname(config)# router ospf process_id
This command enters the router configuration mode for this OSPF process.
The process_id is an internally used identifier for this routing process. It can be any positive integer. This
ID does not have to match the ID on any other device; it is for internal use only. You can use a maximum
of two processes.
Step 2
To define the IP addresses on which OSPF runs and to define the area ID for that interface, enter the
following command:
hostname(config-router)# network ip_address mask area area_id
The following example shows how to enable OSPF:
hostname(config)# router ospf 2
hostname(config-router)# network 10.0.0.0 255.0.0.0 area 0
Redistributing Routes Into OSPF
The security appliance can control the redistribution of routes between OSPF routing processes. The
security appliance matches and changes routes according to settings in the redistribute command or by
using a route map. See also the “Generating a Default Route” section on page 10-17 for another use for
route maps.
To redistribute static, connected, RIP, or OSPF routes into an OSPF process, perform the following steps:
Step 1
(Optional) Create a route-map to further define which routes from the specified routing protocol are
redistributed in to the OSPF routing process. See the “Defining Route Maps” section on page 10-7.
Step 2
If you have not already done so, enter the router configuration mode for the OSPF process you want to
redistribute into by entering the following command:
hostname(config)# router ospf process_id
Step 3
Choose one of the following options to redistribute the selected route type into the RIP routing process.
•
To redistribute connected routes into the OSPF routing process, enter the following command:
hostname(config-router): redistribute connected [[metric metric-value]
[metric-type {type-1 | type-2}] [tag tag_value] [subnets] [route-map map_name]
Cisco Security Appliance Command Line Configuration Guide
10-10
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring OSPF
•
To redistribute static routes into the OSPF routing process, enter the following command:
hostname(config-router): redistribute static [metric metric-value]
[metric-type {type-1 | type-2}] [tag tag_value] [subnets] [route-map map_name]
•
To redistribute routes from an OSPF routing process into the OSPF routing process, enter the
following command:
hostname(config-router): redistribute ospf pid [match {internal | external [1 | 2] |
nssa-external [1 | 2]}] [metric metric-value] [metric-type {type-1 | type-2}]
[tag tag_value] [subnets] [route-map map_name]
You can either use the match options in this command to match and set route properties, or you can
use a route map. The tag and subnets options do not have equivalents in the route-map command.
If you use both a route map and match options in the redistribute command, then they must match
•
To redistribute routes from a RIP routing process into the OSPF routing process, enter the following
command:
hostname(config-router): redistribute rip [metric metric-value]
[metric-type {type-1 | type-2}] [tag tag_value] [subnets] [route-map map_name]
•
To redistribute routes from an EIGRP routing process into the OSPF routing process, enter the
following command:
hostname(config-router): redistribute eigrp as-num [metric metric-value]
[metric-type {type-1 | type-2}] [tag tag_value] [subnets] [route-map map_name]
The following example shows route redistribution from OSPF process 1 into OSPF process 2 by
matching routes with a metric equal to 1. The security appliance redistributes these routes as external
LSAs with a metric of 5, metric type of Type 1, and a tag equal to 1.
hostname(config)# route-map 1-to-2 permit
hostname(config-route-map)# match metric 1
hostname(config-route-map)# set metric 5
hostname(config-route-map)# set metric-type type-1
hostname(config-route-map)# set tag 1
hostname(config-route-map)# router ospf 2
hostname(config-router)# redistribute ospf 1 route-map 1-to-2
The following example shows the specified OSPF process routes being redistributed into OSPF
process 109. The OSPF metric is remapped to 100.
hostname(config)# router ospf 109
hostname(config-router)# redistribute ospf 108 metric 100 subnets
The following example shows route redistribution where the link-state cost is specified as 5 and the
metric type is set to external, indicating that it has lower priority than internal metrics.
hostname(config)# router ospf 1
hostname(config-router)# redistribute ospf 2 metric 5 metric-type external
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-11
Chapter 10
Configuring IP Routing
Configuring OSPF
Configuring OSPF Interface Parameters
You can alter some interface-specific OSPF parameters as necessary. You are not required to alter any
of these parameters, but the following interface parameters must be consistent across all routers in an
attached network: ospf hello-interval, ospf dead-interval, and ospf authentication-key. Be sure that if
you configure any of these parameters, the configurations for all routers on your network have
compatible values.
To configure OSPF interface parameters, perform the following steps:
Step 1
To enter the interface configuration mode, enter the following command:
hostname(config)# interface interface_name
Step 2
Enter any of the following commands:
•
To specify the authentication type for an interface, enter the following command:
hostname(config-interface)# ospf authentication [message-digest | null]
•
To assign a password to be used by neighboring OSPF routers on a network segment that is using
the OSPF simple password authentication, enter the following command:
hostname(config-interface)# ospf authentication-key key
The key can be any continuous string of characters up to 8 bytes in length.
The password created by this command is used as a key that is inserted directly into the OSPF header
when the security appliance software originates routing protocol packets. A separate password can
be assigned to each network on a per-interface basis. All neighboring routers on the same network
must have the same password to be able to exchange OSPF information.
•
To explicitly specify the cost of sending a packet on an OSPF interface, enter the following
command:
hostname(config-interface)# ospf cost cost
The cost is an integer from 1 to 65535.
•
To set the number of seconds that a device must wait before it declares a neighbor OSPF router down
because it has not received a hello packet, enter the following command:
hostname(config-interface)# ospf dead-interval seconds
The value must be the same for all nodes on the network.
•
To specify the length of time between the hello packets that the security appliance sends on an OSPF
interface, enter the following command:
hostname(config-interface)# ospf hello-interval seconds
The value must be the same for all nodes on the network.
•
To enable OSPF MD5 authentication, enter the following command:
hostname(config-interface)# ospf message-digest-key key_id md5 key
Set the following values:
– key_id—An identifier in the range from 1 to 255.
– key—Alphanumeric password of up to 16 bytes.
Cisco Security Appliance Command Line Configuration Guide
10-12
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring OSPF
Usually, one key per interface is used to generate authentication information when sending packets
and to authenticate incoming packets. The same key identifier on the neighbor router must have the
same key value.
We recommend that you not keep more than one key per interface. Every time you add a new key,
you should remove the old key to prevent the local system from continuing to communicate with a
hostile system that knows the old key. Removing the old key also reduces overhead during rollover.
•
To set the priority to help determine the OSPF designated router for a network, enter the following
command:
hostname(config-interface)# ospf priority number_value
The number_value is between 0 to 255.
•
To specify the number of seconds between LSA retransmissions for adjacencies belonging to an
OSPF interface, enter the following command:
hostname(config-interface)# ospf retransmit-interval seconds
The seconds must be greater than the expected round-trip delay between any two routers on the
attached network. The range is from 1 to 65535 seconds. The default is 5 seconds.
•
To set the estimated number of seconds required to send a link-state update packet on an OSPF
interface, enter the following command:
hostname(config-interface)# ospf transmit-delay seconds
The seconds is from 1 to 65535 seconds. The default is 1 second.
•
To specify the interface as a point-to-point, non-broadcast network, enter the following command:
hostname(config-interface)# ospf network point-to-point non-broadcast
When you designate an interface as point-to-point, non-broadcast, you must manually define the
OSPF neighbor; dynamic neighbor discover is not possible. See Defining Static OSPF Neighbors,
page 10-17, for more information. Additionally, you can only define one OSPF neighbor on that
interface.
The following example shows how to configure the OSPF interfaces:
hostname(config)# router ospf 2
hostname(config-router)# network 2.0.0.0 255.0.0.0 area 0
hostname(config-router)# interface inside
hostname(config-interface)# ospf cost 20
hostname(config-interface)# ospf retransmit-interval 15
hostname(config-interface)# ospf transmit-delay 10
hostname(config-interface)# ospf priority 20
hostname(config-interface)# ospf hello-interval 10
hostname(config-interface)# ospf dead-interval 40
hostname(config-interface)# ospf authentication-key cisco
hostname(config-interface)# ospf message-digest-key 1 md5 cisco
hostname(config-interface)# ospf authentication message-digest
The following is sample output from the show ospf command:
hostname(config)# show ospf
Routing Process "ospf 2" with ID 20.1.89.2 and Domain ID 0.0.0.2
Supports only single TOS(TOS0) routes
Supports opaque LSA
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-13
Chapter 10
Configuring IP Routing
Configuring OSPF
Number of external LSA 5. Checksum Sum 0x 26da6
Number of opaque AS LSA 0. Checksum Sum 0x
0
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
External flood list length 0
Area BACKBONE(0)
Number of interfaces in this area is 1
Area has no authentication
SPF algorithm executed 2 times
Area ranges are
Number of LSA 5. Checksum Sum 0x 209a3
Number of opaque link LSA 0. Checksum Sum 0x
0
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
Configuring OSPF Area Parameters
You can configure several area parameters. These area parameters (shown in the following task table)
include setting authentication, defining stub areas, and assigning specific costs to the default summary
route. Authentication provides password-based protection against unauthorized access to an area.
Stub areas are areas into which information on external routes is not sent. Instead, there is a default
external route generated by the ABR, into the stub area for destinations outside the autonomous system.
To take advantage of the OSPF stub area support, default routing must be used in the stub area. To further
reduce the number of LSAs sent into a stub area, you can configure the no-summary keyword of the
area stub command on the ABR to prevent it from sending summary link advertisement (LSA Type 3)
into the stub area.
To specify area parameters for your network, perform the following steps:
Step 1
If you have not already done so, enter the router configuration mode for the OSPF process you want to
configure by entering the following command:
hostname(config)# router ospf process_id
Step 2
Enter any of the following commands:
•
To enable authentication for an OSPF area, enter the following command:
hostname(config-router)# area area-id authentication
•
To enable MD5 authentication for an OSPF area, enter the following command:
hostname(config-router)# area area-id authentication message-digest
•
To define an area to be a stub area, enter the following command:
hostname(config-router)# area area-id stub [no-summary]
•
To assign a specific cost to the default summary route used for the stub area, enter the following
command:
hostname(config-router)# area area-id default-cost cost
The cost is an integer from 1 to 65535. The default is 1.
Cisco Security Appliance Command Line Configuration Guide
10-14
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring OSPF
The following example shows how to configure the OSPF area parameters:
hostname(config)# router
hostname(config-router)#
hostname(config-router)#
hostname(config-router)#
hostname(config-router)#
ospf
area
area
area
area
2
0 authentication
0 authentication message-digest
17 stub
17 default-cost 20
Configuring OSPF NSSA
The OSPF implementation of an NSSA is similar to an OSPF stub area. NSSA does not flood type 5
external LSAs from the core into the area, but it can import autonomous system external routes in a
limited way within the area.
NSSA importsType 7 autonomous system external routes within an NSSA area by redistribution. These
Type 7 LSAs are translated into Type 5 LSAs by NSSA ABRs, which are flooded throughout the whole
routing domain. Summarization and filtering are supported during the translation.
You can simplify administration if you are an ISP or a network administrator that must connect a central
site using OSPF to a remote site that is using a different routing protocol using NSSA.
Before the implementation of NSSA, the connection between the corporate site border router and the
remote router could not be run as an OSPF stub area because routes for the remote site could not be
redistributed into the stub area, and two routing protocols needed to be maintained. A simple protocol
such as RIP was usually run and handled the redistribution. With NSSA, you can extend OSPF to cover
the remote connection by defining the area between the corporate router and the remote router as an
NSSA.
To specify area parameters for your network as needed to configure OSPF NSSA, perform the following
steps:
Step 1
If you have not already done so, enter the router configuration mode for the OSPF process you want to
configure by entering the following command:
hostname(config)# router ospf process_id
Step 2
Enter any of the following commands:
•
To define an NSSA area, enter the following command:
hostname(config-router)# area area-id nssa [no-redistribution]
[default-information-originate]
•
To summarize groups of addresses, enter the following command:
hostname(config-router)# summary address ip_address mask [not-advertise] [tag tag]
This command helps reduce the size of the routing table. Using this command for OSPF causes an
OSPF ASBR to advertise one external route as an aggregate for all redistributed routes that are
covered by the address.
OSPF does not support summary-address 0.0.0.0 0.0.0.0.
In the following example, the summary address 10.1.0.0 includes address 10.1.1.0, 10.1.2.0,
10.1.3.0, and so on. Only the address 10.1.0.0 is advertised in an external link-state advertisement:
hostname(config-router)# summary-address 10.1.1.0 255.255.0.0
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-15
Chapter 10
Configuring IP Routing
Configuring OSPF
Before you use this feature, consider these guidelines:
– You can set a Type 7 default route that can be used to reach external destinations. When
configured, the router generates a Type 7 default into the NSSA or the NSSA area boundary
router.
– Every router within the same area must agree that the area is NSSA; otherwise, the routers will
not be able to communicate.
Configuring Route Summarization Between OSPF Areas
Route summarization is the consolidation of advertised addresses. This feature causes a single summary
route to be advertised to other areas by an area boundary router. In OSPF, an area boundary router
advertises networks in one area into another area. If the network numbers in an area are assigned in a
way such that they are contiguous, you can configure the area boundary router to advertise a summary
route that covers all the individual networks within the area that fall into the specified range.
To define an address range for route summarization, perform the following steps:
Step 1
If you have not already done so, enter the router configuration mode for the OSPF process you want to
configure by entering the following command:
hostname(config)# router ospf process_id
Step 2
To set the address range, enter the following command:
hostname(config-router)# area area-id range ip-address mask [advertise | not-advertise]
The following example shows how to configure route summarization between OSPF areas:
hostname(config)# router ospf 1
hostname(config-router)# area 17 range 12.1.0.0 255.255.0.0
Configuring Route Summarization When Redistributing Routes into OSPF
When routes from other protocols are redistributed into OSPF, each route is advertised individually in
an external LSA. However, you can configure the security appliance to advertise a single route for all
the redistributed routes that are covered by a specified network address and mask. This configuration
decreases the size of the OSPF link-state database.
To configure the software advertisement on one summary route for all redistributed routes covered by a
network address and mask, perform the following steps:
Step 1
If you have not already done so, enter the router configuration mode for the OSPF process you want to
configure by entering the following command:
hostname(config)# router ospf process_id
Step 2
To set the summary address, enter the following command:
hostname(config-router)# summary-address ip_address mask [not-advertise] [tag tag]
Cisco Security Appliance Command Line Configuration Guide
10-16
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring OSPF
Note
OSPF does not support summary-address 0.0.0.0 0.0.0.0.
The following example shows how to configure route summarization. The summary address 10.1.0.0
includes address 10.1.1.0, 10.1.2.0, 10.1.3.0, and so on. Only the address 10.1.0.0 is advertised in an
external link-state advertisement:
hostname(config)# router ospf 1
hostname(config-router)# summary-address 10.1.0.0 255.255.0.0
Defining Static OSPF Neighbors
You need to define static OSPF neighbors to advertise OSPF routes over a point-to-point, non-broadcast
network. This lets you broadcast OSPF advertisements across an existing VPN connection without
having to encapsulate the advertisements in a GRE tunnel.
To define a static OSPF neighbor, perform the following tasks:
Step 1
Create a static route to the OSPF neighbor. See the “Configuring Static and Default Routes” section on
page 10-2 for more information about creating static routes.
Step 2
Define the OSPF neighbor by performing the following tasks:
a.
Enter router configuration mode for the OSPF process. Enter the following command:
hostname(config)# router ospf pid
b.
Define the OSPF neighbor by entering the following command:
hostname(config-router)# neighbor addr [interface if_name]
The addr argument is the IP address of the OSPF neighbor. The if_name is the interface used to
communicate with the neighbor. If the OSPF neighbor is not on the same network as any of the
directly-connected interfaces, you must specify the interface.
Generating a Default Route
You can force an autonomous system boundary router to generate a default route into an OSPF routing
domain. Whenever you specifically configure redistribution of routes into an OSPF routing domain, the
router automatically becomes an autonomous system boundary router. However, an autonomous system
boundary router does not by default generate a default route into the OSPF routing domain.
To generate a default route, perform the following steps:
Step 1
If you have not already done so, enter the router configuration mode for the OSPF process you want to
configure by entering the following command:
hostname(config)# router ospf process_id
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-17
Chapter 10
Configuring IP Routing
Configuring OSPF
Step 2
To force the autonomous system boundary router to generate a default route, enter the following
command:
hostname(config-router)# default-information originate [always] [metric metric-value]
[metric-type {1 | 2}] [route-map map-name]
The following example shows how to generate a default route:
hostname(config)# router ospf 2
hostname(config-router)# default-information originate always
Configuring Route Calculation Timers
You can configure the delay time between when OSPF receives a topology change and when it starts an
SPF calculation. You also can configure the hold time between two consecutive SPF calculations.
To configure route calculation timers, perform the following steps:
Step 1
If you have not already done so, enter the router configuration mode for the OSPF process you want to
configure by entering the following command:
hostname(config)# router ospf process_id
Step 2
To configure the route calculation time, enter the following command:
hostname(config-router)# timers spf spf-delay spf-holdtime
The spf-delay is the delay time (in seconds) between when OSPF receives a topology change and when
it starts an SPF calculation. It can be an integer from 0 to 65535. The default time is 5 seconds. A value
of 0 means that there is no delay; that is, the SPF calculation is started immediately.
The spf-holdtime is the minimum time (in seconds) between two consecutive SPF calculations. It can be
an integer from 0 to 65535. The default time is 10 seconds. A value of 0 means that there is no delay;
that is, two SPF calculations can be done, one immediately after the other.
The following example shows how to configure route calculation timers:
hostname(config)# router ospf 1
hostname(config-router)# timers spf 10 120
Logging Neighbors Going Up or Down
By default, the system sends a system message when an OSPF neighbor goes up or down.
Configure this command if you want to know about OSPF neighbors going up or down without turning
on the debug ospf adjacency command. The log-adj-changes router configuration command provides
a higher level view of the peer relationship with less output. Configure log-adj-changes detail if you
want to see messages for each state change.
Cisco Security Appliance Command Line Configuration Guide
10-18
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring OSPF
To log neighbors going up or down, perform the following steps:
Step 1
If you have not already done so, enter the router configuration mode for the OSPF process you want to
configure by entering the following command:
hostname(config)# router ospf process_id
Step 2
To configure logging for neighbors going up or down, enter the following command:
hostname(config-router)# log-adj-changes [detail]
Logging must be enabled for the the neighbor up/down messages to be sent.
Note
The following example shows how to log neighbors up/down messages:
hostname(config)# router ospf 1
hostname(config-router)# log-adj-changes detail
Displaying OSPF Update Packet Pacing
OSPF update packets are automatically paced so they are not sent less than 33 milliseconds apart.
Without pacing, some update packets could get lost in situations where the link is slow, a neighbor could
not receive the updates quickly enough, or the router could run out of buffer space. For example, without
pacing packets might be dropped if either of the following topologies exist:
•
A fast router is connected to a slower router over a point-to-point link.
•
During flooding, several neighbors send updates to a single router at the same time.
Pacing is also used between resends to increase efficiency and minimize lost retransmissions. You also
can display the LSAs waiting to be sent out an interface. The benefit of the pacing is that OSPF update
and retransmission packets are sent more efficiently.
There are no configuration tasks for this feature; it occurs automatically.
To observe OSPF packet pacing by displaying a list of LSAs waiting to be flooded over a specified
interface, enter the following command:
hostname# show ospf flood-list if_name
Monitoring OSPF
You can display specific statistics such as the contents of IP routing tables, caches, and databases. You
can use the information provided to determine resource utilization and solve network problems. You can
also display information about node reachability and discover the routing path that your device packets
are taking through the network.
To display various OSPF routing statistics, perform one of the following tasks, as needed:
•
To display general information about OSPF routing processes, enter the following command:
hostname# show ospf [process-id [area-id]]
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-19
Chapter 10
Configuring IP Routing
Configuring RIP
•
To display the internal OSPF routing table entries to the ABR and ASBR, enter the following
command:
hostname# show ospf border-routers
•
To display lists of information related to the OSPF database for a specific router, enter the following
command:
hostname# show ospf [process-id [area-id]] database
•
To display a list of LSAs waiting to be flooded over an interface (to observe OSPF packet pacing),
enter the following command:
hostname# show ospf flood-list if-name
•
To display OSPF-related interface information, enter the following command:
hostname# show ospf interface [if_name]
•
To display OSPF neighbor information on a per-interface basis, enter the following command:
hostname# show ospf neighbor [interface-name] [neighbor-id] [detail]
•
To display a list of all LSAs requested by a router, enter the following command:
hostname# show ospf request-list neighbor if_name
•
To display a list of all LSAs waiting to be resent, enter the following command:
hostname# show ospf retransmission-list neighbor if_name
•
To display a list of all summary address redistribution information configured under an OSPF
process, enter the following command:
hostname# show ospf [process-id] summary-address
•
To display OSPF-related virtual links information, enter the following command:
hostname# show ospf [process-id] virtual-links
Restarting the OSPF Process
To restart an OSPF process, clear redistribution, or counters, enter the following command:
hostname(config)# clear ospf pid {process | redistribution | counters
[neighbor [neighbor-interface] [neighbor-id]]}
Configuring RIP
Devices that support RIP send routing-update messages at regular intervals and when the network
topology changes. These RIP packets contain information about the networks that the devices can reach,
as well as the number of routers or gateways that a packet must travel through to reach the destination
address. RIP generates more traffic than OSPF, but is easier to configure.
RIP has advantages over static routes because the initial configuration is simple, and you do not need to
update the configuration when the topology changes. The disadvantage to RIP is that there is more
network and processing overhead than static routing.
The security appliance supports RIP Version 1 and RIP Version 2.
Cisco Security Appliance Command Line Configuration Guide
10-20
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring RIP
This section describes how to configure RIP. This section includes the following topics:
•
Enabling and Configuring RIP, page 10-21
•
Redistributing Routes into the RIP Routing Process, page 10-22
•
Configuring RIP Send/Receive Version on an Interface, page 10-23
•
Enabling RIP Authentication, page 10-23
•
Monitoring RIP, page 10-24
Enabling and Configuring RIP
You can only enable one RIP routing process on the security appliance. After you enable the RIP routing
process, you must define the interfaces that will participate in that routing process using the network
command. By default, the security appliance sends RIP Version 1 updates and accepts RIP Version 1 and
Version 2 updates.
To enable and configure the RIP routing process, perform the following steps:
Step 1
Start the RIP routing process by entering the following command in global configuration mode:
hostname(config): router rip
You enter router configuration mode for the RIP routing process.
Step 2
Specify the interfaces that will participate in the RIP routing process. Enter the following command for
each interface that will participate in the RIP routing process:
hostname(config-router): network network_address
If an interface belongs to a network defined by this command, the interface will participate in the RIP
routing process. If an interface does not belong to a network defined by this command, it will not send
or receive RIP updates.
Step 3
(Optional) Specify the version of RIP used by the security appliance by entering the following command:
hostname(config-router): version [1 | 2]
You can override this setting on a per-interface basis.
Step 4
(Optional) To generate a default route into RIP, enter the following command:
hostname(config-router): default-information originate
Step 5
(Optional) To specify an interface to operate in passive mode, enter the following command:
hostname(config-router): passive-interface [default | if_name]
Using the default keyword causes all interfaces to operate in passive mode. Specifying an interface name
sets only that interface to passive RIP mode. In passive mode, RIP routing updates are accepted by but
not sent out of the specified interface. You can enter this command for each interface you want to set to
passive mode.
Step 6
(Optional) Disable automatic route summarization by entering the following command:
hostname(config-router): no auto-summarize
RIP Version 1 always uses automatic route summarization; you cannot disable it for RIP Version 1. RIP
Version 2 uses route summarization by default; you can disable it using this command.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-21
Chapter 10
Configuring IP Routing
Configuring RIP
Step 7
(Optional) To filter the networks received in updates, perform the following steps:
a.
Create a standard access list permitting the networks you want the RIP process to allow in the
routing table and denying the networks you want the RIP process to discard.
b.
Enter the following command to apply the filter. You can specify an interface to apply the filter to
only those updates received by that interface.
hostname(config-router): distribute-list acl in [interface if_name]
You can enter this command for each interface you want to apply a filter to. If you do not specify an
interface name, the filter is applied to all RIP updates.
Step 8
(Optional) To filter the networks sent in updates, perform the following steps:
a.
Create a standard access list permitting the networks you want the RIP process to advertise and
denying the networks you do not want the RIP process to advertise.
b.
Enter the following command to apply the filter. You can specify an interface to apply the filter to
only those updates sent by that interface.
hostname(config-router): distribute-list acl out [interface if_name]
You can enter this command for each interface you want to apply a filter to. If you do not specify an
interface name, the filter is applied to all RIP updates.
Redistributing Routes into the RIP Routing Process
You can redistribute routes from the OSPF, EIGRP, static, and connected routing processes into the RIP
routing process.
To redistribute a routes into the RIP routing process, perform the following steps:
Step 1
(Optional) Create a route-map to further define which routes from the specified routing protocol are
redistributed in to the RIP routing process. See the “Defining Route Maps” section on page 10-7 for
more information about creating a route map.
Step 2
Choose one of the following options to redistribute the selected route type into the RIP routing process.
•
To redistribute connected routes into the RIP routing process, enter the following command:
hostname(config-router): redistribute connected [metric {metric_value | transparent}]
[route-map map_name]
•
To redistribute static routes into the RIP routing process, enter the following command:
hostname(config-router): redistribute static [metric {metric_value | transparent}]
[route-map map_name]
•
To redistribute routes from an OSPF routing process into the RIP routing process, enter the
following command:
hostname(config-router): redistribute ospf pid [match {internal | external [1 | 2] |
nssa-external [1 | 2]}] [metric {metric_value | transparent}] [route-map map_name]
Cisco Security Appliance Command Line Configuration Guide
10-22
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring RIP
•
To redistribute routes from an EIGRP routing process into the RIP routing process, enter the
following command:
hostname(config-router): redistribute eigrp as-num [metric {metric_value |
transparent}] [route-map map_name]
Configuring RIP Send/Receive Version on an Interface
You can override the globally-set version of RIP the security appliance uses to send and receive RIP
updates on a per-interface basis.
To configure the RIP send and receive version, perform the following steps:
Step 1
(Optional) To specify the version of RIP advertisements sent from an interface, perform the following
steps:
a.
Enter interface configuration mode for the interface you are configuring by entering the following
command:
hostname(config)# interface phy_if
b.
Specify the version of RIP to use when sending RIP updates out of the interface by entering the
following command:
hostname(config-if)# rip send version {[1] [2]}
Step 2
(Optional) To specify the version of RIP advertisements permitted to be received by an interface,
perform the following steps:
a.
Enter interface configuration mode for the interface you are configuring by entering the following
command:
hostname(config)# interface phy_if
b.
Specify the version of RIP to allow when receiving RIP updates on the interface by entering the
following command:
hostname(config-if)# rip receive version {[1] [2]}
RIP updates received on the interface that do not match the allowed version are dropped.
Enabling RIP Authentication
The security appliance supports RIP message authentication for RIP Version 2 messages.
To enable RIP message authentication, perform the following steps:
Step 1
Enter interface configuration mode for the interface you are configuring by entering the following
command:
hostname(config)# interface phy_if
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-23
Chapter 10
Configuring IP Routing
Configuring EIGRP
Step 2
(Optional) Set the authentication mode by entering the following command. By default, text
authentication is used. MD5 authentication is recommended.
hostname(config-if)# rip authentication mode {text | md5}
Step 3
Enable authentication and configure the authentication key by entering the following command:
hostname(config-if)# rip authentication key key key_id key-id
Monitoring RIP
To display various RIP routing statistics, perform one of the following tasks, as needed:
•
To display the contents of the RIP routing database, enter the following command:
hostname# show rip database
•
To display the RIP commands in the running configuration, enter the following command:
hostname# show running-config router rip
Use the following debug commands only to troubleshoot specific problems or during troubleshooting
sessions with Cisco TAC. Debugging output is assigned high priority in the CPU process and can render
the system unusable. It is best to use debug commands during periods of lower network traffic and fewer
users. Debugging during these periods decreases the likelihood that increased debug command
processing overhead will affect system performance.
•
To display RIP processing events, enter the following command:
hostname# debug rip events
•
To display RIP database events, enter the following command:
hostname# debug rip database
Configuring EIGRP
This section describes the configuration and monitoring of EIGRP routing and includes the following
topics:
•
EIGRP Routing Overview, page 10-25
•
Enabling and Configuring EIGRP Routing, page 10-26
•
Enabling and Configuring EIGRP Stub Routing, page 10-27
•
Enabling EIGRP Authentication, page 10-27
•
Defining an EIGRP Neighbor, page 10-28
•
Redistributing Routes Into EIGRP, page 10-29
•
Configuring the EIGRP Hello Interval and Hold Time, page 10-30
•
Disabling Automatic Route Summarization, page 10-30
•
Configuring Summary Aggregate Addresses, page 10-31
•
Disabling EIGRP Split Horizon, page 10-31
Cisco Security Appliance Command Line Configuration Guide
10-24
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring EIGRP
•
Changing the Interface Delay Value, page 10-32
•
Monitoring EIGRP, page 10-32
•
Disabling Neighbor Change and Warning Message Logging, page 10-32
EIGRP Routing Overview
EIGRP is an enhanced version of IGRP developed by Cisco. Unlike IGRP and RIP, EIGRP does not send
out periodic route updates. EIGRP updates are sent out only when the network topology changes.
Neighbor discovery is the process that the security appliance uses to dynamically learn of other routers
on directly attached networks. EIGRP routers send out multicast hello packets to announce their
presence on the network. When the security appliance receives a hello packet from a new neighbor, it
sends its topology table to the neighbor with an initialization bit set. When the neighbor receives the
topology update with the initialization bit set, the neighbor sends its topology table back to the security
appliance.
The hello packets are sent out as multicast messages. No response is expected to a hello message. The
exception to this is for statically defined neighbors. If you use the neighbor command to configure a
neighbor, the hello messages sent to that neighbor are sent as unicast messages. Routing updates and
acknowledgements are sent out as unicast messages.
Once this neighbor relationship is established, routing updates are not exchanged unless there is a change
in the network topology. The neighbor relationship is maintained through the hello packets. Each hello
packet received from a neighbor contains a hold time. This is the time in which the security appliance
can expect to receive a hello packet from that neighbor. If the security appliance does not receive a hello
packet from that neighbor within the hold time advertised by that neighbor, the security appliance
considers that neighbor to be unavailable.
The EIGRP uses an algorithm called DUAL for route computations. DUAL saves all routes to a
destination in the topology table, not just the least-cost route. The least-cost route is inserted into the
routing table. The other routes remain in the topology table. If the main route fails, another route is
chosen from the feasible successors. A successor is a neighboring router used for packet forwarding that
has a least-cost path to a destination. The feasibility calculation guarantees that the path is not part of a
routing loop.
If a feasible successor is not found in the topology table, a route recomputation must occur. During route
recomputation, DUAL queries the EIGRP neighbors for a route, who in turn query their neighbors.
Routers that do no have a feasible successor for the route return an unreachable message.
During route recomputation, DUAL marks the route as active. By default, the security appliance waits
for three minutes to receive a response from its neighbors. If the security appliance does not receive a
response from a neighbor, the route is marked as stuck-in-active. All routes in the topology table that
point to the unresponsive neighbor as a feasibility successor are removed.
Note
EIGRP neighbor relationships are not supported through the IPSec tunnel without a GRE tunnel.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-25
Chapter 10
Configuring IP Routing
Configuring EIGRP
Enabling and Configuring EIGRP Routing
You can only enable one EIGRP routing process on the security appliance.
To enable and configure EIGRP routing, perform the following tasks:
Step 1
Create the EIGRP routing process and enter router configuration mode for that process by entering the
following command:
hostname(config)# router eigrp as-num
The as-num argument is the autonomous system number of the EIGRP routing process.
Step 2
To configure the interfaces and networks that participate in EIGRP routing, configure one or more
network statements by entering the following command:
hostname(config-router)# network ip-addr [mask]
Directly-connected and static networks that fall within the defined network are advertised by the security
appliance. Additionally, only interfaces with an IP address that fall within the defined network
participate in the EIGRP routing process.
If you have an interface that you do not want to participate in EIGRP routing, but that is attached to a
network that you want advertised, configure a network command that covers the network the interface
is attached to, and use the passive-interface command to prevent that interface from sending or
receiving EIGRP updates.
Step 3
(Optional) To prevent an interface from sending or receiving EIGRP routing message, enter the
following command:
hostname(config-router)# passive-interface {default | if-name}
Using the default keyword disables EIGRP routing updates on all interfaces. Specifying an interface
name, as defined by the nameif command, disables EIGRP routing updates on the specified interface.
You can have multiple passive-interface commands in your EIGRP router configuration.
Step 4
(Optional) To control the sending or receiving of candidate default route information, enter the following
command:
hostname(config-router)# no default-information {in | out}
Configuring no default-information in causes the candidate default route bit to be blocked on received
routes. Configuring no default-information out disables the setting of th edefault route bit in advertised
routes.
Step 5
(Optional) To filter networks sent in EIGRP routing updates, perform the following steps:
a.
Create a standard access list that defines the routes you want to advertise.
b.
Enter the following command to apply the filter. You can specify an interface to apply the filter to
only those updates sent by that interface.
hostname(config-router): distribute-list acl out [interface if_name]
You can enter multiple distribute-list commands in your EIGRP router configuration.
Cisco Security Appliance Command Line Configuration Guide
10-26
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring EIGRP
Step 6
(Optional) To filter networks received in EIGRP routing updates, perform the following steps:
a.
Create a standard access list that defines the routes you want to filter from received updates.
b.
Enter the following command to apply the filter. You can specify an interface to apply the filter to
only those updates received by that interface.
hostname(config-router): distribute-list acl in [interface if_name]
You can enter multiple distribute-list commands in your EIGRP router configuration.
Enabling and Configuring EIGRP Stub Routing
You can configure the security appliance as an EIGRP stub router. Stub routing decreases memory and
processing requirements on the security appliance. As a stub router, the security appliance does not need
to maintain a complete EIGRP routing table because it forwards all nonlocal traffic to a distribution
router. Generally, the distribution router need not send anything more than a default route to the stub
router.
Only specified routes are propagated from the stub router to the distribution router. As a stub router, the
security appliance responds to all queries for summaries, connected routes, redistributed static routes,
external routes, and internal routes with the message “inaccessible.” When the security appliance is
configured as a stub, it sends a special peer information packet to all neighboring routers to report its
status as a stub router. Any neighbor that receives a packet informing it of the stub status will not query
the stub router for any routes, and a router that has a stub peer will not query that peer. The stub router
depends on the distribution router to send the proper updates to all peers.
To enable and configure and EIGRP stub routing process, perform the following steps:
Step 1
Create the EIGRP routing process and enter router configuration mode for that process by entering the
following command:
hostname(config)# router eigrp as-num
The as-num argument is the autonomous system number of the EIGRP routing process.
Step 2
Configure the interface connected to the distribution router to participate in EIGRP by entering the
following command:
hostname(config-router)# network ip-addr [mask]
Step 3
Configure the stub routing process by entering the following command. You must specify which
networks are advertised by the stub routing process to the distribution router. Static and connected
networks are not automatically redistributed into the stub routing process.
hostname(config-router)# eigrp stub {receive-only | [connected] [redistributed] [static]
[summary]}
Enabling EIGRP Authentication
EIGRP route authentication provides MD5 authentication of routing updates from the EIGRP routing
protocol. The MD5 keyed digest in each EIGRP packet prevents the introduction of unauthorized or false
routing messages from unapproved sources.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-27
Chapter 10
Configuring IP Routing
Configuring EIGRP
EIGRP route authentication is configured on a per-interface basis. All EIGRP neighbors on interfaces
configured for EIGRP message authentication must be configured with the same authentication mode
and key for adjacencies to be established.
Before you can enable EIGRP route authentication, you must enable EIGRP.
To enable EIGRP authentication on an interface, perform the following steps:
Step 1
Enter interface configuration mode for the interface on which you are configuring EIGRP message
authentication by entering the following command:
hostname(config)# interface phy_if
Step 2
Enable MD5 authentication of EIGRP packets by entering the following command:
hostname(config-if)# authentication mode eigrp as-num md5
The as-num argument is the autonomous system number of the EIGRP routing process configured on the
security appliance. If EIGRP is not enabled or if you enter the wrong number, the security appliance
returns the following error message:
% Asystem(100) specified does not exist
Step 3
Configure the key used by the MD5 algorithm by entering the following command:
hostname(config-if)# authentication key eigrp as-num key key-id key-id
The as-num argument is the autonomous system number of the EIGRP routing process configured on the
security appliance. If EIGRP is not enabled or if you enter the wrong number, the security appliance
returns the following error message:
% Asystem(100) specified does not exist
The key argument can contain up to 16 characters. The key-id argument is a number from 0 to 255.
Defining an EIGRP Neighbor
EIGRP hello packets are sent as multicast packets. If an EIGRP neighbor is located across a
nonbroadcast network, such as a tunnel, you must manually define that neighbor. When you manually
define an EIGRP neighbor, hello packets are sent to that neighbor as unicast messages.
To manually define an EIGRP neighbor, perform the following steps:
Step 1
Enter router configuration mode for the EIGRP routing process by entering the following command:
hostname(config)# router eigrp as-num
The as-num argument is the autonomous system number of the EIGRP routing process.
Step 2
Define the static neighbor by entering the following command:
hostname(config-router)# neighbor ip-addr interface if_name
The ip-addr argument is the IP address of the neighbor. The if-name argument is the name of the
interface, as specified by the nameif command, through which that neighbor is available. You can define
multiple neighbors for an EIGRP routing process.
Cisco Security Appliance Command Line Configuration Guide
10-28
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring EIGRP
Redistributing Routes Into EIGRP
You can redistribute routes discovered by RIP and OSPF into the EIGRP routing process. You can also
redistribute static and connected routes into the EIGRP routing process. You do not need to redistribute
connected routes if they fall within the range of a network statement in the EIGRP configuration.
To redistribute routes into the EIGRP routing process, perform the following steps:
Step 1
(Optional) Create a route-map to further define which routes from the specified routing protocol are
redistributed in to the RIP routing process. See the “Defining Route Maps” section on page 10-7 for
more information about creating a route map.
Step 2
Enter router configuration mode for the EIGRP routing process:
hostname(config)# router eigrp as-num
Step 3
(Optional) Specify the default metrics that should be applied to routes redistributed into the EIGRP
routing process by entering the following command:
hostname(config-router)# default-metric bandwidth delay reliability loading mtu
If you do not specify a default-metric in the EIGRP router configuration, you must specify the metric
values in each redistribute command. If you specify the EIGRP metrics in the redistribute command and
have the default-metric command in the EIGRP router configuration, the metrics in the redistribute
command are used. If you redistribute static or connected into EIGRP, specifying metric in redistribute
command is not a requirement, though recommended.
Step 4
Choose one of the following options to redistribute the selected route type into the EIGRP routing
process.
•
To redistribute connected routes into the EIGRP routing process, enter the following command:
hostname(config-router): redistribute connected [metric bandwidth delay reliability
loading mtu] [route-map map_name]
•
To redistribute static routes into the EIGRP routing process, enter the following command:
hostname(config-router): redistribute static [metric bandwidth delay reliability
loading mtu] [route-map map_name]
•
To redistribute routes from an OSPF routing process into the EIGRP routing process, enter the
following command:
hostname(config-router): redistribute ospf pid [match {internal | external [1 | 2] |
nssa-external [1 | 2]}] [metric bandwidth delay reliability loading mtu] [route-map
map_name]
•
To redistribute routes from a RIP routing process into the EIGRP routing process, enter the followin
gcommand:
hostname(config-router): redistribute rip
[metric bandwidth delay reliability load mtu]
[route-map map_name]
You must specify the EIGRP metric values in the redistribute command if you do not have a
default-metric command in the EIGRP router configuration.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-29
Chapter 10
Configuring IP Routing
Configuring EIGRP
Configuring the EIGRP Hello Interval and Hold Time
The security appliance periodically sends hello packets to discover neighbors and to learn when
neighbors become unreachable or inoperative. By default, hello packets are sent every 5 seconds.
The hello packet advertises the security appliance hold time. The hold time indicates to EIGRP
neighbors the length of time the neighbor should consider the security appliance reachable. If the
neighbor does not receive a hello packet within the advertised hold time, then the security appliance is
considered unreachable. By default, the advertised hold time is 15 seconds (three times the hello
interval).
Both the hello interval and the advertised hold time are configured on a per-interface basis. We
recommend setting the hold time to be at minimum three times the hello interval.
To configure the hello interval and advertised hold time, perform the following steps:
Step 1
Enter interface configuration mode for the interface on which you are configuring hello interval or
advertised hold time by entering the following command:
hostname(config)# interface phy_if
Step 2
To change the hello interval, enter the following command:
hostname(config)# hello-interval eigrp as-num seconds
Step 3
To change the hold time, enter the following command:
hostname(config)# hold-time eigrp as-num seconds
Disabling Automatic Route Summarization
Automatic route summarization is enabled by default. The EIGRP routing process summarizes on
network number boundaries. This can cause routing problems if you have non-contiguous networks.
For example, if you have a router with the networks 192.168.1.0, 192.168.2.0, and 192.168.3.0
connected to it, and those networks all participate in EIGRP, the EIGRP routing process creates the
summary address 192.168.0.0 for those routes. If an additional router is added to the network with the
networks 192.168.10.0 and 192.168.11.0, and those networks participate in EIGRP, they will also be
summarized as 192.168.0.0. To prevent the possibility of traffic being routed to the wrong location, you
should disable automatic route summarization on the routers creating the conflicting summary
addresses.
To disable automatic router summarization, enter the following command in router configuration mode
for the EIGRP routing process:
hostname(config-router)# no auto-summary
Note
Automatic summary addresses have an adminstrative distance of 5. You cannot configure this value.
Cisco Security Appliance Command Line Configuration Guide
10-30
OL-12172-04
Chapter 10
Configuring IP Routing
Configuring EIGRP
Configuring Summary Aggregate Addresses
You can configure a summary addresses on a per-interface basis. You need to manually define summary
addresses if you want to create summary addresses that do not occur at a network number boundary or
if you want to use summary addresses on a security appliance with automatic route summarization
disabled. If any more specific routes are in the routing table, EIGRP will advertise the summary address
out the interface with a metric equal to the minimum of all more specific routes.
To create a summary address, perform the following steps:
Step 1
Enter interface configuration mode for the interface on which you are creating a summary address by
entering the following command:
hostname(config)# interface phy_if
Step 2
Create the summary address by entering the following command:
hostname(config-if)# summary-address eigrp as-num address mask [distance]
By default, EIGRP summary addresses that you define have an administrative distance of 5. You can
change this value by specifying the optional distance argument in the summary-address command.
Disabling EIGRP Split Horizon
Split horizon controls the sending of EIGRP update and query packets. When split horizon is enabled on
an interface, update and query packets are not sent for destinations for which this interface is the next
hop. Controlling update and query packets in this manner reduces the possibility of routing loops.
By default, split horizon is enabled on all interfaces.
Split horizon blocks route information from being advertised by a router out of any interface from which
that information originated. This behavior usually optimizes communications among multiple routing
devices, particularly when links are broken. However, with nonbroadcast networks, there may be
situations where this behavior is not desired. For these situations, including networks in which you have
EIGRP configured, you may want to disable split horizon.
If you disable split horizon on an interface, you must disable it for all routers and access servers on that
interface.
To disable EIGRP split-horizon, perform the following steps:
Step 1
Enter interface configuration mode for the interface on which you are disabling split horizon by entering
the following command:
hostname(config)# interface phy_if
Step 2
To disable split horizon, enter the following command:
hostname(config-if)# no split-horizon eigrp as-number
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-31
Chapter 10
Configuring IP Routing
Configuring EIGRP
Changing the Interface Delay Value
The interface delay value is used in EIGRP distance calculations. You can modify this value on a
per-interface basis.
To change the delay value, perform the following steps:
Step 1
Enter interface configuration mode for the interface on which you are changing the delay value used by
EIGRP by entering the following command:
hostname(config)# interface phy_if
Step 2
To disable split horizon, enter the following command:
hostname(config-if)# delay value
The value entered is in tens of microseconds. So, to set the delay for 2000 microseconds, you would enter
a value of 200.
Step 3
(Optional) To view the delay value assigned to an interface, use the show interface command.
Monitoring EIGRP
You can use the following commands to monitor the EIGRP routing process. For examples and
descriptions of the command output, see the Cisco Security Appliance Command Reference.
•
To display the EIGRP event log, enter the following command:
hostname# show eigrp [as-number] events [{start end} | type]
•
To display the interfaces participating in EIGRP routing, enter the following command:
hostname# show eigrp [as-number] interfaces [if-name] [detail]
•
To display the EIGRP neighbor table, enter the following command:
hostname# show eigrp [as-number] neighbors [detail | static] [if-name]
•
To display the EIGRP topology table, enter the following command:
hostname# show eigrp [as-number] topology [ip-addr [mask] | active | all-links |
pending | summary | zero-successors]
•
To display EIGRP traffic statistics, enter the following command:
hostname# show eigrp [as-number] traffic
Disabling Neighbor Change and Warning Message Logging
By default neighbor change, and neighbor warning messages are logged. You can disable the logging of
neighbor change message and neighbor warning messages.
•
To disable the logging of neighbor change messages, enter the following command in router
configuration mode for the EIGRP routing process:
hostname(config-router)# no eigrp log-neighbor-changes
Cisco Security Appliance Command Line Configuration Guide
10-32
OL-12172-04
Chapter 10
Configuring IP Routing
The Routing Table
•
To disable the logging of neighbor warning messages, enter the following command in router
configuration mode for the EIGRP routing process:
hostname(config-router)# no eigrp log-neighbor-warnings
The Routing Table
This section contains the following topics:
•
Displaying the Routing Table, page 10-33
•
How the Routing Table is Populated, page 10-33
•
How Forwarding Decisions are Made, page 10-35
Displaying the Routing Table
To view the entries in the routing table, enter the following command:
hostname# show route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is 10.86.194.1 to network 0.0.0.0
S
C
S*
10.1.1.0 255.255.255.0 [3/0] via 10.86.194.1, outside
10.86.194.0 255.255.254.0 is directly connected, outside
0.0.0.0 0.0.0.0 [1/0] via 10.86.194.1, outside
On the ASA 5505 adaptive security appliance, the following route is also shown. It is the internal
loopback interface, which is used by the VPN hardware client feature for individual user authentication.
C 127.1.0.0 255.255.0.0 is directly connected, _internal_loopback
How the Routing Table is Populated
The security appliance routing table can be populated by statically defined routes, directly connected
routes, and routes discovered by the RIP, EIGRP, and OSPF routing protocols. Because the security
appliance can run multiple routing protocols in addition to having static and connected routed in the
routing table, it is possible that the same route is discovered or entered in more than one manner. When
two routes to the same destination are put into the routing table, the one that remains in the routing table
is determined as follows:
•
If the two routes have different network prefix lengths (network masks), then both routes are
considered unique and are entered in to the routing table. The packet forwarding logic then
determines which of the two to use.
For example, if the RIP and OSPF processes discovered the following routes:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-33
Chapter 10
Configuring IP Routing
The Routing Table
– RIP: 192.168.32.0/24
– OSPF: 192.168.32.0/19
Even though OSPF routes have the better administrative distance, both routes are installed in the
routing table because each of these routes has a different prefix length (subnet mask). They are
considered different destinations and the packet forwarding logic determine which route to use.
•
If the security appliance learns about multiple paths to the same destination from a single routing
protocol, such as RIP, the route with the better metric (as determined by the routing protocol) is
entered into the routing table.
Metrics are values associated with specific routes, ranking them from most preferred to least
preferred. The parameters used to determine the metrics differ for different routing protocols. The
path with the lowest metric is selected as the optimal path and installed in the routing table. If there
are multiple paths to the same destination with equal metrics, load balancing is done on these equal
cost paths.
•
If the security appliance learns about a destination from more than one routing protocol, the
administrative distances of the routes are compared and the routes with lower administrative
distance is entered into the routing table.
You can change the administrative distances for routes discovered by or redistributed into a routing
protocol. If two routes from two different routing protocols have the same administrative distance,
then the route with the lower default administrative distance is entered into the routing table. In the
case of EIGRP and OSPF routes, if the EIGRP route and the OSPF route have the same
administrative distance, then the EIGRP route is chosen by default.
Administrative distance is a route parameter that the security appliance uses to select the best path when
there are two or more different routes to the same destination from two different routing protocols.
Because the routing protocols have metrics based on algorithms that are different from the other
protocols, it is not always possible to determine the “best path” for two routes to the same destination
that were generated by different routing protocols.
Each routing protocol is prioritized using an administrative distance value. Table 10-1 shows the default
administrative distance values for the routing protocols supported by the security appliance.
Table 10-1
Default Administrative Distance for Supported Routing Protocols
Route Source
Default Administrative Distance
Connected interface
0
Static route
1
EIGRP Summary Route
5
Internal EIGRP
90
OSPF
110
RIP
120
EIGRP external route
170
Unknown
255
The smaller the administrative distance value, the more preference is given to the protocol. For example,
if the security appliance receives a route to a certain network from both an OSPF routing process (default
administrative distance - 110) and a RIP routing process (default administrative distance - 120), the
security appliance chooses the OSPF route because OSPF has a higher preference. This means the router
adds the OSPF version of the route to the routing table.
Cisco Security Appliance Command Line Configuration Guide
10-34
OL-12172-04
Chapter 10
Configuring IP Routing
The Routing Table
In the above example, if the source of the OSPF-derived route was lost (for example, due to a power
shutdown), the security appliance would then use the RIP-derived route until the OSPF-derived route
reappears.
The administrative distance is a local setting. For example, if you use the distance-ospf command to
change the administrative distance of routes obtained through OSPF, that change would only affect the
routing table for the security appliance the command was entered on. The administrative distance is not
advertised in routing updates.
Administrative distance does not affect the routing process. The OSPF and RIP routing processes only
advertise the routes that have been discovered by the routing process or redistributed into the routing
process. For example, the RIP routing process advertises RIP routes, even if routes discovered by the
OSPF routing process are used in the security appliance routing table.
Backup Routes
A backup route is registered when the initial attempt to install the route in the routing table fails because
another route was installed instead. If the route that was installed in the routing table fails, the routing
table maintenance process calls each routing protocol process that has registered a backup route and
requests them to reinstall the route in the routing table. If there are multiple protocols with registered
backup routes for the failed route, the preferred route is chosen based on administrative distance.
Because of this process, you can create “floating” static routes that are installed in the routing table when
the route discovered by a dynamic routing protocol fails. A floating static route is simply a static route
configured with a greater administrative distance than the dynamic routing protocols running on the
security appliance. When the corresponding route discover by a dynamic routing process fails, the static
route is installed in the routing table.
How Forwarding Decisions are Made
Forwarding decisions are made as follows:
•
If the destination does not match an entry in the routing table, the packet is forwarded through the
interface specified for the default route. If a default route has not been configured, the packet is
discarded.
•
If the destination matches a single entry in the routing table, the packet is forwarded through the
interface associated with that route.
•
If the destination matches more than one entry in the routing table, and the entries all have the same
network prefix length, the packets for that destination are distributed among the interfaces
associated with that route.
•
If the destination matches more than one entry in the routing table, and the entries have different
network prefix lengths, then the packet is forwarded out of the interface associated with the route
that has the longer network prefix length.
For example, a packet destined for 192.168.32.1 arrives on an interface of a security appliance with the
following routes in the routing table:
hostname# show route
....
R
192.168.32.0/24 [120/4] via 10.1.1.2
O
192.168.32.0/19 [110/229840] via 10.1.1.3
....
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
10-35
Chapter 10
Configuring IP Routing
Dynamic Routing and Failover
In this case, a packet destined to 192.168.32.1 is directed toward 10.1.1.2, because 192.168.32.1 falls
within the 192.168.32.0/24 network. It also falls within the other route in the routing table, but the
192.168.32.0/24 has the longest prefix within the routing table (24 bits verses 19 bits). Longer prefixes
are always preferred over shorter ones when forwarding a packet.
Dynamic Routing and Failover
Dynamic routes are not replicated to the standby unit or failover group in a failover configuration.
Therefore, immediately after a failover occurs, some packets received by the security appliance may be
dropped because of a lack of routing information or routed to a default static route while the routing table
is repopulated by the configured dynamic routing protocols.
Cisco Security Appliance Command Line Configuration Guide
10-36
OL-12172-04
CH A P T E R
11
Configuring DHCP, DDNS, and WCCP Services
This chapter describes how to configure the DHCP server, dynamic DNS (DDNS) update methods, and
WCCP on the security appliance. DHCP provides network configuration parameters, such as IP
addresses, to DHCP clients. The security appliance can provide a DHCP server or DHCP relay services
to DHCP clients attached to security appliance interfaces. The DHCP server provides network
configuration parameters directly to DHCP clients. DHCP relay passes DHCP requests received on one
interface to an external DHCP server located behind a different interface.
DDNS update integrates DNS with DHCP. The two protocols are complementary: DHCP centralizes and
automates IP address allocation; DDNS update automatically records the association between assigned
addresses and hostnames at pre-defined intervals. DDNS allows frequently changing address-hostname
associations to be updated frequently. Mobile hosts, for example, can then move freely on a network
without user or administrator intervention. DDNS provides the necessary dynamic updating and
synchronizing of the name to address and address to name mappings on the DNS server.
WCCP specifies interactions between one or more routers, Layer 3 switches, or security appliances and
one or more web caches. The feature transparently redirects selected types of traffic to a group of web
cache engines to optimize resource usage and lower response times.
Note
The security appliance does not support QIP DHCP servers for use with DHCP Proxy.
This chapter includes the following sections:
•
Configuring a DHCP Server, page 11-1
•
Configuring DHCP Relay Services, page 11-5
•
Configuring Dynamic DNS, page 11-6
•
Configuring Web Cache Services Using WCCP, page 11-9
Configuring a DHCP Server
This section describes how to configure DHCP server provided by the security appliance. This section
includes the following topics:
•
Enabling the DHCP Server, page 11-2
•
Configuring DHCP Options, page 11-3
•
Using Cisco IP Phones with a DHCP Server, page 11-4
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
11-1
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring a DHCP Server
Enabling the DHCP Server
The security appliance can act as a DHCP server. DHCP is a protocol that supplies network settings to
hosts including the host IP address, the default gateway, and a DNS server.
Note
The security appliance DHCP server does not support BOOTP requests.
In multiple context mode, you cannot enable the DHCP server or DHCP relay on an interface that is used
by more than one context.
You can configure a DHCP server on each interface of the security appliance. Each interface can have
its own pool of addresses to draw from. However the other DHCP settings, such as DNS servers, domain
name, options, ping timeout, and WINS servers, are configured globally and used by the DHCP server
on all interfaces.
You cannot configure a DHCP client or DHCP Relay services on an interface on which the server is
enabled. Additionally, DHCP clients must be directly connected to the interface on which the server is
enabled.
When it receives a DHCP request, the security appliance sends a discovery message to the DHCP server.
This message includes the IP address (within a subnetwork) configured with the dhcp-network-scope
command in the group policy. If the server has an address pool that falls within that subnetwork, it sends
the offer message with the pool information to the IP address—not to the source IP address of the
discovery message.
For example, if the server has a pool of the range 209.165.200.225 to 209.165.200.254, mask
255.255.255.0, and the IP address specified by the dhcp-network-scope command is 209.165.200.1, the
server sends that pool in the offer message to the security appliance.
To enable the DHCP server on a given security appliance interface, perform the following steps:
Step 1
Create a DHCP address pool. Enter the following command to define the address pool:
hostname(config)# dhcpd address ip_address-ip_address interface_name
The security appliance assigns a client one of the addresses from this pool to use for a given length of time.
These addresses are the local, untranslated addresses for the directly connected network.
The address pool must be on the same subnet as the security appliance interface.
Step 2
(Optional) To specify the IP address(es) of the DNS server(s) the client will use, enter the following
command:
hostname(config)# dhcpd dns dns1 [dns2]
You can specify up to two DNS servers.
Step 3
(Optional) To specify the IP address(es) of the WINS server(s) the client will use, enter the following
command:
hostname(config)# dhcpd wins wins1 [wins2]
You can specify up to two WINS servers.
Step 4
(Optional) To change the lease length to be granted to the client, enter the following command:
hostname(config)# dhcpd lease lease_length
Cisco Security Appliance Command Line Configuration Guide
11-2
OL-12172-04
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring a DHCP Server
This lease equals the amount of time (in seconds) the client can use its allocated IP address before the
lease expires. Enter a value between 300 to 1,048,575. The default value is 3600 seconds.
Step 5
(Optional) To configure the domain name the client uses, enter the following command:
hostname(config)# dhcpd domain domain_name
Step 6
(Optional) To configure the DHCP ping timeout value, enter the following command:
hostname(config)# dhcpd ping_timeout milliseconds
To avoid address conflicts, the security appliance sends two ICMP ping packets to an address before
assigning that address to a DHCP client. This command specifies the timeout value for those packets.
Step 7
(Transparent Firewall Mode) Define a default gateway. To define the default gateway that is sent to
DHCP clients, enter the following command.
hostname(config)# dhcpd option 3 ip gateway_ip
If you do not use the DHCP option 3 to define the default gateway, DHCP clients use the IP address of
the management interface. The management interface does not route traffic.
Step 8
To enable the DHCP daemon within the security appliance to listen for DHCP client requests on the
enabled interface, enter the following command:
hostname(config)# dhcpd enable interface_name
For example, to assign the range 10.0.1.101 to 10.0.1.110 to hosts connected to the inside interface, enter
the following commands:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
dhcpd
dhcpd
dhcpd
dhcpd
dhcpd
dhcpd
address 10.0.1.101-10.0.1.110 inside
dns 209.165.201.2 209.165.202.129
wins 209.165.201.5
lease 3000
domain example.com
enable inside
Configuring DHCP Options
You can configure the security appliance to send information for the DHCP options listed in RFC 2132.
The DHCP options fall into one of three categories:
•
Options that return an IP address.
•
Options that return a text string.
•
Options that return a hexadecimal value.
The security appliance supports all three categories of DHCP options. To configure a DHCP option, do
one of the following:
•
To configure a DHCP option that returns one or two IP addresses, enter the following command:
hostname(config)# dhcpd option code ip addr_1 [addr_2]
•
To configure a DHCP option that returns a text string, enter the following command:
hostname(config)# dhcpd option code ascii text
•
To configure a DHCP option that returns a hexadecimal value, enter the following command:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
11-3
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring a DHCP Server
hostname(config)# dhcpd option code hex value
Note
The security appliance does not verify that the option type and value that you provide match the expected
type and value for the option code as defined in RFC 2132. For example, you can enter the dhcpd option
46 ascii hello command and the security appliance accepts the configuration although option 46 is
defined in RFC 2132 as expecting a single-digit, hexadecimal value. For more information about the
option codes and their associated types and expected values, refer to RFC 2132.
Table 11-1 shows the DHCP options that are not supported by the dhcpd option command.
Table 11-1
Unsupported DHCP Options
Option Code
Description
0
DHCPOPT_PAD
1
HCPOPT_SUBNET_MASK
12
DHCPOPT_HOST_NAME
50
DHCPOPT_REQUESTED_ADDRESS
51
DHCPOPT_LEASE_TIME
52
DHCPOPT_OPTION_OVERLOAD
53
DHCPOPT_MESSAGE_TYPE
54
DHCPOPT_SERVER_IDENTIFIER
58
DHCPOPT_RENEWAL_TIME
59
DHCPOPT_REBINDING_TIME
61
DHCPOPT_CLIENT_IDENTIFIER
67
DHCPOPT_BOOT_FILE_NAME
82
DHCPOPT_RELAY_INFORMATION
255
DHCPOPT_END
Specific options, DHCP option 3, 66, and 150, are used to configure Cisco IP Phones. See the “Using
Cisco IP Phones with a DHCP Server” section on page 11-4 topic for more information about
configuring those options.
Using Cisco IP Phones with a DHCP Server
Enterprises with small branch offices that implement a Cisco IP Telephony Voice over IP solution
typically implement Cisco CallManager at a central office to control Cisco IP Phones at small branch
offices. This implementation allows centralized call processing, reduces the equipment required, and
eliminates the administration of additional Cisco CallManager and other servers at branch offices.
Cisco IP Phones download their configuration from a TFTP server. When a Cisco IP Phone starts, if it
does not have both the IP address and TFTP server IP address preconfigured, it sends a request with
option 150 or 66 to the DHCP server to obtain this information.
•
DHCP option 150 provides the IP addresses of a list of TFTP servers.
•
DHCP option 66 gives the IP address or the hostname of a single TFTP server.
Cisco Security Appliance Command Line Configuration Guide
11-4
OL-12172-04
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring DHCP Relay Services
Cisco IP Phones might also include DHCP option 3 in their requests, which sets the default route.
Cisco IP Phones might include both option 150 and 66 in a single request. In this case, the security
appliance DHCP server provides values for both options in the response if they are configured on the
security appliance.
You can configure the security appliance to send information for most options listed in RFC 2132. The
following example shows the syntax for any option number, as well as the syntax for commonly-used
options 66, 150, and 3:
•
To provide information for DHCP requests that include an option number as specified in RFC-2132,
enter the following command:
hostname(config)# dhcpd option number value
•
To provide the IP address or name of a TFTP server for option 66, enter the following command:
hostname(config)# dhcpd option 66 ascii server_name
•
To provide the IP address or names of one or two TFTP servers for option 150, enter the following
command:
hostname(config)# dhcpd option 150 ip server_ip1 [server_ip2]
The server_ip1 is the IP address or name of the primary TFTP server while server_ip2 is the
IP address or name of the secondary TFTP server. A maximum of two TFTP servers can be
identified using option 150.
•
To set the default route, enter the following command:
hostname(config)# dhcpd option 3 ip router_ip1
Configuring DHCP Relay Services
A DHCP relay agent allows the security appliance to forward DHCP requests from clients to a router
connected to a different interface.
The following restrictions apply to the use of the DHCP relay agent:
•
The relay agent cannot be enabled if the DHCP server feature is also enabled.
•
DHCP clients must be directly connected to the security appliance and cannot send requests through
another relay agent or a router.
•
For multiple context mode, you cannot enable DHCP relay on an interface that is used by more than
one context.
•
DHCP Relay services are not available in transparent firewall mode. A security appliance in
transparent firewall mode only allows ARP traffic through; all other traffic requires an access list.
To allow DHCP requests and replies through the security appliance in transparent mode, you need
to configure two access lists, one that allows DCHP requests from the inside interface to the outside,
and one that allows the replies from the server in the other direction.
•
When DHCP relay is enabled and more than one DHCP relay server is defined, the security
appliance forwards client requests to each defined DHCP relay server. Replies from the servers are
also forwarded to the client until the client DHCP relay binding is removed. The binding is removed
when the security appliance receives any of the following DHCP messages: ACK, NACK, or
decline.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
11-5
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring Dynamic DNS
Note
You cannot enable DHCP Relay on an interface running DHCP Proxy. You must Remove VPN DHCP
configuration first or you will see an error message. This error happens if both DHCP relay and DHCP
proxy are enabled. Ensure that either DHCP relay or DHCP proxy are enabled, but not both.
To enable DHCP relay, perform the following steps:
Step 1
To set the IP address of a DHCP server on a different interface from the DHCP client, enter the following
command:
hostname(config)# dhcprelay server ip_address if_name
You can use this command up to 4 times to identify up to 4 servers.
Step 2
To enable DHCP relay on the interface connected to the clients, enter the following command:
hostname(config)# dhcprelay enable interface
Step 3
(Optional) To set the number of seconds allowed for relay address negotiation, enter the following
command:
hostname(config)# dhcprelay timeout seconds
Step 4
(Optional) To change the first default router address in the packet sent from the DHCP server to the
address of the security appliance interface, enter the following command:
hostname(config)# dhcprelay setroute interface_name
This action allows the client to set its default route to point to the security appliance even if the DHCP
server specifies a different router.
If there is no default router option in the packet, the security appliance adds one containing the interface
address.
The following example enables the security appliance to forward DHCP requests from clients connected
to the inside interface to a DHCP server on the outside interface:
hostname(config)# dhcprelay server 201.168.200.4
hostname(config)# dhcprelay enable inside
hostname(config)# dhcprelay setroute inside
Configuring Dynamic DNS
This section describes examples for configuring the security appliance to support Dynamic DNS. DDNS
update integrates DNS with DHCP. The two protocols are complementary—DHCP centralizes and
automates IP address allocation, while dynamic DNS update automatically records the association
between assigned addresses and hostnames. When you use DHCP and dynamic DNS update, this
configures a host automatically for network access whenever it attaches to the IP network. You can locate
and reach the host using its permanent, unique DNS hostname. Mobile hosts, for example, can move
freely without user or administrator intervention.
DDNS provides address and domain name mappings so hosts can find each other even though their
DHCP-assigned IP addresses change frequently. The DDNS name and address mappings are held on the
DHCP server in two resource records: the A RR contains the name to IP address mapping while the PTR
Cisco Security Appliance Command Line Configuration Guide
11-6
OL-12172-04
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring Dynamic DNS
RR maps addresses to names. Of the two methods for performing DDNS updates—the IETF standard
defined by RFC 2136 and a generic HTTP method—the security appliance supports the IETF method in
this release.
The two most common DDNS update configurations are:
•
The DHCP client updates the A RR while the DHCP server updates PTR RR.
•
The DHCP server updates both the A and PTR RRs.
In general, the DHCP server maintains DNS PTR RRs on behalf of clients. Clients may be configured
to perform all desired DNS updates. The server may be configured to honor these updates or not. To
update the PTR RR, the DHCP server must know the Fully Qualified Domain Name of the client. The
client provides an FQDN to the server using a DHCP option called Client FQDN.
The following examples present these common scenarios:
•
Example 1: Client Updates Both A and PTR RRs for Static IP Addresses, page 11-7
•
Example 2: Client Updates Both A and PTR RRs; DHCP Server Honors Client Update Request;
FQDN Provided Through Configuration, page 11-7
•
Example 3: Client Includes FQDN Option Instructing Server Not to Update Either RR; Server
Overrides Client and Updates Both RRs., page 11-8
•
Example 4: Client Asks Server To Perform Both Updates; Server Configured to Update PTR RR
Only; Honors Client Request and Updates Both A and PTR RR, page 11-9
•
Example 5: Client Updates A RR; Server Updates PTR RR, page 11-9
Example 1: Client Updates Both A and PTR RRs for Static IP Addresses
The following example configures the client to request that it update both A and PTR resource records
for static IP addresses. To configure this example, perform the following steps:
Step 1
To define a DDNS update method called ddns-2 that requests that the client update both the A and PTR
RRs, enter the following commands:
hostname(config)# ddns update method ddns-2
hostname(DDNS-update-method)# ddns both
Step 2
To associate the method ddns-2 with the eth1 interface, enter the following commands:
hostname(DDNS-update-method)# interface eth1
hostname(config-if)# ddns update ddns-2
hostname(config-if)# ddns update hostname asa.example.com
Step 3
To configure a static IP address for eth1, enter the following commands:
hostname(config-if)# ip address 10.0.0.40 255.255.255.0
Example 2: Client Updates Both A and PTR RRs; DHCP Server Honors Client
Update Request; FQDN Provided Through Configuration
The following example configures 1) the DHCP client to request that it update both the A and PTR RRs,
and 2) the DHCP server to honor the requests. To configure this example, perform the following steps:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
11-7
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring Dynamic DNS
Step 1
To configure the DHCP client to request that the DHCP server perform no updates, enter the following
command:
hostname(config)# dhcp-client update dns server none
Step 2
To create a DDNS update method named ddns-2 on the DHCP client that requests that the client perform
both A and PTR updates, enter the following commands:
hostname(config)# ddns update method ddns-2
hostname(DDNS-update-method)# ddns both
Step 3
To associate the method named ddns-2 with the security appliance interface named Ethernet0, and enable
DHCP on the interface, enter the following commands:
hostname(DDNS-update-method)# interface Ethernet0
hostname(if-config)# ddns update ddns-2
hostname(if-config)# ddns update hostname asa.example.com
hostname(if-config)# ip address dhcp
Step 4
To configure the DHCP server, enter the following command:
hostname(if-config)# dhcpd update dns
Example 3: Client Includes FQDN Option Instructing Server Not to Update Either
RR; Server Overrides Client and Updates Both RRs.
The following example configures the DHCP client to include the FQDN option instructing the DHCP
server not to update either the A or PTR updates. The example also configures the server to override the
client request. As a result, the client backs off without performing any updates.
To configure this scenario, perform the following steps:
Step 1
To configure the update method named ddns-2 to request that it make both A and PTR RR updates, enter
the following commands:
hostname(config)# ddns update method ddns-2
hostname(DDNS-update-method)# ddns both
Step 2
To assign the DDNS update method named ddns-2 on interface Ethernet0 and provide the client
hostname (asa), enter the following commands:
hostname(DDNS-update-method)# interface Ethernet0
hostname(if-config)# ddns update ddns-2
hostname(if-config)# ddns update hostname asa.example.com
Step 3
To enable the DHCP client feature on the interface, enter the following commands:
hostname(if-config)# dhcp client update dns server none
hostname(if-config)# ip address dhcp
Step 4
To configure the DHCP server to override the client update requests, enter the following command:
hostname(if-config)# dhcpd update dns both override
Cisco Security Appliance Command Line Configuration Guide
11-8
OL-12172-04
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring Web Cache Services Using WCCP
Example 4: Client Asks Server To Perform Both Updates; Server Configured to
Update PTR RR Only; Honors Client Request and Updates Both A and PTR RR
The following example configures the server to perform only PTR RR updates by default. However, the
server honors the client request that it perform both A and PTR updates. The server also forms the FQDN
by appending the domain name (example.com) to the hostname provided by the client (asa).
To configure this scenario, perform the following steps:
Step 1
To configure the DHCP client on interface Ethernet0, enter the following commands:
hostname(config)# interface Ethernet0
hostname(config-if)# dhcp client update dns both
hostname(config-if)# ddns update hostname asa
Step 2
To configure the DHCP server, enter the following commands:
hostname(config-if)# dhcpd update dns
hostname(config-if)# dhcpd domain example.com
Example 5: Client Updates A RR; Server Updates PTR RR
The following example configures the client to update the A resource record and the server to update the
PTR records. Also, the client uses the domain name from the DHCP server to form the FQDN.
To configure this scenario, perform the following steps:
Step 1
To define the DDNS update method named ddns-2, enter the following commands:
hostname(config)# ddns update method ddns-2
hostname(DDNS-update-method)# ddns
Step 2
To configure the DHCP client for interface Ethernet0 and assign the update method to the interface, enter
the following commands:
hostname(DDNS-update-method)# interface Ethernet0
hostname(config-if)# dhcp client update dns
hostname(config-if)# ddns update ddns-2
hostname(config-if)# ddns update hostname asa
Step 3
To configure the DHCP server, enter the following commands:
hostname(config-if)# dhcpd update dns
hostname(config-if)# dhcpd domain example.com
Configuring Web Cache Services Using WCCP
The purpose of web caching is to reduce latency and network traffic. Previously-accessed web pages are
stored in a cache buffer, so if a user needs the page again, they can retrieve it from the cache instead of
the web server.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
11-9
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring Web Cache Services Using WCCP
WCCP specifies interactions between the security appliance and external web caches. The feature
transparently redirects selected types of traffic to a group of web cache engines to optimize resource
usage and lower response times. The security appliance only supports WCCP version 2.
Using a security appliance as an intermediary eliminates the need for a separate router to do the WCCP
redirect because the security appliance takes care of redirecting requests to cache engines. When the
security appliance knows when a packet needs redirection, it skips TCP state tracking, TCP sequence
number randomization, and NAT on these traffic flows.
This section includes the following topics:
•
WCCP Feature Support, page 11-10
•
WCCP Interaction With Other Features, page 11-10
•
Enabling WCCP Redirection, page 11-11
WCCP Feature Support
The following WCCPv2 features are supported with the security appliance:
•
Redirection of multiple TCP/UDP port-destined traffic.
•
Authentication for cache engines in a service group.
The following WCCPv2 features are not supported with the security appliance:
•
Multiple routers in a service group is not supported. Multiple Cache Engines in a service group is
still supported.
•
Multicast WCCP is not supported.
•
The Layer 2 redirect method is not supported; only GRE encapsulation is supported.
•
WCCP source address spoofing.
WCCP Interaction With Other Features
In the security appliance implementation of WCCP, the following applies as to how the protocol interacts
with other configurable features:
•
An ingress access list entry always takes higher priority over WCCP. For example, if an access list
does not permit a client to communicate with a server then traffic will not be redirected to a cache
engine. Both ingress interface access lists and egress interface access lists will be applied.
•
TCP intercept, authorization, URL filtering, inspect engines, and IPS features are not applied to a
redirected flow of traffic.
•
When a cache engine cannot service a request and packet is returned, or when a cache miss happens
on a cache engine and it requests data from a web server, then the contents of the traffic flow will
be subject to all the other configured features of the security appliance.
•
In failover, WCCP redirect tables are not replicated to standby units. After a failover, packets will
not be redirected until the tables are rebuilt. Sessions redirected prior to failover will likely be reset
by the web server.
Cisco Security Appliance Command Line Configuration Guide
11-10
OL-12172-04
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring Web Cache Services Using WCCP
Enabling WCCP Redirection
There are two steps to configuring WCCP redirection on the security appliance. The first involves
identifying the service to be redirected with the wccp command, and the second is defining on which
interface the redirection occurs with the wccp redirect command. The wccp command can optionally
also define which cache engines can participate in the service group, and what traffic should be
redirected to the cache engine.
WCCP redirect is supported only on the ingress of an interface. The only topology that the security
appliance supports is when client and cache engine are behind the same interface of the security
appliance and the cache engine can directly communicate with the client without going through the
security appliance.
The following configuration tasks assume you have already installed and configured the cache engines
you wish to include in your network.
To configure WCCP redirection, perform the following steps:
Step 1
To enable a WCCP service group, enter the following command:
hostname(config)# wccp {web-cache | service_number} [redirect-list access_list]
[group-list access_list] [password password]
The standard service is web-cache, which intercepts TCP port 80 (HTTP) traffic and redirects that traffic
to the cache engines, but you can identify a service number if desired between 0 and 254. For example,
to transparently redirect native FTP traffic to a cache engine, use WCCP service 60. You can enter this
command multiple times for each service group you want to enable.
The redirect-list access_list argument controls traffic redirected to this service group.
The group-list access_list argument determines which web cache IP addresses are allowed to participate
in the service group.
The password password argument specifies MD5 authentication for messages received from the service
group. Messages that are not accepted by the authentication are discarded.
Step 2
To enable WCCP redirection on an interface, enter the following command:
hostname(config)# wccp interface interface_name {web-cache | service_number} redirect in
The standard service is web-cache, which intercepts TCP port 80 (HTTP) traffic and redirects that traffic
to the cache engines, but you can identify a service number if desired between 0 and 254. For example,
to transparently redirect native FTP traffic to a cache engine, use WCCP service 60. You can enter this
command multiple times for each service group you want to participate in.
For example, to enable the standard web-cache service and redirect HTTP traffic that enters the inside
interface to a web cache, enter the following commands:
hostname(config)# wccp web-cache
hostname(config)# wccp interface inside web-cache redirect in
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
11-11
Chapter 11
Configuring DHCP, DDNS, and WCCP Services
Configuring Web Cache Services Using WCCP
Cisco Security Appliance Command Line Configuration Guide
11-12
OL-12172-04
CH A P T E R
12
Configuring Multicast Routing
This chapter describes how to configure multicast routing. This chapter includes the following topics:
•
Multicast Routing Overview, page 12-1
•
Enabling Multicast Routing, page 12-2
•
Configuring IGMP Features, page 12-2
•
Configuring Stub Multicast Routing, page 12-5
•
Configuring a Static Multicast Route, page 12-6
•
Configuring PIM Features, page 12-6
•
For More Information about Multicast Routing, page 12-10
Multicast Routing Overview
The security appliance supports both stub multicast routing and PIM multicast routing. However, you
cannot configure both concurrently on a single security appliance.
Note
Only the UDP transport layer is supported for multicast routing.
Stub multicast routing provides dynamic host registration and facilitates multicast routing. When
configured for stub multicast routing, the security appliance acts as an IGMP proxy agent. Instead of
fully participating in multicast routing, the security appliance forwards IGMP messages to an upstream
multicast router, which sets up delivery of the multicast data. When configured for stub multicast
routing, the security appliance cannot be configured for PIM.
The security appliance supports both PIM-SM and bi-directional PIM. PIM-SM is a multicast routing
protocol that uses the underlying unicast routing information base or a separate multicast-capable
routing information base. It builds unidirectional shared trees rooted at a single Rendezvous Point per
multicast group and optionally creates shortest-path trees per multicast source.
Bi-directional PIM is a variant of PIM-SM that builds bi-directional shared trees connecting multicast
sources and receivers. Bi-directional trees are built using a DF election process operating on each link
of the multicast topology. With the assistance of the DF, multicast data is forwarded from sources to the
Rendezvous Point, and therefore along the shared tree to receivers, without requiring source-specific
state. The DF election takes place during Rendezvous Point discovery and provides a default route to the
Rendezvous Point.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
12-1
Chapter 12
Configuring Multicast Routing
Enabling Multicast Routing
Note
If the security appliance is the PIM RP, use the untranslated outside address of the security appliance as
the RP address.
Enabling Multicast Routing
Enabling multicast routing lets the security appliance forward multicast packets. Enabling multicast
routing automatically enables PIM and IGMP on all interfaces. To enable multicast routing, enter the
following command:
hostname(config)# multicast-routing
The number of entries in the multicast routing tables are limited by the amount of RAM on the system.
Table 12-1 lists the maximum number of entries for specific multicast tables based on the amount of
RAM on the security appliance. Once these limits are reached, any new entries are discarded.
Table 12-1
Entry Limits for Multicast Tables
Table
16 MB 128 MB 128+ MB
MFIB
1000
3000
5000
IGMP Groups 1000
3000
5000
PIM Routes
7000
12000
3000
Configuring IGMP Features
IP hosts use IGMP to report their group memberships to directly connected multicast routers. IGMP uses
group addresses (Class D IP address) as group identifiers. Host group address can be in the range
224.0.0.0 to 239.255.255.255. The address 224.0.0.0 is never assigned to any group. The address
224.0.0.1 is assigned to all systems on a subnet. The address 224.0.0.2 is assigned to all routers on a
subnet.
When you enable multicast routing on the security appliance, IGMP Version 2 is automatically enabled
on all interfaces.
Note
Only the no igmp command appears in the interface configuration when you use the show run
command. If the multicast-routing command appears in the device configuration, then IGMP is
automatically enabled on all interfaces.
This section describes how to configure optional IGMP setting on a per-interface basis. This section
includes the following topics:
•
Disabling IGMP on an Interface, page 12-3
•
Configuring Group Membership, page 12-3
•
Configuring a Statically Joined Group, page 12-3
•
Controlling Access to Multicast Groups, page 12-3
•
Limiting the Number of IGMP States on an Interface, page 12-4
•
Modifying the Query Interval and Query Timeout, page 12-4
Cisco Security Appliance Command Line Configuration Guide
12-2
OL-12172-04
Chapter 12
Configuring Multicast Routing
Configuring IGMP Features
•
Changing the Query Response Time, page 12-5
•
Changing the IGMP Version, page 12-5
Disabling IGMP on an Interface
You can disable IGMP on specific interfaces. This is useful if you know that you do not have any
multicast hosts on a specific interface and you want to prevent the security appliance from sending host
query messages on that interface.
To disable IGMP on an interface, enter the following command:
hostname(config-if)# no igmp
To reenable IGMP on an interface, enter the following command:
hostname(config-if)# igmp
Note
Only the no igmp command appears in the interface configuration.
Configuring Group Membership
You can configure the security appliance to be a member of a multicast group. Configuring the security
appliance to join a multicast group causes upstream routers to maintain multicast routing table
information for that group and keep the paths for that group active.
To have the security appliance join a multicast group, enter the following command:
hostname(config-if)# igmp join-group group-address
Configuring a Statically Joined Group
Sometimes a group member cannot report its membership in the group, or there may be no members of
a group on the network segment, but you still want multicast traffic for that group to be sent to that
network segment. You can have multicast traffic for that group sent to the segment in one of two ways:
•
Using the igmp join-group command (see Configuring Group Membership, page 12-3). This causes
the security appliance to accept and to forward the multicast packets.
•
Using the igmp static-group command. The security appliance does not accept the multicast
packets but rather forwards them to the specified interface.
To configure a statically joined multicast group on an interface, enter the following command:
hostname(config-if)# igmp static-group group-address
Controlling Access to Multicast Groups
To control the multicast groups that hosts on the security appliance interface can join, perform the
following steps:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
12-3
Chapter 12
Configuring Multicast Routing
Configuring IGMP Features
Step 1
Create an access list for the multicast traffic. You can create more than one entry for a single access list.
You can use extended or standard access lists.
•
To create a standard access list, enter the following command:
hostname(config)# access-list name standard [permit | deny] ip_addr mask
The ip_addr argument is the IP address of the multicast group being permitted or denied.
•
To create an extended access list, enter the following command:
hostname(config)# access-list name extended [permit | deny] protocol src_ip_addr
src_mask dst_ip_addr dst_mask
The dst_ip_addr argument is the IP address of the multicast group being permitted or denied.
Step 2
Apply the access list to an interface by entering the following command:
hostname(config-if)# igmp access-group acl
The acl argument is the name of a standard or extended IP access list.
Limiting the Number of IGMP States on an Interface
You can limit the number of IGMP states resulting from IGMP membership reports on a per-interface
basis. Membership reports exceeding the configured limits are not entered in the IGMP cache and traffic
for the excess membership reports is not forwarded.
To limit the number of IGMP states on an interface, enter the following command:
hostname(config-if)# igmp limit number
Valid values range from 0 to 500, with 500 being the default value. Setting this value to 0 prevents
learned groups from being added, but manually defined memberships (using the igmp join-group and
igmp static-group commands) are still permitted. The no form of this command restores the default
value.
Modifying the Query Interval and Query Timeout
The security appliance sends query messages to discover which multicast groups have members on the
networks attached to the interfaces. Members respond with IGMP report messages indicating that they
want to receive multicast packets for specific groups. Query messages are addressed to the all-systems
multicast group, which has an address of 224.0.0.1, with a time-to-live value of 1.
These messages are sent periodically to refresh the membership information stored on the security
appliance. If the security appliance discovers that there are no local members of a multicast group still
attached to an interface, it stops forwarding multicast packet for that group to the attached network and
it sends a prune message back to the source of the packets.
By default, the PIM designated router on the subnet is responsible for sending the query messages. By
default, they are sent once every 125 seconds. To change this interval, enter the following command:
hostname(config-if)# igmp query-interval seconds
Cisco Security Appliance Command Line Configuration Guide
12-4
OL-12172-04
Chapter 12
Configuring Multicast Routing
Configuring Stub Multicast Routing
If the security appliance does not hear a query message on an interface for the specified timeout value
(by default, 255 seconds), then the security appliance becomes the designated router and starts sending
the query messages. To change this timeout value, enter the following command:
hostname(config-if)# igmp query-timeout seconds
Note
The igmp query-timeout and igmp query-interval commands require IGMP Version 2.
Changing the Query Response Time
By default, the maximum query response time advertised in IGMP queries is 10 seconds. If the security
appliance does not receive a response to a host query within this amount of time, it deletes the group.
To change the maximum query response time, enter the following command:
hostname(config-if)# igmp query-max-response-time seconds
Changing the IGMP Version
By default, the security appliance runs IGMP Version 2, which enables several additional features such
as the igmp query-timeout and igmp query-interval commands.
All multicast routers on a subnet must support the same version of IGMP. The security appliance does
not automatically detect version 1 routers and switch to version 1. However, a mix of IGMP Version 1
and 2 hosts on the subnet works; the security appliance running IGMP Version 2 works correctly when
IGMP Version 1 hosts are present.
To control which version of IGMP is running on an interface, enter the following command:
hostname(config-if)# igmp version {1 | 2}
Configuring Stub Multicast Routing
A security appliance acting as the gateway to the stub area does not need to participate in PIM. Instead,
you can configure it to act as an IGMP proxy agent and forward IGMP messages from hosts connected
on one interface to an upstream multicast router on another. To configure the security appliance as an
IGMP proxy agent, forward the host join and leave messages from the stub area interface to an upstream
interface.
To forward the host join and leave messages, enter the following command from the interface attached
to the stub area:
hostname(config-if)# igmp forward interface if_name
Note
Stub Multicast Routing and PIM are not supported concurrently.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
12-5
Chapter 12
Configuring Multicast Routing
Configuring a Static Multicast Route
Configuring a Static Multicast Route
When using PIM, the security appliance expects to receive packets on the same interface where it sends
unicast packets back to the source. In some cases, such as bypassing a route that does not support
multicast routing, you may want unicast packets to take one path and multicast packets to take another.
Static multicast routes are not advertised or redistributed.
To configure a static multicast route for PIM, enter the following command:
hostname(config)# mroute src_ip src_mask {input_if_name | rpf_neighbor} [distance]
To configure a static multicast route for a stub area, enter the following command:
hostname(config)# mroute src_ip src_mask input_if_name [dense output_if_name] [distance]
Note
The dense output_if_name keyword and argument pair is only supported for stub multicast routing.
Configuring PIM Features
Routers use PIM to maintain forwarding tables for forwarding multicast diagrams. When you enable
multicast routing on the security appliance, PIM and IGMP are automatically enabled on all interfaces.
Note
PIM is not supported with PAT. The PIM protocol does not use ports and PAT only works with protocols
that use ports.
This section describes how to configure optional PIM settings. This section includes the following
topics:
•
Disabling PIM on an Interface, page 12-6
•
Configuring a Static Rendezvous Point Address, page 12-7
•
Configuring the Designated Router Priority, page 12-7
•
Filtering PIM Register Messages, page 12-7
•
Configuring PIM Message Intervals, page 12-8
•
Configuring a Multicast Boundary, page 12-8
•
Filtering PIM Neighbors, page 12-8
•
Supporting Mixed Bidirectional/Sparse-Mode PIM Networks, page 12-9
Disabling PIM on an Interface
You can disable PIM on specific interfaces. To disable PIM on an interface, enter the following
command:
hostname(config-if)# no pim
To reenable PIM on an interface, enter the following command:
hostname(config-if)# pim
Cisco Security Appliance Command Line Configuration Guide
12-6
OL-12172-04
Chapter 12
Configuring Multicast Routing
Configuring PIM Features
Note
Only the no pim command appears in the interface configuration.
Configuring a Static Rendezvous Point Address
All routers within a common PIM sparse mode or bidir domain require knowledge of the PIM RP
address. The address is statically configured using the pim rp-address command.
Note
The security appliance does not support Auto-RP or PIM BSR; you must use the pim rp-address
command to specify the RP address.
You can configure the security appliance to serve as RP to more than one group. The group range
specified in the access list determines the PIM RP group mapping. If an access list is not specified, then
the RP for the group is applied to the entire multicast group range (224.0.0.0/4).
To configure the address of the PIM PR, enter the following command:
hostname(config)# pim rp-address ip_address [acl] [bidir]
The ip_address argument is the unicast IP address of the router to be a PIM RP. The acl argument is the
name or number of a standard access list that defines which multicast groups the RP should be used with.
Do not use a host ACL with this command. Excluding the bidir keyword causes the groups to operate
in PIM sparse mode.
Note
The security appliance always advertises the bidir capability in the PIM hello messages regardless of the
actual bidir configuration.
Configuring the Designated Router Priority
The DR is responsible for sending PIM register, join, and prune messaged to the RP. When there is more
than one multicast router on a network segment, there is an election process to select the DR based on
DR priority. If multiple devices have the same DR priority, then the device with the highest IP address
becomes the DR.
By default, the security appliance has a DR priority of 1. You can change this value by entering the
following command:
hostname(config-if)# pim dr-priority num
The num argument can be any number from 1 to 4294967294.
Filtering PIM Register Messages
You can configure the security appliance to filter PIM register messages. To filter PIM register messages,
enter the following command:
hostname(config)# pim accept-register {list acl | route-map map-name}
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
12-7
Chapter 12
Configuring Multicast Routing
Configuring PIM Features
Configuring PIM Message Intervals
Router query messages are used to elect the PIM DR. The PIM DR is responsible for sending router
query messages. By default, router query messages are sent every 30 seconds. You can change this value
by entering the following command:
hostname(config-if)# pim hello-interval seconds
Valid values for the seconds argument range from 1 to 3600 seconds.
Every 60 seconds, the security appliance sends PIM join/prune messages. To change this value, enter the
following command:
hostname(config-if)# pim join-prune-interval seconds
Valid values for the seconds argument range from 10 to 600 seconds.
Configuring a Multicast Boundary
Address scoping defines domain boundaries so that domains with RPs that have the same IP address do
not leak into each other. Scoping is performed on the subnet boundaries within large domains and on the
boundaries between the domain and the Internet.
You can set up an administratively scoped boundary on an interface for multicast group addresses using
the multicast boundary command. IANA has designated the multicast address range 239.0.0.0 to
239.255.255.255 as the administratively scoped addresses. This range of addresses can be reused in
domains administered by different organizations. They would be considered local, not globally unique.
To configure a multicast boundary, enter the following command:
hostname(config-if)# multicast boundary acl [filter-autorp]
A standard ACL defines the range of addresses affected. When a boundary is set up, no multicast data
packets are allowed to flow across the boundary from either direction. The boundary allows the same
multicast group address to be reused in different administrative domains.
You can configure the filter-autorp keyword to examine and filter Auto-RP discovery and
announcement messages at the administratively scoped boundary. Any Auto-RP group range
announcements from the Auto-RP packets that are denied by the boundary access control list (ACL) are
removed. An Auto-RP group range announcement is permitted and passed by the boundary only if all
addresses in the Auto-RP group range are permitted by the boundary ACL. If any address is not
permitted, the entire group range is filtered and removed from the Auto-RP message before the Auto-RP
message is forwarded.
Filtering PIM Neighbors
You can define the routers that can become PIM neighbors with the pim neighbor-filter command. By
filtering the routers that can become PIM neighbors, you can:
•
Prevent unauthorized routers from becoming PIM neighbors.
•
Prevent attached stub routers from participating in PIM.
To define the neighbors that can become a PIM neighbor, perform the following steps:
Cisco Security Appliance Command Line Configuration Guide
12-8
OL-12172-04
Chapter 12
Configuring Multicast Routing
Configuring PIM Features
Step 1
Use the access-list command to define a standard access list defines the routers you want to participate
in PIM.
For example the following access list, when used with the pim neighbor-filter command, prevents the
10.1.1.1 router from becoming a PIM neighbor:
hostname(config)# access-list pim_nbr deny 10.1.1.1 255.255.255.255
Step 2
Use the pim neighbor-filter command on an interface to filter the neighbor routers.
For example, the following commands prevent the 10.1.1.1 router from becoming a PIM neighbor on
interface GigabitEthernet0/3:
hostname(config)# interface GigabitEthernet0/3
hostname(config-if)# pim neighbor-filter pim_nbr
Supporting Mixed Bidirectional/Sparse-Mode PIM Networks
Bidirectional PIM allows multicast routers to keep reduced state information. All of the multicast routers
in a segment must be bidirectionally enabled in order for bidir to elect a DF.
The pim bidir-neighbor-filter command enables the transition from a sparse-mode-only network to a
bidir network by letting you specify the routers that should participate in DF election while still allowing
all routers to participate in the sparse-mode domain. The bidir-enabled routers can elect a DF from
among themselves, even when there are non-bidir routers on the segment. Multicast boundaries on the
non-bidir routers prevent PIM messages and data from the bidir groups from leaking in or out of the bidir
subset cloud.
When the pim bidir-neighbor-filter command is enabled, the routers that are permitted by the ACL are
considered to be bidir-capable. Therefore:
•
If a permitted neighbor does not support bidir, the DF election does not occur.
•
If a denied neighbor supports bidir, then DF election does not occur.
•
If a denied neighbor des not support bidir, the DF election occurs.
To control which neighbors can participate in the DF election, perform the following steps:
Step 1
Use the access-list command to define a standard access list that permits the routers you want to
participate in the DF election and denies all others.
For example, the following access list permits the routers at 10.1.1.1 and 10.2.2.2 to participate in the
DF election and denies all others:
hostname(config)# access-list pim_bidir permit 10.1.1.1 255.255.255.255
hostname(config)# access-list pim_bidir permit 10.1.1.2 255.255.255.255
hostname(config)# access-list pim_bidir deny any
Step 2
Enable the pim bidir-neighbor-filter command on an interface.
The following example applies the access list created previous step to the interface GigabitEthernet0/3.
hostname(config)# interface GigabitEthernet0/3
hostname(config-if)# pim bidir-neighbor-filter pim_bidir
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
12-9
Chapter 12
Configuring Multicast Routing
For More Information about Multicast Routing
For More Information about Multicast Routing
The following RFCs from the IETF provide technical details about the IGMP and multicast routing
standards used for implementing the SMR feature:
•
RFC 2236 IGMPv2
•
RFC 2362 PIM-SM
•
RFC 2588 IP Multicast and Firewalls
•
RFC 2113 IP Router Alert Option
•
IETF draft-ietf-idmr-igmp-proxy-01.txt
Cisco Security Appliance Command Line Configuration Guide
12-10
OL-12172-04
CH A P T E R
13
Configuring IPv6
This chapter describes how to enable and configure IPv6 on the security appliance. IPv6 is available in
Routed firewall mode only.
This chapter includes the following sections:
•
IPv6-enabled Commands, page 13-1
•
Configuring IPv6, page 13-2
•
Verifying the IPv6 Configuration, page 13-11
For an sample IPv6 configuration, see Appendix A, “Sample Configurations.”
IPv6-enabled Commands
The following security appliance commands can accept and display IPv6 addresses:
•
capture
•
configure
•
copy
•
http
•
name
•
object-group
•
ping
•
show conn
•
show local-host
•
show tcpstat
•
ssh
•
telnet
•
tftp-server
•
who
•
write
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
13-1
Chapter 13
Configuring IPv6
Configuring IPv6
Note
Failover does not support IPv6. The ipv6 address command does not support setting standby addresses
for failover configurations. The failover interface ip command does not support using IPv6 addresses
on the failover and Stateful Failover interfaces.
When entering IPv6 addresses in commands that support them, simply enter the IPv6 address using
standard IPv6 notation, for example: ping fe80::2e0:b6ff:fe01:3b7a. The security appliance
correctly recognizes and processes the IPv6 address. However, you must enclose the IPv6 address in
square brackets ([ ]) in the following situations:
•
You need to specify a port number with the address, for example:
[fe80::2e0:b6ff:fe01:3b7a]:8080.
•
The command uses a colon as a separator, such as the write net and config net commands, for
example: configure net [fe80::2e0:b6ff:fe01:3b7a]:/tftp/config/pixconfig.
The following commands were modified to work for IPv6:
•
debug
•
fragment
•
ip verify
•
mtu
•
icmp (entered as ipv6 icmp)
The following inspection engines support IPv6:
•
FTP
•
HTTP
•
ICMP
•
SIP
•
SMTP
•
TCP
•
UDP
Configuring IPv6
This section contains the following topics:
•
Configuring IPv6 on an Interface, page 13-3
•
Configuring a Dual IP Stack on an Interface, page 13-4
•
Enforcing the Use of Modified EUI-64 Interface IDs in IPv6 Addresses, page 13-4
•
Configuring IPv6 Duplicate Address Detection, page 13-4
•
Configuring IPv6 Default and Static Routes, page 13-5
•
Configuring IPv6 Access Lists, page 13-6
•
Configuring IPv6 Neighbor Discovery, page 13-7
•
Configuring a Static IPv6 Neighbor, page 13-11
Cisco Security Appliance Command Line Configuration Guide
13-2
OL-12172-04
Chapter 13
Configuring IPv6
Configuring IPv6
Configuring IPv6 on an Interface
At a minimum, each interface needs to be configured with an IPv6 link-local address. Additionally, you
can add a global address to the interface.
Note
The security appliance does not support IPv6 anycast addresses.
You can configure both IPv6 and IPv4 addresses on an interface.
To configure IPv6 on an interface, perform the following steps:
Step 1
Enter interface configuration mode for the interface on which you are configuring the IPv6 addresses:
hostname(config)# interface if
Step 2
Configure an IPv6 address on the interface. You can assign several IPv6 addresses to an interface, such
as an IPv6 link-local and a global address. However, at a minimum, you must configure a link-local
address.
There are several methods for configuring IPv6 addresses. Pick the method that suits your needs from
the following:
•
The simplest method is to enable stateless autoconfiguration on the interface. Enabling stateless
autoconfiguration on the interface configures IPv6 addresses based on prefixes received in Router
Advertisement messages. A link-local address, based on the Modified EUI-64 interface ID, is
automatically generated for the interface when stateless autoconfiguration is enabled. To enable
stateless autoconfiguration, enter the following command:
hostname(config-if)# ipv6 address autoconfig
•
If you only need to configure a link-local address on the interface and are not going to assign any
other IPv6 addresses to the interface, you have the option of manually defining the link-local address
or generating one based on the interface MAC address (Modified EUI-64 format):
– Enter the following command to manually specify the link-local address:
hostname(config-if)# ipv6 address ipv6-address link-local
– Enter the following command to enable IPv6 on the interface and automatically generate the
link-local address using the Modified EUI-64 interface ID based on the interface MAC address:
hostname(config-if)# ipv6 enable
Note
•
You do not need to use the ipv6 enable command if you enter any other ipv6 address
commands on an interface; IPv6 support is automatically enabled as soon as you assign an
IPv6 address to the interface.
Assign a global address to the interface. When you assign a global address, a link-local address is
automatically created. Enter the following command to add a global to the interface. Use the
optional eui-64 keyword to use the Modified EUI-64 interface ID in the low order 64 bits of the
address.
hostname(config-if)# ipv6 address ipv6-prefix/prefix-length [eui-64]
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
13-3
Chapter 13
Configuring IPv6
Configuring IPv6
Step 3
(Optional) Suppress Router Advertisement messages on an interface. By default, Router Advertisement
messages are automatically sent in response to router solicitation messages. You may want to disable
these messages on any interface for which you do not want the security appliance to supply the IPv6
prefix (for example, the outside interface).
Enter the following command to suppress Router Advertisement messages on an interface:
hostname(config-if)# ipv6 nd suppress-ra
Configuring a Dual IP Stack on an Interface
The security appliance supports the configuration of both IPv6 and IPv4 on an interface. You do not need
to enter any special commands to do so; simply enter the IPv4 configuration commands and IPv6
configuration commands as you normally would. Make sure you configure a default route for both IPv4
and IPv6.
Enforcing the Use of Modified EUI-64 Interface IDs in IPv6 Addresses
RFC 3513: Internet Protocol Version 6 (IPv6) Addressing Architecture requires that the interface
identifier portion of all unicast IPv6 addresses, except those that start with binary value 000, be 64 bits
long and be constructed in Modified EUI-64 format. The security appliance can enforce this requirement
for hosts attached to the local link.
To enforce the use of Modified EUI-64 format interface identifiers in IPv6 addresses on a local link,
enter the following command:
hostname(config)# ipv6 enforce-eui64 if_name
The if_name argument is the name of the interface, as specified by the nameif command, on which you
are enabling the address format enforcement.
When this command is enabled on an interface, the source addresses of IPv6 packets received on that
interface are verified against the source MAC addresses to ensure that the interface identifiers use the
Modified EUI-64 format. If the IPv6 packets do not use the Modified EUI-64 format for the interface
identifier, the packets are dropped and the following system log message is generated:
%PIX|ASA-3-325003: EUI-64 source address check failed.
The address format verification is only performed when a flow is created. Packets from an existing flow
are not checked. Additionally, the address verification can only be performed for hosts on the local link.
Packets received from hosts behind a router will fail the address format verification, and be dropped,
because their source MAC address will be the router MAC address and not the host MAC address.
Configuring IPv6 Duplicate Address Detection
During the stateless autoconfiguration process, duplicate address detection verifies the uniqueness of
new unicast IPv6 addresses before the addresses are assigned to interfaces (the new addresses remain in
a tentative state while duplicate address detection is performed). Duplicate address detection is
performed first on the new link-local address. When the link local address is verified as unique, then
duplicate address detection is performed all the other IPv6 unicast addresses on the interface.
Cisco Security Appliance Command Line Configuration Guide
13-4
OL-12172-04
Chapter 13
Configuring IPv6
Configuring IPv6
Duplicate address detection is suspended on interfaces that are administratively down. While an
interface is administratively down, the unicast IPv6 addresses assigned to the interface are set to a
pending state. An interface returning to an administratively up state restarts duplicate address detection
for all of the unicast IPv6 addresses on the interface.
When a duplicate address is identified, the state of the address is set to DUPLICATE, the address is not
used, and the following error message is generated:
%PIX|ASA-4-325002: Duplicate address ipv6_address/MAC_address on interface
If the duplicate address is the link-local address of the interface, the processing of IPv6 packets is
disabled on the interface. If the duplicate address is a global address, the address is not used. However,
all configuration commands associated with the duplicate address remain as configured while the state
of the address is set to DUPLICATE.
If the link-local address for an interface changes, duplicate address detection is performed on the new
link-local address and all of the other IPv6 address associated with the interface are regenerated
(duplicate address detection is performed only on the new link-local address).
The security appliance uses neighbor solicitation messages to perform duplicate address detection. By
default, the number of times an interface performs duplicate address detection is 1.
To change the number of duplicate address detection attempts, enter the following command:
hostname(config-if)# ipv6 nd dad attempts value
The value argument can be any value from 0 to 600. Setting the value argument to 0 disables duplicate
address detection on the interface.
When you configure an interface to send out more than one duplicate address detection attempt, you can
also use the ipv6 nd ns-interval command to configure the interval at which the neighbor solicitation
messages are sent out. By default, they are sent out once every 1000 milliseconds.
To change the neighbor solicitation message interval, enter the following command:
hostname(config-if)# ipv6 nd ns-interval value
The value argument can be from 1000 to 3600000 milliseconds.
Note
Changing this value changes it for all neighbor solicitation messages sent out on the interface, not just
those used for duplicate address detection.
Configuring IPv6 Default and Static Routes
The security appliance automatically routes IPv6 traffic between directly connected hosts if the
interfaces to which the hosts are attached are enabled for IPv6 and the IPv6 ACLs allow the traffic.
The security appliance does not support dynamic routing protocols. Therefore, to route IPv6 traffic to a
non-connected host or network, you need to define a static route to the host or network or, at a minimum,
a default route. Without a static or default route defined, traffic to non-connected hosts or networks
generate the following error message:
%PIX|ASA-6-110001: No route to dest_address from source_address
You can add a default route and static routes using the ipv6 route command.
To configure an IPv6 default route and static routes, perform the following steps:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
13-5
Chapter 13
Configuring IPv6
Configuring IPv6
Step 1
To add the default route, use the following command:
hostname(config)# ipv6 route if_name ::/0 next_hop_ipv6_addr
The address ::/0 is the IPv6 equivalent of “any.”
Step 2
(Optional) Define IPv6 static routes. Use the following command to add an IPv6 static route to the IPv6
routing table:
hostname(config)# ipv6 route if_name destination next_hop_ipv6_addr [admin_distance]
Note
The ipv6 route command works like the route command used to define IPv4 static routes.
Configuring IPv6 Access Lists
Configuring an IPv6 access list is similar configuring an IPv4 access, but with IPv6 addresses.
To configure an IPv6 access list, perform the following steps:
Step 1
Create an access entry. To create an access list, use the ipv6 access-list command to create entries for
the access list. There are two main forms of this command to choose from, one for creating access list
entries specifically for ICMP traffic, and one to create access list entries for all other types of IP traffic.
•
To create an IPv6 access list entry specifically for ICMP traffic, enter the following command:
hostname(config)# ipv6 access-list id [line num] {permit | deny} icmp source
destination [icmp_type]
•
To create an IPv6 access list entry, enter the following command:
hostname(config)# ipv6 access-list id [line num] {permit | deny} protocol source
[src_port] destination [dst_port]
The following describes the arguments for the ipv6 access-list command:
•
id—The name of the access list. Use the same id in each command when you are entering multiple
entries for an access list.
•
line num—When adding an entry to an access list, you can specify the line number in the list where
the entry should appear.
•
permit | deny—Determines whether the specified traffic is blocked or allowed to pass.
•
icmp—Indicates that the access list entry applies to ICMP traffic.
•
protocol—Specifies the traffic being controlled by the access list entry. This can be the name (ip,
tcp, or udp) or number (1-254) of an IP protocol. Alternatively, you can specify a protocol object
group using object-group grp_id.
•
source and destination—Specifies the source or destination of the traffic. The source or destination
can be an IPv6 prefix, in the format prefix/length, to indicate a range of addresses, the keyword any,
to specify any address, or a specific host designated by host host_ipv6_addr.
Cisco Security Appliance Command Line Configuration Guide
13-6
OL-12172-04
Chapter 13
Configuring IPv6
Configuring IPv6
Step 2
•
src_port and dst_port—The source and destination port (or service) argument. Enter an operator (lt
for less than, gt for greater than, eq for equal to, neq for not equal to, or range for an inclusive
range) followed by a space and a port number (or two port numbers separated by a space for the
range keyword).
•
icmp_type—Specifies the ICMP message type being filtered by the access rule. The value can be a
valid ICMP type number (from 0 to 155) or one of the ICMP type literals as shown in Appendix C,
“Addresses, Protocols, and Ports”. Alternatively, you can specify an ICMP object group using
object-group id.
To apply the access list to an interface, enter the following command:
hostname(config)# access-group access_list_name {in | out} interface if_name
Configuring IPv6 Neighbor Discovery
The IPv6 neighbor discovery process uses ICMPv6 messages and solicited-node multicast addresses to
determine the link-layer address of a neighbor on the same network (local link), verify the reachability
of a neighbor, and keep track of neighboring routers.
This section contains the following topics:
•
Configuring Neighbor Solicitation Messages, page 13-7
•
Configuring Router Advertisement Messages, page 13-9
Configuring Neighbor Solicitation Messages
Neighbor solicitation messages (ICMPv6 Type 135) are sent on the local link by nodes attempting to
discover the link-layer addresses of other nodes on the local link. The neighbor solicitation message is
sent to the solicited-node multicast address.The source address in the neighbor solicitation message is
the IPv6 address of the node sending the neighbor solicitation message. The neighbor solicitation
message also includes the link-layer address of the source node.
After receiving a neighbor solicitation message, the destination node replies by sending a neighbor
advertisement message (ICPMv6 Type 136) on the local link. The source address in the neighbor
advertisement message is the IPv6 address of the node sending the neighbor advertisement message; the
destination address is the IPv6 address of the node that sent the neighbor solicitation message. The data
portion of the neighbor advertisement message includes the link-layer address of the node sending the
neighbor advertisement message.
After the source node receives the neighbor advertisement, the source node and destination node can
communicate. Figure 13-1 shows the neighbor solicitation and response process.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
13-7
Chapter 13
Configuring IPv6
Configuring IPv6
Figure 13-1
IPv6 Neighbor Discovery—Neighbor Solicitation Message
ICMPv6 Type = 135
Src = A
Dst = solicited-node multicast of B
Data = link-layer address of A
Query = what is your link address?
A and B can now exchange
packets on this link
132958
ICMPv6 Type = 136
Src = B
Dst = A
Data = link-layer address of B
Neighbor solicitation messages are also used to verify the reachability of a neighbor after the link-layer
address of a neighbor is identified. When a node wants to verifying the reachability of a neighbor, the
destination address in a neighbor solicitation message is the unicast address of the neighbor.
Neighbor advertisement messages are also sent when there is a change in the link-layer address of a node
on a local link. When there is such a change, the destination address for the neighbor advertisement is
the all-nodes multicast address.
You can configure the neighbor solicitation message interval and neighbor reachable time on a
per-interface basis. See the following topics for more information:
•
Configuring the Neighbor Solicitation Message Interval, page 13-8
•
Configuring the Neighbor Reachable Time, page 13-8
Configuring the Neighbor Solicitation Message Interval
To configure the interval between IPv6 neighbor solicitation retransmissions on an interface, enter the
following command:
hostname(config-if)# ipv6 nd ns-interval value
Valid values for the value argument range from 1000 to 3600000 milliseconds. The default value is 1000
milliseconds.
This setting is also sent in router advertisement messages.
Configuring the Neighbor Reachable Time
The neighbor reachable time enables detecting unavailable neighbors. Shorter configured times enable
detecting unavailable neighbors more quickly; however, shorter times consume more IPv6 network
bandwidth and processing resources in all IPv6 network devices. Very short configured times are not
recommended in normal IPv6 operation.
To configure the amount of time that a remote IPv6 node is considered reachable after a reachability
confirmation event has occurred, enter the following command:
hostname(config-if)# ipv6 nd reachable-time value
Cisco Security Appliance Command Line Configuration Guide
13-8
OL-12172-04
Chapter 13
Configuring IPv6
Configuring IPv6
Valid values for the value argument range from 0 to 3600000 milliseconds. The default is 0.
This information is also sent in router advertisement messages.
When 0 is used for the value, the reachable time is sent as undetermined. It is up to the receiving devices
to set and track the reachable time value. To see the time used by the security appliance when this value
is set to 0, use the show ipv6 interface command to display information about the IPv6 interface,
including the ND reachable time being used.
Configuring Router Advertisement Messages
Router advertisement messages (ICMPv6 Type 134) are periodically sent out each IPv6 configured
interface of the security appliance. The router advertisement messages are sent to the all-nodes multicast
address.
IPv6 Neighbor Discovery—Router Advertisement Message
Router
advertisement
Router
advertisement
Router advertisement packet definitions:
ICMPv6 Type = 134
Src = router link-local address
Dst = all-nodes multicast address
Data = options, prefix, lifetime, autoconfig flag
132917
Figure 13-2
Router advertisement messages typically include the following information:
•
One or more IPv6 prefix that nodes on the local link can use to automatically configure their IPv6
addresses.
•
Lifetime information for each prefix included in the advertisement.
•
Sets of flags that indicate the type of autoconfiguration (stateless or stateful) that can be completed.
•
Default router information (whether the router sending the advertisement should be used as a default
router and, if so, the amount of time (in seconds) the router should be used as a default router).
•
Additional information for hosts, such as the hop limit and MTU a host should use in packets that it
originates.
•
The amount of time between neighbor solicitation message retransmissions on a given link.
•
The amount of time a node considers a neighbor reachable.
Router advertisements are also sent in response to router solicitation messages (ICMPv6 Type 133).
Router solicitation messages are sent by hosts at system startup so that the host can immediately
autoconfigure without needing to wait for the next scheduled router advertisement message. Because
router solicitation messages are usually sent by hosts at system startup, and the host does not have a
configured unicast address, the source address in router solicitation messages is usually the unspecified
IPv6 address (0:0:0:0:0:0:0:0). If the host has a configured unicast address, the unicast address of the
interface sending the router solicitation message is used as the source address in the message. The
destination address in router solicitation messages is the all-routers multicast address with a scope of the
link. When a router advertisement is sent in response to a router solicitation, the destination address in
the router advertisement message is the unicast address of the source of the router solicitation message.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
13-9
Chapter 13
Configuring IPv6
Configuring IPv6
You can configure the following settings for router advertisement messages:
•
The time interval between periodic router advertisement messages.
•
The router lifetime value, which indicates the amount of time IPv6 nodes should consider the
security appliance to be the default router.
•
The IPv6 network prefixes in use on the link.
•
Whether or not an interface transmits router advertisement messages.
Unless otherwise noted, the router advertisement message settings are specific to an interface and are
entered in interface configuration mode. See the following topics for information about changing these
settings:
•
Configuring the Router Advertisement Transmission Interval, page 13-10
•
Configuring the Router Lifetime Value, page 13-10
•
Configuring the IPv6 Prefix, page 13-10
•
Suppressing Router Advertisement Messages, page 13-11
Configuring the Router Advertisement Transmission Interval
By default, router advertisements are sent out every 200 seconds. To change the interval between router
advertisement transmissions on an interface, enter the following command:
ipv6 nd ra-interval [msec] value
Valid values range from 3 to 1800 seconds (or 500 to 1800000 milliseconds if the msec keyword is used).
The interval between transmissions should be less than or equal to the IPv6 router advertisement lifetime
if the security appliance is configured as a default router by using the ipv6 nd ra-lifetime command. To
prevent synchronization with other IPv6 nodes, randomly adjust the actual value used to within 20
percent of the desired value.
Configuring the Router Lifetime Value
The router lifetime value specifies how long nodes on the local link should consider the security
appliance the default router on the link.
To configure the router lifetime value in IPv6 router advertisements on an interface, enter the following
command:
hostname(config-if)# ipv6 nd ra-lifetime seconds
Valid values range from 0 to 9000 seconds. The default is 1800 seconds. Entering 0 indicates that the
security appliance should not be considered a default router on the selected interface.
Configuring the IPv6 Prefix
Stateless autoconfiguration uses IPv6 prefixes provided in router advertisement messages to create the
global unicast address from the link-local address.
To configure which IPv6 prefixes are included in IPv6 router advertisements, enter the following
command:
hostname(config-if)# ipv6 nd prefix ipv6-prefix/prefix-length
Note
For stateless autoconfiguration to work properly, the advertised prefix length in router advertisement
messages must always be 64 bits.
Cisco Security Appliance Command Line Configuration Guide
13-10
OL-12172-04
Chapter 13
Configuring IPv6
Verifying the IPv6 Configuration
Suppressing Router Advertisement Messages
By default, Router Advertisement messages are automatically sent in response to router solicitation
messages. You may want to disable these messages on any interface for which you do not want the
security appliance to supply the IPv6 prefix (for example, the outside interface).
To suppress IPv6 router advertisement transmissions on an interface, enter the following command:
hostname(config-if)# ipv6 nd suppress-ra
Entering this command causes the security appliance to appear as a regular IPv6 neighbor on the link
and not as an IPv6 router.
Configuring a Static IPv6 Neighbor
You can manually define a neighbor in the IPv6 neighbor cache. If an entry for the specified IPv6 address
already exists in the neighbor discovery cache—learned through the IPv6 neighbor discovery
process—the entry is automatically converted to a static entry. Static entries in the IPv6 neighbor
discovery cache are not modified by the neighbor discovery process.
To configure a static entry in the IPv6 neighbor discovery cache, enter the following command:
hostname(config-if)# ipv6 neighbor ipv6_address if_name mac_address
The ipv6_address argument is the link-local IPv6 address of the neighbor, the if_name argument is the
interface through which the neighbor is available, and the mac_address argument is the MAC address of
the neighbor interface.
Note
The clear ipv6 neighbors command does not remove static entries from the IPv6 neighbor discovery
cache; it only clears the dynamic entries.
Verifying the IPv6 Configuration
This section describes how to verify your IPv6 configuration. You can use various show commands to
verify your IPv6 settings.
This section includes the following topics:
•
The show ipv6 interface Command, page 13-11
•
The show ipv6 route Command, page 13-12
The show ipv6 interface Command
To display the IPv6 interface settings, enter the following command:
hostname# show ipv6 interface [if_name]
Including the interface name, such as “outside”, displays the settings for the specified interface.
Excluding the name from the command displays the setting for all interfaces that have IPv6 enabled on
them. The output for the command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
13-11
Chapter 13
Configuring IPv6
Verifying the IPv6 Configuration
•
The multicast groups the interface belongs to.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
The following is sample output from the show ipv6 interface command:
hostname# show ipv6 interface
ipv6interface is down, line protocol is down
IPv6 is enabled, link-local address is fe80::20d:88ff:feee:6a82 [TENTATIVE]
No global unicast address is configured
Joined group address(es):
ff02::1
ff02::1:ffee:6a82
ICMP error messages limited to one every 100 milliseconds
ICMP redirects are enabled
ND DAD is enabled, number of DAD attempts: 1
ND reachable time is 30000 milliseconds
Note
The show interface command only displays the IPv4 settings for an interface. To see the IPv6
configuration on an interface, you need to use the show ipv6 interface command. The show ipv6
interface command does not display any IPv4 settings for the interface (if both types of addresses are
configured on the interface).
The show ipv6 route Command
To display the routes in the IPv6 routing table, enter the following command:
hostname# show ipv6 route
The output from the show ipv6 route command is similar to the IPv4 show route command. It displays
the following information:
•
The protocol that derived the route.
•
The IPv6 prefix of the remote network.
•
The administrative distance and metric for the route.
•
The address of the next-hop router.
•
The interface through which the next hop router to the specified network is reached.
The following is sample output from the show ipv6 route command:
hostname# show ipv6 route
IPv6 Routing Table - 7 entries
Codes: C - Connected, L - Local, S - Static
L
fe80::/10 [0/0]
via ::, inside
L
fec0::a:0:0:a0a:a70/128 [0/0]
via ::, inside
C
fec0:0:0:a::/64 [0/0]
via ::, inside
L
ff00::/8 [0/0]
via ::, inside
Cisco Security Appliance Command Line Configuration Guide
13-12
OL-12172-04
CH A P T E R
14
Configuring AAA Servers and the Local Database
This chapter describes support for AAA (pronounced “triple A”) and how to configure AAA servers and
the local database.
This chapter contains the following sections:
•
AAA Overview, page 14-1
•
AAA Server and Local Database Support, page 14-3
•
Configuring the Local Database, page 14-7
•
Identifying AAA Server Groups and Servers, page 14-9
•
Configuring an LDAP Server, page 14-12
•
Using Certificates and User Login Credentials, page 14-16
•
Supporting a Zone Labs Integrity Server, page 14-17
AAA Overview
AAA enables the security appliance to determine who the user is (authentication), what the user can do
(authorization), and what the user did (accounting).
AAA provides an extra level of protection and control for user access than using access lists alone. For
example, you can create an access list allowing all outside users to access Telnet on a server on the DMZ
network. If you want only some users to access the server and you might not always know IP addresses
of these users, you can enable AAA to allow only authenticated and/or authorized users to make it
through the security appliance. (The Telnet server enforces authentication, too; the security appliance
prevents unauthorized users from attempting to access the server.)
You can use authentication alone or with authorization and accounting. Authorization always requires a
user to be authenticated first. You can use accounting alone, or with authentication and authorization.
This section includes the following topics:
•
About Authentication, page 14-2
•
About Authorization, page 14-2
•
About Accounting, page 14-2
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-1
Chapter 14
Configuring AAA Servers and the Local Database
AAA Overview
About Authentication
Authentication controls access by requiring valid user credentials, which are typically a username and
password. You can configure the security appliance to authenticate the following items:
•
All administrative connections to the security appliance including the following sessions:
– Telnet
– SSH
– Serial console
– ASDM (using HTTPS)
– VPN management access
•
The enable command
•
Network access
•
VPN access
About Authorization
Authorization controls access per user after users authenticate. You can configure the security appliance
to authorize the following items:
•
Management commands
•
Network access
•
VPN access
Authorization controls the services and commands available to each authenticated user. Were you not to
enable authorization, authentication alone would provide the same access to services for all
authenticated users.
If you need the control that authorization provides, you can configure a broad authentication rule, and
then have a detailed authorization configuration. For example, you authenticate inside users who attempt
to access any server on the outside network and then limit the outside servers that a particular user can
access using authorization.
The security appliance caches the first 16 authorization requests per user, so if the user accesses the same
services during the current authentication session, the security appliance does not resend the request to
the authorization server.
About Accounting
Accounting tracks traffic that passes through the security appliance, enabling you to have a record of
user activity. If you enable authentication for that traffic, you can account for traffic per user. If you do
not authenticate the traffic, you can account for traffic per IP address. Accounting information includes
when sessions start and stop, username, the number of bytes that pass through the security appliance for
the session, the service used, and the duration of each session.
Cisco Security Appliance Command Line Configuration Guide
14-2
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
AAA Server and Local Database Support
AAA Server and Local Database Support
The security appliance supports a variety of AAA server types and a local database that is stored on the
security appliance. This section describes support for each AAA server type and the local database.
This section contains the following topics:
•
Summary of Support, page 14-3
•
RADIUS Server Support, page 14-4
•
TACACS+ Server Support, page 14-5
•
RSA/SDI Server Support, page 14-5
•
NT Server Support, page 14-6
•
Kerberos Server Support, page 14-6
•
LDAP Server Support, page 14-6
•
SSO Support for Clientless SSL VPN with HTTP Forms, page 14-6
•
Local Database Support, page 14-6
Summary of Support
Table 14-1 summarizes the support for each AAA service by each AAA server type, including the local
database. For more information about support for a specific AAA server type, refer to the topics
following the table.
Table 14-1
Summary of AAA Support
Database Type
Local
RADIUS
TACACS+
SDI
NT
Kerberos
LDAP
HTTP
Form
VPN users1
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes2
Firewall sessions
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Administrators
Yes
Yes
Yes
Yes3
Yes
Yes
Yes
No
Yes
Yes
No
No
No
No
Yes
No
Yes
No
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
AAA Service
Authentication of...
Authorization of...
VPN users
Firewall sessions
Administrators
No
Yes
Yes
5
4
Accounting of...
VPN connections
No
Yes
Firewall sessions
No
Yes
Administrators
No
Yes
6
1. For SSL VPN connections, either PAP or MS-CHAPv2 can be used.
2. HTTP Form protocol supports single sign-on authentication for Clientless SSL VPN users only.
3. SDI is not supported for HTTP administrative access.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-3
Chapter 14
Configuring AAA Servers and the Local Database
AAA Server and Local Database Support
4. For firewall sessions, RADIUS authorization is supported with user-specific access lists only, which are received or
specified in a RADIUS authentication response.
5. Local command authorization is supported by privilege level only.
6. Command accounting is available for TACACS+ only.
RADIUS Server Support
The ASA supports the following RADIUS servers for AAA, in addition to the one available on the ASA
itself:
•
Cisco Secure ACS 3.2, 4.0, 4.1
•
RSA Radius in RSA Authentication Manager 5.2 & 6.1
Authentication Methods
The security appliance supports the following authentication methods with RADIUS:
Note
•
PAP—For all connection types.
•
CHAP—For L2TP-over-IPSec.
•
MS-CHAPv1—For L2TP-over-IPSec.
•
MS-CHAPv2—For L2TP-over-IPSec, and for regular IPSec remote access connections when the
password-management feature is enabled. You can also use MS-CHAPv2 with Clientless
connections.
•
Authentication Proxy modes—Including RADIUS to Active Directory, RADIUS to RSA/SDI,
RADIUS to Token-server, and RSA/SI to RADIUS,
To enable MSChapV2 as the protocol used between the security appliance and the RADIUS server for a
clientless connection, password management must be enabled in the tunnel-group general-attributes.
Enabling password management prevents usernames and passwords from being transmitted in clear text
between the security appliance and the RADIUS server. See the description of the
password-management command for details.
Attribute Support
The security appliance supports the following sets of RADIUS attributes:
•
Authentication attributes defined in RFC 2138.
•
Accounting attributes defined in RFC 2139.
•
RADIUS attributes for tunneled protocol support, defined in RFC 2868.
•
Cisco IOS VSAs, identified by RADIUS vendor ID 9.
•
Cisco VPN-related VSAs, identified by RADIUS vendor ID 3076.
•
Microsoft VSAs, defined in RFC 2548.
Cisco Security Appliance Command Line Configuration Guide
14-4
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
AAA Server and Local Database Support
RADIUS Authorization Functions
The security appliance can use RADIUS servers for user authorization for network access using dynamic
access lists or access list names per user. To implement dynamic access lists, you must configure the
RADIUS server to support it. When the user authenticates, the RADIUS server sends a downloadable
access list or access list name to the security appliance. Access to a given service is either permitted or
denied by the access list. The security appliance deletes the access list when the authentication session
expires.
TACACS+ Server Support
The security appliance supports TACACS+ authentication with ASCII, PAP, CHAP, and MS-CHAPv1.
RSA/SDI Server Support
The RSA SecureID servers are also known as SDI servers.
This section contains the following topics:
•
RSA/SDI Version Support, page 14-5
•
Two-step Authentication Process, page 14-5
•
SDI Primary and Replica Servers, page 14-5
RSA/SDI Version Support
The security appliance supports SDI Version 5.0 and 6.0. SDI uses the concepts of an SDI primary and
SDI replica servers. Each primary and its replicas share a single node secret file. The node secret file has
its name based on the hexadecimal value of the ACE/Server IP address with .sdi appended.
A version 5.0 or 6.0 SDI server that you configure on the security appliance can be either the primary or
any one of the replicas. See the “SDI Primary and Replica Servers” section on page 14-5 for information
about how the SDI agent selects servers to authenticate users.
Two-step Authentication Process
SDI version 5.0 and 6.0 uses a two-step process to prevent an intruder from capturing information from
an RSA SecurID authentication request and using it to authenticate to another server. The Agent first
sends a lock request to the SecurID server before sending the user authentication request. The server
locks the username, preventing another (replica) server from accepting it. This means that the same user
cannot authenticate to two security appliances using the same authentication servers simultaneously.
After a successful username lock, the security appliance sends the passcode.
SDI Primary and Replica Servers
The security appliance obtains the server list when the first user authenticates to the configured server,
which can be either a primary or a replica. The security appliance then assigns priorities to each of the
servers on the list, and subsequent server selection derives at random from those assigned priorities. The
highest priority servers have a higher likelihood of being selected.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-5
Chapter 14
Configuring AAA Servers and the Local Database
AAA Server and Local Database Support
NT Server Support
The security appliance supports Microsoft Windows server operating systems that support NTLM
version 1, collectively referred to as NT servers.
Note
NT servers have a maximum length of 14 characters for user passwords. Longer passwords are truncated.
This is a limitation of NTLM version 1.
Kerberos Server Support
The security appliance supports 3DES, DES, and RC4 encryption types.
Note
The security appliance does not support changing user passwords during tunnel negotiation. To avoid
this situation happening inadvertently, disable password expiration on the Kerberos/Active Directory
server for users connecting to the security appliance.
For a simple Kerberos server configuration example, see Example 14-2 on page 14-12.
LDAP Server Support
The security appliance supports LDAP. For detailed information, see the “Configuring an LDAP Server”
section on page 14-12.
SSO Support for Clientless SSL VPN with HTTP Forms
The security appliance can use the HTTP Form protocol for single sign-on (SSO) authentication of
Clientless SSL VPN users only. Single sign-on support lets Clientless SSL VPN users enter a username
and password only once to access multiple protected services and Web servers. The Clientless SSL VPN
server running on the security appliance acts as a proxy for the user to the authenticating server. When
a user logs in, the Clientless SSL VPN server sends an SSO authentication request, including username
and password, to the authenticating server using HTTPS. If the server approves the authentication
request, it returns an SSO authentication cookie to the Clientless SSL VPN server. The security
appliance keeps this cookie on behalf of the user and uses it to authenticate the user to secure websites
within the domain protected by the SSO server.
In addition to the HTTP Form protocol, Clientless SSL VPN administrators can choose to configure SSO
with the HTTP Basic and NTLM authentication protocols (the auto-signon command), or with
Computer Associates eTrust SiteMinder SSO server (formerly Netegrity SiteMinder) as well. For an
in-depth discussion of configuring SSO with either HTTP Forms, auto-signon or SiteMinder, see the
Configuring Clientless SSL VPN chapter.
Local Database Support
The security appliance maintains a local database that you can populate with user profiles.
This section contains the following topics:
Cisco Security Appliance Command Line Configuration Guide
14-6
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
Configuring the Local Database
•
User Profiles, page 14-7
•
Fallback Support, page 14-7
User Profiles
User profiles contain, at a minimum, a username. Typically, a password is assigned to each username,
although passwords are optional.
The username attributes command lets you enter the username mode. In this mode, you can add other
information to a specific user profile. The information you can add includes VPN-related attributes, such
as a VPN session timeout value.
Fallback Support
The local database can act as a fallback method for several functions. This behavior is designed to help
you prevent accidental lockout from the security appliance.
For users who need fallback support, we recommend that their usernames and passwords in the local
database match their usernames and passwords in the AAA servers. This provides transparent fallback
support. Because the user cannot determine whether a AAA server or the local database is providing the
service, using usernames and passwords on AAA servers that are different than the usernames and
passwords in the local database means that the user cannot be certain which username and password
should be given.
The local database supports the following fallback functions:
•
Console and enable password authentication—When you use the aaa authentication console
command, you can add the LOCAL keyword after the AAA server group tag. If the servers in the
group all are unavailable, the security appliance uses the local database to authenticate
administrative access. This can include enable password authentication, too.
•
Command authorization—When you use the aaa authorization command command, you can
add the LOCAL keyword after the AAA server group tag. If the TACACS+ servers in the group all
are unavailable, the local database is used to authorize commands based on privilege levels.
•
VPN authentication and authorization—VPN authentication and authorization are supported to
enable remote access to the security appliance if AAA servers that normally support these VPN
services are unavailable. The authentication-server-group command, available in tunnel-group
general attributes mode, lets you specify the LOCAL keyword when you are configuring attributes
of a tunnel group. When VPN client of an administrator specifies a tunnel group configured to
fallback to the local database, the VPN tunnel can be established even if the AAA server group is
unavailable, provided that the local database is configured with the necessary attributes.
Configuring the Local Database
This section describes how to manage users in the local database. You can use the local database for
CLI access authentication, privileged mode authentication, command authorization, network access
authentication, and VPN authentication and authorization. You cannot use the local database for network
access authorization. The local database does not support accounting.
For multiple context mode, you can configure usernames in the system execution space to provide
individual logins using the login command; however, you cannot configure any aaa commands in the
system execution space.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-7
Chapter 14
Configuring AAA Servers and the Local Database
Configuring the Local Database
To define a user account in the local database, perform the following steps:
Step 1
To create the user account, enter the following command:
hostname(config)# username name {nopassword | password password [mschap]} [privilege
priv_level]
where the username keyword is a string from 4 to 64 characters long.
The password password argument is a string from 3 to 16 characters long.
The mschap keyword specifies that the password is e converted to unicode and hashed using MD4 after
you enter it. Use this keyword if users are authenticated using MSCHAPv1 or MSCHAPv2.
The privilege level argument sets the privilege level from 0 to 15. The default is 2. This privilege level
is used with command authorization.
Caution
If you do not use command authorization (the aaa authorization command LOCAL command), then
the default level 2 allows management access to privileged EXEC mode. If you want to limit access to
privileged EXEC mode, either set the privilege level to 0 or 1, or use the service-type command (see
Step 4).
The nopassword keyword creates a user account with no password.
Note
The encrypted and nt-encrypted keywords are typically for display only. When you define a password
in the username command, the security appliance encrypts it when it saves it to the configuration for
security purposes. When you enter the show running-config command, the username command does
not show the actual password; it shows the encrypted password followed by the encrypted or
nt-encrypted keyword (when you specify mschap). For example, if you enter the password “test,” the
show running-config display would appear to be something like the following:
username pat password DLaUiAX3l78qgoB5c7iVNw== nt-encrypted
The only time you would actually enter the encrypted or nt-encrypted keyword at the CLI is if you are
cutting and pasting a configuration to another security appliance and you are using the same password.
Step 2
(Optional) To enforce user-specific access levels for users who authenticate for management access (see
the aaa authentication console LOCAL command), enter the following command:
hostname(config)# aaa authorization exec authentication-server
This command enables management authorization for local users and for any users authenticated by
RADIUS, LDAP, and TACACS+. See the “Limiting User CLI and ASDM Access with Management
Authorization” section on page 42-7 for information about configuring a user on a AAA server to
accommodate management authorization.
For a local user, configure the level of access using the service-type command as described in Step 4.
Step 3
(Optional) To configure username attributes, enter the following command:
hostname(config)# username username attributes
where the username argument is the username you created in Step 1.
Step 4
(Optional) If you configured management authorization in Step 2, enter the following command to
configure the user level:
Cisco Security Appliance Command Line Configuration Guide
14-8
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
Identifying AAA Server Groups and Servers
hostname(config-username)# service-type {admin | nas-prompt | remote-access}
where the admin keyword allows full access to any services specified by the aaa authentication console
LOCAL commands. admin is the default.
The nas-prompt keyword allows access to the CLI when you configure the aaa authentication {telnet
| ssh | serial} console LOCAL command, but denies ASDM configuration access if you configure the
aaa authentication http console LOCAL command. ASDM monitoring access is allowed. If you
configure enable authentication with the aaa authentication enable console LOCAL command, the
user cannot access privileged EXEC mode using the enable command (or by using the login command).
The remote-access keyword denies management access. The user cannot use any services specified by
the aaa authentication console LOCAL commands (excluding the serial keyword; serial access is
allowed).
Step 5
(Optional) If you are using this username for VPN authentication, you can configure many VPN
attributes for the user. See the “Configuring User Attributes” section on page 32-75.
For example, the following command assigns a privilege level of 15 to the admin user account:
hostname(config)# username admin password passw0rd privilege 15
The following command creates a user account with no password:
hostname(config)# username bcham34 nopassword
The following commands enable management authorization, creates a user account with a password,
enters username attributes configuration mode, and specifies the service-type attribute:
hostname(config)# aaa authorization exec authentication-server
hostname(config)# username rwilliams password gOgeOus
hostname(config)# username rwilliams attributes
hostname(config-username)# service-type nas-prompt
Identifying AAA Server Groups and Servers
If you want to use an external AAA server for authentication, authorization, or accounting, you must first
create at least one AAA server group per AAA protocol and add one or more servers to each group. You
identify AAA server groups by name. Each server group is specific to one type of server: Kerberos,
LDAP, NT, RADIUS, SDI, or TACACS+.
The security appliance contacts the first server in the group. If that server is unavailable, the security
appliance contacts the next server in the group, if configured. If all servers in the group are unavailable,
the security appliance tries the local database if you configured it as a fallback method (management
authentication and authorization only). If you do not have a fallback method, the security appliance
continues to try the AAA servers.
To create a server group and add AAA servers to it, follow these steps:
Step 1
For each AAA server group you need to create, follow these steps:
a.
Identify the server group name and the protocol. To do so, enter the following command:
hostname(config)# aaa-server server_group protocol {kerberos | ldap | nt | radius |
sdi | tacacs+}
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-9
Chapter 14
Configuring AAA Servers and the Local Database
Identifying AAA Server Groups and Servers
For example, to use RADIUS to authenticate network access and TACACS+ to authenticate CLI
access, you need to create at least two server groups, one for RADIUS servers and one for TACACS+
servers.
You can have up to 15 single-mode server groups or 4 multi-mode server groups. Each server group
can have up to 16 servers in single mode or up to 4 servers in multi-mode.
When you enter a aaa-server protocol command, you enter group mode.
b.
If you want to specify the maximum number of requests sent to a AAA server in the group before
trying the next server, enter the following command:
hostname(config-aaa-server-group)# max-failed-attempts number
The number can be between 1 and 5. The default is 3.
If you configured a fallback method using the local database (for management access only; see the
“Configuring AAA for System Administrators” section on page 42-5 and the “Configuring
TACACS+ Command Authorization” section on page 42-14 to configure the fallback mechanism),
and all the servers in the group fail to respond, then the group is considered to be unresponsive, and
the fallback method is tried. The server group remains marked as unresponsive for a period of 10
minutes (by default) so that additional AAA requests within that period do not attempt to contact
the server group, and the fallback method is used immediately. To change the unresponsive period
from the default, see the reactivation-mode command in the following step.
If you do not have a fallback method, the security appliance continues to retry the servers in the
group.
c.
If you want to specify the method (reactivation policy) by which failed servers in a group are
reactivated, enter the following command:
hostname(config-aaa-server-group)# # reactivation-mode {depletion [deadtime minutes] |
timed}
Where the depletion keyword reactivates failed servers only after all of the servers in the group are
inactive.
The deadtime minutes argument specifies the amount of time in minutes, between 0 and 1440, that
elapses between the disabling of the last server in the group and the subsequent re-enabling of all
servers. The default is 10 minutes.
The timed keyword reactivates failed servers after 30 seconds of down time.
d.
If you want to send accounting messages to all servers in the group (RADIUS or TACACS+ only),
enter the following command:
hostname(config-aaa-server-group)# accounting-mode simultaneous
To restore the default of sending messages only to the active server, enter the accounting-mode
single command.
Step 2
For each AAA server on your network, follow these steps:
a.
Identify the server, including the AAA server group it belongs to. To do so, enter the following
command:
hostname(config)# aaa-server server_group (interface_name) host server_ip
When you enter a aaa-server host command, you enter host mode.
b.
As needed, use host mode commands to further configure the AAA server.
Cisco Security Appliance Command Line Configuration Guide
14-10
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
Identifying AAA Server Groups and Servers
The commands in host mode do not apply to all AAA server types. Table 14-2 lists the available
commands, the server types they apply to, and whether a new AAA server definition has a default
value for that command. Where a command is applicable to the server type you specified and no
default value is provided (indicated by “—”), use the command to specify the value. For more
information about these commands, see the Cisco Security Appliance Command Reference.
Table 14-2
Host Mode Commands, Server Types, and Defaults
Command
Applicable AAA Server Types Default Value
accounting-port
RADIUS
1646
acl-netmask-convert
RADIUS
standard
authentication-port
RADIUS
1645
kerberos-realm
Kerberos
—
key
RADIUS
—
TACACS+
—
ldap-attribute-map
LDAP
—
ldap-base-dn
LDAP
—
ldap-login-dn
LDAP
—
ldap-login-password
LDAP
—
ldap-naming-attribute
LDAP
—
ldap-over-ssl
LDAP
—
ldap-scope
LDAP
—
nt-auth-domain-controller NT
—
radius-common-pw
RADIUS
—
retry-interval
Kerberos
10 seconds
RADIUS
10 seconds
SDI
10 seconds
sasl-mechanism
LDAP
—
server-port
Kerberos
88
LDAP
389
NT
139
SDI
5500
TACACS+
49
server-type
LDAP
auto-discovery
timeout
All
10 seconds
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-11
Chapter 14
Configuring AAA Servers and the Local Database
Configuring an LDAP Server
Example 14-1 shows commands that add one TACACS+ group with one primary and one backup server,
one RADIUS group with a single server, and an NT domain server.
Example 14-1 Multiple AAA Server Groups and Servers
hostname(config)# aaa-server AuthInbound protocol tacacs+
hostname(config-aaa-server-group)# max-failed-attempts 2
hostname(config-aaa-server-group)# reactivation-mode depletion deadtime 20
hostname(config-aaa-server-group)# exit
hostname(config)# aaa-server AuthInbound (inside) host 10.1.1.1
hostname(config-aaa-server-host)# key TACPlusUauthKey
hostname(config-aaa-server-host)# exit
hostname(config)# aaa-server AuthInbound (inside) host 10.1.1.2
hostname(config-aaa-server-host)# key TACPlusUauthKey2
hostname(config-aaa-server-host)# exit
hostname(config)# aaa-server AuthOutbound protocol radius
hostname(config-aaa-server-group)# exit
hostname(config)# aaa-server AuthOutbound (inside) host 10.1.1.3
hostname(config-aaa-server-host)# key RadUauthKey
hostname(config-aaa-server-host)# exit
hostname(config)# aaa-server NTAuth protocol nt
hostname(config-aaa-server-group)# exit
hostname(config)# aaa-server NTAuth (inside) host 10.1.1.4
hostname(config-aaa-server-host)# nt-auth-domain-controller primary1
hostname(config-aaa-server-host)# exit
Example 14-2 shows commands that configure a Kerberos AAA server group named watchdogs, add a
AAA server to the group, and define the Kerberos realm for the server. Because Example 14-2 does not
define a retry interval or the port that the Kerberos server listens to, the security appliance uses the
default values for these two server-specific parameters. Table 14-2 lists the default values for all AAA
server host mode commands.
Note
Kerberos realm names use numbers and upper-case letters only. Although the security appliance accepts
lower-case letters for a realm name, it does not translate lower-case letters to upper-case letters. Be sure
to use upper-case letters only.
Example 14-2 Kerberos Server Group and Server
hostname(config)# aaa-server watchdogs protocol kerberos
hostname(config-aaa-server-group)# aaa-server watchdogs host 192.168.3.4
hostname(config-aaa-server-host)# kerberos-realm EXAMPLE.COM
hostname(config-aaa-server-host)# exit
hostname(config)#
Configuring an LDAP Server
This section describes using an LDAP directory with the security appliance for user authentication and
VPN authorization. This section includes the following topics:
•
Authentication with LDAP, page 14-13
•
Authorization with LDAP for VPN, page 14-14
•
LDAP Attribute Mapping, page 14-15
For example configuration procedures used to set up LDAP authentication or authorization, see
Appendix D, “Configuring an External Server for Authorization and Authentication”.
Cisco Security Appliance Command Line Configuration Guide
14-12
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
Configuring an LDAP Server
Authentication with LDAP
During authentication, the security appliance acts as a client proxy to the LDAP server for the user, and
authenticates to the LDAP server in either plain text or using the Simple Authentication and Security
Layer (SASL) protocol. By default, the security appliance passes authentication parameters, usually a
username and password, to the LDAP server in plain text. Whether using SASL or plain text, you can
secure the communications between the security appliance and the LDAP server with SSL using the
ldap-over-ssl command.
Note
If you do not configure SASL, we strongly recommend that you secure LDAP communications with
SSL. See the ldap-over-ssl command in the Cisco Security Appliance Command Reference.
When user LDAP authentication has succeeded, the LDAP server returns the attributes for the
authenticated user. For VPN authentication, these attributes generally include authorization data which
is applied to the VPN session. Thus, using LDAP accomplishes authentication and authorization in a
single step.
Securing LDAP Authentication with SASL
The security appliance supports the following SASL mechanisms, listed in order of increasing strength:
•
Digest-MD5 — The security appliance responds to the LDAP server with an MD5 value computed
from the username and password.
•
Kerberos — The security appliance responds to the LDAP server by sending the username and realm
using the GSSAPI (Generic Security Services Application Programming Interface) Kerberos
mechanism.
You can configure the security appliance and LDAP server to support any combination of these SASL
mechanisms. If you configure multiple mechanisms, the security appliance retrieves the list of SASL
mechanisms configured on the server and sets the authentication mechanism to the strongest mechanism
configured on both the security appliance and the server. For example, if both the LDAP server and the
security appliance support both mechanisms, the security appliance selects Kerberos, the stronger of the
mechanisms.
The following example configures the security appliance for authentication to an LDAP directory server
named ldap_dir_1 using the digest-MD5 SASL mechanism, and communicating over an SSL-secured
connection:
hostname(config)# aaa-server ldap_dir_1 protocol ldap
hostname(config-aaa-server-group)# aaa-server ldap_dir_1 host 10.1.1.4
hostname(config-aaa-server-host)# sasl-mechanism digest-md5
hostname(config-aaa-server-host)# ldap-over-ssl enable
hostname(config-aaa-server-host)#
Setting the LDAP Server Type
The security appliance supports LDAP version 3 and is compatible with the Sun Microsystems JAVA
System Directory Server (formerly named the Sun ONE Directory Server), the Microsoft Active
Directory, and other LDAPv3 directory servers.
By default, the security appliance auto-detects whether it is connected to a Microsoft Active Directory,
a Sun LDAP directory server, or a generic LDAPv3 directory server. However, if auto-detection fails to
determine the LDAP server type, and you know the server is either a Microsoft, Sun or generic LDAP
server, you can manually configure the server type using the keywords sun, microsoft, or generic. The
following example sets the LDAP directory server ldap_dir_1 to the Sun Microsystems type:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-13
Chapter 14
Configuring AAA Servers and the Local Database
Configuring an LDAP Server
hostname(config)# aaa-server ldap_dir_1 protocol ldap
hostname(config-aaa-server-group)# aaa-server ldap_dir_1 host 10.1.1.4
hostname(config-aaa-server-host)# server-type sun
hostname(config-aaa-server-host)#
Note
•
Sun—The DN configured on the security appliance to access a Sun directory server must be able to
access the default password policy on that server. We recommend using the directory administrator,
or a user with directory administrator privileges, as the DN. Alternatively, you can place an ACI on
the default password policy.
•
Microsoft—You must configure LDAP over SSL to enable password management with Microsoft
Active Directory.
•
Generic—The security appliance does not support password management with a generic LDAPv3
directory server.
Authorization with LDAP for VPN
When user LDAP authentication for VPN access has succeeded, the security appliance queries the LDAP
server which returns LDAP attributes. These attributes generally include authorization data that applies
to the VPN session. Thus, using LDAP accomplishes authentication and authorization in a single step.
There may be cases, however, where you require authorization from an LDAP directory server that is
separate and distinct from the authentication mechanism. For example, if you use an SDI or certificate
server for authentication, no authorization information is passed back. For user authorizations in this
case, you can query an LDAP directory after successful authentication, accomplishing authentication
and authorization in two steps.
To set up VPN user authorization using LDAP, you must first create a AAA server group and a tunnel
group. You then associate the server and tunnel groups using the tunnel-group general-attributes
command. While there are other authorization-related commands and options available for specific
requirements, the following example shows fundamental commands for enabling user authorization with
LDAP. This example then creates an IPSec remote access tunnel group named remote-1, and assigns that
new tunnel group to the previously created ldap_dir_1 AAA server for authorization.
hostname(config)# tunnel-group remote-1 type ipsec-ra
hostname(config)# tunnel-group remote-1 general-attributes
hostname(config-general)# authorization-server-group ldap_dir_1
hostname(config-general)#
After you complete this fundamental configuration work, you can configure additional LDAP
authorization parameters such as a directory password, a starting point for searching a directory, and the
scope of a directory search:
hostname(config)# aaa-server ldap_dir_1 protocol ldap
hostname(config-aaa-server-group)# aaa-server ldap_dir_1 host 10.1.1.4
hostname(config-aaa-server-host)# ldap-login-dn obscurepassword
hostname(config-aaa-server-host)# ldap-base-dn starthere
hostname(config-aaa-server-host)# ldap-scope subtree
hostname(config-aaa-server-host)#
See LDAP commands in the Cisco Security Appliance Command Reference for more information.
Cisco Security Appliance Command Line Configuration Guide
14-14
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
Configuring an LDAP Server
LDAP Attribute Mapping
If you are introducing a security appliance to an existing LDAP directory, your existing LDAP attribute
names and values are probably different from the existing ones. You must create LDAP attribute maps
that map your existing user-defined attribute names and values to Cisco attribute names and values that
are compatible with the security appliance. You can then bind these attribute maps to LDAP servers or
remove them as needed. You can also show or clear attribute maps.
Note
To use the attribute mapping features correctly, you need to understand the Cisco LDAP attribute names
and values as well as the user-defined attribute names and values.
The following command, entered in global configuration mode, creates an unpopulated LDAP attribute
map table named att_map_1:
hostname(config)# ldap attribute-map att_map_1
hostname(config-ldap-attribute-map)#
The following commands map the user-defined attribute name department to the Cisco attribute name
IETF-Radius-Class. The second command maps the user-defined attribute value Engineering to the
user-defined attribute department and the Cisco-defined attribute value group1.
hostname(config)# ldap attribute-map att_map_1
hostname(config-ldap-attribute-map)# map-name department IETF-Radius-Class
hostname(config-ldap-attribute-map)# map-value department Engineering group1
hostname(config-ldap-attribute-map)#
The following commands bind the attribute map att_map_1 to the LDAP server ldap_dir_1:
hostname(config)# aaa-server ldap_dir_1 host 10.1.1.4
hostname(config-aaa-server-host)# ldap-attribute-map att_map_1
hostname(config-aaa-server-host)#
Note
The command to create an attribute map (ldap attribute-map) and the command to bind it to an LDAP
server (ldap-attribute-map) differ only by a hyphen and the mode.
The following commands display or clear all LDAP attribute maps in the running configuration:
hostname# show running-config all ldap attribute-map
hostname(config)# clear configuration ldap attribute-map
hostname(config)#
The names of frequently mapped Cisco LDAP attributes and the type of user-defined attributes they
would commonly be mapped to include:
IETF-Radius-Class — Department or user group
IETF-Radius-Filter-Id — Access control list
IETF-Radius-Framed-IP-Address — A static IP address
IPSec-Banner1 — A organization title
Tunneling-Protocols — Allow or deny dial-in
The following example shows how to limit management sessions to the security appliance based on an
LDAP attribute called accessType. The accessType attribute has three possible values:
•
VPN
•
admin
•
helpdesk
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-15
Chapter 14
Configuring AAA Servers and the Local Database
Using Certificates and User Login Credentials
Each value is mapped to one of the valid IETF RADIUS Service-Types that the security appliance
supports: remote-access (Service-Type 5) Outbound, admin (Service-Type 6) Administrative, and
nas-prompt (Service-Type 7) NAS Prompt.
hostname(config)# ldap attribute-map
hostname(config-ldap-attribute-map)#
hostname(config-ldap-attribute-map)#
hostname(config-ldap-attribute-map)#
hostname(config-ldap-attribute-map)#
MGMT
map-name accessType IETF-Radius-Service-Type
map-value accessType VPN 5
map-value accessType admin 6
map-value accessType helpdesk 7
hostname(config-ldap-attribute-map)# aaa-server LDAP protocol ldap
hostname(config-aaa-server-group)# aaa-server LDAP (inside) host 10.1.254.91
hostname(config-aaa-server-host)# ldap-base-dn CN=Users,DC=cisco,DC=local
hostname(config-aaa-server-host)# ldap-scope subtree
hostname(config-aaa-server-host)# ldap-login-password test
hostname(config-aaa-server-host)# ldap-login-dn
CN=Administrator,CN=Users,DC=cisco,DC=local
hostname(config-aaa-server-host)# server-type auto-detect
hostname(config-aaa-server-host)# ldap-attribute-map MGMT
For a list of Cisco LDAP attribute names and values, see Appendix D, “Configuring an External Server
for Authorization and Authentication”. Alternatively, you can enter “?” within ldap-attribute-map mode
to display the complete list of Cisco LDAP attribute names, as shown in the following example:
hostname(config)# ldap attribute-map att_map_1
hostname(config-ldap-attribute-map)# map-name att_map_1 ?
ldap mode commands/options:
cisco-attribute-names:
Access-Hours
Allow-Network-Extension-Mode
Auth-Service-Type
Authenticated-User-Idle-Timeout
Authorization-Required
Authorization-Type
:
:
X509-Cert-Data
hostname(config-ldap-attribute-map)#
Using Certificates and User Login Credentials
The following section describes the different methods of using certificates and user login credentials
(username and password) for authentication and authorization. This applies to both IPSec and Clientless
SSL VPN.
In all cases, LDAP authorization does not use the password as a credential. RADIUS authorization uses
either a common password for all users or the username as a password.
Using User Login Credentials
The default method for authentication and authorization uses the user login credentials.
•
Authentication
– Enabled by authentication server group setting
– Uses the username and password as credentials
Cisco Security Appliance Command Line Configuration Guide
14-16
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
Supporting a Zone Labs Integrity Server
•
Authorization
– Enabled by authorization server group setting
– Uses the username as a credential
Using certificates
If user digital certificates are configured, the security appliance first validates the certificate. It does not,
however, use any of the DNs from the certificates as a username for the authentication.
If both authentication and authorization are enabled, the security appliance uses the user login
credentials for both user authentication and authorization.
•
Authentication
– Enabled by authentication server group setting
– Uses the username and password as credentials
•
Authorization
– Enabled by authorization server group setting
– Uses the username as a credential
If authentication is disabled and authorization is enabled, the security appliance uses the primary DN
field for authorization.
•
Authentication
– DISABLED (set to None) by authentication server group setting
– No credentials used
•
Authorization
– Enabled by authorization server group setting
– Uses the username value of the certificate primary DN field as a credential
Note
If the primary DN field is not present in the certificate, the security appliance uses the secondary DN
field value as the username for the authorization request.
For example, consider a user certificate that contains the following Subject DN fields and values:
Cn=anyuser,OU=sales;O=XYZCorporation;L=boston;S=mass;C=us;ea=anyuser@example.com.
If the Primary DN = EA (E-mail Address) and the Secondary DN = CN (Common Name), then the
username used in the authorization request would be anyuser@example.com.
Supporting a Zone Labs Integrity Server
This section introduces the Zone Labs Integrity Server, also called Check Point Integrity Server, and
presents an example procedure for configuring the security appliance to support the Zone Labs Integrity
Server. The Integrity server is a central management station for configuring and enforcing security
policies on remote PCs. If a remote PC does not conform to the security policy dictated by the Integrity
Server, it will not be granted access to the private network protected by the Integrity Server and security
appliance.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-17
Chapter 14
Configuring AAA Servers and the Local Database
Supporting a Zone Labs Integrity Server
This section includes the following topics:
•
Overview of Integrity Server and Security Appliance Interaction, page 14-18
•
Configuring Integrity Server Support, page 14-18
Overview of Integrity Server and Security Appliance Interaction
The VPN client software and the Integrity client software are co-resident on a remote PC. The following
steps summarize the actions of the remote PC, security appliance, and Integrity server in the
establishment of a session between the PC and the enterprise private network:
Note
1.
The VPN client software (residing on the same remote PC as the Integrity client software) connects
to the security appliance and tells the security appliance what type of firewall client it is.
2.
Once it approves the client firewall type, the security appliance passes Integrity server address
information back to the Integrity client.
3.
With the security appliance acting as a proxy, the Integrity client establishes a restricted connection
with the Integrity server. A restricted connection is only between the Integrity client and server.
4.
The Integrity server determines if the Integrity client is in compliance with the mandated security
policies. If the client is in compliance with security policies, the Integrity server instructs the
security appliance to open the connection and provide the client with connection details.
5.
On the remote PC, the VPN client passes connection details to the Integrity client and signals that
policy enforcement should begin immediately and the client can no enter the private network.
6.
Once the connection is established, the server continues to monitor the state of the client using client
heartbeat messages.
The current release of the security appliance supports one Integrity Server at a time even though the user
interfaces support the configuration of up to five Integrity Servers. If the active Server fails, configure
another Integrity Server on the security appliance and then reestablish the client VPN session.
Configuring Integrity Server Support
This section describes an example procedure for configuring the security appliance to support the Zone
Labs Integrity Servers. The procedure involves configuring address, port, connection fail timeout and
fail states, and SSL certificate parameters.
First, you must configure the hostname or IP address of the Integrity server. The following example
commands, entered in global configuration mode, configure an Integrity server using the IP address
10.0.0.5. They also specify port 300 (the default port is 5054) and the inside interface for
communications with the Integrity server.
hostname(config)# zonelabs-integrity server-address 10.0.0.5
hostname(config)# zonelabs-integrity port 300
hostname(config)# zonelabs-integrity interface inside
hostname(config)#
If the connection between the security appliance and the Integrity server fails, the VPN client
connections remain open by default so that the enterprise VPN is not disrupted by the failure of an
Integrity server. However, you may want to close the VPN connections if the Zone Labs Integrity Server
Cisco Security Appliance Command Line Configuration Guide
14-18
OL-12172-04
Chapter 14
Configuring AAA Servers and the Local Database
Supporting a Zone Labs Integrity Server
fails. The following commands ensure that the security appliance waits 12 seconds for a response from
either the active or standby Integrity servers before declaring an the Integrity server as failed and closing
the VPN client connections:
hostname(config)# zonelabs-integrity fail-timeout 12
hostname(config)# zonelabs-integrity fail-close
hostname(config)#
The following command returns the configured VPN client connection fail state to the default and
ensures the client connections remain open:
hostname(config)# zonelabs-integrity fail-open
hostname(config)#
The following example commands specify that the Integrity server connects to port 300 (default is port
80) on the security appliance to request the server SSL certificate. While the server SSL certificate is
always authenticated, these commands also specify that the client SSL certificate of the Integrity server
be authenticated.
hostname(config)# zonelabs-integrity ssl-certificate-port 300
hostname(config)# zonelabs-integrity ssl-client-authentication
hostname(config)#
To set the firewall client type to the Zone Labs Integrity type, use the client-firewall command as
described in the “Configuring Firewall Policies” section on page 32-60. The command arguments that
specify firewall policies are not used when the firewall type is zonelabs-integrity because the Integrity
server determines the policies.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
14-19
Chapter 14
Configuring AAA Servers and the Local Database
Supporting a Zone Labs Integrity Server
Cisco Security Appliance Command Line Configuration Guide
14-20
OL-12172-04
CH A P T E R
15
Configuring Failover
This chapter describes the security appliance failover feature, which lets you configure two security
appliances so that one takes over operation if the other one fails.
This chapter includes the following sections:
•
Understanding Failover, page 15-1
•
Configuring Failover, page 15-20
•
Controlling and Monitoring Failover, page 15-51
•
Remote Command Execution, page 15-53
•
Auto Update Server Support in Failover Configurations, page 15-56
For failover configuration examples, see Appendix A, “Sample Configurations.”
Understanding Failover
The failover configuration requires two identical security appliances connected to each other through a
dedicated and, optionally, a Stateful Failover link. The health of the active interfaces and units is
monitored to determine if specific failover conditions are met. If those conditions are met, failover
occurs.
The security appliance supports two failover configurations, Active/Active failover and Active/Standby
failover. Each failover configuration has its own method for determining and performing failover.
With Active/Active failover, both units can pass network traffic. This also lets you configure traffic
sharing on your network. Active/Active failover is available only on units running in multiple context
mode.
With Active/Standby failover, only one unit passes traffic while the other unit waits in a standby state.
Active/Standby failover is available on units running in either single or multiple context mode.
Both failover configurations support stateful or stateless (regular) failover.
Note
When the security appliance is configured for Active/Active stateful failover, you cannot enable IPSec
or SSL VPN. Therefore, these features are unavailable. VPN failover is available for Active/Standby
failover configurations only.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-1
Chapter 15
Configuring Failover
Understanding Failover
This section includes the following topics:
Failover System Requirements, page 15-2
•
The Failover and Stateful Failover Links, page 15-3
•
Active/Active and Active/Standby Failover, page 15-6
•
Stateless (Regular) and Stateful Failover, page 15-16
•
Failover Health Monitoring, page 15-18
•
Failover Feature/Platform Matrix, page 15-19
•
Failover Times by Platform, page 15-20
Failover System Requirements
This section describes the hardware, software, and license requirements for security appliances in a
failover configuration. This section contains the following topics:
•
Hardware Requirements, page 15-2
•
Software Requirements, page 15-2
•
License Requirements, page 15-3
Hardware Requirements
The two units in a failover configuration must have the same hardware configuration. They must be the
same model, have the same number and types of interfaces, the same amount of RAM, and, for the ASA
5500 series security appliance, the same SSMs installed (if any).
Note
The two units do not have to have the same size Flash memory. If using units with different Flash
memory sizes in your failover configuration, make sure the unit with the smaller Flash memory has
enough space to accommodate the software image files and the configuration files. If it does not,
configuration synchronization from the unit with the larger Flash memory to the unit with the smaller
Flash memory will fail.
Software Requirements
The two units in a failover configuration must be in the operating modes (routed or transparent, single
or multiple context). They have the same major (first number) and minor (second number) software
version. However, you can use different versions of the software during an upgrade process; for example,
you can upgrade one unit from Version 7.0(1) to Version 7.0(2) and have failover remain active. We
recommend upgrading both units to the same version to ensure long-term compatibility.
See “Performing Zero Downtime Upgrades for Failover Pairs” section on page 43-5 for more
information about upgrading the software on a failover pair.
Cisco Security Appliance Command Line Configuration Guide
15-2
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
License Requirements
On the PIX 500 series security appliance, at least one of the units must have an unrestricted (UR) license.
The other unit can have a Failover Only (FO) license, a Failover Only Active-Active (FO_AA) license,
or another UR license. Units with a Restricted license cannot be used for failover, and two units with FO
or FO_AA licenses cannot be used together as a failover pair.
Note
The FO license does not support Active/Active failover.
The FO and FO_AA licenses are intended to be used solely for units in a failover configuration and not
for units in standalone mode. If a failover unit with one of these licenses is used in standalone mode, the
unit reboots at least once every 24 hours until the unit is returned to failover duty. A unit with an FO or
FO_AA license operates in standalone mode if it is booted without being connected to a failover peer
with a UR license. If the unit with a UR license in a failover pair fails and is removed from the
configuration, the unit with the FO or FO_AA license does not automatically reboot every 24 hours; it
operates uninterrupted unless the it is manually rebooted.
When the unit automatically reboots, the following message displays on the console:
=========================NOTICE=========================
This machine is running in secondary mode without
a connection to an active primary PIX. Please
check your connection to the primary system.
REBOOTING....
========================================================
The ASA 5500 series adaptive security appliance platform does not have this restriction.
Note
The licensed features (such as SSL VPN peers or security contexts, for example) on both security
appliances participating in failover must be identical.
The Failover and Stateful Failover Links
This section describes the failover and the Stateful Failover links, which are dedicated connections
between the two units in a failover configuration. This section includes the following topics:
•
Failover Link, page 15-3
•
Stateful Failover Link, page 15-5
Failover Link
The two units in a failover pair constantly communicate over a failover link to determine the operating
status of each unit. The following information is communicated over the failover link:
•
The unit state (active or standby).
•
Power status (cable-based failover only—available only on the PIX 500 series security appliance).
•
Hello messages (keep-alives).
•
Network link status.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-3
Chapter 15
Configuring Failover
Understanding Failover
Caution
•
MAC address exchange.
•
Configuration replication and synchronization.
All information sent over the failover and Stateful Failover links is sent in clear text unless you secure
the communication with a failover key. If the security appliance is used to terminate VPN tunnels, this
information includes any usernames, passwords and preshared keys used for establishing the tunnels.
Transmitting this sensitive data in clear text could pose a significant security risk. We recommend
securing the failover communication with a failover key if you are using the security appliance to
terminate VPN tunnels.
On the PIX 500 series security appliance, the failover link can be either a LAN-based connection or a
dedicated serial Failover cable. On the ASA 5500 series adaptive security appliance, the failover link can
only be a LAN-based connection.
This section includes the following topics:
•
LAN-Based Failover Link, page 15-4
•
Serial Cable Failover Link (PIX Security Appliance Only), page 15-4
LAN-Based Failover Link
You can use any unused Ethernet interface on the device as the failover link; however, you cannot specify
an interface that is currently configured with a name. The LAN failover link interface is not configured
as a normal networking interface. It exists for failover communication only. This interface should only
be used for the LAN failover link (and optionally for the stateful failover link).
Connect the LAN failover link in one of the following two ways:
•
Using a switch, with no other device on the same network segment (broadcast domain or VLAN) as
the LAN failover interfaces of the ASA.
•
Using a crossover Ethernet cable to connect the appliances directly, without the need for an external
switch.
Note
When you use a crossover cable for the LAN failover link, if the LAN interface fails, the link is brought
down on both peers. This condition may hamper troubleshooting efforts because you cannot easily
determine which interface failed and caused the link to come down.
Note
The ASA supports Auto-MDI/MDIX on its copper Ethernet ports, so you can either use a crossover cable
or a straight-through cable. If you use a straight-through cable, the interface automatically detects the
cable and swaps one of the transmit/receive pairs to MDIX.
Serial Cable Failover Link (PIX Security Appliance Only)
The serial Failover cable, or “cable-based failover,” is only available on the PIX 500 series security
appliance. If the two units are within six feet of each other, then we recommend that you use the serial
Failover cable.
The cable that connects the two units is a modified RS-232 serial link cable that transfers data at
117,760 bps (115 Kbps). One end of the cable is labeled “Primary”. The unit attached to this end of the
cable automatically becomes the primary unit. The other end of the cable is labeled “Secondary”. The
Cisco Security Appliance Command Line Configuration Guide
15-4
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
unit attached to this end of the cable automatically becomes the secondary unit. You cannot override
these designations in the PIX 500 series security appliance software. If you purchased a PIX 500 series
security appliance failover bundle, this cable is included. To order a spare, use part number PIX-FO=.
The benefits of using cable-based failover include:
•
The PIX 500 series security appliance can immediately detect a power loss on the peer unit and
differentiate between a power loss from an unplugged cable.
•
The standby unit can communicate with the active unit and can receive the entire configuration
without having to be bootstrapped for failover. In LAN-based failover you need to configure the
failover link on the standby unit before it can communicate with the active unit.
•
The switch between the two units in LAN-based failover can be another point of hardware failure;
cable-based failover eliminates this potential point of failure.
•
You do not have to dedicate an Ethernet interface (and switch) to the failover link.
•
The cable determines which unit is primary and which is secondary, eliminating the need to
manually enter that information in the unit configurations.
The disadvantages include:
•
Distance limitation—the units cannot be separated by more than 6 feet.
•
Slower configuration replication.
Stateful Failover Link
To use Stateful Failover, you must configure a Stateful Failover link to pass all state information. You
have three options for configuring a Stateful Failover link:
•
You can use a dedicated Ethernet interface for the Stateful Failover link.
•
If you are using LAN-based failover, you can share the failover link.
•
You can share a regular data interface, such as the inside interface. However, this option is not
recommended.
If you are using a dedicated Ethernet interface for the Stateful Failover link, you can use either a switch
or a crossover cable to directly connect the units. If you use a switch, no other hosts or routers should be
on this link.
Note
Enable the PortFast option on Cisco switch ports that connect directly to the security appliance.
If you use a data interface as the Stateful Failover link, you receive the following warning when you
specify that interface as the Stateful Failover link:
******* WARNING ***** WARNING ******* WARNING ****** WARNING *********
Sharing Stateful failover interface with regular data interface is not
a recommended configuration due to performance and security concerns.
******* WARNING ***** WARNING ******* WARNING ****** WARNING *********
Sharing a data interface with the Stateful Failover interface can leave you vulnerable to replay attacks.
Additionally, large amounts of Stateful Failover traffic may be sent on the interface, causing
performance problems on that network segment.
Note
Using a data interface as the Stateful Failover interface is only supported in single context, routed mode.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-5
Chapter 15
Configuring Failover
Understanding Failover
In multiple context mode, the Stateful Failover link resides in the system context. This interface and the
failover interface are the only interfaces in the system context. All other interfaces are allocated to and
configured from within security contexts.
Note
Caution
The IP address and MAC address for the Stateful Failover link does not change at failover unless the
Stateful Failover link is configured on a regular data interface.
All information sent over the failover and Stateful Failover links is sent in clear text unless you secure
the communication with a failover key. If the security appliance is used to terminate VPN tunnels, this
information includes any usernames, passwords and preshared keys used for establishing the tunnels.
Transmitting this sensitive data in clear text could pose a significant security risk. We recommend
securing the failover communication with a failover key if you are using the security appliance to
terminate VPN tunnels.
Failover Interface Speed for Stateful Links
If you use the failover link as the Stateful Failover link, you should use the fastest Ethernet interface
available. If you experience performance problems on that interface, consider dedicating a separate
interface for the Stateful Failover interface.
Use the following failover interface speed guidelines for Cisco PIX security appliances and Cisco ASA
adaptive security appliances:
•
Cisco ASA 5520/5540/5550 and PIX 515E/535
– The stateful link speed should match the fastest data link
•
Cisco ASA 5510 and PIX 525
– Stateful link speed can be 100 Mbps, even though the data interface can operate at 1 Gigabit due
to the CPU speed limitation.
For optimum performance when using long distance LAN failover, the latency for the failover link
should be less than 10 milliseconds and no more than 250 milliseconds. If latency is more than 10
milliseconds, some performance degradation occurs due to retransmission of failover messages.
All platforms support sharing of failover heartbeat and stateful link, but we recommend using a separate
heartbeat link on systems with high Stateful Failover traffic.
Active/Active and Active/Standby Failover
This section describes each failover configuration in detail. This section includes the following topics:
•
Active/Standby Failover, page 15-7
•
Active/Active Failover, page 15-11
•
Determining Which Type of Failover to Use, page 15-15
Cisco Security Appliance Command Line Configuration Guide
15-6
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
Active/Standby Failover
This section describes Active/Standby failover and includes the following topics:
•
Active/Standby Failover Overview, page 15-7
•
Primary/Secondary Status and Active/Standby Status, page 15-7
•
Device Initialization and Configuration Synchronization, page 15-8
•
Command Replication, page 15-8
•
Failover Triggers, page 15-10
•
Failover Actions, page 15-10
Active/Standby Failover Overview
Active/Standby failover lets you use a standby security appliance to take over the functionality of a failed
unit. When the active unit fails, it changes to the standby state while the standby unit changes to the
active state. The unit that becomes active assumes the IP addresses (or, for transparent firewall, the
management IP address) and MAC addresses of the failed unit and begins passing traffic. The unit that
is now in standby state takes over the standby IP addresses and MAC addresses. Because network
devices see no change in the MAC to IP address pairing, no ARP entries change or time out anywhere
on the network.
Note
During a successful failover event on the security appliance, the interfaces are brought down, roles are
switched (IP addresses and MAC addresses are swapped), and the interfaces are brought up again.
However, the process is transparent to users. The security appliance does not send link-down messages
or system log messages to notify users that interfaces were taken down during failover (or link-up
messages for interfaces brought up by the failover process).
Note
For multiple context mode, the security appliance can fail over the entire unit (including all contexts)
but cannot fail over individual contexts separately.
Primary/Secondary Status and Active/Standby Status
The main differences between the two units in a failover pair are related to which unit is active and which
unit is standby, namely which IP addresses to use and which unit actively passes traffic.
However, a few differences exist between the units based on which unit is primary (as specified in the
configuration) and which unit is secondary:
•
The primary unit always becomes the active unit if both units start up at the same time (and are of
equal operational health).
•
The primary unit MAC addresses are always coupled with the active IP addresses. The exception to
this rule occurs when the secondary unit is active, and cannot obtain the primary unit MAC addresses
over the failover link. In this case, the secondary unit MAC addresses are used.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-7
Chapter 15
Configuring Failover
Understanding Failover
Device Initialization and Configuration Synchronization
Configuration synchronization occurs when one or both devices in the failover pair boot. Configurations
are always synchronized from the active unit to the standby unit. When the standby unit completes its
initial startup, it clears its running configuration (except for the failover commands needed to
communicate with the active unit), and the active unit sends its entire configuration to the standby unit.
The active unit is determined by the following:
Note
•
If a unit boots and detects a peer already running as active, it becomes the standby unit.
•
If a unit boots and does not detect a peer, it becomes the active unit.
•
If both units boot simultaneously, then the primary unit becomes the active unit and the secondary
unit becomes the standby unit.
If the secondary unit boots without detecting the primary unit, it becomes the active unit. It uses its own
MAC addresses for the active IP addresses. However, when the primary unit becomes available, the
secondary unit changes the MAC addresses to those of the primary unit, which can cause an interruption
in your network traffic. To avoid this, configure the failover pair with virtual MAC addresses. See the
“Configuring Virtual MAC Addresses” section on page 15-28 for more information.
When the replication starts, the security appliance console on the active unit displays the message
“Beginning configuration replication: Sending to mate,” and when it is complete, the security appliance
displays the message “End Configuration Replication to mate.” During replication, commands entered
on the active unit may not replicate properly to the standby unit, and commands entered on the standby
unit may be overwritten by the configuration being replicated from the active unit. Avoid entering
commands on either unit in the failover pair during the configuration replication process. Depending
upon the size of the configuration, replication can take from a few seconds to several minutes.
Note
The crypto ca server command and related sub-commands are not synchronized to the failover peer.
On the standby unit, the configuration exists only in running memory. To save the configuration to Flash
memory after synchronization:
Note
•
For single context mode, enter the write memory command on the active unit. The command is
replicated to the standby unit, which proceeds to write its configuration to Flash memory.
•
For multiple context mode, enter the write memory all command on the active unit from the system
execution space. The command is replicated to the standby unit, which proceeds to write its
configuration to Flash memory. Using the all keyword with this command causes the system and all
context configurations to be saved.
Startup configurations saved on external servers are accessible from either unit over the network and do
not need to be saved separately for each unit. Alternatively, you can copy the contexts on disk from the
active unit to an external server, and then copy them to disk on the standby unit, where they become
available when the unit reloads.
Command Replication
Command replication always flows from the active unit to the standby unit. As commands are entered
on the active unit, they are sent across the failover link to the standby unit. You do not have to save the
active configuration to Flash memory to replicate the commands.
Cisco Security Appliance Command Line Configuration Guide
15-8
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
Table 15-1 lists the commands that are and are not replicated to the standby unit.
Table 15-1
Command Replication
Commands Replicated to the Standby Unit
Commands Not Replicated to the Standby Unit
all configuration commands except for the mode, all forms of the copy command except for copy
firewall, and failover lan unit commands
running-config startup-config
Note
copy running-config startup-config
all forms of the write command except for write
memory
delete
crypto ca server and associated sub-commands
mkdir
debug
rename
failover lan unit
rmdir
firewall
write memory
mode
—
show
—
terminal pager and pager
Changes made on the standby unit are not replicated to the active unit. If you enter a command on the
standby unit, the security appliance displays the message **** WARNING **** Configuration
Replication is NOT performed from Standby unit to Active unit. Configurations are no
longer synchronized.
This message displays even when you enter many commands that do not affect
the configuration.
If you enter the write standby command on the active unit, the standby unit clears its running
configuration (except for the failover commands used to communicate with the active unit), and the
active unit sends its entire configuration to the standby unit.
For multiple context mode, when you enter the write standby command in the system execution space,
all contexts are replicated. If you enter the write standby command within a context, the command
replicates only the context configuration.
Replicated commands are stored in the running configuration. To save the replicated commands to the
Flash memory on the standby unit:
•
For single context mode, enter the copy running-config startup-config command on the active unit.
The command is replicated to the standby unit, which proceeds to write its configuration to Flash
memory.
•
For multiple context mode, enter the copy running-config startup-config command on the active
unit from the system execution space and within each context on disk. The command is replicated
to the standby unit, which proceeds to write its configuration to Flash memory. Contexts with startup
configurations on external servers are accessible from either unit over the network and do not need
to be saved separately for each unit. Alternatively, you can copy the contexts on disk from the active
unit to an external server, and then copy them to disk on the standby unit.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-9
Chapter 15
Configuring Failover
Understanding Failover
Failover Triggers
The unit can fail if one of the following events occurs:
•
The unit has a hardware failure or a power failure.
•
The unit has a software failure.
•
Too many monitored interfaces fail.
•
The no failover active command is entered on the active unit or the failover active command is
entered on the standby unit.
Failover Actions
In Active/Standby failover, failover occurs on a unit basis. Even on systems running in multiple context
mode, you cannot fail over individual or groups of contexts.
Table 15-2 shows the failover action for each failure event. For each failure event, the table shows the
failover policy (failover or no failover), the action taken by the active unit, the action taken by the
standby unit, and any special notes about the failover condition and actions.
Table 15-2
Failover Behavior
Failure Event
Policy
Active Action
Standby Action
Notes
Active unit failed (power or
hardware)
Failover
n/a
Become active
No hello messages are received on
any monitored interface or the
failover link.
Formerly active unit recovers
No failover
Become standby
No action
None.
Standby unit failed (power or
hardware)
No failover
Mark standby as
failed
n/a
When the standby unit is marked as
failed, then the active unit does not
attempt to fail over, even if the
interface failure threshold is
surpassed.
Failover link failed during
operation
No failover
Mark failover
interface as failed
Mark failover
interface as failed
You should restore the failover link
as soon as possible because the
unit cannot fail over to the standby
unit while the failover link is down.
Failover link failed at startup
No failover
Mark failover
interface as failed
Become active
If the failover link is down at
startup, both units become active.
Stateful Failover link failed
No failover
No action
No action
State information becomes out of
date, and sessions are terminated if
a failover occurs.
Interface failure on active unit Failover
above threshold
Mark active as
failed
Become active
None.
Interface failure on standby
unit above threshold
No action
Mark standby as
failed
When the standby unit is marked as
failed, then the active unit does not
attempt to fail over even if the
interface failure threshold is
surpassed.
Mark active as
failed
No failover
Cisco Security Appliance Command Line Configuration Guide
15-10
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
Active/Active Failover
This section describes Active/Active failover. This section includes the following topics:
•
Active/Active Failover Overview, page 15-11
•
Primary/Secondary Status and Active/Standby Status, page 15-12
•
Device Initialization and Configuration Synchronization, page 15-12
•
Command Replication, page 15-13
•
Failover Triggers, page 15-14
•
Failover Actions, page 15-14
Active/Active Failover Overview
Active/Active failover is only available to security appliances in multiple context mode. In an
Active/Active failover configuration, both security appliances can pass network traffic.
In Active/Active failover, you divide the security contexts on the security appliance into failover groups.
A failover group is simply a logical group of one or more security contexts. You can create a maximum
of two failover groups on the security appliance. The admin context is always a member of failover
group 1. Any unassigned security contexts are also members of failover group 1 by default.
The failover group forms the base unit for failover in Active/Active failover. Interface failure monitoring,
failover, and active/standby status are all attributes of a failover group rather than the unit. When an
active failover group fails, it changes to the standby state while the standby failover group becomes
active. The interfaces in the failover group that becomes active assume the MAC and IP addresses of the
interfaces in the failover group that failed. The interfaces in the failover group that is now in the standby
state take over the standby MAC and IP addresses.
Note
During a successful failover event on the security appliance, the interfaces are brought down, roles are
switched (IP addresses and MAC addresses are swapped), and the interfaces are brought up again.
However, the security appliance does not send link-down messages or system log messages to notify
users that interfaces were taken down during failover (or link-up messages for interfaces brought up by
the failover process).
Note
A failover group failing on a unit does not mean that the unit has failed. The unit may still have another
failover group passing traffic on it.
When creating the failover groups, you should create them on the unit that will have failover group 1 in
the active state.
Note
Active/Active failover generates virtual MAC addresses for the interfaces in each failover group. If you
have more than one Active/Active failover pair on the same network, it is possible to have the same
default virtual MAC addresses assigned to the interfaces on one pair as are assigned to the interfaces of
the other pairs because of the way the default virtual MAC addresses are determined. To avoid having
duplicate MAC addresses on your network, make sure you assign each physical interface a virtual active
and standby MAC address.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-11
Chapter 15
Configuring Failover
Understanding Failover
Primary/Secondary Status and Active/Standby Status
As in Active/Standby failover, one unit in an Active/Active failover pair is designated the primary unit,
and the other unit the secondary unit. Unlike Active/Standby failover, this designation does not indicate
which unit becomes active when both units start simultaneously. Instead, the primary/secondary
designation does two things:
•
Determines which unit provides the running configuration to the pair when they boot
simultaneously.
•
Determines on which unit each failover group appears in the active state when the units boot
simultaneously. Each failover group in the configuration is configured with a primary or secondary
unit preference. You can configure both failover groups be in the active state on a single unit in the
pair, with the other unit containing the failover groups in the standby state. However, a more typical
configuration is to assign each failover group a different role preference to make each one active on
a different unit, distributing the traffic across the devices.
Note
The security appliance also provides load balancing, which is different from failover. Both
failover and load balancing can exist on the same configuration. For information about load
balancing, see Understanding Load Balancing, page 31-6.
Which unit each failover group becomes active on is determined as follows:
•
When a unit boots while the peer unit is not available, both failover groups become active on the
unit.
•
When a unit boots while the peer unit is active (with both failover groups in the active state), the
failover groups remain in the active state on the active unit regardless of the primary or secondary
preference of the failover group until one of the following:
– A failover occurs.
– You manually force the failover group to the other unit with the no failover active command.
– You configured the failover group with the preempt command, which causes the failover group
to automatically become active on the preferred unit when the unit becomes available.
•
When both units boot at the same time, each failover group becomes active on its preferred unit after
the configurations have been synchronized.
Device Initialization and Configuration Synchronization
Configuration synchronization occurs when one or both units in a failover pair boot. The configurations
are synchronized as follows:
•
When a unit boots while the peer unit is active (with both failover groups active on it), the booting
unit contacts the active unit to obtain the running configuration regardless of the primary or
secondary designation of the booting unit.
•
When both units boot simultaneously, the secondary unit obtains the running configuration from the
primary unit.
When the replication starts, the security appliance console on the unit sending the configuration displays
the message “Beginning configuration replication: Sending to mate,” and when it is complete, the
security appliance displays the message “End Configuration Replication to mate.” During replication,
commands entered on the unit sending the configuration may not replicate properly to the peer unit, and
commands entered on the unit receiving the configuration may be overwritten by the configuration being
Cisco Security Appliance Command Line Configuration Guide
15-12
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
received. Avoid entering commands on either unit in the failover pair during the configuration
replication process. Depending upon the size of the configuration, replication can take from a few
seconds to several minutes.
On the unit receiving the configuration, the configuration exists only in running memory. To save the
configuration to Flash memory after synchronization enter the write memory all command in the system
execution space on the unit that has failover group 1 in the active state. The command is replicated to
the peer unit, which proceeds to write its configuration to Flash memory. Using the all keyword with this
command causes the system and all context configurations to be saved.
Note
Startup configurations saved on external servers are accessible from either unit over the network and do
not need to be saved separately for each unit. Alternatively, you can copy the contexts configuration files
from the disk on the primary unit to an external server, and then copy them to disk on the secondary unit,
where they become available when the unit reloads.
Command Replication
After both units are running, commands are replicated from one unit to the other as follows:
•
Commands entered within a security context are replicated from the unit on which the security
context appears in the active state to the peer unit.
A context is considered in the active state on a unit if the failover group to which it belongs is
in the active state on that unit.
Note
•
Commands entered in the system execution space are replicated from the unit on which failover
group 1 is in the active state to the unit on which failover group 1 is in the standby state.
•
Commands entered in the admin context are replicated from the unit on which failover group 1 is in
the active state to the unit on which failover group 1 is in the standby state.
Failure to enter the commands on the appropriate unit for command replication to occur causes the
configurations to be out of synchronization. Those changes may be lost the next time the initial
configuration synchronization occurs.
Table 15-3 shows the commands that are and are not replicated to the standby unit:
Table 15-3
Command Replication
Commands Replicated to the Standby Unit
Commands Not Replicated to the Standby Unit
all configuration commands except for the mode, all forms of the copy command except for copy
firewall, and failover lan unit commands
running-config startup-config
copy running-config startup-config
all forms of the write command except for write
memory
delete
debug
mkdir
failover lan unit
rename
firewall
rmdir
mode
write memory
show
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-13
Chapter 15
Configuring Failover
Understanding Failover
You can use the write standby command to resynchronize configurations that have become out of sync.
For Active/Active failover, the write standby command behaves as follows:
•
If you enter the write standby command in the system execution space, the system configuration
and the configurations for all of the security contexts on the security appliance is written to the peer
unit. This includes configuration information for security contexts that are in the standby state. You
must enter the command in the system execution space on the unit that has failover group 1 in the
active state.
Note
•
If there are security contexts in the active state on the peer unit, the write standby command
causes active connections through those contexts to be terminated. Use the failover active
command on the unit providing the configuration to make sure all contexts are active on that
unit before entering the write standby command.
If you enter the write standby command in a security context, only the configuration for the security
context is written to the peer unit. You must enter the command in the security context on the unit
where the security context appears in the active state.
Replicated commands are not saved to the Flash memory when replicated to the peer unit. They are
added to the running configuration. To save replicated commands to Flash memory on both units, use
the write memory or copy running-config startup-config command on the unit that you made the
changes on. The command is replicated to the peer unit and cause the configuration to be saved to Flash
memory on the peer unit.
Failover Triggers
In Active/Active failover, failover can be triggered at the unit level if one of the following events occurs:
•
The unit has a hardware failure.
•
The unit has a power failure.
•
The unit has a software failure.
•
The no failover active or the failover active command is entered in the system execution space.
Failover is triggered at the failover group level when one of the following events occurs:
•
Too many monitored interfaces in the group fail.
•
The no failover active group group_id or failover active group group_id command is entered.
You configure the failover threshold for each failover group by specifying the number or percentage of
interfaces within the failover group that must fail before the group fails. Because a failover group can
contain multiple contexts, and each context can contain multiple interfaces, it is possible for all
interfaces in a single context to fail without causing the associated failover group to fail.
See the “Failover Health Monitoring” section on page 15-18 for more information about interface and
unit monitoring.
Failover Actions
In an Active/Active failover configuration, failover occurs on a failover group basis, not a system basis.
For example, if you designate both failover groups as active on the primary unit, and failover group 1
fails, then failover group 2 remains active on the primary unit while failover group 1 becomes active on
the secondary unit.
Cisco Security Appliance Command Line Configuration Guide
15-14
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
Note
When configuring Active/Active failover, make sure that the combined traffic for both units is within the
capacity of each unit.
Table 15-4 shows the failover action for each failure event. For each failure event, the policy (whether
or not failover occurs), actions for the active failover group, and actions for the standby failover group
are given.
Table 15-4
Failover Behavior for Active/Active Failover
Active Group
Action
Standby Group
Action
Failure Event
Policy
Notes
A unit experiences a power or
software failure
Failover
Become standby Become active
Mark as failed
Mark active as
failed
When a unit in a failover pair fails,
any active failover groups on that
unit are marked as failed and
become active on the peer unit.
Interface failure on active failover
group above threshold
Failover
Mark active
group as failed
Become active
None.
Interface failure on standby failover
group above threshold
No failover No action
Mark standby
group as failed
When the standby failover group is
marked as failed, the active failover
group does not attempt to fail over,
even if the interface failure
threshold is surpassed.
Formerly active failover group
recovers
No failover No action
No action
Unless configured with the
preempt command, the failover
groups remain active on their
current unit.
Failover link failed at startup
No failover Become active
Become active
If the failover link is down at
startup, both failover groups on
both units become active.
Stateful Failover link failed
No failover No action
No action
State information becomes out of
date, and sessions are terminated if
a failover occurs.
Failover link failed during operation
No failover n/a
n/a
Each unit marks the failover
interface as failed. You should
restore the failover link as soon as
possible because the unit cannot fail
over to the standby unit while the
failover link is down.
Determining Which Type of Failover to Use
The type of failover you choose depends upon your security appliance configuration and how you plan
to use the security appliances.
If you are running the security appliance in single mode, then you can use only Active/Standby failover.
Active/Active failover is only available to security appliances running in multiple context mode.
If you are running the security appliance in multiple context mode, then you can configure either
Active/Active failover or Active/Standby failover.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-15
Chapter 15
Configuring Failover
Understanding Failover
•
To allow both members of the failover pair to share the traffic, use Active/Active failover. Do not
exceed 50% load on each device.
•
If you do not want to share the traffic in this way, use Active/Standby or Active/Active failover.
Table 15-5 provides a comparison of some of the features supported by each type of failover
configuration:
Table 15-5
Failover Configuration Feature Support
Feature
Active/Active
Active/Standby
Single Context Mode
No
Yes
Multiple Context Mode
Yes
Yes
Traffic Sharing Network Configurations
Yes
No
Unit Failover
Yes
Yes
Failover of Groups of Contexts
Yes
No
Failover of Individual Contexts
No
No
Stateless (Regular) and Stateful Failover
The security appliance supports two types of failover, regular and stateful. This section includes the
following topics:
•
Stateless (Regular) Failover, page 15-16
•
Stateful Failover, page 15-16
Stateless (Regular) Failover
When a failover occurs, all active connections are dropped. Clients need to reestablish connections when
the new active unit takes over.
Note
In Release 8.0 and later, some configuration elements for WebVPN (such as bookmarks and
customization) use the VPN failover subsystem, which is part of Stateful Failover. You must use Stateful
Failover to synchronize these elements between the members of the failover pair. Stateless (regular)
failover is not recommended for WebVPN.
Stateful Failover
When Stateful Failover is enabled, the active unit continually passes per-connection state information to
the standby unit. After a failover occurs, the same connection information is available at the new active
unit. Supported end-user applications are not required to reconnect to keep the same communication
session.
Cisco Security Appliance Command Line Configuration Guide
15-16
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
Table 15-6 list the state information that is and is not passed to the standby unit when Stateful Failover
is enabled.
Table 15-6
State Information
State Information Passed to Standby Unit
State Information Not Passed to Standby Unit
NAT translation table.
The HTTP connection table (unless HTTP
replication is enabled).
TCP connection states.
The user authentication (uauth) table.
UDP connection states.
The routing tables. After a failover occurs, some
packets may be lost or routed out of the wrong
interface (the default route) while the dynamic
routing protocols rediscover routes.
The ARP table.
State information for Security Service Modules.
The Layer 2 bridge table (when running in
transparent firewall mode).
DHCP server address leases.
The HTTP connection states (if HTTP replication Stateful failover for phone proxy. When the active
is enabled).
unit goes down, the call fails, media stops
flowing, and the phone should unregister from the
failed unit and reregister with the active unit. The
call must be re-established.
The ISAKMP and IPSec SA table.
—
GTP PDP connection database.
—
SIP signalling sessions.
—
The following WebVPN features are not supported with Stateful Failover:
Note
•
Smart Tunnels
•
Port Forwarding
•
Plugins
•
Java Applets
•
IPv6 clientless or Anyconnect sessions
•
Citrix authentication (Citrix users must reauthenticate after failover)
If failover occurs during an active Cisco IP SoftPhone session, the call remains active because the call
session state information is replicated to the standby unit. When the call is terminated, the IP SoftPhone
client loses connection with the Cisco CallManager. This occurs because there is no session information
for the CTIQBE hangup message on the standby unit. When the IP SoftPhone client does not receive a
response back from the Call Manager within a certain time period, it considers the CallManager
unreachable and unregisters itself.
For VPN failover, VPN end-users should not have to reauthenticate or reconnect the VPN session in the
event of a failover. However, applications operating over the VPN connection could lose packets during
the failover process and not recover from the packet loss.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-17
Chapter 15
Configuring Failover
Understanding Failover
Failover Health Monitoring
The security appliance monitors each unit for overall health and for interface health. See the following
sections for more information about how the security appliance performs tests to determine the state of
each unit:
•
Unit Health Monitoring, page 15-18
•
Interface Monitoring, page 15-18
Unit Health Monitoring
The security appliance determines the health of the other unit by monitoring the failover link. When a
unit does not receive three consecutive hello messages on the failover link, the unit sends interface hello
messages on each interface, including the failover interface, to validate whether or not the peer interface
is responsive. The action that the security appliance takes depends upon the response from the other unit.
See the following possible actions:
Note
•
If the security appliance receives a response on the failover interface, then it does not fail over.
•
If the security appliance does not receive a response on the failover link, but receives a response on
another interface, then the unit does not failover. The failover link is marked as failed. You should
restore the failover link as soon as possible because the unit cannot fail over to the standby while
the failover link is down.
•
If the security appliance does not receive a response on any interface, then the standby unit switches
to active mode and classifies the other unit as failed.
If a failed unit does not recover and you believe it should not be failed, you can reset the state by entering
the failover reset command. If the failover condition persists, however, the unit will fail again.
You can configure the frequency of the hello messages and the hold time before failover occurs. A faster
poll time and shorter hold time speed the detection of unit failures and make failover occur more quickly,
but it can also cause “false” failures due to network congestion delaying the keepalive packets. See
Configuring Unit Health Monitoring, page 15-41 for more information about configuring unit health
monitoring.
Interface Monitoring
You can monitor up to 250 interfaces divided between all contexts. You should monitor important
interfaces, for example, you might configure one context to monitor a shared interface (because the
interface is shared, all contexts benefit from the monitoring).
When a unit does not receive hello messages on a monitored interface for half of the configured hold
time, it runs the following tests:
1.
Link Up/Down test—A test of the interface status. If the Link Up/Down test indicates that the
interface is operational, then the security appliance performs network tests. The purpose of these
tests is to generate network traffic to determine which (if either) unit has failed. At the start of each
test, each unit clears its received packet count for its interfaces. At the conclusion of each test, each
unit looks to see if it has received any traffic. If it has, the interface is considered operational. If one
unit receives traffic for a test and the other unit does not, the unit that received no traffic is
considered failed. If neither unit has received traffic, then the next test is used.
Cisco Security Appliance Command Line Configuration Guide
15-18
OL-12172-04
Chapter 15
Configuring Failover
Understanding Failover
2.
Network Activity test—A received network activity test. The unit counts all received packets for up
to 5 seconds. If any packets are received at any time during this interval, the interface is considered
operational and testing stops. If no traffic is received, the ARP test begins.
3.
ARP test—A reading of the unit ARP cache for the 2 most recently acquired entries. One at a time,
the unit sends ARP requests to these machines, attempting to stimulate network traffic. After each
request, the unit counts all received traffic for up to 5 seconds. If traffic is received, the interface is
considered operational. If no traffic is received, an ARP request is sent to the next machine. If at the
end of the list no traffic has been received, the ping test begins.
4.
Broadcast Ping test—A ping test that consists of sending out a broadcast ping request. The unit then
counts all received packets for up to 5 seconds. If any packets are received at any time during this
interval, the interface is considered operational and testing stops.
If all network tests fail for an interface, but this interface on the other unit continues to successfully pass
traffic, then the interface is considered to be failed. If the threshold for failed interfaces is met, then a
failover occurs. If the other unit interface also fails all the network tests, then both interfaces go into the
“Unknown” state and do not count towards the failover limit.
An interface becomes operational again if it receives any traffic. A failed security appliance returns to
standby mode if the interface failure threshold is no longer met.
Note
If a failed unit does not recover and you believe it should not be failed, you can reset the state by entering
the failover reset command. If the failover condition persists, however, the unit will fail again.
Failover Feature/Platform Matrix
Table 15-7 shows the failover features supported by each hardware platform.
Table 15-7
Failover Feature Support by Platform
Cable-Based
Failover
LAN-Based
Failover
Stateful
Failover
Active/Standby
Failover
Active/Active
Failover
No
Yes
No
Yes
No
ASA 5500 series adaptive security No
appliance (other than the ASA
5505)
Yes
Yes
Yes
Yes
PIX 500 series security appliance
Yes
Yes
Yes
Yes
Platform
ASA 5505 adaptive security
appliance
Yes
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-19
Chapter 15
Configuring Failover
Configuring Failover
Failover Times by Platform
Table 15-8 shows the minimum, default, and maximum failover times for the PIX 500 series security
appliance.
Table 15-8
PIX 500 Series Security Appliance Failover Times.
Failover Condition
Minimum
Default
Maximum
Active unit loses power or stops normal operation.
800 milliseconds
45 seconds
45 seconds
Active unit interface link down.
500 milliseconds
5 seconds
15 seconds
Active unit interface up, but connection problem
causes interface testing.
5 seconds
25 seconds
75 seconds
Table 15-9 shows the minimum, default, and maximum failover times for the ASA 5500 series adaptive
security appliance.
Table 15-9
ASA 5500 series adaptive security appliance failover times.
Failover Condition
Minimum
Default
Maximum
Active unit loses power or stops normal operation.
800 milliseconds
15 seconds
45 seconds
Active unit main board interface link down.
500 milliseconds
5 seconds
15 seconds
Active unit 4GE card interface link down.
2 seconds
5 seconds
15 seconds
Active unit IPS or CSC card fails.
2 seconds
2 seconds
2 seconds
Active unit interface up, but connection problem
causes interface testing.
5 seconds
25 seconds
75 seconds
Configuring Failover
This section describes how to configure failover and includes the following topics:
•
Failover Configuration Limitations, page 15-20
•
Configuring Active/Standby Failover, page 15-21
•
Configuring Active/Active Failover, page 15-29
•
Configuring Unit Health Monitoring, page 15-41
•
Configuring Failover Communication Authentication/Encryption, page 15-41
•
Verifying the Failover Configuration, page 15-42
Failover Configuration Limitations
You cannot configure failover with the following type of IP addresses:
•
IP addresses obtained through DHCP
•
IP addresses obtained through PPPoE
•
IPv6 addresses
Cisco Security Appliance Command Line Configuration Guide
15-20
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Additionally, the following restrictions apply:
•
Stateful Failover is not supported on the ASA 5505 adaptive security appliance.
•
Active/Active failover is not supported on the ASA 5505 adaptive security appliance.
•
You cannot configure failover when Easy VPN remote is enabled on the ASA 5505 adaptive security
appliance.
•
VPN failover is not supported in multiple context mode.
•
CA server is not supported. If you have a CA server configured on the active unit, the CA server
functionality will be lost when the unit fails over. The crypto ca server command and associated
commands are not synchronized or replicated to the peer unit.
Configuring Active/Standby Failover
This section provides step-by-step procedures for configuring Active/Standby failover. This section
includes the following topics:
•
Prerequisites, page 15-21
•
Configuring Cable-Based Active/Standby Failover (PIX 500 Series Security Appliance Only),
page 15-21
•
Configuring LAN-Based Active/Standby Failover, page 15-23
•
Configuring Optional Active/Standby Failover Settings, page 15-26
Prerequisites
Before you begin, verify the following:
•
Both units have the same hardware, software configuration, and proper license.
•
Both units are in the same mode (single or multiple, transparent or routed).
Configuring Cable-Based Active/Standby Failover (PIX 500 Series Security Appliance Only)
Follow these steps to configure Active/Standby failover using a serial cable as the failover link. The
commands in this task are entered on the primary unit in the failover pair. The primary unit is the unit
that has the end of the cable labeled “Primary” plugged into it. For devices in multiple context mode, the
commands are entered in the system execution space unless otherwise noted.
You do not need to bootstrap the secondary unit in the failover pair when you use cable-based failover.
Leave the secondary unit powered off until instructed to power it on.
Cable-based failover is only available on the PIX 500 series security appliance.
To configure cable-based Active/Standby failover, perform the following steps:
Step 1
Connect the Failover cable to the PIX 500 series security appliances. Make sure that you attach the end
of the cable marked “Primary” to the unit you use as the primary unit, and that you attach the end of the
cable marked “Secondary” to the other unit.
Step 2
Power on the primary unit.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-21
Chapter 15
Configuring Failover
Configuring Failover
Step 3
If you have not done so already, configure the active and standby IP addresses for each data interface
(routed mode), for the management IP address (transparent mode), or for the management-only
interface. To receive packets from both units in a failover pair, standby IP addresses need to be
configured on all interfaces. The standby IP address is used on the security appliance that is currently
the standby unit, and it must be in the same subnet as the active IP address.
Note
Do not configure an IP address for the Stateful Failover link if you are going to use a dedicated
Stateful Failover interface. You use the failover interface ip command to configure a dedicated
Stateful Failover interface in a later step.
hostname(config-if)# ip address active_addr netmask standby standby_addr
In routed firewall mode and for the management-only interface, this command is entered in interface
configuration mode for each interface. In transparent firewall mode, the command is entered in global
configuration mode.
In multiple context mode, you must configure the interface addresses from within each context. Use the
changeto context command to switch between contexts. The command prompt changes to
hostname/context(config-if)#, where context is the name of the current context. You must enter a
management IP address for each context in transparent firewall multiple context mode.
Step 4
(Optional) To enable Stateful Failover, configure the Stateful Failover link.
Note
a.
Stateful Failover is not available on the ASA 5505 adaptive security appliance.
Specify the interface to be used as the Stateful Failover link:
hostname(config)# failover link if_name phy_if
The if_name argument assigns a logical name to the interface specified by the phy_if argument. The
phy_if argument can be the physical port name, such as Ethernet1, or a previously created
subinterface, such as Ethernet0/2.3. This interface should not be used for any other purpose.
b.
Assign an active and standby IP address to the Stateful Failover link:
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
Note
If the Stateful Failover link uses a data interface, skip this step. You have already defined the
active and standby IP addresses for the interface.
The standby IP address must be in the same subnet as the active IP address. You do not need to
identify the standby IP address subnet mask.
The Stateful Failover link IP address and MAC address do not change at failover unless it uses a data
interface. The active IP address always stays with the primary unit, while the standby IP address
stays with the secondary unit.
c.
Enable the interface:
hostname(config)# interface phy_if
hostname(config-if)# no shutdown
Step 5
Enable failover:
hostname(config)# failover
Cisco Security Appliance Command Line Configuration Guide
15-22
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Step 6
Power on the secondary unit and enable failover on the unit if it is not already enabled:
hostname(config)# failover
The active unit sends the configuration in running memory to the standby unit. As the configuration
synchronizes, the messages “Beginning configuration replication: sending to mate.” and “End
Configuration Replication to mate” appear on the primary console.
Step 7
Save the configuration to Flash memory on the primary unit. Because the commands entered on the
primary unit are replicated to the secondary unit, the secondary unit also saves its configuration to Flash
memory.
hostname(config)# copy running-config startup-config
Configuring LAN-Based Active/Standby Failover
This section describes how to configure Active/Standby failover using an Ethernet failover link. When
configuring LAN-based failover, you must bootstrap the secondary device to recognize the failover link
before the secondary device can obtain the running configuration from the primary device.
Note
If you are changing from cable-based failover to LAN-based failover, you can skip any steps, such as
assigning the active and standby IP addresses for each interface, that you completed for the cable-based
failover configuration.
This section includes the following topics:
•
Configuring the Primary Unit, page 15-23
•
Configuring the Secondary Unit, page 15-25
Configuring the Primary Unit
Follow these steps to configure the primary unit in a LAN-based, Active/Standby failover configuration.
These steps provide the minimum configuration needed to enable failover on the primary unit. For
multiple context mode, all steps are performed in the system execution space unless otherwise noted.
To configure the primary unit in an Active/Standby failover pair, perform the following steps:
Step 1
If you have not done so already, configure the active and standby IP addresses for each data interface
(routed mode), for the management IP address (transparent mode), or for the management-only
interface. To receive packets from both units in a failover pair, standby IP addresses need to be
configured on all interfaces. The standby IP address is used on the security appliance that is currently
the standby unit, and it must be in the same subnet as the active IP address.
Note
Do not configure an IP address for the Stateful Failover link if you are going to use a dedicated
Stateful Failover interface. You use the failover interface ip command to configure a dedicated
Stateful Failover interface in a later step.
hostname(config-if)# ip address active_addr netmask standby standby_addr
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-23
Chapter 15
Configuring Failover
Configuring Failover
In routed firewall mode and for the management-only interface, this command is entered in interface
configuration mode for each interface. In transparent firewall mode, the command is entered in global
configuration mode.
In multiple context mode, you must configure the interface addresses from within each context. Use the
changeto context command to switch between contexts. The command prompt changes to
hostname/context(config-if)#, where context is the name of the current context. You must enter a
management IP address for each context in transparent firewall multiple context mode.
Step 2
(PIX 500 series security appliance only) Enable LAN-based failover:
hostname(config)# failover lan enable
Step 3
Designate the unit as the primary unit:
hostname(config)# failover lan unit primary
Step 4
Define the failover interface:
a.
Specify the interface to be used as the failover interface:
hostname(config)# failover lan interface if_name phy_if
The if_name argument assigns a name to the interface specified by the phy_if argument. The phy_if
argument can be the physical port name, such as Ethernet1, or a previously created subinterface,
such as Ethernet0/2.3. On the ASA 5505 adaptive security appliance, the phy_if specifies a VLAN.
b.
Assign the active and standby IP address to the failover link:
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
The standby IP address must be in the same subnet as the active IP address. You do not need to
identify the standby address subnet mask.
The failover link IP address and MAC address do not change at failover. The active IP address for
the failover link always stays with the primary unit, while the standby IP address stays with the
secondary unit.
c.
Enable the interface:
hostname(config)# interface phy_if
hostname(config-if)# no shutdown
Step 5
(Optional) To enable Stateful Failover, configure the Stateful Failover link.
Note
a.
Stateful Failover is not available on the ASA 5505 adaptive security appliance.
Specify the interface to be used as Stateful Failover link:
hostname(config)# failover link if_name phy_if
Note
If the Stateful Failover link uses the failover link or a data interface, then you only need to
supply the if_name argument.
The if_name argument assigns a logical name to the interface specified by the phy_if argument. The
phy_if argument can be the physical port name, such as Ethernet1, or a previously created
subinterface, such as Ethernet0/2.3. This interface should not be used for any other purpose (except,
optionally, the failover link).
b.
Assign an active and standby IP address to the Stateful Failover link.
Cisco Security Appliance Command Line Configuration Guide
15-24
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Note
If the Stateful Failover link uses the failover link or data interface, skip this step. You have
already defined the active and standby IP addresses for the interface.
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
The standby IP address must be in the same subnet as the active IP address. You do not need to
identify the standby address subnet mask.
The Stateful Failover link IP address and MAC address do not change at failover unless it uses a data
interface. The active IP address always stays with the primary unit, while the standby IP address
stays with the secondary unit.
c.
Enable the interface.
Note
If the Stateful Failover link uses the failover link or data interface, skip this step. You have
already enabled the interface.
hostname(config)# interface phy_if
hostname(config-if)# no shutdown
Step 6
Enable failover:
hostname(config)# failover
Step 7
Save the system configuration to Flash memory:
hostname(config)# copy running-config startup-config
Configuring the Secondary Unit
The only configuration required on the secondary unit is for the failover interface. The secondary unit
requires these commands to initially communicate with the primary unit. After the primary unit sends
its configuration to the secondary unit, the only permanent difference between the two configurations is
the failover lan unit command, which identifies each unit as primary or secondary.
For multiple context mode, all steps are performed in the system execution space unless noted otherwise.
To configure the secondary unit, perform the following steps:
Step 1
(PIX 500 series security appliance only) Enable LAN-based failover:
hostname(config)# failover lan enable
Step 2
Define the failover interface. Use the same settings as you used for the primary unit.
a.
Specify the interface to be used as the failover interface:
hostname(config)# failover lan interface if_name phy_if
The if_name argument assigns a name to the interface specified by the phy_if argument.
b.
Assign the active and standby IP address to the failover link. To receive packets from both units in
a failover pair, standby IP addresses need to be configured on all interfaces.
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-25
Chapter 15
Configuring Failover
Configuring Failover
Note
c.
Enter this command exactly as you entered it on the primary unit when you configured the
failover interface on the primary unit (including the same IP address).
Enable the interface:
hostname(config)# interface phy_if
hostname(config-if)# no shutdown
Step 3
(Optional) Designate this unit as the secondary unit:
hostname(config)# failover lan unit secondary
Note
Step 4
This step is optional because by default units are designated as secondary unless previously
configured.
Enable failover:
hostname(config)# failover
After you enable failover, the active unit sends the configuration in running memory to the standby unit.
As the configuration synchronizes, the messages “Beginning configuration replication: Sending to mate”
and “End Configuration Replication to mate” appear on the active unit console.
Step 5
After the running configuration has completed replication, save the configuration to Flash memory:
hostname(config)# copy running-config startup-config
Configuring Optional Active/Standby Failover Settings
You can configure the following optional Active/Standby failover setting when you are initially
configuring failover or after failover has already been configured. Unless otherwise noted, the
commands should be entered on the active unit.
This section includes the following topics:
•
Enabling HTTP Replication with Stateful Failover, page 15-26
•
Disabling and Enabling Interface Monitoring, page 15-27
•
Configuring Interface Health Monitoring, page 15-27
•
Configuring Failover Criteria, page 15-28
•
Configuring Virtual MAC Addresses, page 15-28
Enabling HTTP Replication with Stateful Failover
To allow HTTP connections to be included in the state information replication, you need to enable HTTP
replication. Because HTTP connections are typically short-lived, and because HTTP clients typically
retry failed connection attempts, HTTP connections are not automatically included in the replicated state
information.
Enter the following command in global configuration mode to enable HTTP state replication when
Stateful Failover is enabled:
hostname(config)# failover replication http
Cisco Security Appliance Command Line Configuration Guide
15-26
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Disabling and Enabling Interface Monitoring
By default, monitoring physical interfaces is enabled and monitoring subinterfaces is disabled. You can
monitor up to 250 interfaces on a unit. You can control which interfaces affect your failover policy by
disabling the monitoring of specific interfaces and enabling the monitoring of others. This lets you
exclude interfaces attached to less critical networks from affecting your failover policy.
For units in multiple configuration mode, use the following commands to enable or disable health
monitoring for specific interfaces:
•
To disable health monitoring for an interface, enter the following command within a context:
hostname/context(config)# no monitor-interface if_name
•
To enable health monitoring for an interface, enter the following command within a context:
hostname/context(config)# monitor-interface if_name
For units in single configuration mode, use the following commands to enable or disable health
monitoring for specific interfaces:
•
To disable health monitoring for an interface, enter the following command in global configuration
mode:
hostname(config)# no monitor-interface if_name
•
To enable health monitoring for an interface, enter the following command in global configuration
mode:
hostname(config)# monitor-interface if_name
Configuring Interface Health Monitoring
The security appliance sends hello packets out of each data interface to monitor interface health. If the
security appliance does not receive a hello packet from the corresponding interface on the peer unit for
over half of the hold time, then the additional interface testing begins. If a hello packet or a successful
test result is not received within the specified hold time, the interface is marked as failed. Failover occurs
if the number of failed interfaces meets the failover criteria.
Decreasing the poll and hold times enables the security appliance to detect and respond to interface
failures more quickly, but may consume more system resources.
To change the interface poll time, enter the following command in global configuration mode:
hostname(config)# failover polltime interface [msec] time [holdtime time]
Valid values for the poll time are from 1 to 15 seconds or, if the optional msec keyword is used, from
500 to 999 milliseconds. The hold time determines how long it takes from the time a hello packet is
missed to when the interface is marked as failed. Valid values for the hold time are from 5 to 75 seconds.
You cannot enter a hold time that is less than 5 times the poll time.
Note
If the interface link is down, interface testing is not conducted and the standby unit could become active
in just one interface polling period if the number of failed interface meets or exceeds the configured
failover criteria.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-27
Chapter 15
Configuring Failover
Configuring Failover
Configuring Failover Criteria
By default, a single interface failure causes failover. You can specify a specific number of interfaces or
a percentage of monitored interfaces that must fail before a failover occurs.
To change the default failover criteria, enter the following command in global configuration mode:
hostname(config)# failover interface-policy num[%]
When specifying a specific number of interfaces, the num argument can be from 1 to 250. When
specifying a percentage of interfaces, the num argument can be from 1 to 100.
Configuring Virtual MAC Addresses
In Active/Standby failover, the MAC addresses for the primary unit are always associated with the active
IP addresses. If the secondary unit boots first and becomes active, it uses the burned-in MAC address for
its interfaces. When the primary unit comes online, the secondary unit obtains the MAC addresses from
the primary unit. The change can disrupt network traffic.
You can configure virtual MAC addresses for each interface to ensure that the secondary unit uses the
correct MAC addresses when it is the active unit, even if it comes online before the primary unit. If you
do not specify virtual MAC addresses the failover pair uses the burned-in NIC addresses as the MAC
addresses.
Note
You cannot configure a virtual MAC address for the failover or Stateful Failover links. The MAC and IP
addresses for those links do not change during failover.
Enter the following command on the active unit to configure the virtual MAC addresses for an interface:
hostname(config)# failover mac address phy_if active_mac standby_mac
The phy_if argument is the physical name of the interface, such as Ethernet1. The active_mac and
standby_mac arguments are MAC addresses in H.H.H format, where H is a 16-bit hexadecimal digit. For
example, the MAC address 00-0C-F1-42-4C-DE would be entered as 000C.F142.4CDE.
The active_mac address is associated with the active IP address for the interface, and the standby_mac
is associated with the standby IP address for the interface.
There are multiple ways to configure virtual MAC addresses on the security appliance. When more than
one method has been used to configure virtual MAC addresses, the security appliance uses the following
order of preference to determine which virtual MAC address is assigned to an interface:
1.
The mac-address command (in interface configuration mode) address.
2.
The failover mac address command address.
3.
The mac-address auto command generated address.
4.
The burned-in MAC address.
Use the show interface command to display the MAC address used by an interface.
Cisco Security Appliance Command Line Configuration Guide
15-28
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Configuring Active/Active Failover
This section describes how to configure Active/Active failover.
Note
Active/Active failover is not available on the ASA 5505 adaptive security appliance.
This section includes the following topics:
•
Prerequisites, page 15-29
•
Configuring Cable-Based Active/Active Failover (PIX 500 series security appliance), page 15-29
•
Configuring LAN-Based Active/Active Failover, page 15-31
•
Configuring Optional Active/Active Failover Settings, page 15-35
Prerequisites
Before you begin, verify the following:
•
Both units have the same hardware, software configuration, and proper license.
•
Both units are in multiple context mode.
Configuring Cable-Based Active/Active Failover (PIX 500 series security appliance)
Follow these steps to configure Active/Active failover using a serial cable as the failover link. The
commands in this task are entered on the primary unit in the failover pair. The primary unit is the unit
that has the end of the cable labeled “Primary” plugged into it. For devices in multiple context mode, the
commands are entered in the system execution space unless otherwise noted.
You do not need to bootstrap the secondary unit in the failover pair when you use cable-based failover.
Leave the secondary unit powered off until instructed to power it on.
Cable-based failover is only available on the PIX 500 series security appliance.
To configure cable-based, Active/Active failover, perform the following steps:
Step 1
Connect the failover cable to the PIX 500 series security appliances. Make sure that you attach the end
of the cable marked “Primary” to the unit you use as the primary unit, and that you attach the end of the
cable marked “Secondary” to the unit you use as the secondary unit.
Step 2
Power on the primary unit.
Step 3
If you have not done so already, configure the active and standby IP addresses for each data interface
(routed mode), for the management IP address (transparent mode), or for the management-only
interface. To receive packets from both units in a failover pair, standby IP addresses need to be
configured on all interfaces. The standby IP address is used on the security appliance that is currently
the standby unit, and it must be in the same subnet as the active IP address.
You must configure the interface addresses from within each context. Use the changeto context
command to switch between contexts. The command prompt changes to
hostname/context(config-if)#, where context is the name of the current context. You must enter a
management IP address for each context in transparent firewall multiple context mode.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-29
Chapter 15
Configuring Failover
Configuring Failover
Note
Do not configure an IP address for the Stateful Failover link if you are going to use a dedicated
Stateful Failover interface. You use the failover interface ip command to configure a dedicated
Stateful Failover interface in a later step.
hostname/context(config-if)# ip address active_addr netmask standby standby_addr
In routed firewall mode and for the management-only interface, this command is entered in interface
configuration mode for each interface. In transparent firewall mode, the command is entered in global
configuration mode.
Step 4
(Optional) To enable Stateful Failover, configure the Stateful Failover link.
a.
Specify the interface to be used as Stateful Failover link:
hostname(config)# failover link if_name phy_if
The if_name argument assigns a logical name to the interface specified by the phy_if argument. The
phy_if argument can be the physical port name, such as Ethernet1, or a previously created
subinterface, such as Ethernet0/2.3. This interface should not be used for any other purpose (except,
optionally, the failover link).
b.
Assign an active and standby IP address to the Stateful Failover link:
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
The standby IP address must be in the same subnet as the active IP address. You do not need to
identify the standby IP address subnet mask.
The Stateful Failover link IP address and MAC address do not change at failover except for when
Stateful Failover uses a regular data interface. The active IP address always stays with the primary
unit, while the standby IP address stays with the secondary unit.
c.
Enable the interface:
hostname(config)# interface phy_if
hostname(config-if)# no shutdown
Step 5
Configure the failover groups. You can have at most two failover groups. The failover group command
creates the specified failover group if it does not exist and enters the failover group configuration mode.
For each failover group, you need to specify whether the failover group has primary or secondary
preference using the primary or secondary command. You can assign the same preference to both
failover groups. For traffic sharing configurations, you should assign each failover group a different unit
preference.
The following example assigns failover group 1 a primary preference and failover group 2 a secondary
preference:
hostname(config)# failover group 1
hostname(config-fover-group)# primary
hostname(config-fover-group)# exit
hostname(config)# failover group 2
hostname(config-fover-group)# secondary
hostname(config-fover-group)# exit
Step 6
Assign each user context to a failover group using the join-failover-group command in context
configuration mode.
Any unassigned contexts are automatically assigned to failover group 1. The admin context is always a
member of failover group 1.
Enter the following commands to assign each context to a failover group:
Cisco Security Appliance Command Line Configuration Guide
15-30
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
hostname(config)# context context_name
hostname(config-context)# join-failover-group {1 | 2}
hostname(config-context)# exit
Step 7
Enable failover:
hostname(config)# failover
Step 8
Power on the secondary unit and enable failover on the unit if it is not already enabled:
hostname(config)# failover
The active unit sends the configuration in running memory to the standby unit. As the configuration
synchronizes, the messages “Beginning configuration replication: Sending to mate” and “End
Configuration Replication to mate” appear on the primary console.
Step 9
Save the configuration to Flash memory on the Primary unit. Because the commands entered on the
primary unit are replicated to the secondary unit, the secondary unit also saves its configuration to Flash
memory.
hostname(config)# copy running-config startup-config
Step 10
If necessary, force any failover group that is active on the primary to the active state on the secondary.
To force a failover group to become active on the secondary unit, issue the following command in the
system execution space on the primary unit:
hostname# no failover active group group_id
The group_id argument specifies the group you want to become active on the secondary unit.
Configuring LAN-Based Active/Active Failover
This section describes how to configure Active/Active failover using an Ethernet failover link. When
configuring LAN-based failover, you must bootstrap the secondary device to recognize the failover link
before the secondary device can obtain the running configuration from the primary device.
This section includes the following topics:
•
Configure the Primary Unit, page 15-31
•
Configure the Secondary Unit, page 15-33
Configure the Primary Unit
To configure the primary unit in an Active/Active failover configuration, perform the following steps:
Step 1
If you have not done so already, configure the active and standby IP addresses for each data interface
(routed mode), for the management IP address (transparent mode), or for the management-only
interface. To receive packets from both units in a failover pair, standby IP addresses need to be
configured on all interfaces. The standby IP address is used on the security appliance that is currently
the standby unit, and it must be in the same subnet as the active IP address.
You must configure the interface addresses from within each context. Use the changeto context
command to switch between contexts. The command prompt changes to
hostname/context(config-if)#, where context is the name of the current context. In transparent
firewall mode, you must enter a management IP address for each context.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-31
Chapter 15
Configuring Failover
Configuring Failover
Note
Do not configure an IP address for the Stateful Failover link if you are going to use a dedicated
Stateful Failover interface. You use the failover interface ip command to configure a dedicated
Stateful Failover interface in a later step.
hostname/context(config-if)# ip address active_addr netmask standby standby_addr
In routed firewall mode and for the management-only interface, this command is entered in interface
configuration mode for each interface. In transparent firewall mode, the command is entered in global
configuration mode.
Step 2
Configure the basic failover parameters in the system execution space.
a.
(PIX 500 series security appliance only) Enable LAN-based failover:
hostname(config)# hostname(config)# failover lan enable
b.
Designate the unit as the primary unit:
hostname(config)# failover lan unit primary
c.
Specify the failover link:
hostname(config)# failover lan interface if_name phy_if
The if_name argument assigns a logical name to the interface specified by the phy_if argument. The
phy_if argument can be the physical port name, such as Ethernet1, or a previously created
subinterface, such as Ethernet0/2.3. On the ASA 5505 adaptive security appliance, the phy_if
specifies a VLAN. This interface should not be used for any other purpose (except, optionally, the
Stateful Failover link).
d.
Specify the failover link active and standby IP addresses:
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
The standby IP address must be in the same subnet as the active IP address. You do not need to
identify the standby IP address subnet mask. The failover link IP address and MAC address do not
change at failover. The active IP address always stays with the primary unit, while the standby IP
address stays with the secondary unit.
Step 3
(Optional) To enable Stateful Failover, configure the Stateful Failover link:
a.
Specify the interface to be used as Stateful Failover link:
hostname(config)# failover link if_name phy_if
The if_name argument assigns a logical name to the interface specified by the phy_if argument. The
phy_if argument can be the physical port name, such as Ethernet1, or a previously created
subinterface, such as Ethernet0/2.3. This interface should not be used for any other purpose (except,
optionally, the failover link).
Note
b.
If the Stateful Failover link uses the failover link or a regular data interface, then you only
need to supply the if_name argument.
Assign an active and standby IP address to the Stateful Failover link.
Note
If the Stateful Failover link uses the failover link or a regular data interface, skip this step.
You have already defined the active and standby IP addresses for the interface.
Cisco Security Appliance Command Line Configuration Guide
15-32
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
The standby IP address must be in the same subnet as the active IP address. You do not need to
identify the standby address subnet mask.
The state link IP address and MAC address do not change at failover. The active IP address always
stays with the primary unit, while the standby IP address stays with the secondary unit.
c.
Enable the interface.
Note
If the Stateful Failover link uses the failover link or regular data interface, skip this step. You
have already enabled the interface.
hostname(config)# interface phy_if
hostname(config-if)# no shutdown
Step 4
Configure the failover groups. You can have at most two failover groups. The failover group command
creates the specified failover group if it does not exist and enters the failover group configuration mode.
For each failover group, specify whether the failover group has primary or secondary preference using
the primary or secondary command. You can assign the same preference to both failover groups. For
traffic sharing configurations, you should assign each failover group a different unit preference.
The following example assigns failover group 1 a primary preference and failover group 2 a secondary
preference:
hostname(config)# failover group 1
hostname(config-fover-group)# primary
hostname(config-fover-group)# exit
hostname(config)# failover group 2
hostname(config-fover-group)# secondary
hostname(config-fover-group)# exit
Step 5
Assign each user context to a failover group using the join-failover-group command in context
configuration mode.
Any unassigned contexts are automatically assigned to failover group 1. The admin context is always a
member of failover group 1.
Enter the following commands to assign each context to a failover group:
hostname(config)# context context_name
hostname(config-context)# join-failover-group {1 | 2}
hostname(config-context)# exit
Step 6
Enable failover:
hostname(config)# failover
Configure the Secondary Unit
When configuring LAN-based Active/Active failover, you need to bootstrap the secondary unit to
recognize the failover link. This allows the secondary unit to communicate with and receive the running
configuration from the primary unit.
To bootstrap the secondary unit in an Active/Active failover configuration, perform the following steps:
Step 1
(PIX 500 series security appliance only) Enable LAN-based failover:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-33
Chapter 15
Configuring Failover
Configuring Failover
hostname(config)# failover lan enable
Step 2
Define the failover interface. Use the same settings as you used for the primary unit:
a.
Specify the interface to be used as the failover interface:
hostname(config)# failover lan interface if_name phy_if
The if_name argument assigns a logical name to the interface specified by the phy_if argument. The
phy_if argument can be the physical port name, such as Ethernet1, or a previously created
subinterface, such as Ethernet0/2.3. On the ASA 5505 adaptive security appliance, the phy_if
specifies a VLAN.
b.
Assign the active and standby IP address to the failover link. To receive packets from both units in
a failover pair, standby IP addresses need to be configured on all interfaces.
hostname(config)# failover interface ip if_name ip_addr mask standby ip_addr
Note
Enter this command exactly as you entered it on the primary unit when you configured the
failover interface (including the same IP address).
The standby IP address must be in the same subnet as the active IP address. You do not need to
identify the standby address subnet mask.
c.
Enable the interface:
hostname(config)# interface phy_if
hostname(config-if)# no shutdown
Step 3
(Optional) Designate this unit as the secondary unit:
hostname(config)# failover lan unit secondary
Note
Step 4
This step is optional because by default units are designated as secondary unless previously
configured otherwise.
Enable failover:
hostname(config)# failover
After you enable failover, the active unit sends the configuration in running memory to the standby unit.
As the configuration synchronizes, the messages Beginning configuration replication: Sending to
mate and End Configuration Replication to mate appear on the active unit console.
Step 5
After the running configuration has completed replication, enter the following command to save the
configuration to Flash memory:
hostname(config)# copy running-config startup-config
Step 6
If necessary, force any failover group that is active on the primary to the active state on the secondary
unit. To force a failover group to become active on the secondary unit, enter the following command in
the system execution space on the primary unit:
hostname# no failover active group group_id
The group_id argument specifies the group you want to become active on the secondary unit.
Cisco Security Appliance Command Line Configuration Guide
15-34
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Configuring Optional Active/Active Failover Settings
The following optional Active/Active failover settings can be configured when you are initially
configuring failover or after you have already established failover. Unless otherwise noted, the
commands should be entered on the unit that has failover group 1 in the active state.
This section includes the following topics:
•
Configuring Failover Group Preemption, page 15-35
•
Enabling HTTP Replication with Stateful Failover, page 15-35
•
Disabling and Enabling Interface Monitoring, page 15-36
•
Configuring Interface Health Monitoring, page 15-36
•
Configuring Failover Criteria, page 15-36
•
Configuring Virtual MAC Addresses, page 15-36
•
Configuring Support for Asymmetrically Routed Packets, page 15-37
Configuring Failover Group Preemption
Assigning a primary or secondary priority to a failover group specifies which unit the failover group
becomes active on when both units boot simultaneously. However, if one unit boots before the other, then
both failover groups become active on that unit. When the other unit comes online, any failover groups
that have the unit as a priority do not become active on that unit unless manually forced over, a failover
occurs, or the failover group is configured with the preempt command. The preempt command causes
a failover group to become active on the designated unit automatically when that unit becomes available.
Enter the following commands to configure preemption for the specified failover group:
hostname(config)# failover group {1 | 2}
hostname(config-fover-group)# preempt [delay]
You can enter an optional delay value, which specifies the number of seconds the failover group remains
active on the current unit before automatically becoming active on the designated unit.
Enabling HTTP Replication with Stateful Failover
To allow HTTP connections to be included in the state information, you need to enable HTTP
replication. Because HTTP connections are typically short-lived, and because HTTP clients typically
retry failed connection attempts, HTTP connections are not automatically included in the replicated state
information. You can use the replication http command to cause a failover group to replicate HTTP state
information when Stateful Failover is enabled.
To enable HTTP state replication for a failover group, enter the following command. This command only
affects the failover group in which it was configured. To enable HTTP state replication for both failover
groups, you must enter this command in each group. This command should be entered in the system
execution space.
hostname(config)# failover group {1 | 2}
hostname(config-fover-group)# replication http
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-35
Chapter 15
Configuring Failover
Configuring Failover
Disabling and Enabling Interface Monitoring
You can monitor up to 250 interfaces on a unit. By default, monitoring of physical interfaces is enabled
and the monitoring of subinterfaces is disabled. You can control which interfaces affect your failover
policy by disabling the monitoring of specific interfaces and enabling the monitoring of others. This lets
you exclude interfaces attached to less critical networks from affecting your failover policy.
To disable health monitoring on an interface, enter the following command within a context:
hostname/context(config)# no monitor-interface if_name
To enable health monitoring on an interface, enter the following command within a context:
hostname/context(config)# monitor-interface if_name
Configuring Interface Health Monitoring
The security appliance sends hello packets out of each data interface to monitor interface health. If the
security appliance does not receive a hello packet from the corresponding interface on the peer unit for
over half of the hold time, then the additional interface testing begins. If a hello packet or a successful
test result is not received within the specified hold time, the interface is marked as failed. Failover occurs
if the number of failed interfaces meets the failover criteria.
Decreasing the poll and hold times enables the security appliance to detect and respond to interface
failures more quickly, but may consume more system resources.
To change the default interface poll time, enter the following commands:
hostname(config)# failover group {1 | 2}
hostname(config-fover-group)# polltime interface seconds
Valid values for the poll time are from 1 to 15 seconds or, if the optional msec keyword is used, from
500 to 999 milliseconds. The hold time determines how long it takes from the time a hello packet is
missed to when the interface is marked as failed. Valid values for the hold time are from 5 to 75 seconds.
You cannot enter a hold time that is less than 5 times the poll time.
Configuring Failover Criteria
By default, if a single interface fails failover occurs. You can specify a specific number of interfaces or
a percentage of monitored interfaces that must fail before a failover occurs. The failover criteria is
specified on a failover group basis.
To change the default failover criteria for the specified failover group, enter the following commands:
hostname(config)# failover group {1 | 2}
hostname(config-fover-group)# interface-policy num[%]
When specifying a specific number of interfaces, the num argument can be from 1 to 250. When
specifying a percentage of interfaces, the num argument can be from 1 to 100.
Configuring Virtual MAC Addresses
Active/Active failover uses virtual MAC addresses on all interfaces. If you do not specify the virtual
MAC addresses, then they are computed as follows:
•
Active unit default MAC address: 00a0.c9physical_port_number.failover_group_id01.
•
Standby unit default MAC address: 00a0.c9physical_port_number.failover_group_id02.
Cisco Security Appliance Command Line Configuration Guide
15-36
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Note
If you have more than one Active/Active failover pair on the same network, it is possible to have the
same default virtual MAC addresses assigned to the interfaces on one pair as are assigned to the
interfaces of the other pairs because of the way the default virtual MAC addresses are determined. To
avoid having duplicate MAC addresses on your network, make sure you assign each physical interface
a virtual active and standby MAC address for all failover groups.
You can configure specific active and standby MAC addresses for an interface by entering the following
commands:
hostname(config)# failover group {1 | 2}
hostname(config-fover-group)# mac address phy_if active_mac standby_mac
The phy_if argument is the physical name of the interface, such as Ethernet1. The active_mac and
standby_mac arguments are MAC addresses in H.H.H format, where H is a 16-bit hexadecimal digit. For
example, the MAC address 00-0C-F1-42-4C-DE would be entered as 000C.F142.4CDE.
The active_mac address is associated with the active IP address for the interface, and the standby_mac
is associated with the standby IP address for the interface.
There are multiple ways to configure virtual MAC addresses on the security appliance. When more than
one method has been used to configure virtual MAC addresses, the security appliance uses the following
order of preference to determine which virtual MAC address is assigned to an interface:
1.
The mac-address command (in interface configuration mode) address.
2.
The failover mac address command address.
3.
The mac-address auto command generate address.
4.
The automatically generated failover MAC address.
Use the show interface command to display the MAC address used by an interface.
Configuring Support for Asymmetrically Routed Packets
When running in Active/Active failover, a unit may receive a return packet for a connection that
originated through its peer unit. Because the security appliance that receives the packet does not have
any connection information for the packet, the packet is dropped. This most commonly occurs when the
two security appliances in an Active/Active failover pair are connected to different service providers and
the outbound connection does not use a NAT address.
You can prevent the return packets from being dropped using the asr-group command on interfaces
where this is likely to occur. When an interface configured with the asr-group command receives a
packet for which it has no session information, it checks the session information for the other interfaces
that are in the same group. If it does not find a match, the packet is dropped. If it finds a match, then one
of the following actions occurs:
•
If the incoming traffic originated on a peer unit, some or all of the layer 2 header is rewritten and
the packet is redirected to the other unit. This redirection continues as long as the session is active.
•
If the incoming traffic originated on a different interface on the same unit, some or all of the layer
2 header is rewritten and the packet is reinjected into the stream.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-37
Chapter 15
Configuring Failover
Configuring Failover
Note
Using the asr-group command to configure asymmetric routing support is more secure than using the
static command with the nailed option.
The asr-group command does not provide asymmetric routing; it restores asymmetrically routed packets
to the correct interface.
Prerequisites
You must have to following configured for asymmetric routing support to function properly:
•
Active/Active Failover
•
Stateful Failover—passes state information for sessions on interfaces in the active failover group to
the standby failover group.
•
replication http—HTTP session state information is not passed to the standby failover group, and
therefore is not present on the standby interface. For the security appliance to be able re-route
asymmetrically routed HTTP packets, you need to replicate the HTTP state information.
You can configure the asr-group command on an interface without having failover configured, but it
does not have any effect until Stateful Failover is enabled.
Configuring Support for Asymmetrically Routed Packets
To configure support for asymmetrically routed packets, perform the following steps:
Step 1
Configure Active/Active Stateful Failover for the failover pair. See Configuring Active/Active Failover,
page 15-29.
Step 2
For each interface that you want to participate in asymmetric routing support enter the following
command. You must enter the command on the unit where the context is in the active state so that the
command is replicated to the standby failover group. For more information about command replication,
see Command Replication, page 15-13.
hostname/ctx(config)# interface phy_if
hostname/ctx(config-if)# asr-group num
Valid values for num range from 1 to 32. You need to enter the command for each interface that
participates in the asymmetric routing group. You can view the number of ASR packets transmitted,
received, or dropped by an interface using the show interface detail command. You can have more than
one ASR group configured on the security appliance, but only one per interface. Only members of the
same ASR group are checked for session information.
Example
Figure 15-1 shows an example of using the asr-group command for asymmetric routing support.
Cisco Security Appliance Command Line Configuration Guide
15-38
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Figure 15-1
ASR Example
ISP A
ISP B
192.168.1.1
192.168.2.2
192.168.2.1
192.168.1.2
SecAppA
SecAppB
Failover/State link
Return Traffic
250093
Outbound Traffic
Inside
network
The two units have the following configuration (configurations show only the relevant commands). The
device labeled SecAppA in the diagram is the primary unit in the failover pair.
Example 15-1 Primary Unit System Configuration
hostname primary
interface GigabitEthernet0/1
description LAN/STATE Failover Interface
interface GigabitEthernet0/2
no shutdown
interface GigabitEthernet0/3
no shutdown
interface GigabitEthernet0/4
no shutdown
interface GigabitEthernet0/5
no shutdown
failover
failover lan unit primary
failover lan interface folink GigabitEthernet0/1
failover link folink
failover interface ip folink 10.0.4.1 255.255.255.0 standby 10.0.4.11
failover group 1
primary
failover group 2
secondary
admin-context admin
context admin
description admin
allocate-interface GigabitEthernet0/2
allocate-interface GigabitEthernet0/3
config-url flash:/admin.cfg
join-failover-group 1
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-39
Chapter 15
Configuring Failover
Configuring Failover
context ctx1
description context 1
allocate-interface GigabitEthernet0/4
allocate-interface GigabitEthernet0/5
config-url flash:/ctx1.cfg
join-failover-group 2
Example 15-2 admin Context Configuration
hostname SecAppA
interface GigabitEthernet0/2
nameif outsideISP-A
security-level 0
ip address 192.168.1.1 255.255.255.0 standby 192.168.1.2
asr-group 1
interface GigabitEthernet0/3
nameif inside
security-level 100
ip address 10.1.0.1 255.255.255.0 standby 10.1.0.11
monitor-interface outside
Example 15-3 ctx1 Context Configuration
hostname SecAppB
interface GigabitEthernet0/4
nameif outsideISP-B
security-level 0
ip address 192.168.2.2 255.255.255.0 standby 192.168.2.1
asr-group 1
interface GigabitEthernet0/5
nameif inside
security-level 100
ip address 10.2.20.1 255.255.255.0 standby 10.2.20.11
Figure 15-1 on page 15-39 shows the ASR support working as follows:
1.
An outbound session passes through security appliance SecAppA. It exits interface outsideISP-A
(192.168.1.1).
2.
Because of asymmetric routing configured somewhere upstream, the return traffic comes back
through the interface outsideISP-B (192.168.2.2) on security appliance SecAppB.
3.
Normally the return traffic would be dropped because there is no session information for the traffic
on interface 192.168.2.2. However, the interface is configure with the command asr-group 1. The
unit looks for the session on any other interface configured with the same ASR group ID.
4.
The session information is found on interface outsideISP-A (192.168.1.2), which is in the standby
state on the unit SecAppB. Stateful Failover replicated the session information from SecAppA to
SecAppB.
5.
Instead of being dropped, the layer 2 header is re-written with information for interface 192.168.1.1
and the traffic is redirected out of the interface 192.168.1.2, where it can then return through the
interface on the unit from which it originated (192.168.1.1 on SecAppA). This forwarding continues
as needed until the session ends.
Cisco Security Appliance Command Line Configuration Guide
15-40
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Configuring Unit Health Monitoring
The security appliance sends hello packets over the failover interface to monitor unit health. If the
standby unit does not receive a hello packet from the active unit for two consecutive polling periods, it
sends additional testing packets through the remaining device interfaces. If a hello packet or a response
to the interface test packets is not received within the specified hold time, the standby unit becomes
active.
You can configure the frequency of hello messages when monitoring unit health. Decreasing the poll
time allows a unit failure to be detected more quickly, but consumes more system resources.
To change the unit poll time, enter the following command in global configuration mode:
hostname(config)# failover polltime [msec] time [holdtime [msec] time]
You can configure the polling frequency from 1 to 15 seconds or, if the optional msec keyword is used,
from 200 to 999 milliseconds. The hold time determines how long it takes from the time a hello packet
is missed to when failover occurs. The hold time must be at least 3 times the poll time. You can configure
the hold time from 1 to 45 seconds or, if the optional msec keyword is used, from 800 to 990
milliseconds.
Setting the security appliance to use the minimum poll and hold times allows it to detect and respond to
unit failures in under a second, but it also increases system resource usage and can cause false failure
detection in cases where the networks are congested or where the security appliance is running near full
capacity.
Configuring Failover Communication Authentication/Encryption
You can encrypt and authenticate the communication between failover peers by specifying a shared
secret or hexadecimal key.
Note
On the PIX 500 series security appliance, if you are using the dedicated serial failover cable to connect
the units, then communication over the failover link is not encrypted even if a failover key is configured.
The failover key only encrypts LAN-based failover communication.
Caution
All information sent over the failover and Stateful Failover links is sent in clear text unless you secure
the communication with a failover key. If the security appliance is used to terminate VPN tunnels, this
information includes any usernames, passwords and preshared keys used for establishing the tunnels.
Transmitting this sensitive data in clear text could pose a significant security risk. We recommend
securing the failover communication with a failover key if you are using the security appliance to
terminate VPN tunnels.
Enter the following command on the active unit of an Active/Standby failover pair or on the unit that has
failover group 1 in the active state of an Active/Active failover pair:
hostname(config)# failover key {secret | hex key}
The secret argument specifies a shared secret that is used to generate the encryption key. It can be from
1 to 63 characters. The characters can be any combination of numbers, letters, or punctuation. The hex
key argument specifies a hexadecimal encryption key. The key must be 32 hexadecimal characters (0-9,
a-f).
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-41
Chapter 15
Configuring Failover
Configuring Failover
Note
To prevent the failover key from being replicated to the peer unit in clear text for an existing failover
configuration, disable failover on the active unit (or in the system execution space on the unit that has
failover group 1 in the active state), enter the failover key on both units, and then reenable failover. When
failover is reenabled, the failover communication is encrypted with the key.
For new LAN-based failover configurations, the failover key command should be part of the failover
pair bootstrap configuration.
Verifying the Failover Configuration
This section describes how to verify your failover configuration. This section includes the following
topics:
•
Using the show failover Command, page 15-42
•
Viewing Monitored Interfaces, page 15-50
•
Displaying the Failover Commands in the Running Configuration, page 15-50
•
Testing the Failover Functionality, page 15-51
Using the show failover Command
This section describes the show failover command output. On each unit you can verify the failover status
by entering the show failover command. The information displayed depends upon whether you are using
Active/Standby or Active/Active failover.
This section includes the following topics:
•
show failover—Active/Standby, page 15-42
•
Show Failover—Active/Active, page 15-46
show failover—Active/Standby
The following is sample output from the show failover command for Active/Standby Failover.
Table 15-10 provides descriptions for the information shown.
hostname# show failover
Failover On
Cable status: N/A - LAN-based failover enabled
Failover unit Primary
Failover LAN Interface: fover Ethernet2 (up)
Unit Poll frequency 1 seconds, holdtime 3 seconds
Interface Poll frequency 15 seconds
Interface Policy 1
Monitored Interfaces 2 of 250 maximum
failover replication http
Last Failover at: 22:44:03 UTC Dec 8 2004
This host: Primary - Active
Active time: 13434 (sec)
Interface inside (10.130.9.3): Normal
Interface outside (10.132.9.3): Normal
Other host: Secondary - Standby Ready
Active time: 0 (sec)
Interface inside (10.130.9.4): Normal
Interface outside (10.132.9.4): Normal
Cisco Security Appliance Command Line Configuration Guide
15-42
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Stateful Failover Logical Update Statistics
Link : fover Ethernet2 (up)
Stateful Obj
xmit
xerr
rcv
General
1950
0
1733
sys cmd
1733
0
1733
up time
0
0
0
RPC services
0
0
0
TCP conn
6
0
0
UDP conn
0
0
0
ARP tbl
106
0
0
Xlate_Timeout
0
0
0
VPN IKE upd
15
0
0
VPN IPSEC upd
90
0
0
VPN CTCP upd
0
0
0
VPN SDI upd
0
0
0
VPN DHCP upd
0
0
0
SIP Session
0
0
0
rerr
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Logical Update Queue Information
Cur
Max
Total
Recv Q:
0
2
1733
Xmit Q:
0
2
15225
In multiple context mode, using the show failover command in a security context displays the failover
information for that context. The information is similar to the information shown when using the
command in single context mode. Instead of showing the active/standby status of the unit, it displays the
active/standby status of the context. Table 15-10 provides descriptions for the information shown.
Failover On
Last Failover at: 04:03:11 UTC Jan 4 2003
This context: Negotiation
Active time: 1222 (sec)
Interface outside (192.168.5.121): Normal
Interface inside (192.168.0.1): Normal
Peer context: Not Detected
Active time: 0 (sec)
Interface outside (192.168.5.131): Normal
Interface inside (192.168.0.11): Normal
Stateful Failover Logical Update Statistics
Status: Configured.
Stateful Obj
xmit
xerr
rcv
RPC services
0
0
0
TCP conn
99
0
0
UDP conn
0
0
0
ARP tbl
22
0
0
Xlate_Timeout
0
0
0
GTP PDP
0
0
0
GTP PDPMCB
0
0
0
SIP Session
0
0
0
rerr
0
0
0
0
0
0
0
0
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-43
Chapter 15
Configuring Failover
Configuring Failover
Table 15-10
Show Failover Display Description
Field
Failover
Cable status:
Options
•
On
•
Off
•
Normal—The cable is connected to both units, and they both have
power.
•
My side not connected—The serial cable is not connected to this
unit. It is unknown if the cable is connected to the other unit.
•
Other side is not connected—The serial cable is connected to this
unit, but not to the other unit.
•
Other side powered off—The other unit is turned off.
•
N/A—LAN-based failover is enabled.
Failover Unit
Primary or Secondary.
Failover LAN Interface
Displays the logical and physical name of the failover link.
Unit Poll frequency
Displays the number of seconds between hello messages sent to the
peer unit and the number of seconds during which the unit must receive
a hello message on the failover link before declaring the peer failed.
Interface Poll frequency
n seconds
The number of seconds you set with the failover polltime interface
command. The default is 15 seconds.
Interface Policy
Displays the number or percentage of interfaces that must fail to trigger
failover.
Monitored Interfaces
Displays the number of interfaces monitored out of the maximum
possible.
failover replication http
Displays if HTTP state replication is enabled for Stateful Failover.
Last Failover at:
The date and time of the last failover in the following form:
hh:mm:ss UTC DayName Month Day yyyy
UTC (Coordinated Universal Time) is equivalent to GMT (Greenwich
Mean Time).
This host:
For each host, the display shows the following information.
Other host:
Primary or Secondary
Active time:
•
Active
•
Standby
n (sec)
The amount of time the unit has been active. This time is cumulative,
so the standby unit, if it was active in the past, also shows a value.
slot x
Information about the module in the slot or empty.
Cisco Security Appliance Command Line Configuration Guide
15-44
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Table 15-10
Show Failover Display Description (continued)
Field
Options
Interface name (n.n.n.n): For each interface, the display shows the IP address currently being
used on each unit, as well as one of the following conditions:
Stateful Failover Logical
Update Statistics
Link
Stateful Obj
•
Failed—The interface has failed.
•
No Link—The interface line protocol is down.
•
Normal—The interface is working correctly.
•
Link Down—The interface has been administratively shut down.
•
Unknown—The security appliance cannot determine the status of
the interface.
•
Waiting—Monitoring of the network interface on the other unit has
not yet started.
The following fields relate to the Stateful Failover feature. If the Link
field shows an interface name, the Stateful Failover statistics are shown.
•
interface_name—The interface used for the Stateful Failover link.
•
Unconfigured—You are not using Stateful Failover.
•
up—The interface is up and functioning.
•
down—The interface is either administratively shutdown or is
physically down.
•
failed—The interface has failed and is not passing stateful data.
For each field type, the following statistics are shown. They are
counters for the number of state information packets sent between the
two units; the fields do not necessarily show active connections through
the unit.
•
xmit—Number of transmitted packets to the other unit.
•
xerr—Number of errors that occurred while transmitting packets to
the other unit.
•
rcv—Number of received packets.
•
rerr—Number of errors that occurred while receiving packets from
the other unit.
General
Sum of all stateful objects.
sys cmd
Logical update system commands; for example, LOGIN and Stay
Alive.
up time
Up time, which the active unit passes to the standby unit.
RPC services
Remote Procedure Call connection information.
TCP conn
TCP connection information.
UDP conn
Dynamic UDP connection information.
ARP tbl
Dynamic ARP table information.
L2BRIDGE tbl
Layer 2 bridge table information (transparent firewall mode only).
Xlate_Timeout
Indicates connection translation timeout information.
VPN IKE upd
IKE connection information.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-45
Chapter 15
Configuring Failover
Configuring Failover
Table 15-10
Show Failover Display Description (continued)
Field
Options
VPN IPSEC upd
IPSec connection information.
VPN CTCP upd
cTCP tunnel connection information.
VPN SDI upd
SDI AAA connection information.
VPN DHCP upd
Tunneled DHCP connection information.
GTP PDP
GTP PDP update information. This information appears only if inspect
GTP is enabled.
GTP PDPMCB
GTP PDPMCB update information. This information appears only if
inspect GTP is enabled.
Logical Update Queue
Information
For each field type, the following statistics are used:
•
Cur—Current number of packets
•
Max—Maximum number of packets
•
Total—Total number of packets
Recv Q
The status of the receive queue.
Xmit Q
The status of the transmit queue.
Show Failover—Active/Active
The following is sample output from the show failover command for Active/Active Failover.
Table 15-11 provides descriptions for the information shown.
hostname# show failover
Failover On
Failover unit Primary
Failover LAN Interface: third GigabitEthernet0/2 (up)
Unit Poll frequency 1 seconds, holdtime 15 seconds
Interface Poll frequency 4 seconds
Interface Policy 1
Monitored Interfaces 8 of 250 maximum
failover replication http
Group 1 last failover at: 13:40:18 UTC Dec 9 2004
Group 2 last failover at: 13:40:06 UTC Dec 9 2004
This host:
Group 1
Group 2
Primary
State:
Active time:
State:
Active time:
Active
2896 (sec)
Standby Ready
0 (sec)
slot 0: ASA-5530 hw/sw rev (1.0/7.0(0)79) status (Up Sys)
slot 1: SSM-IDS-20 hw/sw rev (1.0/5.0(0.11)S91(0.11)) status (Up)
admin Interface outside (10.132.8.5): Normal
admin Interface third (10.132.9.5): Normal
admin Interface inside (10.130.8.5): Normal
admin Interface fourth (10.130.9.5): Normal
ctx1 Interface outside (10.1.1.1): Normal
ctx1 Interface inside (10.2.2.1): Normal
ctx2 Interface outside (10.3.3.2): Normal
ctx2 Interface inside (10.4.4.2): Normal
Other host:
Secondary
Cisco Security Appliance Command Line Configuration Guide
15-46
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Group 1
Group 2
State:
Active time:
State:
Active time:
Standby Ready
190 (sec)
Active
3322 (sec)
slot 0: ASA-5530 hw/sw rev (1.0/7.0(0)79) status (Up Sys)
slot 1: SSM-IDS-20 hw/sw rev (1.0/5.0(0.1)S91(0.1)) status (Up)
admin Interface outside (10.132.8.6): Normal
admin Interface third (10.132.9.6): Normal
admin Interface inside (10.130.8.6): Normal
admin Interface fourth (10.130.9.6): Normal
ctx1 Interface outside (10.1.1.2): Normal
ctx1 Interface inside (10.2.2.2): Normal
ctx2 Interface outside (10.3.3.1): Normal
ctx2 Interface inside (10.4.4.1): Normal
Stateful Failover Logical Update Statistics
Link : third GigabitEthernet0/2 (up)
Stateful Obj
xmit
xerr
rcv
General
1973
0
1895
sys cmd
380
0
380
up time
0
0
0
RPC services
0
0
0
TCP conn
1435
0
1450
UDP conn
0
0
0
ARP tbl
124
0
65
Xlate_Timeout
0
0
0
VPN IKE upd
15
0
0
VPN IPSEC upd
90
0
0
VPN CTCP upd
0
0
0
VPN SDI upd
0
0
0
VPN DHCP upd
0
0
0
SIP Session
0
0
0
rerr
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Logical Update Queue Information
Cur
Max
Total
Recv Q:
0
1
1895
Xmit Q:
0
0
1940
The following is sample output from the show failover group command for Active/Active Failover. The
information displayed is similar to that of the show failover command, but limited to the specified
group. Table 15-11 provides descriptions for the information shown.
hostname# show failover group 1
Last Failover at: 04:09:59 UTC Jan 4 2005
This host:
Secondary
State:
Active time:
Active
186 (sec)
admin Interface outside (192.168.5.121): Normal
admin Interface inside (192.168.0.1): Normal
Other host:
Primary
State:
Active time:
Standby
0 (sec)
admin Interface outside (192.168.5.131): Normal
admin Interface inside (192.168.0.11): Normal
Stateful Failover Logical Update Statistics
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-47
Chapter 15
Configuring Failover
Configuring Failover
Status: Configured.
RPC services
0
TCP conn
33
UDP conn
0
ARP tbl
12
Xlate_Timeout
0
GTP PDP
0
GTP PDPMCB
0
SIP Session
0
Table 15-11
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Show Failover Display Description
Field
Failover
Options
•
On
•
Off
Failover Unit
Primary or Secondary.
Failover LAN Interface
Displays the logical and physical name of the failover link.
Unit Poll frequency
Displays the number of seconds between hello messages sent to the
peer unit and the number of seconds during which the unit must receive
a hello message on the failover link before declaring the peer failed.
Interface Poll frequency
n seconds
The number of seconds you set with the failover polltime interface
command. The default is 15 seconds.
Interface Policy
Displays the number or percentage of interfaces that must fail before
triggering failover.
Monitored Interfaces
Displays the number of interfaces monitored out of the maximum
possible.
Group 1 Last Failover at:
The date and time of the last failover for each group in the following
form:
Group 2 Last Failover at:
hh:mm:ss UTC DayName Month Day yyyy
UTC (Coordinated Universal Time) is equivalent to GMT (Greenwich
Mean Time).
This host:
For each host, the display shows the following information.
Other host:
Role
System State
Primary or Secondary
•
Active or Standby Ready
•
Active Time in seconds
Group 1 State
•
Active or Standby Ready
Group 2 State
•
Active Time in seconds
slot x
Information about the module in the slot or empty.
Cisco Security Appliance Command Line Configuration Guide
15-48
OL-12172-04
Chapter 15
Configuring Failover
Configuring Failover
Table 15-11
Show Failover Display Description (continued)
Field
Options
context Interface name
(n.n.n.n):
Stateful Failover Logical
Update Statistics
Link
Stateful Obj
For each interface, the display shows the IP address currently being
used on each unit, as well as one of the following conditions:
•
Failed—The interface has failed.
•
No link—The interface line protocol is down.
•
Normal—The interface is working correctly.
•
Link Down—The interface has been administratively shut down.
•
Unknown—The security appliance cannot determine the status of
the interface.
•
Waiting—Monitoring of the network interface on the other unit has
not yet started.
The following fields relate to the Stateful Failover feature. If the Link
field shows an interface name, the Stateful Failover statistics are shown.
•
interface_name—The interface used for the Stateful Failover link.
•
Unconfigured—You are not using Stateful Failover.
•
up—The interface is up and functioning.
•
down—The interface is either administratively shutdown or is
physically down.
•
failed—The interface has failed and is not passing stateful data.
For each field type, the following statistics are used. They are counters
for the number of state information packets sent between the two units;
the fields do not necessarily show active connections through the unit.
•
xmit—Number of transmitted packets to the other unit
•
xerr—Number of errors that occurred while transmitting packets to
the other unit
•
rcv—Number of received packets
•
rerr—Number of errors that occurred while receiving packets from
the other unit
General
Sum of all stateful objects.
sys cmd
Logical update system commands; for example, LOGIN and Stay
Alive.
up time
Up time, which the active unit passes to the standby unit.
RPC services
Remote Procedure Call connection information.
TCP conn
TCP connection information.
UDP conn
Dynamic UDP connection information.
ARP tbl
Dynamic ARP table information.
L2BRIDGE tbl
Layer 2 bridge table information (transparent firewall mode only).
Xlate_Timeout
Indicates connection translation timeout information.
VPN IKE upd
IKE connection information.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-49
Chapter 15
Configuring Failover
Configuring Failover
Table 15-11
Show Failover Display Description (continued)
Field
Options
VPN IPSEC upd
IPSec connection information.
VPN CTCP upd
cTCP tunnel connection information.
VPN SDI upd
SDI AAA connection information.
VPN DHCP upd
Tunneled DHCP connection information.
GTP PDP
GTP PDP update information. This information appears only if inspect
GTP is enabled.
GTP PDPMCB
GTP PDPMCB update information. This information appears only if
inspect GTP is enabled.
Logical Update Queue
Information
For each field type, the following statistics are used:
•
Cur—Current number of packets
•
Max—Maximum number of packets
•
Total—Total number of packets
Recv Q
The status of the receive queue.
Xmit Q
The status of the transmit queue.
Viewing Monitored Interfaces
To view the status of monitored interfaces, enter the following command. In single context mode, enter
this command in global configuration mode. In multiple context mode, enter this command within a
context.
primary/context(config)# show monitor-interface
For example:
hostname/context(config)# show monitor-interface
This host: Primary - Active
Interface outside (192.168.1.2): Normal
Interface inside (10.1.1.91): Normal
Other host: Secondary - Standby
Interface outside (192.168.1.3): Normal
Interface inside (10.1.1.100): Normal
Displaying the Failover Commands in the Running Configuration
To view the failover commands in the running configuration, enter the following command:
hostname(config)# show running-config failover
All of the failover commands are displayed. On units running multiple context mode, enter this command
in the system execution space. Entering show running-config all failover displays the failover
commands in the running configuration and includes commands for which you have not changed the
default value.
Cisco Security Appliance Command Line Configuration Guide
15-50
OL-12172-04
Chapter 15
Configuring Failover
Controlling and Monitoring Failover
Testing the Failover Functionality
To test failover functionality, perform the following steps:
Step 1
Test that your active unit or failover group is passing traffic as expected by using FTP (for example) to
send a file between hosts on different interfaces.
Step 2
Force a failover to the standby unit by entering the following command:
•
For Active/Standby failover, enter the following command on the active unit:
hostname(config)# no failover active
•
For Active/Active failover, enter the following command on the unit where the failover group
containing the interface connecting your hosts is active:
hostname(config)# no failover active group group_id
Step 3
Use FTP to send another file between the same two hosts.
Step 4
If the test was not successful, enter the show failover command to check the failover status.
Step 5
When you are finished, you can restore the unit or failover group to active status by enter the following
command:
•
For Active/Standby failover, enter the following command on the active unit:
hostname(config)# failover active
•
For Active/Active failover, enter the following command on the unit where the failover group
containing the interface connecting your hosts is active:
hostname(config)# failover active group group_id
Controlling and Monitoring Failover
This sections describes how to control and monitor failover. This section includes the following topics:
•
Forcing Failover, page 15-51
•
Disabling Failover, page 15-52
•
Restoring a Failed Unit or Failover Group, page 15-52
•
Monitoring Failover, page 15-53
Forcing Failover
To force the standby unit or failover group to become active, enter one of the following commands:
•
For Active/Standby failover:
Enter the following command on the standby unit:
hostname# failover active
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-51
Chapter 15
Configuring Failover
Controlling and Monitoring Failover
Or, enter the following command on the active unit:
hostname# no failover active
•
For Active/Active failover:
Enter the following command in the system execution space of the unit where the failover group is
in the standby state:
hostname# failover active group group_id
Or, enter the following command in the system execution space of the unit where the failover group
is in the active state:
hostname# no failover active group group_id
Entering the following command in the system execution space causes all failover groups to become
active:
hostname# failover active
Disabling Failover
To disable failover, enter the following command:
hostname(config)# no failover
Disabling failover on an Active/Standby pair causes the active and standby state of each unit to be
maintained until you restart. For example, the standby unit remains in standby mode so that both units
do not start passing traffic. To make the standby unit active (even with failover disabled), see the
“Forcing Failover” section on page 15-51.
Disabling failover on an Active/Active failover pair causes the failover groups to remain in the active
state on whichever unit they are currently active on, no matter which unit they are configured to prefer.
Enter the no failover command in the system execution space.
Restoring a Failed Unit or Failover Group
To restore a failed unit to an unfailed state, enter the following command:
hostname(config)# failover reset
To restore a failed Active/Active failover group to an unfailed state, enter the following command:
hostname(config)# failover reset group group_id
Restoring a failed unit or group to an unfailed state does not automatically make it active; restored units
or groups remain in the standby state until made active by failover (forced or natural). An exception is a
failover group configured with the preempt command. If previously active, a failover group becomes
active if it is configured with the preempt command and if the unit on which it failed is the preferred
unit.
Cisco Security Appliance Command Line Configuration Guide
15-52
OL-12172-04
Chapter 15
Configuring Failover
Remote Command Execution
Monitoring Failover
When a failover occurs, both security appliances send out system messages. This section includes the
following topics:
•
Failover System Messages, page 15-53
•
Debug Messages, page 15-53
•
SNMP, page 15-53
Failover System Messages
The security appliance issues a number of system messages related to failover at priority level 2, which
indicates a critical condition. To view these messages, see the Cisco Security Appliance Logging
Configuration and System Log Messages to enable logging and to see descriptions of the system
messages.
Note
During switchover, failover logically shuts down and then bring up interfaces, generating syslog 411001
and 411002 messages. This is normal activity.
Debug Messages
To see debug messages, enter the debug fover command. See the Cisco Security Appliance Command
Reference for more information.
Note
Because debugging output is assigned high priority in the CPU process, it can drastically affect system
performance. For this reason, use the debug fover commands only to troubleshoot specific problems or
during troubleshooting sessions with Cisco TAC.
SNMP
To receive SNMP syslog traps for failover, configure the SNMP agent to send SNMP traps to SNMP
management stations, define a syslog host, and compile the Cisco syslog MIB into your SNMP
management station. See the snmp-server and logging commands in the Cisco Security Appliance
Command Reference for more information.
Remote Command Execution
Remote command execution lets you send commands entered at the command line to a specific failover
peer.
Because configuration commands are replicated from the active unit or context to the standby unit or
context, you can use the failover exec command to enter configuration commands on the correct unit,
no matter which unit you are logged-in to. For example, if you are logged-in to the standby unit, you can
use the failover exec active command to send configuration changes to the active unit. Those changes
are then replicated to the standby unit. Do not use the failover exec command to send configuration
commands to the standby unit or context; those configuration changes are not replicated to the active
unit and the two configurations will no longer be synchronized.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-53
Chapter 15
Configuring Failover
Remote Command Execution
Output from configuration, exec, and show commands is displayed in the current terminal session, so
you can use the failover exec command to issue show commands on a peer unit and view the results in
the current terminal.
You must have sufficient privileges to execute a command on the local unit to execute the command on
the peer unit.
To send a command to a failover peer, perform the following steps:
Step 1
If you are in multiple context mode, use the changeto command to change to the context you want to
configure. You cannot change contexts on the failover peer with the failover exec command.
If you are in single context mode, skip to the next step.
Step 2
Use the following command to send commands to he specified failover unit:
hostname(config)# failover exec {active | mate | standby}
Use the active or standby keyword to cause the command to be executed on the specified unit, even if
that unit is the current unit. Use the mate keyword to cause the command to be executed on the failover
peer.
Commands that cause a command mode change do not change the prompt for the current session. You
must use the show failover exec command to display the command mode the command is executed in.
See Changing Command Modes, page 15-54, for more information.
Changing Command Modes
The failover exec command maintains a command mode state that is separate from the command mode
of your terminal session. By default, the failover exec command mode starts in global configuration
mode for the specified device. You can change that command mode by sending the appropriate command
(such as the interface command) using the failover exec command. The session prompt does not change
when you change mode using failover exec.
For example, if you are logged-in to global configuration mode of the active unit of a failover pair, and
you use the failover exec active command to change to interface configuration mode, the terminal
prompt remains in global configuration mode, but commands entered using failover exec are entered in
interface configuration mode.
The following examples shows the difference between the terminal session mode and the failover exec
command mode. In the example, the administrator changes the failover exec mode on the active unit to
interface configuration mode for the interface GigabitEthernet0/1. After that, all commands entered
using failover exec active are sent to interface configuration mode for interface GigabitEthernet0/1. The
administrator then uses failover exec active to assign an IP address to that interface. Although the prompt
indicates global configuration mode, the failover exec active mode is in interface configuration mode.
hostname(config)# failover exec active interface GigabitEthernet0/1
hostname(config)# failover exec active ip address 192.168.1.1 255.255.255.0 standby
192.168.1.2
hostname(config)# router rip
hostname(config-router)#
Changing commands modes for your current session to the device does not affect the command mode
used by the failover exec command. For example, if you are in interface configuration mode on the
active unit, and you have not changed the failover exec command mode, the following command would
Cisco Security Appliance Command Line Configuration Guide
15-54
OL-12172-04
Chapter 15
Configuring Failover
Remote Command Execution
be executed in global configuration mode. The result would be that your session to the device remains
in interface configuration mode, while commands entered using failover exec active are sent to router
configuration mode for the specified routing process.
hostname(config-if)# failover exec active router ospf 100
hostname(config-if)#
Use the show failover exec command to display the command mode on the specified device in which
commands sent with the failover exec command are executed. The show failover exec command takes
the same keywords as the failover exec command: active, mate, or standby. The failover exec mode for
each device is tracked separately.
For example, the following is sample output from the show failover exec command entered on the
standby unit:
hostname(config)# failover exec active interface GigabitEthernet0/1
hostname(config)# sh failover exec active
Active unit Failover EXEC is at interface sub-command mode
hostname(config)# sh failover exec standby
Standby unit Failover EXEC is at config mode
hostname(config)# sh failover exec mate
Active unit Failover EXEC is at interface sub-command mode
Security Considerations
The failover exec command uses the failover link to send commands to and receive the output of the
command execution from the peer unit. You should use the failover key command to encrypt the failover
link to prevent eavesdropping or man-in-the-middle attacks.
Limitations of Remote Command Execution
•
If you upgrade one unit using the zero-downtime upgrade procedure and not the other, both units
must be running software that supports the failover exec command for the command to work.
•
Command completion and context help is not available for the commands in the cmd_string
argument.
•
In multiple context mode, you can only send commands to the peer context on the peer unit. To send
commands to a different context, you must first change to that context on the unit you are logged-in
to.
•
You cannot use the following commands with the failover exec command:
– changeto
– debug (undebug)
•
If the standby unit is in the failed state, it can still receive commands from the failover exec
command if the failure is due to a service card failure; otherwise, the remote command execution
will fail.
•
You cannot use the failover exec command to switch from privileged EXEC mode to global
configuration mode on the failover peer. For example, if the current unit is in privileged EXEC
mode, and you enter failover exec mate configure terminal, the show failover exec mate output
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-55
Chapter 15
Configuring Failover
Auto Update Server Support in Failover Configurations
will show that the failover exec session is in global configuration mode. However, entering
configuration commands for the peer unit using failover exec will fail until you enter global
configuration mode on the current unit.
•
You cannot enter recursive failover exec commands, such as failover exec mate failover exec mate
command.
•
Commands that require user input or confirmation must use the /nonconfirm option.
Auto Update Server Support in Failover Configurations
You can use Auto Update Server to deploy software images and configuration files to security appliances
in an Active/Standby failover configuration. To enable Auto Update on an Active/Standby failover
configuration, enter the Auto Update Server configuration on the primary unit in the failover pair. See
Configuring Auto Update Support, page 43-19, for more information.
The following restrictions and behaviors apply to Auto Update Server support in failover configurations:
•
Only single mode, Active/Standby configurations are supported.
•
When loading a new platform software image, the failover pair stops passing traffic.
•
When using LAN-based failover, new configurations must not change the failover link
configuration. If they do, communication between the units will fail.
•
Only the primary unit will perform the call home to the Auto Update Server. The primary unit must
be in the active state to call home. If it is not, the security appliance automatically fails over to the
primary unit.
•
Only the primary unit downloads the software image or configuration file. The software image or
configuration is then copied to the secondary unit.
•
The interface MAC address and hardware-serial ID is from the primary unit.
•
The configuration file stored on the Auto Update Server or HTTP server is for the primary unit only.
Auto Update Process Overview
The following is an overview of the Auto Update process in failover configurations. This process
assumes that failover is enabled and operational. The Auto Update process cannot occur if the units are
synchronizing configurations, if the standby unit is in the failed state for any reason other than SSM card
failure, or if the failover link is down.
1.
Both units exchange the platform and ASDM software checksum and version information.
2.
The primary unit contacts the Auto Update Server. If the primary unit is not in the active state, the
security appliance first fails over to the primary unit and then contacts the Auto Update Server.
3.
The Auto Update Server replies with software checksum and URL information.
4.
If the primary unit determines that the platform image file needs to be updated for either the active
or standby unit, the following occurs:
a. The primary unit retrieves the appropriate files from the HTTP server using the URL from the
Auto Update Server.
b. The primary unit copies the image to the standby unit and then updates the image on itself.
c. If both units have new image, the secondary (standby) unit is reloaded first.
Cisco Security Appliance Command Line Configuration Guide
15-56
OL-12172-04
Chapter 15
Configuring Failover
Auto Update Server Support in Failover Configurations
– If hitless upgrade can be performed when secondary unit boots, then the secondary unit becomes
the active unit and the primary unit reloads. The primary unit becomes the active unit when it
has finished loading.
– If hitless upgrade cannot be performed when the standby unit boots, then both units reload at
the same time.
d. If only the secondary (standby) unit has new image, then only the secondary unit reloads. The
primary unit waits until the secondary unit finishes reloading.
e. If only the primary (active) unit has new image, the secondary unit becomes the active unit, and
the primary unit reloads.
f. The update process starts again at step 1.
5.
If the security appliance determines that the ASDM file needs to be updated for either the primary
or secondary unit, the following occurs:
a. The primary unit retrieves the ASDM image file from the HTTP server using the URL provided
by the Auto Update Server.
b. The primary unit copies the ASDM image to the standby unit, if needed.
c. The primary unit updates the ASDM image on itself.
d. The update process starts again at step 1.
6.
If the primary unit determines that the configuration needs to be updated, the following occurs:
a. The primary unit retrieves the configuration file from the using the specified URL.
b. The new configuration replaces the old configuration on both units simultaneously.
c. The update process begins again at step 1.
7.
If the checksums match for all image and configuration files, no updates are required. The process
ends until the next poll time.
Monitoring the Auto Update Process
You can use the debug auto-update client or debug fover cmd-exe commands to display the actions
performed during the Auto Update process. The following is sample output from the debug auto-update
client command.
Auto-update client: Sent DeviceDetails to /cgi-bin/dda.pl of server 192.168.0.21
Auto-update client: Processing UpdateInfo from server 192.168.0.21
Component: asdm, URL: http://192.168.0.21/asdm.bint, checksum:
0x94bced0261cc992ae710faf8d244cf32
Component: config, URL: http://192.168.0.21/config-rms.xml, checksum:
0x67358553572688a805a155af312f6898
Component: image, URL: http://192.168.0.21/cdisk73.bin, checksum:
0x6d091b43ce96243e29a62f2330139419
Auto-update client: need to update img, act: yes, stby yes
name
ciscoasa(config)# Auto-update client: update img on stby unit...
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 1, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 1001, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 1501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 2001, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 2501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 3001, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 3501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 4001, len = 1024
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
15-57
Chapter 15
Configuring Failover
Auto Update Server Support in Failover Configurations
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 4501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 5001, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 5501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 6001, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 6501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 7001, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 7501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 8001, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 8501, len = 1024
auto-update: Fover copyfile, seq = 4 type = 1, pseq = 9001, len = 1024
auto-update: Fover file copy waiting at clock tick 6129280
fover_parse: Rcvd file copy ack, ret = 0, seq = 4
auto-update: Fover filecopy returns value: 0 at clock tick 6150260, upd time 145980 msecs
Auto-update client: update img on active unit...
fover_parse: Rcvd image info from mate
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
auto-update: HA safe reload: reload active waiting with mate state: 20
Beginning configuration replication: Sending to mate.
auto-update: HA safe reload: reload active waiting with mate state: 50
auto-update: HA safe reload: reload active waiting with mate state: 50
auto-update: HA safe reload: reload active waiting with mate state: 80
Sauto-update: HA safe reload: reload active unit at clock tick: 6266860
Auto-update client: Succeeded: Image, version: 0x6d091b43ce96243e29a62f2330139419
The following system log message is generated if the Auto Update process fails:
%PIX|ASA4-612002: Auto Update failed: file version: version reason: reason
The file is “image”, “asdm”, or “configuration”, depending on which update failed. The version is the
version number of the update. And the reason is the reason the update failed.
Cisco Security Appliance Command Line Configuration Guide
15-58
OL-12172-04
CH A P T E R
16
Using Modular Policy Framework
This chapter describes how to use Modular Policy Framework to create security policies for TCP and
general connection settings, inspections, IPS, CSC, and QoS. This chapter includes the following
sections:
•
Information About Modular Policy Framework, page 16-1
•
Identifying Traffic (Layer 3/4 Class Map), page 16-4
•
Configuring Special Actions for Application Inspections (Inspection Policy Map), page 16-8
•
Defining Actions (Layer 3/4 Policy Map), page 16-16
•
Applying Actions to an Interface (Service Policy), page 16-23
•
Modular Policy Framework Examples, page 16-24
Information About Modular Policy Framework
Modular Policy Framework provides a consistent and flexible way to configure security appliance
features. For example, you can use Modular Policy Framework to create a timeout configuration that is
specific to a particular TCP application, as opposed to one that applies to all TCP applications. This
section includes the following topics:
•
Modular Policy Framework Supported Features, page 16-1
•
Modular Policy Framework Configuration Overview, page 16-2
•
Default Global Policy, page 16-3
Modular Policy Framework Supported Features
Modular Policy Framework supports the following features:
•
QoS input policing—See Chapter 25, “Configuring QoS.”
•
TCP normalization, TCP and UDP connection limits and timeouts, and TCP sequence number
randomization—See the “Configuring TCP Normalization” section on page 24-12, and the
“Configuring Connection Limits and Timeouts” section on page 24-17.
•
CSC—See the “Managing the CSC SSM” section on page 23-9.
•
Application inspection (multiple types)—See Chapter 26, “Configuring Application Layer Protocol
Inspection.”
•
IPS—See the “Managing the AIP SSM” section on page 23-1.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-1
Chapter 16
Using Modular Policy Framework
Information About Modular Policy Framework
•
QoS output policing—See Chapter 25, “Configuring QoS.”
•
QoS standard priority queue—See Chapter 25, “Configuring QoS.”
•
QoS traffic shaping, hierarchical priority queue—See Chapter 25, “Configuring QoS.”
Modular Policy Framework Configuration Overview
Configuring Modular Policy Framework consists of the following tasks:
1.
Identify the traffic on which you want to perform Modular Policy Framework actions by creating
Layer 3/4 class maps. For example, you might want to perform actions on all traffic that passes
through the security appliance; or you might only want to perform certain actions on traffic from
10.1.1.0/24 to any destination address.
Layer 3/4 Class Map
241506
Layer 3/4 Class Map
See the “Identifying Traffic (Layer 3/4 Class Map)” section on page 16-4.
2.
If one of the actions you want to perform is application inspection, and you want to perform
additional actions on some inspection traffic, then create an inspection policy map. The inspection
policy map identifies the traffic and specifies what to do with it. For example, you might want to
drop all HTTP requests with a body length greater than 1000 bytes.
Inspection Policy Map Actions
241507
Inspection Class Map/
Match Commands
You can create a self-contained inspection policy map that identifies the traffic directly with match
commands, or you can create an inspection class map for reuse or for more complicated matching.
See the “Defining Actions in an Inspection Policy Map” section on page 16-9 and the “Identifying
Traffic in an Inspection Class Map” section on page 16-12.
3.
If you want to match text with a regular expression within inspected packets, you can create a regular
expression or a group of regular expressions (a regular expression class map). Then, when you
define the traffic to match for the inspection policy map, you can call on an existing regular
expression. For example, you might want to drop all HTTP requests with a URL including the text
“example.com.”
Cisco Security Appliance Command Line Configuration Guide
16-2
OL-12172-04
Chapter 16
Using Modular Policy Framework
Information About Modular Policy Framework
Inspection Policy Map Actions
241509
Inspection Class Map/
Match Commands
Regular Expression Statement/
Regular Expression Class Map
See the “Creating a Regular Expression” section on page 16-13 and the “Creating a Regular
Expression Class Map” section on page 16-16.
4.
Define the actions you want to perform on each Layer 3/4 class map by creating a Layer 3/4 policy
map. Then, determine on which interfaces you want to apply the policy map using a service policy.
Layer 3/4 Policy Map
Connection Limits
Connection Limits
Service Policy
Inspection
Inspection
241508
IPS
See the “Defining Actions (Layer 3/4 Policy Map)” section on page 16-16 and the “Applying
Actions to an Interface (Service Policy)” section on page 16-23.
Default Global Policy
By default, the configuration includes a policy that matches all default application inspection traffic and
applies certain inspections to the traffic on all interfaces (a global policy). Not all inspections are enabled
by default. You can only apply one global policy, so if you want to alter the global policy, you need to
either edit the default policy or disable it and apply a new one. (An interface policy overrides the global
policy for a particular feature.)
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-3
Chapter 16
Using Modular Policy Framework
Identifying Traffic (Layer 3/4 Class Map)
The default policy configuration includes the following commands:
class-map inspection_default
match default-inspection-traffic
policy-map type inspect dns preset_dns_map
parameters
message-length maximum 512
policy-map global_policy
class inspection_default
inspect dns preset_dns_map
inspect ftp
inspect h323 h225
inspect h323 ras
inspect rsh
inspect rtsp
inspect esmtp
inspect sqlnet
inspect skinny
inspect sunrpc
inspect xdmcp
inspect sip
inspect netbios
inspect tftp
service-policy global_policy global
Note
See the “Incompatibility of Certain Feature Actions” section on page 16-20 for more information about
the special match default-inspection-traffic command used in the default class map.
Identifying Traffic (Layer 3/4 Class Map)
A Layer 3/4 class map identifies Layer 3 and 4 traffic to which you want to apply actions. You can create
multiple Layer 3/4 class maps for each Layer 3/4 policy map.
This section includes the following topics:
•
Default Class Maps, page 16-4
•
Maximum Class Maps, page 16-5
•
Creating a Layer 3/4 Class Map for Through Traffic, page 16-5
•
Creating a Layer 3/4 Class Map for Management Traffic, page 16-7
Default Class Maps
The configuration includes a default Layer 3/4 class map that the security appliance uses in the default
global policy. It is called inspection_default and matches the default inspection traffic:
class-map inspection_default
match default-inspection-traffic
Note
See the “Incompatibility of Certain Feature Actions” section on page 16-20 for more information about
the special match default-inspection-traffic command used in the default class map.
Cisco Security Appliance Command Line Configuration Guide
16-4
OL-12172-04
Chapter 16
Using Modular Policy Framework
Identifying Traffic (Layer 3/4 Class Map)
Another class map that exists in the default configuration is called class-default, and it matches all
traffic:
class-map class-default
match any
This class map appears at the end of all Layer 3/4 policy maps and essentially tells the security appliance
to not perform any actions on all other traffic. You can use the class-default class map if desired, rather
than making your own match any class map. In fact, some features are only available for class-default,
such as QoS traffic shaping.
Maximum Class Maps
The maximum number of class maps of all types is 255 in single mode or per context in multiple mode.
Class maps include the following types:
•
Layer 3/4 class maps (for through traffic and management traffic)
•
Inspection class maps
•
Regular expression class maps
•
match commands used directly underneath an inspection policy map
This limit also includes default class maps of all types. See the “Default Class Maps” section on
page 16-4.
Creating a Layer 3/4 Class Map for Through Traffic
A Layer 3/4 class map matches traffic based on protocols, ports, IP addresses and other Layer 3 or 4
attributes.
To define a Layer 3/4 class map, perform the following steps:
Step 1
Create a Layer 3/4 class map by entering the following command:
hostname(config)# class-map class_map_name
hostname(config-cmap)#
Where class_map_name is a string up to 40 characters in length. The name “class-default” is reserved.
All types of class maps use the same name space, so you cannot reuse a name already used by another
type of class map. The CLI enters class-map configuration mode.
Step 2
(Optional) Add a description to the class map by entering the following command:
hostname(config-cmap)# description string
Step 3
Define the traffic to include in the class by matching one of the following characteristics. Unless
otherwise specified, you can include only one match command in the class map.
•
Any traffic—The class map matches all traffic.
hostname(config-cmap)# match any
•
Access list—The class map matches traffic specified by an extended access list. If the security
appliance is operating in transparent firewall mode, you can use an EtherType access list.
hostname(config-cmap)# match access-list access_list_name
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-5
Chapter 16
Using Modular Policy Framework
Identifying Traffic (Layer 3/4 Class Map)
For more information about creating access lists, see the “Adding an Extended Access List” section
on page 18-5 or the “Adding an EtherType Access List” section on page 18-8.
For information about creating access lists with NAT, see the “IP Addresses Used for Access Lists
When You Use NAT” section on page 18-3.
•
TCP or UDP destination ports—The class map matches a single port or a contiguous range of ports.
hostname(config-cmap)# match port {tcp | udp} {eq port_num | range port_num port_num}
Tip
For applications that use multiple, non-contiguous ports, use the match access-list command
and define an ACE to match each port.
For a list of ports you can specify, see the “TCP and UDP Ports” section on page C-11.
For example, enter the following command to match TCP packets on port 80 (HTTP):
hostname(config-cmap)# match tcp eq 80
•
Default traffic for inspection—The class map matches the default TCP and UDP ports used by all
applications that the security appliance can inspect.
hostname(config-cmap)# match default-inspection-traffic
This command, which is used in the default global policy, is a special CLI shortcut that when used
in a policy map, ensures that the correct inspection is applied to each packet, based on the
destination port of the traffic. For example, when UDP traffic for port 69 reaches the security
appliance, then the security appliance applies the TFTP inspection; when TCP traffic for port 21
arrives, then the security appliance applies the FTP inspection. So in this case only, you can
configure multiple inspections for the same class map (with the exception of WAAS inspection,
which can be configured with other inspections. See the “Incompatibility of Certain Feature
Actions” section on page 16-20 for more information about combining actions). Normally, the
security appliance does not use the port number to determine the inspection applied, thus giving you
the flexibility to apply inspections to non-standard ports, for example.
See the “Default Inspection Policy” section on page 26-3 for a list of default ports. Not all
applications whose ports are included in the match default-inspection-traffic command are
enabled by default in the policy map.
You can specify a match access-list command along with the match default-inspection-traffic
command to narrow the matched traffic. Because the match default-inspection-traffic command
specifies the ports to match, any ports in the access list are ignored.
•
DSCP value in an IP header—The class map matches up to eight DSCP values.
hostname(config-cmap)# match dscp value1 [value2] [...] [value8]
For example, enter the following:
hostname(config-cmap)# match dscp af43 cs1 ef
•
Precedence—The class map matches up to four precedence values, represented by the TOS byte in
the IP header.
hostname(config-cmap)# match precedence value1 [value2] [value3] [value4]
where value1 through value4 can be 0 to 7, corresponding to the possible precedences.
•
RTP traffic—The class map matches RTP traffic.
hostname(config-cmap)# match rtp starting_port range
Cisco Security Appliance Command Line Configuration Guide
16-6
OL-12172-04
Chapter 16
Using Modular Policy Framework
Identifying Traffic (Layer 3/4 Class Map)
The starting_port specifies an even-numbered UDP destination port between 2000 and 65534. The
range specifies the number of additional UDP ports to match above the starting_port, between 0 and
16383.
•
Tunnel group traffic—The class map matches traffic for a tunnel group to which you want to apply
QoS.
hostname(config-cmap)# match tunnel-group name
You can also specify one other match command to refine the traffic match. You can specify any of
the preceding commands, except for the match any, match access-list, or match
default-inspection-traffic commands. Or you can enter the following command to police each
flow:
hostname(config-cmap)# match flow ip destination address
All traffic going to a unique IP destination address is considered a flow.
The following is an example for the class-map command:
hostname(config)# access-list udp permit udp any any
hostname(config)# access-list tcp permit tcp any any
hostname(config)# access-list host_foo permit ip any 10.1.1.1 255.255.255.255
hostname(config)# class-map all_udp
hostname(config-cmap)# description "This class-map matches all UDP traffic"
hostname(config-cmap)# match access-list udp
hostname(config-cmap)# class-map all_tcp
hostname(config-cmap)# description "This class-map matches all TCP traffic"
hostname(config-cmap)# match access-list tcp
hostname(config-cmap)# class-map all_http
hostname(config-cmap)# description "This class-map matches all HTTP traffic"
hostname(config-cmap)# match port tcp eq http
hostname(config-cmap)# class-map to_server
hostname(config-cmap)# description "This class-map matches all traffic to server 10.1.1.1"
hostname(config-cmap)# match access-list host_foo
Creating a Layer 3/4 Class Map for Management Traffic
For management traffic to the security appliance, you might want to perform actions specific to this kind
of traffic. You can specify a management class map that can match an access list or TCP or UDP ports.
The types of actions available for a management class map in the policy map are specialized for
management traffic. Namely, this type of class map lets you inspect RADIUS accounting traffic and set
connection limits.
To create a class map for management traffic to the security appliance, perform the following steps:
Step 1
Create a class map by entering the following command:
hostname(config)# class-map type management class_map_name
hostname(config-cmap)#
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-7
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
Where class_map_name is a string up to 40 characters in length. The name “class-default” is reserved.
All types of class maps use the same name space, so you cannot reuse a name already used by another
type of class map. The CLI enters class-map configuration mode.
Step 2
(Optional) Add a description to the class map by entering the following command:
hostname(config-cmap)# description string
Step 3
Define the traffic to include in the class by matching one of the following characteristics. You can
include only one match command in the class map.
•
Access list—The class map matches traffic specified by an extended access list. If the security
appliance is operating in transparent firewall mode, you can use an EtherType access list.
hostname(config-cmap)# match access-list access_list_name
For more information about creating access lists, see the “Adding an Extended Access List” section
on page 18-5 or the “Adding an EtherType Access List” section on page 18-8.
For information about creating access lists with NAT, see the “IP Addresses Used for Access Lists
When You Use NAT” section on page 18-3.
•
TCP or UDP destination ports—The class map matches a single port or a contiguous range of ports.
hostname(config-cmap)# match port {tcp | udp} {eq port_num | range port_num port_num}
Tip
For applications that use multiple, non-contiguous ports, use the match access-list command
and define an ACE to match each port.
For a list of ports you can specify, see the “TCP and UDP Ports” section on page C-11.
For example, enter the following command to match TCP packets on port 80 (HTTP):
hostname(config-cmap)# match tcp eq 80
Configuring Special Actions for Application Inspections
(Inspection Policy Map)
Modular Policy Framework lets you configure special actions for many application inspections. When
you enable an inspection engine in the Layer 3/4 policy map, you can also optionally enable actions as
defined in an inspection policy map. When the inspection policy map matches traffic within the Layer
3/4 class map for which you have defined an inspection action, then that subset of traffic will be acted
upon as specified (for example, dropped or rate-limited).
This section includes the following topics:
•
Inspection Policy Map Overview, page 16-9
•
Defining Actions in an Inspection Policy Map, page 16-9
•
Identifying Traffic in an Inspection Class Map, page 16-12
•
Creating a Regular Expression, page 16-13
•
Creating a Regular Expression Class Map, page 16-16
Cisco Security Appliance Command Line Configuration Guide
16-8
OL-12172-04
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
Inspection Policy Map Overview
See the “Configuring Application Inspection” section on page 26-5 for a list of applications that support
inspection policy maps.
An inspection policy map consists of one or more of the following elements. The exact options available
for an inspection policy map depends on the application.
•
Traffic matching command—You can define a traffic matching command directly in the inspection
policy map to match application traffic to criteria specific to the application, such as a URL string,
for which you then enable actions.
– Some traffic matching commands can specify regular expressions to match text inside a packet.
Be sure to create and test the regular expressions before you configure the policy map, either
singly or grouped together in a regular expression class map.
•
Inspection class map—(Not available for all applications. See the CLI help for a list of supported
applications.) An inspection class map includes traffic matching commands that match application
traffic with criteria specific to the application, such as a URL string. You then identify the class map
in the policy map and enable actions. The difference between creating a class map and defining the
traffic match directly in the inspection policy map is that you can create more complex match criteria
and you can reuse class maps.
– Some traffic matching commands can specify regular expressions to match text inside a packet.
Be sure to create and test the regular expressions before you configure the policy map, either
singly or grouped together in a regular expression class map.
•
Parameters—Parameters affect the behavior of the inspection engine.
The default inspection policy map configuration includes the following commands, which sets the
maximum message length for DNS packets to be 512 bytes:
policy-map type inspect dns preset_dns_map
parameters
message-length maximum 512
Note
There are other default inspection policy maps such as policy-map type inspect esmtp
_default_esmtp_map. These default policy maps are created implicitly by the command inspect
protocol. For example, inspect esmtp implicitly uses the policy map “_default_esmtp_map.” All the
default policy maps can be shown by using the show running-config all policy-map command.
Defining Actions in an Inspection Policy Map
When you enable an inspection engine in the Layer 3/4 policy map, you can also optionally enable
actions as defined in an inspection policy map.
To create an inspection policy map, perform the following steps:
Step 1
(Optional) Create an inspection class map according to the “Identifying Traffic in an Inspection Class
Map” section on page 16-12. Alternatively, you can identify the traffic directly within the policy map.
Step 2
To create the inspection policy map, enter the following command:
hostname(config)# policy-map type inspect application policy_map_name
hostname(config-pmap)#
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-9
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
See the “Configuring Application Inspection” section on page 26-5 for a list of applications that support
inspection policy maps.
The policy_map_name argument is the name of the policy map up to 40 characters in length. All types
of policy maps use the same name space, so you cannot reuse a name already used by another type of
policy map. The CLI enters policy-map configuration mode.
Step 3
To apply actions to matching traffic, perform the following steps:
a.
Specify the traffic on which you want to perform actions using one of the following methods:
•
Specify the inspection class map that you created in the “Identifying Traffic in an Inspection
Class Map” section on page 16-12 by entering the following command:
hostname(config-pmap)# class class_map_name
hostname(config-pmap-c)#
Not all applications support inspection class maps.
•
b.
Specify traffic directly in the policy map using one of the match commands described for each
application in Chapter 26, “Configuring Application Layer Protocol Inspection.” If you use a
match not command, then any traffic that matches the criterion in the match not command does
not have the action applied.
Specify the action you want to perform on the matching traffic by entering the following command:
hostname(config-pmap-c)# {[drop [send-protocol-error] |
drop-connection [send-protocol-error]| mask | reset] [log] | rate-limit message_rate}
Not all options are available for each application. Other actions specific to the application might also
be available. See Chapter 26, “Configuring Application Layer Protocol Inspection,” for the exact
options available.
The drop keyword drops all packets that match.
The send-protocol-error keyword sends a protocol error message.
The drop-connection keyword drops the packet and closes the connection.
The mask keyword masks out the matching portion of the packet.
The reset keyword drops the packet, closes the connection, and sends a TCP reset to the server
and/or client.
The log keyword, which you can use alone or with one of the other keywords, sends a system log
message.
The rate-limit message_rate argument limits the rate of messages.
Note
You can specify multiple class or match commands in the policy map.
If a packet matches multiple different match or class commands, then the order in which the security
appliance applies the actions is determined by internal security appliance rules, and not by the order they
are added to the policy map. The internal rules are determined by the application type and the logical
progression of parsing a packet, and are not user-configurable. For example for HTTP traffic, parsing a
Request Method field precedes parsing the Header Host Length field; an action for the Request Method
field occurs before the action for the Header Host Length field. For example, the following match
commands can be entered in any order, but the match request method get command is matched first.
match request header host length gt 100
reset
match request method get
log
Cisco Security Appliance Command Line Configuration Guide
16-10
OL-12172-04
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
If an action drops a packet, then no further actions are performed in the inspection policy map. For
example, if the first action is to reset the connection, then it will never match any further match or class
commands. If the first action is to log the packet, then a second action, such as resetting the connection,
can occur. (You can configure both the reset (or drop-connection, and so on.) and the log action for the
same match or class command, in which case the packet is logged before it is reset for a given match.)
If a packet matches multiple match or class commands that are the same, then they are matched in the
order they appear in the policy map. For example, for a packet with the header length of 1001, it will
match the first command below, and be logged, and then will match the second command and be reset.
If you reverse the order of the two match commands, then the packet will be dropped and the connection
reset before it can match the second match command; it will never be logged.
match request header length gt 100
log
match request header length gt 1000
reset
A class map is determined to be the same type as another class map or match command based on the
lowest priority match command in the class map (the priority is based on the internal rules). If a class
map has the same type of lowest priority match command as another class map, then the class maps are
matched according to the order they are added to the policy map. If the lowest priority command for each
class map is different, then the class map with the higher priority match command is matched first. For
example, the following three class maps contain two types of match commands: match request-cmd
(higher priority) and match filename (lower priority). The ftp3 class map includes both commands, but
it is ranked according to the lowest priority command, match filename. The ftp1 class map includes the
highest priority command, so it is matched first, regardless of the order in the policy map. The ftp3 class
map is ranked as being of the same priority as the ftp2 class map, which also contains the match
filename command. They are matched according to the order in the policy map: ftp3 and then ftp2.
class-map type inspect ftp match-all ftp1
match request-cmd get
class-map type inspect ftp match-all ftp2
match filename regex abc
class-map type inspect ftp match-all ftp3
match request-cmd get
match filename regex abc
policy-map type inspect ftp ftp
class ftp3
log
class ftp2
log
class ftp1
log
Step 4
To configure parameters that affect the inspection engine, enter the following command:
hostname(config-pmap)# parameters
hostname(config-pmap-p)#
The CLI enters parameters configuration mode. For the parameters available for each application, see
Chapter 26, “Configuring Application Layer Protocol Inspection.”
The following is an example of an HTTP inspection policy map and the related class maps. This policy
map is activated by the Layer 3/4 policy map, which is enabled by the service policy.
hostname(config)# regex url_example example\.com
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-11
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
hostname(config)# regex url_example2 example2\.com
hostname(config)# class-map type regex match-any URLs
hostname(config-cmap)# match regex url_example
hostname(config-cmap)# match regex url_example2
hostname(config-cmap)#
hostname(config-cmap)#
hostname(config-cmap)#
hostname(config-cmap)#
class-map type inspect http match-all http-traffic
match req-resp content-type mismatch
match request body length gt 1000
match not request uri regex class URLs
hostname(config-cmap)# policy-map type inspect http http-map1
hostname(config-pmap)# class http-traffic
hostname(config-pmap-c)# drop-connection log
hostname(config-pmap-c)# match req-resp content-type mismatch
hostname(config-pmap-c)# reset log
hostname(config-pmap-c)# parameters
hostname(config-pmap-p)# protocol-violation action log
hostname(config-pmap-p)# policy-map test
hostname(config-pmap)# class test (a Layer 3/4 class
hostname(config-pmap-c)# inspect http http-map1
map not shown)
hostname(config-pmap-c)# service-policy test interface outside
Identifying Traffic in an Inspection Class Map
This type of class map allows you to match criteria that is specific to an application. For example, for
DNS traffic, you can match the domain name in a DNS query.
Note
Not all applications support inspection class maps. See the CLI help for a list of supported applications.
A class map groups multiple traffic matches (in a match-all class map), or lets you match any of a list of
matches (in a match-any class map). The difference between creating a class map and defining the traffic
match directly in the inspection policy map is that the class map lets you group multiple match
commands, and you can reuse class maps. For the traffic that you identify in this class map, you can
specify actions such as dropping, resetting, and/or logging the connection in the inspection policy map.
If you want to perform different actions on different types of traffic, you should identify the traffic
directly in the policy map.
To define an inspection class map, perform the following steps:
Step 1
(Optional) If you want to match based on a regular expression, see the “Creating a Regular Expression”
section on page 16-13 and the “Creating a Regular Expression Class Map” section on page 16-16.
Step 2
Create a class map by entering the following command:
hostname(config)# class-map type inspect application [match-all | match-any]
class_map_name
hostname(config-cmap)#
Where the application is the application you want to inspect. For supported applications, see the CLI
help for a list of supported applications or see Chapter 26, “Configuring Application Layer Protocol
Inspection.”
The class_map_name argument is the name of the class map up to 40 characters in length.
Cisco Security Appliance Command Line Configuration Guide
16-12
OL-12172-04
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
The match-all keyword is the default, and specifies that traffic must match all criteria to match the class
map.
The match-any keyword specifies that the traffic matches the class map if it matches at least one of the
criteria.
The CLI enters class-map configuration mode, where you can enter one or more match commands.
Step 3
(Optional) To add a description to the class map, enter the following command:
hostname(config-cmap)# description string
Step 4
Define the traffic to include in the class by entering one or more match commands available for your
application.
To specify traffic that should not match the class map, use the match not command. For example, if the
match not command specifies the string “example.com,” then any traffic that includes “example.com”
does not match the class map.
To see the match commands available for each application, see Chapter 26, “Configuring Application
Layer Protocol Inspection.”
The following example creates an HTTP class map that must match all criteria:
hostname(config-cmap)#
hostname(config-cmap)#
hostname(config-cmap)#
hostname(config-cmap)#
class-map type inspect http match-all http-traffic
match req-resp content-type mismatch
match request body length gt 1000
match not request uri regex class URLs
The following example creates an HTTP class map that can match any of the criteria:
hostname(config-cmap)#
hostname(config-cmap)#
hostname(config-cmap)#
hostname(config-cmap)#
class-map type inspect http match-any monitor-http
match request method get
match request method put
match request method post
Creating a Regular Expression
A regular expression matches text strings either literally as an exact string, or by using metacharacters
so you can match multiple variants of a text string. You can use a regular expression to match the content
of certain application traffic; for example, you can match a URL string inside an HTTP packet.
Use Ctrl+V to escape all of the special characters in the CLI, such as question mark (?) or a tab. For
example, type d[Ctrl+V]?g to enter d?g in the configuration.
See the regex command in the Cisco Security Appliance Command Reference for performance impact
information when matching a regular expression to packets.
Note
As an optimization, the security appliance searches on the deobfuscated URL. Deobfuscation
compresses multiple forward slashes (/) into a single slash. For strings that commonly use double
slashes, like “http://”, be sure to search for “http:/” instead.
Table 16-1 lists the metacharacters that have special meanings.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-13
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
Table 16-1
regex Metacharacters
Character Description
Notes
.
Dot
Matches any single character. For example, d.g matches
dog, dag, dtg, and any word that contains those
characters, such as doggonnit.
(exp)
Subexpression
A subexpression segregates characters from surrounding
characters, so that you can use other metacharacters on
the subexpression. For example, d(o|a)g matches dog
and dag, but do|ag matches do and ag. A subexpression
can also be used with repeat quantifiers to differentiate
the characters meant for repetition. For example,
ab(xy){3}z matches abxyxyxyz.
|
Alternation
Matches either expression it separates. For example,
dog|cat matches dog or cat.
?
Question mark
A quantifier that indicates that there are 0 or 1 of the
previous expression. For example, lo?se matches lse or
lose.
Note
You must enter Ctrl+V and then the question
mark or else the help function is invoked.
*
Asterisk
A quantifier that indicates that there are 0, 1 or any
number of the previous expression. For example, lo*se
matches lse, lose, loose, and so on.
+
Plus
A quantifier that indicates that there is at least 1 of the
previous expression. For example, lo+se matches lose
and loose, but not lse.
{x} or {x,} Minimum repeat quantifier
Repeat at least x times. For example, ab(xy){2,}z
matches abxyxyz, abxyxyxyz, and so on.
[abc]
Character class
Matches any character in the brackets. For example,
[abc] matches a, b, or c.
[^abc]
Negated character class
Matches a single character that is not contained within
the brackets. For example, [^abc] matches any character
other than a, b, or c. [^A-Z] matches any single
character that is not an uppercase letter.
[a-c]
Character range class
Matches any character in the range. [a-z] matches any
lowercase letter. You can mix characters and ranges:
[abcq-z] matches a, b, c, q, r, s, t, u, v, w, x, y, z, and so
does [a-cq-z].
The dash (-) character is literal only if it is the last or the
first character within the brackets: [abc-] or [-abc].
""
Quotation marks
Preserves trailing or leading spaces in the string. For
example, " test" preserves the leading space when it
looks for a match.
^
Caret
Specifies the beginning of a line.
\
Escape character
When used with a metacharacter, matches a literal
character. For example, \[ matches the left square
bracket.
Cisco Security Appliance Command Line Configuration Guide
16-14
OL-12172-04
Chapter 16
Using Modular Policy Framework
Configuring Special Actions for Application Inspections (Inspection Policy Map)
Table 16-1
regex Metacharacters (continued)
Character Description
Notes
char
Character
When character is not a metacharacter, matches the
literal character.
\r
Carriage return
Matches a carriage return 0x0d.
\n
Newline
Matches a new line 0x0a.
\t
Tab
Matches a tab 0x09.
\f
Formfeed
Matches a form feed 0x0c.
\xNN
Escaped hexadecimal number
Matches an ASCII character using hexadecimal (exactly
two digits).
\NNN
Escaped octal number
Matches an ASCII character as octal (exactly three
digits). For example, the character 040 represents a
space.
To test and create a regular expression, perform the following steps:
Step 1
To test a regular expression to make sure it matches what you think it will match, enter the following
command:
hostname(config)# test regex input_text regular_expression
Where the input_text argument is a string you want to match using the regular expression, up to 201
characters in length.
The regular_expression argument can be up to 100 characters in length.
Use Ctrl+V to escape all of the special characters in the CLI. For example, to enter a tab in the input
text in the test regex command, you must enter test regex "test[Ctrl+V Tab]" "test\t".
If the regular expression matches the input text, you see the following message:
INFO: Regular expression match succeeded.
If the regular expression does not match the input text, you see the following message:
INFO: Regular expression match failed.
Step 2
To add a regular expression after you tested it, enter the following command:
hostname(config)# regex name regular_expression
Where the name argument can be up to 40 characters in length.
The regular_expression argument can be up to 100 characters in length.
The following example creates two regular expressions for use in an inspection policy map:
hostname(config)# regex url_example example\.com
hostname(config)# regex url_example2 example2\.com
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-15
Chapter 16
Using Modular Policy Framework
Defining Actions (Layer 3/4 Policy Map)
Creating a Regular Expression Class Map
A regular expression class map identifies one or more regular expressions. You can use a regular
expression class map to match the content of certain traffic; for example, you can match URL strings
inside HTTP packets.
To create a regular expression class map, perform the following steps:
Step 1
Create one or more regular expressions according to the “Creating a Regular Expression” section.
Step 2
Create a class map by entering the following command:
hostname(config)# class-map type regex match-any class_map_name
hostname(config-cmap)#
Where class_map_name is a string up to 40 characters in length. The name “class-default” is reserved.
All types of class maps use the same name space, so you cannot reuse a name already used by another
type of class map.
The match-any keyword specifies that the traffic matches the class map if it matches at least one of the
regular expressions.
The CLI enters class-map configuration mode.
Step 3
(Optional) Add a description to the class map by entering the following command:
hostname(config-cmap)# description string
Step 4
Identify the regular expressions you want to include by entering the following command for each regular
expression:
hostname(config-cmap)# match regex regex_name
The following example creates two regular expressions, and adds them to a regular expression class map.
Traffic matches the class map if it includes the string “example.com” or “example2.com.”
hostname(config)# regex url_example example\.com
hostname(config)# regex url_example2 example2\.com
hostname(config)# class-map type regex match-any URLs
hostname(config-cmap)# match regex url_example
hostname(config-cmap)# match regex url_example2
Defining Actions (Layer 3/4 Policy Map)
This section describes how to associate actions with Layer 3/4 class maps by creating a Layer 3/4 policy
map. This section includes the following topics:
•
Information About Layer 3/4 Policy Maps, page 16-17
•
Default Layer 3/4 Policy Map, page 16-21
•
Adding a Layer 3/4 Policy Map, page 16-22
Cisco Security Appliance Command Line Configuration Guide
16-16
OL-12172-04
Chapter 16
Using Modular Policy Framework
Defining Actions (Layer 3/4 Policy Map)
Information About Layer 3/4 Policy Maps
This section describes how Layer 3/4 policy maps work, and includes the following topics:
•
Policy Map Guidelines, page 16-17
•
Hierarchical Policy Maps, page 16-17
•
Feature Directionality, page 16-18
•
Feature Matching Guidelines Within a Policy Map, page 16-18
•
Order in Which Multiple Feature Actions are Applied, page 16-19
•
Incompatibility of Certain Feature Actions, page 16-20
•
Order in Which Multiple Feature Actions are Applied, page 16-19
Policy Map Guidelines
See the following guidelines for using policy maps:
•
You can only assign one policy map per interface. (However you can create up to 64 policy maps in
the configuration.)
•
You can apply the same policy map to multiple interfaces.
•
You can identify multiple Layer 3/4 class maps in a Layer 3/4 policy map.
•
For each class map, you can assign multiple actions from one or more feature types, if supported.
See the “Incompatibility of Certain Feature Actions” section on page 16-20.
Hierarchical Policy Maps
If you enable QoS traffic shaping for a class map, then you can optionally enable priority queueing for
a subset of shaped traffic. To do so, you need to create a policy map for the priority queueing, and then
within the traffic shaping policy map, you can call the priority class map. Only the traffic shaping class
map is applied to an interface.
See Chapter 25, “QoS Overview,” for more information about this feature.
Hierarchical policy maps are only supported for traffic shaping and priority queueing.
To implement a hierarchical policy map, perform the following tasks:
1.
Identify the prioritized traffic according to the “Identifying Traffic (Layer 3/4 Class Map)” section
on page 16-4.
You can create multiple class maps to be used in the hierarchical policy map.
2.
Create a policy map according to the “Defining Actions (Layer 3/4 Policy Map)” section on
page 16-16, and identify the sole action for each class map as priority.
3.
Create a separate policy map according to the “Defining Actions (Layer 3/4 Policy Map)” section
on page 16-16, and identify the shape action for the class-default class map.
Traffic shaping can only be applied the to class-default class map.
4.
For the same class map, identify the priority policy map that you created in Step 2 using the
service-policy priority_policy_map command.
5.
Apply the shaping policy map to the interface accrding to “Applying Actions to an Interface (Service
Policy)” section on page 16-23.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-17
Chapter 16
Using Modular Policy Framework
Defining Actions (Layer 3/4 Policy Map)
Feature Directionality
Actions are applied to traffic bidirectionally or unidirectionally depending on the feature. For features
that are applied bidirectionally, all traffic that enters or exits the interface to which you apply the policy
map is affected if the traffic matches the class map for both directions.
Note
When you use a global policy, all features are unidirectional; features that are normally bidirectional
when applied to a single interface only apply to the ingress of each interface when applied globally.
Because the policy is applied to all interfaces, the policy will be applied in both directions so
bidirectionality in this case is redundant.
For features that are applied unidirectionally, for example QoS priority queue, only traffic that exits the
interface to which you apply the policy map is affected. See Table 16-2 for the directionality of each
feature.
Table 16-2
Feature Directionality
Feature
Single Interface Direction Global Direction
Application inspection (multiple types)
Bidirectional
Ingress
CSC
Bidirectional
Ingress
IPS
Bidirectional
Ingress
QoS input policing
Ingress
Ingress
QoS output policing
Egress
Egress
QoS standard priority queue
Egress
Egress
QoS traffic shaping, hierarchical priority
queue
Egress
Egress
TCP normalization, TCP and UDP connection Bidirectional
limits and timeouts, and TCP sequence number
randomization
Ingress
Feature Matching Guidelines Within a Policy Map
See the following guidelines for how a packet matches class maps in a policy map:
1.
A packet can match only one class map in the policy map for each feature type.
2.
When the packet matches a class map for a feature type, the security appliance does not attempt to
match it to any subsequent class maps for that feature type.
3.
If the packet matches a subsequent class map for a different feature type, however, then the security
appliance also applies the actions for the subsequent class map, if supported. See the
“Incompatibility of Certain Feature Actions” section on page 16-20 for more information about
unsupported combinations.
For example, if a packet matches a class map for connection limits, and also matches a class map for
application inspection, then both class map actions are applied.
If a packet matches a class map for HTTP inspection, but also matches another class map that includes
HTTP inspection, then the second class map actions are not applied.
Cisco Security Appliance Command Line Configuration Guide
16-18
OL-12172-04
Chapter 16
Using Modular Policy Framework
Defining Actions (Layer 3/4 Policy Map)
Note
Application inspection includes multiple inspection types, and each inspection type is a separate feature
when you consider the matching guidelines above.
Order in Which Multiple Feature Actions are Applied
The order in which different types of actions in a policy map are performed is independent of the order
in which the actions appear in the policy map. Actions are performed in the following order:
1.
QoS input policing
2.
TCP normalization, TCP and UDP connection limits and timeouts, and TCP sequence number
randomization
Note
When a the security appliance performs a proxy service (such as AAA or CSC) or it modifies
the TCP payload (such as FTP inspection), the TCP normalizer acts in dual mode, where it is
applied before and after the proxy or payload modifying service.
3.
CSC
4.
Application inspection (multiple types)
The order of application inspections applied when a class of traffic is classified for multiple
inspections is as follows. Only one inspection type can be applied to the same traffic. WAAS
inspection is an exception, because it can applied along with other inspections for the same traffic.
See the “Incompatibility of Certain Feature Actions” section on page 16-20 for more information.
a. CTIQBE
b. DNS
c. FTP
d. GTP
e. H323
f. HTTP
g. ICMP
h. ICMP error
i. ILS
j. MGCP
k. NetBIOS
l. PPTP
m. Sun RPC
n. RSH
o. RTSP
p. SIP
q. Skinny
r. SMTP
s. SNMP
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-19
Chapter 16
Using Modular Policy Framework
Defining Actions (Layer 3/4 Policy Map)
t. SQL*Net
u. TFTP
v. XDMCP
w. DCERPC
x. Instant Messaging
Note
RADIUS accounting is not listed because it is the only inspection allowed on management
traffic. WAAS is not listed because it can be configured along with other inspections for the
same traffic.
5.
IPS
6.
QoS output policing
7.
QoS standard priority queue
8.
QoS traffic shaping, hierarchical priority queue
Incompatibility of Certain Feature Actions
Some features are not compatible with each other for the same traffic. For example, you cannot configure
QoS priority queueing and QoS policing for the same set of traffic. Also, most inspections should not be
combined with another inspection, so the security appliance only applies one inspection if you configure
multiple inspections for the same traffic. In this case, the feature that is applied is the higher priority
feature in the list in the “Order in Which Multiple Feature Actions are Applied” section on page 16-19.
For information about compatibility of each feature, see the chapter or section for your feature.
Note
The match default-inspection-traffic command, which is used in the default global policy, is a special
CLI shortcut to match the default ports for all inspections. When used in a policy map, this class map
ensures that the correct inspection is applied to each packet, based on the destination port of the traffic.
For example, when UDP traffic for port 69 reaches the security appliance, then the security appliance
applies the TFTP inspection; when TCP traffic for port 21 arrives, then the security appliance applies
the FTP inspection. So in this case only, you can configure multiple inspections for the same class map.
Normally, the security appliance does not use the port number to determine the inspection applied, thus
giving you the flexibility to apply inspections to non-standard ports, for example.
An example of a misconfiguration is if you configure multiple inspections in the same policy map and
do not use the default-inspection-traffic shortcut. In Example 16-1, traffic destined to port 21 is
mistakenly configured for both FTP and HTTP inspection. In Example 16-2, traffic destined to port 80
is mistakenly configured for both FTP and HTTP inspection. In both cases of misconfiguration
examples, only the FTP inspection is applied, because FTP comes before HTTP in the order of
inspections applied.
Example 16-1 Misconfiguration for FTP packets: HTTP Inspection Also Configured
class-map ftp
match port tcp 21
class-map http
match port tcp 21
policy-map test
class ftp
[it should be 80]
Cisco Security Appliance Command Line Configuration Guide
16-20
OL-12172-04
Chapter 16
Using Modular Policy Framework
Defining Actions (Layer 3/4 Policy Map)
inspect ftp
class http
inspect http
Example 16-2 Misconfiguration for HTTP packets: FTP Inspection Also Configured
class-map ftp
match port tcp 80
class-map http
match port tcp 80
policy-map test
class http
inspect http
class ftp
inspect ftp
[it should be 21]
Feature Matching Guidelines for Multiple Policy Maps
For TCP and UDP traffic (and ICMP when you enable stateful ICMP inspection), Modular Policy
Framework operates on traffic flows, and not just individual packets. If traffic is part of an existing
connection that matches a feature in a policy on one interface, that traffic flow cannot also match the
same feature in a policy on another interface; only the first policy is used.
For example, if HTTP traffic matches a policy on the inside interface to inspect HTTP traffic, and you
have a separate policy on the outside interface for HTTP inspection, then that traffic is not also inspected
on the egress of the outside interface. Similarly, the return traffic for that connection will not be
inspected by the ingress policy of the outside interface, nor by the egress policy of the inside interface.
For traffic that is not treated as a flow, for example ICMP when you do not enable stateful ICMP
inspection, returning traffic can match a different policy map on the returning interface. For example, if
you configure IPS inspection on the inside and outside interfaces, but the inside policy uses virtual
sensor 1 while the outside policy uses virtual sensor 2, then a non-stateful Ping will match virtual sensor
1 outbound, but will match virtual sensor 2 inbound.
Default Layer 3/4 Policy Map
The configuration includes a default Layer 3/4 policy map that the security appliance uses in the default
global policy. It is called global_policy and performs inspection on the default inspection traffic. You
can only apply one global policy, so if you want to alter the global policy, you need to either reconfigure
the default policy or disable it and apply a new one.
The default policy map configuration includes the following commands:
policy-map global_policy
class inspection_default
inspect dns preset_dns_map
inspect ftp
inspect h323 h225
inspect h323 ras
inspect rsh
inspect rtsp
inspect esmtp
inspect sqlnet
inspect skinny
inspect sunrpc
inspect xdmcp
inspect sip
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-21
Chapter 16
Using Modular Policy Framework
Defining Actions (Layer 3/4 Policy Map)
inspect netbios
inspect tftp
Note
See the “Incompatibility of Certain Feature Actions” section on page 16-20 for more information about
the special match default-inspection-traffic command used in the default class map.
Adding a Layer 3/4 Policy Map
The maximum number of policy maps is 64. To create a Layer 3/4 policy map, perform the following
steps:
Step 1
Add the policy map by entering the following command:
hostname(config)# policy-map policy_map_name
The policy_map_name argument is the name of the policy map up to 40 characters in length. All types
of policy maps use the same name space, so you cannot reuse a name already used by another type of
policy map. The CLI enters policy-map configuration mode.
Step 2
(Optional) Specify a description for the policy map:
hostname(config-pmap)# description text
Step 3
Specify a previously configured Layer 3/4 class map using the following command:
hostname(config-pmap)# class class_map_name
where the class_map_name is the name of the class map you created earlier. See the “Identifying Traffic
(Layer 3/4 Class Map)” section on page 16-4 to add a class map.
Step 4
Specify one or more actions for this class map.
•
IPS. See the “Diverting Traffic to the AIP SSM” section on page 23-8.
•
CSC. See the “Diverting Traffic to the CSC SSM” section on page 23-16.
•
TCP normalization. See the “Configuring TCP Normalization” section on page 24-12.
•
TCP and UDP connection limits and timeouts, and TCP sequence number randomization. See the
“Configuring Connection Limits and Timeouts” section on page 24-17.
•
QoS. See Chapter 25, “Configuring QoS.”
Note
•
Application inspection. See Chapter 26, “Configuring Application Layer Protocol Inspection.”
Note
Step 5
You can configure a hierarchical policy map for the traffic shaping and priority queue
features. See the “Hierarchical Policy Maps” section on page 16-17 for more information.
If there is no match default_inspection_traffic command in a class map, then at most one
inspect command is allowed to be configured under the class.
Repeat Step 3 and Step 4 for each class map you want to include in this policy map.
Cisco Security Appliance Command Line Configuration Guide
16-22
OL-12172-04
Chapter 16
Using Modular Policy Framework
Applying Actions to an Interface (Service Policy)
The following is an example of a policy-map command for connection policy. It limits the number of
connections allowed to the web server 10.1.1.1:
hostname(config)# access-list http-server permit tcp any host 10.1.1.1
hostname(config)# class-map http-server
hostname(config-cmap)# match access-list http-server
hostname(config)# policy-map global-policy
hostname(config-pmap)# description This policy map defines a policy concerning connection
to http server.
hostname(config-pmap)# class http-server
hostname(config-pmap-c)# set connection conn-max 256
The following example shows how multi-match works in a policy map:
hostname(config)# class-map inspection_default
hostname(config-cmap)# match default-inspection-traffic
hostname(config)# class-map http_traffic
hostname(config-cmap)# match port tcp eq 80
hostname(config)# policy-map outside_policy
hostname(config-pmap)# class inspection_default
hostname(config-pmap-c)# inspect http http_map
hostname(config-pmap-c)# inspect sip
hostname(config-pmap)# class http_traffic
hostname(config-pmap-c)# set connection timeout tcp 0:10:0
The following example shows how traffic matches the first available class map, and will not match any
subsequent class maps that specify actions in the same feature domain:
hostname(config)# class-map telnet_traffic
hostname(config-cmap)# match port tcp eq 23
hostname(config)# class-map ftp_traffic
hostname(config-cmap)# match port tcp eq 21
hostname(config)# class-map tcp_traffic
hostname(config-cmap)# match port tcp range 1 65535
hostname(config)# class-map udp_traffic
hostname(config-cmap)# match port udp range 0 65535
hostname(config)# policy-map global_policy
hostname(config-pmap)# class telnet_traffic
hostname(config-pmap-c)# set connection timeout tcp 0:0:0
hostname(config-pmap-c)# set connection conn-max 100
hostname(config-pmap)# class ftp_traffic
hostname(config-pmap-c)# set connection timeout tcp 0:5:0
hostname(config-pmap-c)# set connection conn-max 50
hostname(config-pmap)# class tcp_traffic
hostname(config-pmap-c)# set connection timeout tcp 2:0:0
hostname(config-pmap-c)# set connection conn-max 2000
When a Telnet connection is initiated, it matches class telnet_traffic. Similarly, if an FTP connection is
initiated, it matches class ftp_traffic. For any TCP connection other than Telnet and FTP, it will match
class tcp_traffic. Even though a Telnet or FTP connection can match class tcp_traffic, the security
appliance does not make this match because they previously matched other classes.
Applying Actions to an Interface (Service Policy)
To activate the Layer 3/4 policy map, create a service policy that applies it to one or more interfaces or
that applies it globally to all interfaces. Interface service policies take precedence over the global service
policy for a given feature. For example, if you have a global policy with FTP inspection, and an interface
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-23
Chapter 16
Using Modular Policy Framework
Modular Policy Framework Examples
policy with TCP normalization, then both FTP inspection and TCP normalization are applied to the
interface. However, if you have a global policy with FTP inspection, and an interface policy with FTP
inspection, then only the interface policy FTP inspection is applied to that interface.
•
To create a service policy by associating a policy map with an interface, enter the following
command:
hostname(config)# service-policy policy_map_name interface interface_name
•
To create a service policy that applies to all interfaces that do not have a specific policy, enter the
following command:
hostname(config)# service-policy policy_map_name global
By default, the configuration includes a global policy that matches all default application inspection
traffic and applies inspection to the traffic globally. You can only apply one global policy, so if you
want to alter the global policy, you need to either edit the default policy or disable it and apply a new
one.
The default service policy includes the following command:
service-policy global_policy global
For example, the following command enables the inbound_policy policy map on the outside interface:
hostname(config)# service-policy inbound_policy interface outside
The following commands disable the default global policy, and enables a new one called
new_global_policy on all other security appliance interfaces:
hostname(config)# no service-policy global_policy global
hostname(config)# service-policy new_global_policy global
Modular Policy Framework Examples
This section includes several Modular Policy Framework examples, and includes the following topics:
•
Applying Inspection and QoS Policing to HTTP Traffic, page 16-25
•
Applying Inspection to HTTP Traffic Globally, page 16-25
•
Applying Inspection and Connection Limits to HTTP Traffic to Specific Servers, page 16-26
•
Applying Inspection to HTTP Traffic with NAT, page 16-27
Cisco Security Appliance Command Line Configuration Guide
16-24
OL-12172-04
Chapter 16
Using Modular Policy Framework
Modular Policy Framework Examples
Applying Inspection and QoS Policing to HTTP Traffic
In this example (see Figure 16-1), any HTTP connection (TCP traffic on port 80) that enters or exits the
security appliance through the outside interface is classified for HTTP inspection. Any HTTP traffic that
exits the outside interface is classified for policing.
HTTP Inspection and QoS Policing
Security
appliance
port 80
A
insp.
police
port 80
insp.
Host A
inside
outside
Host B
143356
Figure 16-1
See the following commands for this example:
hostname(config)# class-map http_traffic
hostname(config-cmap)# match port tcp eq 80
hostname(config)# policy-map http_traffic_policy
hostname(config-pmap)# class http_traffic
hostname(config-pmap-c)# inspect http
hostname(config-pmap-c)# police output 250000
hostname(config)# service-policy http_traffic_policy interface outside
Applying Inspection to HTTP Traffic Globally
In this example (see Figure 16-2), any HTTP connection (TCP traffic on port 80) that enters the security
appliance through any interface is classified for HTTP inspection. Because the policy is a global policy,
inspection occurs only as the traffic enters each interface.
Figure 16-2
Global HTTP Inspection
Security
appliance
port 80
A
Host A
inside
port 80 insp.
outside
Host B
143414
insp.
See the following commands for this example:
hostname(config)# class-map http_traffic
hostname(config-cmap)# match port tcp eq 80
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-25
Chapter 16
Using Modular Policy Framework
Modular Policy Framework Examples
hostname(config)# policy-map http_traffic_policy
hostname(config-pmap)# class http_traffic
hostname(config-pmap-c)# inspect http
hostname(config)# service-policy http_traffic_policy global
Applying Inspection and Connection Limits to HTTP Traffic to Specific Servers
In this example (see Figure 16-3), any HTTP connection destined for Server A (TCP traffic on port 80)
that enters the security appliance through the outside interface is classified for HTTP inspection and
maximum connection limits. Connections initiated from server A to Host A does not match the access
list in the class map, so it is not affected.
Any HTTP connection destined for Server B that enters the security appliance through the inside
interface is classified for HTTP inspection. Connections initiated from server B to Host B does not match
the access list in the class map, so it is not affected.
Figure 16-3
HTTP Inspection and Connection Limits to Specific Servers
Server A
Real Address: 192.168.1.2
Mapped Address: 209.165.201.1
Security
appliance
port 80
insp.
set conns
port 80
insp. inside
Host B
Real Address: 192.168.1.1
Mapped Address: 209.165.201.2:port
outside
Server B
209.165.200.227
143357
Host A
209.165.200.226
See the following commands for this example:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
static (inside,outside) 209.165.201.1 192.168.1.2
nat (inside) 1 192.168.1.0 255.255.255.0
global (outside) 1 209.165.201.2
access-list serverA extended permit tcp any host 209.165.201.1 eq 80
access-list ServerB extended permit tcp any host 209.165.200.227 eq 80
hostname(config)# class-map http_serverA
hostname(config-cmap)# match access-list serverA
hostname(config)# class-map http_serverB
hostname(config-cmap)# match access-list serverB
hostname(config)# policy-map policy_serverA
hostname(config-pmap)# class http_serverA
hostname(config-pmap-c)# inspect http
hostname(config-pmap-c)# set connection conn-max 100
hostname(config)# policy-map policy_serverB
hostname(config-pmap)# class http_serverB
hostname(config-pmap-c)# inspect http
hostname(config)# service-policy policy_serverB interface inside
hostname(config)# service-policy policy_serverA interface outside
Cisco Security Appliance Command Line Configuration Guide
16-26
OL-12172-04
Chapter 16
Using Modular Policy Framework
Modular Policy Framework Examples
Applying Inspection to HTTP Traffic with NAT
In this example, the Host on the inside network has two addresses: one is the real IP address 192.168.1.1,
and the other is a mapped IP address used on the outside network, 209.165.200.225. Because the policy
is applied to the inside interface, where the real address is used, then you must use the real IP address in
the access list in the class map. If you applied it to the outside interface, you would use the mapped
address.
Figure 16-4
HTTP Inspection with NAT
port 80
insp. inside
outside
Host
Real IP: 192.168.1.1
Mapped IP: 209.165.200.225
Server
209.165.201.1
143416
Security
appliance
See the following commands for this example:
hostname(config)# static (inside,outside) 209.165.200.225 192.168.1.1
hostname(config)# access-list http_client extended permit tcp host 192.168.1.1 any eq 80
hostname(config)# class-map http_client
hostname(config-cmap)# match access-list http_client
hostname(config)# policy-map http_client
hostname(config-pmap)# class http_client
hostname(config-pmap-c)# inspect http
hostname(config)# service-policy http_client interface inside
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
16-27
Chapter 16
Using Modular Policy Framework
Modular Policy Framework Examples
Cisco Security Appliance Command Line Configuration Guide
16-28
OL-12172-04
PA R T
2
Configuring the Firewall
CH A P T E R
17
Firewall Mode Overview
This chapter describes how the firewall works in each firewall mode. To set the firewall mode, see the
“Setting Transparent or Routed Firewall Mode” section on page 2-5.
Note
In multiple context mode, you cannot set the firewall mode separately for each context; you can only set
the firewall mode for the entire security appliance.
This chapter includes the following sections:
•
Routed Mode Overview, page 17-1
•
Transparent Mode Overview, page 17-7
Routed Mode Overview
In routed mode, the security appliance is considered to be a router hop in the network. It can use OSPF
or RIP (in single context mode). Routed mode supports many interfaces. Each interface is on a different
subnet. You can share interfaces between contexts.
This section includes the following topics:
•
IP Routing Support, page 17-1
•
How Data Moves Through the Security Appliance in Routed Firewall Mode, page 17-1
IP Routing Support
The security appliance acts as a router between connected networks, and each interface requires an
IP address on a different subnet. In single context mode, the routed firewall supports OSPF and RIP.
Multiple context mode supports static routes only. We recommend using the advanced routing
capabilities of the upstream and downstream routers instead of relying on the security appliance for
extensive routing needs.
How Data Moves Through the Security Appliance in Routed Firewall Mode
This section describes how data moves through the security appliance in routed firewall mode, and
includes the following topics:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-1
Chapter 17
Firewall Mode Overview
Routed Mode Overview
•
An Inside User Visits a Web Server, page 17-2
•
An Outside User Visits a Web Server on the DMZ, page 17-3
•
An Inside User Visits a Web Server on the DMZ, page 17-4
•
An Outside User Attempts to Access an Inside Host, page 17-5
•
A DMZ User Attempts to Access an Inside Host, page 17-6
An Inside User Visits a Web Server
Figure 17-1 shows an inside user accessing an outside web server.
Figure 17-1
Inside to Outside
www.example.com
Outside
209.165.201.2
Source Addr Translation
10.1.2.27
209.165.201.10
10.1.2.1
10.1.1.1
DMZ
User
10.1.2.27
Web Server
10.1.1.3
92404
Inside
The following steps describe how data moves through the security appliance (see Figure 17-1):
1.
The user on the inside network requests a web page from www.example.com.
2.
The security appliance receives the packet and because it is a new session, the security appliance
verifies that the packet is allowed according to the terms of the security policy (access lists, filters,
AAA).
For multiple context mode, the security appliance first classifies the packet according to either a
unique interface or a unique destination address associated with a context; the destination address
is associated by matching an address translation in a context. In this case, the interface would be
unique; the www.example.com IP address does not have a current address translation in a context.
Cisco Security Appliance Command Line Configuration Guide
17-2
OL-12172-04
Chapter 17
Firewall Mode Overview
Routed Mode Overview
3.
The security appliance translates the local source address (10.1.2.27) to the global address
209.165.201.10, which is on the outside interface subnet.
The global address could be on any subnet, but routing is simplified when it is on the outside
interface subnet.
4.
The security appliance then records that a session is established and forwards the packet from the
outside interface.
5.
When www.example.com responds to the request, the packet goes through the security appliance,
and because the session is already established, the packet bypasses the many lookups associated
with a new connection. The security appliance performs NAT by translating the global destination
address to the local user address, 10.1.2.27.
6.
The security appliance forwards the packet to the inside user.
An Outside User Visits a Web Server on the DMZ
Figure 17-2 shows an outside user accessing the DMZ web server.
Figure 17-2
Outside to DMZ
User
Outside
209.165.201.2
Inside
10.1.1.1
DMZ
Web Server
10.1.1.3
92406
10.1.2.1
Dest Addr Translation
10.1.1.13
209.165.201.3
The following steps describe how data moves through the security appliance (see Figure 17-2):
1.
A user on the outside network requests a web page from the DMZ web server using the global
destination address of 209.165.201.3, which is on the outside interface subnet.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-3
Chapter 17
Firewall Mode Overview
Routed Mode Overview
2.
The security appliance receives the packet and because it is a new session, the security appliance
verifies that the packet is allowed according to the terms of the security policy (access lists, filters,
AAA).
For multiple context mode, the security appliance first classifies the packet according to either a
unique interface or a unique destination address associated with a context; the destination address
is associated by matching an address translation in a context. In this case, the classifier “knows” that
the DMZ web server address belongs to a certain context because of the server address translation.
3.
The security appliance translates the destination address to the local address 10.1.1.3.
4.
The security appliance then adds a session entry to the fast path and forwards the packet from the
DMZ interface.
5.
When the DMZ web server responds to the request, the packet goes through the security appliance
and because the session is already established, the packet bypasses the many lookups associated
with a new connection. The security appliance performs NAT by translating the local source address
to 209.165.201.3.
6.
The security appliance forwards the packet to the outside user.
An Inside User Visits a Web Server on the DMZ
Figure 17-3 shows an inside user accessing the DMZ web server.
Figure 17-3
Inside to DMZ
Outside
209.165.201.2
10.1.2.1
DMZ
92403
Inside
10.1.1.1
User
10.1.2.27
Web Server
10.1.1.3
Cisco Security Appliance Command Line Configuration Guide
17-4
OL-12172-04
Chapter 17
Firewall Mode Overview
Routed Mode Overview
The following steps describe how data moves through the security appliance (see Figure 17-3):
1.
A user on the inside network requests a web page from the DMZ web server using the destination
address of 10.1.1.3.
2.
The security appliance receives the packet and because it is a new session, the security appliance
verifies that the packet is allowed according to the terms of the security policy (access lists, filters,
AAA).
For multiple context mode, the security appliance first classifies the packet according to either a
unique interface or a unique destination address associated with a context; the destination address
is associated by matching an address translation in a context. In this case, the interface is unique;
the web server IP address does not have a current address translation.
3.
The security appliance then records that a session is established and forwards the packet out of the
DMZ interface.
4.
When the DMZ web server responds to the request, the packet goes through the fast path, which lets
the packet bypass the many lookups associated with a new connection.
5.
The security appliance forwards the packet to the inside user.
An Outside User Attempts to Access an Inside Host
Figure 17-4 shows an outside user attempting to access the inside network.
Figure 17-4
Outside to Inside
www.example.com
Outside
209.165.201.2
Inside
User
10.1.2.27
10.1.1.1
DMZ
92407
10.1.2.1
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-5
Chapter 17
Firewall Mode Overview
Routed Mode Overview
The following steps describe how data moves through the security appliance (see Figure 17-4):
1.
A user on the outside network attempts to reach an inside host (assuming the host has a routable
IP address).
If the inside network uses private addresses, no outside user can reach the inside network without
NAT. The outside user might attempt to reach an inside user by using an existing NAT session.
2.
The security appliance receives the packet and because it is a new session, the security appliance
verifies if the packet is allowed according to the security policy (access lists, filters, AAA).
3.
The packet is denied, and the security appliance drops the packet and logs the connection attempt.
If the outside user is attempting to attack the inside network, the security appliance employs many
technologies to determine if a packet is valid for an already established session.
A DMZ User Attempts to Access an Inside Host
Figure 17-5 shows a user in the DMZ attempting to access the inside network.
Figure 17-5
DMZ to Inside
Outside
209.165.201.2
10.1.2.1
10.1.1.1
DMZ
User
10.1.2.27
Web Server
10.1.1.3
92402
Inside
The following steps describe how data moves through the security appliance (see Figure 17-5):
1.
A user on the DMZ network attempts to reach an inside host. Because the DMZ does not have to
route the traffic on the Internet, the private addressing scheme does not prevent routing.
2.
The security appliance receives the packet and because it is a new session, the security appliance
verifies if the packet is allowed according to the security policy (access lists, filters, AAA).
3.
The packet is denied, and the security appliance drops the packet and logs the connection attempt.
Cisco Security Appliance Command Line Configuration Guide
17-6
OL-12172-04
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
Transparent Mode Overview
Traditionally, a firewall is a routed hop and acts as a default gateway for hosts that connect to one of its
screened subnets. A transparent firewall, on the other hand, is a Layer 2 firewall that acts like a “bump
in the wire,” or a “stealth firewall,” and is not seen as a router hop to connected devices.
This section describes transparent firewall mode, and includes the following topics:
•
Transparent Firewall Network, page 17-7
•
Allowing Layer 3 Traffic, page 17-7
•
Allowed MAC Addresses, page 17-7
•
Passing Traffic Not Allowed in Routed Mode, page 17-8
•
MAC Address vs. Route Lookups, page 17-8
•
Using the Transparent Firewall in Your Network, page 17-9
•
Transparent Firewall Guidelines, page 17-9
•
Unsupported Features in Transparent Mode, page 17-10
•
How Data Moves Through the Transparent Firewall, page 17-11
Transparent Firewall Network
The security appliance connects the same network on its inside and outside interfaces. Because the
firewall is not a routed hop, you can easily introduce a transparent firewall into an existing network.
Allowing Layer 3 Traffic
IPv4 traffic is allowed through the transparent firewall automatically from a higher security interface to
a lower security interface, without an access list. ARPs are allowed through the transparent firewall in
both directions without an access list. ARP traffic can be controlled by ARP inspection. For Layer 3
traffic travelling from a low to a high security interface, an extended access list is required on the low
security interface. See the “Adding an Extended Access List” section on page 18-5 for more information.
Allowed MAC Addresses
The following destination MAC addresses are allowed through the transparent firewall. Any MAC
address not on this list is dropped.
•
TRUE broadcast destination MAC address equal to FFFF.FFFF.FFFF
•
IPv4 multicast MAC addresses from 0100.5E00.0000 to 0100.5EFE.FFFF
•
IPv6 multicast MAC addresses from 3333.0000.0000 to 3333.FFFF.FFFF
•
BPDU multicast address equal to 0100.0CCC.CCCD
•
Appletalk multicast MAC addresses from 0900.0700.0000 to 0900.07FF.FFFF
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-7
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
Passing Traffic Not Allowed in Routed Mode
In routed mode, some types of traffic cannot pass through the security appliance even if you allow it in
an access list. The transparent firewall, however, can allow almost any traffic through using either an
extended access list (for IP traffic) or an EtherType access list (for non-IP traffic).
Note
The transparent mode security appliance does not pass CDP packets or IPv6 packets, or any packets that
do not have a valid EtherType greater than or equal to 0x600. For example, you cannot pass IS-IS
packets. An exception is made for BPDUs, which are supported.
For example, you can establish routing protocol adjacencies through a transparent firewall; you can
allow OSPF, RIP, EIGRP, or BGP traffic through based on an extended access list. Likewise, protocols
like HSRP or VRRP can pass through the security appliance.
Non-IP traffic (for example AppleTalk, IPX, BPDUs, and MPLS) can be configured to go through using
an EtherType access list.
For features that are not directly supported on the transparent firewall, you can allow traffic to pass
through so that upstream and downstream routers can support the functionality. For example, by using
an extended access list, you can allow DHCP traffic (instead of the unsupported DHCP relay feature) or
multicast traffic such as that created by IP/TV.
MAC Address vs. Route Lookups
When the security appliance runs in transparent mode without NAT, the outgoing interface of a packet
is determined by performing a MAC address lookup instead of a route lookup. Route statements can still
be configured, but they only apply to security appliance-originated traffic. For example, if your syslog
server is located on a remote network, you must use a static route so the security appliance can reach
that subnet.
An exception to this rule is when you use voice inspections and the endpoint is at least one hop away
from the security appliance. For example, if you use the transparent firewall between a CCM and an
H.323 gateway, and there is a router between the transparent firewall and the H.323 gateway, then you
need to add a static route on the security appliance for the H.323 gateway for successful call completion.
If you use NAT, then the security appliance uses a route lookup instead of a MAC address lookup. In
some cases, you will need static routes. For example, if the real destination address is not
directly-connected to the security appliance, then you need to add a static route on the security appliance
for the real destination address that points to the downstream router.
Cisco Security Appliance Command Line Configuration Guide
17-8
OL-12172-04
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
Using the Transparent Firewall in Your Network
Figure 17-6 shows a typical transparent firewall network where the outside devices are on the same
subnet as the inside devices. The inside router and hosts appear to be directly connected to the outside
router.
Figure 17-6
Transparent Firewall Network
Internet
10.1.1.1
Network A
Management IP
10.1.1.2
10.1.1.3
Network B
92411
192.168.1.2
Transparent Firewall Guidelines
Follow these guidelines when planning your transparent firewall network:
•
A management IP address is required; for multiple context mode, an IP address is required for each
context.
Unlike routed mode, which requires an IP address for each interface, a transparent firewall has an
IP address assigned to the entire device. The security appliance uses this IP address as the source
address for packets originating on the security appliance, such as system messages or AAA
communications.
The management IP address must be on the same subnet as the connected network. You cannot set
the subnet to a host subnet (255.255.255.255).
You can configure an IP address for the Management 0/0 management-only interface. This IP
address can be on a separate subnet from the main management IP address.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-9
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
If the management IP address is not configured, transient traffic does not pass through the
transparent firewall. For multiple context mode, transient traffic does not pass through virtual
contexts.
Note
•
The transparent security appliance uses an inside interface and an outside interface only. If your
platform includes a dedicated management interface, you can also configure the management
interface or subinterface for management traffic only.
In single mode, you can only use two data interfaces (and the dedicated management interface, if
available) even if your security appliance includes more than two interfaces.
•
Each directly connected network must be on the same subnet.
•
Do not specify the security appliance management IP address as the default gateway for connected
devices; devices need to specify the router on the other side of the security appliance as the default
gateway.
•
For multiple context mode, each context must use different interfaces; you cannot share an interface
across contexts.
•
For multiple context mode, each context typically uses a different subnet. You can use overlapping
subnets, but your network topology requires router and NAT configuration to make it possible from
a routing standpoint.
Unsupported Features in Transparent Mode
Table 17-1 lists the features are not supported in transparent mode.
Table 17-1
Unsupported Features in Transparent Mode
Feature
Description
Dynamic DNS
—
DHCP relay
The transparent firewall can act as a DHCP server, but it does not
support the DHCP relay commands. DHCP relay is not required
because you can allow DHCP traffic to pass through using two
extended access lists: one that allows DCHP requests from the inside
interface to the outside, and one that allows the replies from the server
in the other direction.
Dynamic routing protocols
You can, however, add static routes for traffic originating on the
security appliance. You can also allow dynamic routing protocols
through the security appliance using an extended access list.
IPv6
You also cannot allow IPv6 using an EtherType access list.
Multicast
You can allow multicast traffic through the security appliance by
allowing it in an extended access list.
Cisco Security Appliance Command Line Configuration Guide
17-10
OL-12172-04
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
Table 17-1
Unsupported Features in Transparent Mode (continued)
Feature
Description
QoS
—
VPN termination for through
traffic
The transparent firewall supports site-to-site VPN tunnels for
management connections only. It does not terminate VPN connections
for traffic through the security appliance. You can pass VPN traffic
through the security appliance using an extended access list, but it
does not terminate non-management connections. WebVPN is also not
supported.
How Data Moves Through the Transparent Firewall
Figure 17-7 shows a typical transparent firewall implementation with an inside network that contains a
public web server. The security appliance has an access list so that the inside users can access Internet
resources. Another access list lets the outside users access only the web server on the inside network.
Figure 17-7
Typical Transparent Firewall Data Path
www.example.com
Internet
209.165.201.2
Management IP
209.165.201.6
Web Server
209.165.200.225
Host
209.165.201.3
92412
209.165.200.230
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-11
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
This section describes how data moves through the security appliance, and includes the following topics:
•
An Inside User Visits a Web Server, page 17-12
•
An Inside User Visits a Web Server Using NAT, page 17-13
•
An Outside User Visits a Web Server on the Inside Network, page 17-14
•
An Outside User Attempts to Access an Inside Host, page 17-15
An Inside User Visits a Web Server
Figure 17-8 shows an inside user accessing an outside web server.
Figure 17-8
Inside to Outside
www.example.com
Internet
209.165.201.2
Host
209.165.201.3
92408
Management IP
209.165.201.6
The following steps describe how data moves through the security appliance (see Figure 17-8):
1.
The user on the inside network requests a web page from www.example.com.
2.
The security appliance receives the packet and adds the source MAC address to the MAC address
table, if required. Because it is a new session, it verifies that the packet is allowed according to the
terms of the security policy (access lists, filters, AAA).
For multiple context mode, the security appliance first classifies the packet according to a unique
interface.
3.
The security appliance records that a session is established.
4.
If the destination MAC address is in its table, the security appliance forwards the packet out of the
outside interface. The destination MAC address is that of the upstream router, 209.186.201.2.
Cisco Security Appliance Command Line Configuration Guide
17-12
OL-12172-04
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
If the destination MAC address is not in the security appliance table, the security appliance attempts
to discover the MAC address by sending an ARP request and a ping. The first packet is dropped.
5.
The web server responds to the request; because the session is already established, the packet
bypasses the many lookups associated with a new connection.
6.
The security appliance forwards the packet to the inside user.
An Inside User Visits a Web Server Using NAT
Figure 17-8 shows an inside user accessing an outside web server.
Figure 17-9
Inside to Outside with NAT
www.example.com
Internet
Static route on router
to 209.165.201.0/27
through security appliance
Source Addr Translation
10.1.2.27
209.165.201.10
10.1.2.1
Management IP
10.1.2.2
Host
10.1.2.27
191243
Security
appliance
The following steps describe how data moves through the security appliance (see Figure 17-8):
1.
The user on the inside network requests a web page from www.example.com.
2.
The security appliance receives the packet and adds the source MAC address to the MAC address
table, if required. Because it is a new session, it verifies that the packet is allowed according to the
terms of the security policy (access lists, filters, AAA).
For multiple context mode, the security appliance first classifies the packet according to a unique
interface.
3.
The security appliance translates the real address (10.1.2.27) to the mapped address 209.165.201.10.
Because the mapped address is not on the same network as the outside interface, then be sure the
upstream router has a static route to the mapped network that points to the security appliance.
4.
The security appliance then records that a session is established and forwards the packet from the
outside interface.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-13
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
5.
If the destination MAC address is in its table, the security appliance forwards the packet out of the
outside interface. The destination MAC address is that of the upstream router, 209.165.201.2.
If the destination MAC address is not in the security appliance table, the security appliance attempts
to discover the MAC address by sending an ARP request and a ping. The first packet is dropped.
6.
The web server responds to the request; because the session is already established, the packet
bypasses the many lookups associated with a new connection.
7.
The security appliance performs NAT by translating the mapped address to the real address,
10.1.2.27.
An Outside User Visits a Web Server on the Inside Network
Figure 17-10 shows an outside user accessing the inside web server.
Figure 17-10
Outside to Inside
Host
Internet
209.165.201.2
Management IP
209.165.201.6
209.165.201.1
Web Server
209.165.200.225
92409
209.165.200.230
The following steps describe how data moves through the security appliance (see Figure 17-10):
1.
A user on the outside network requests a web page from the inside web server.
2.
The security appliance receives the packet and adds the source MAC address to the MAC address
table, if required. Because it is a new session, it verifies that the packet is allowed according to the
terms of the security policy (access lists, filters, AAA).
Cisco Security Appliance Command Line Configuration Guide
17-14
OL-12172-04
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
For multiple context mode, the security appliance first classifies the packet according to a unique
interface.
3.
The security appliance records that a session is established.
4.
If the destination MAC address is in its table, the security appliance forwards the packet out of the
inside interface. The destination MAC address is that of the downstream router, 209.186.201.1.
If the destination MAC address is not in the security appliance table, the security appliance attempts
to discover the MAC address by sending an ARP request and a ping. The first packet is dropped.
5.
The web server responds to the request; because the session is already established, the packet
bypasses the many lookups associated with a new connection.
6.
The security appliance forwards the packet to the outside user.
An Outside User Attempts to Access an Inside Host
Figure 17-11 shows an outside user attempting to access a host on the inside network.
Figure 17-11
Outside to Inside
Host
Internet
209.165.201.2
92410
Management IP
209.165.201.6
Host
209.165.201.3
The following steps describe how data moves through the security appliance (see Figure 17-11):
1.
A user on the outside network attempts to reach an inside host.
2.
The security appliance receives the packet and adds the source MAC address to the MAC address
table, if required. Because it is a new session, it verifies if the packet is allowed according to the
terms of the security policy (access lists, filters, AAA).
For multiple context mode, the security appliance first classifies the packet according to a unique
interface.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
17-15
Chapter 17
Firewall Mode Overview
Transparent Mode Overview
3.
The packet is denied, and the security appliance drops the packet.
4.
If the outside user is attempting to attack the inside network, the security appliance employs many
technologies to determine if a packet is valid for an already established session.
Cisco Security Appliance Command Line Configuration Guide
17-16
OL-12172-04
CH A P T E R
18
Identifying Traffic with Access Lists
This chapter describes how to identify traffic with access lists. This chapter includes the following
topics:
•
Access List Overview, page 18-1
•
Adding an Extended Access List, page 18-5
•
Adding an EtherType Access List, page 18-8
•
Adding a Standard Access List, page 18-11
•
Adding a Webtype Access List, page 18-11
•
Simplifying Access Lists with Object Grouping, page 18-12
•
Adding Remarks to Access Lists, page 18-19
•
Scheduling Extended Access List Activation, page 18-19
•
Logging Access List Activity, page 18-21
For information about IPv6 access lists, see the “Configuring IPv6 Access Lists” section on page 13-6.
Access List Overview
Access lists are made up of one or more Access Control Entries. An ACE is a single entry in an access
list that specifies a permit or deny rule, and is applied to a protocol, a source and destination IP address
or network, and optionally the source and destination ports.
Access lists are used in a variety of features. If your feature uses Modular Policy Framework, you can
use an access list to identify traffic within a traffic class map. For more information on Modular Policy
Framework, see Chapter 16, “Using Modular Policy Framework.”
This section includes the following topics:
•
Access List Types, page 18-2
•
Access Control Entry Order, page 18-2
•
Access Control Implicit Deny, page 18-3
•
IP Addresses Used for Access Lists When You Use NAT, page 18-3
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-1
Chapter 18
Identifying Traffic with Access Lists
Access List Overview
Access List Types
Table 18-1 lists the types of access lists and some common uses for them.
Table 18-1
Access List Types and Common Uses
Access List Use
Access List Type
Description
Control network access for IP traffic
(routed and transparent mode)
Extended
The security appliance does not allow any traffic from a
lower security interface to a higher security interface
unless it is explicitly permitted by an extended access list.
Note
Identify traffic for AAA rules
Extended
To access the security appliance interface for
management access, you do not also need an
access list allowing the host IP address. You only
need to configure management access according
to Chapter 42, “Managing System Access.”
AAA rules use access lists to identify traffic.
Control network access for IP traffic for a Extended,
given user
downloaded from a
AAA server per user
You can configure the RADIUS server to download a
dynamic access list to be applied to the user, or the server
can send the name of an access list that you already
configured on the security appliance.
Identify addresses for NAT (policy NAT
and NAT exemption)
Extended
Policy NAT lets you identify local traffic for address
translation by specifying the source and destination
addresses in an extended access list.
Establish VPN access
Extended
You can use an extended access list in VPN commands.
Identify traffic in a traffic class map for
Modular Policy Framework
Extended
Access lists can be used to identify traffic in a class map,
which is used for features that support Modular Policy
Framework. Features that support Modular Policy
Framework include TCP and general connection settings,
and inspection.
For transparent firewall mode, control
network access for non-IP traffic
EtherType
You can configure an access list that controls traffic based
on its EtherType.
Identify OSPF route redistribution
Standard
Standard access lists include only the destination address.
You can use a standard access list to control the
redistribution of OSPF routes.
Filtering for WebVPN
Webtype
You can configure a Webtype access list to filter URLs.
EtherType
Access Control Entry Order
An access list is made up of one or more Access Control Entries. Depending on the access list type, you
can specify the source and destination addresses, the protocol, the ports (for TCP or UDP), the ICMP
type (for ICMP), or the EtherType.
Each ACE that you enter for a given access list name is appended to the end of the access list.
The order of ACEs is important. When the security appliance decides whether to forward or drop a
packet, the security appliance tests the packet against each ACE in the order in which the entries are
listed. After a match is found, no more ACEs are checked. For example, if you create an ACE at the
beginning of an access list that explicitly permits all traffic, no further statements are ever checked.
Cisco Security Appliance Command Line Configuration Guide
18-2
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Access List Overview
You can disable an ACE by specifying the keyword inactive in the access-list command.
Access Control Implicit Deny
Access lists have an implicit deny at the end of the list, so unless you explicitly permit it, traffic cannot
pass. For example, if you want to allow all users to access a network through the security appliance
except for particular addresses, then you need to deny the particular addresses and then permit all others.
For EtherType access lists, the implicit deny at the end of the access list does not affect IP traffic or
ARPs; for example, if you allow EtherType 8037, the implicit deny at the end of the access list does not
now block any IP traffic that you previously allowed with an extended access list (or implicitly allowed
from a high security interface to a low security interface). However, if you explicitly deny all traffic with
an EtherType ACE, then IP and ARP traffic is denied.
IP Addresses Used for Access Lists When You Use NAT
When you use NAT, the IP addresses you specify for an access list depend on the interface to which the
access list is attached; you need to use addresses that are valid on the network connected to the interface.
This guideline applies for both inbound and outbound access lists: the direction does not determine the
address used, only the interface does.
For example, you want to apply an access list to the inbound direction of the inside interface. You
configure the security appliance to perform NAT on the inside source addresses when they access outside
addresses. Because the access list is applied to the inside interface, the source addresses are the original
untranslated addresses. Because the outside addresses are not translated, the destination address used in
the access list is the real address (see Figure 18-1).
Figure 18-1
IP Addresses in Access Lists: NAT Used for Source Addresses
209.165.200.225
Outside
Inside
Inbound ACL
Permit from 10.1.1.0/24 to 209.165.200.225
10.1.1.0/24
209.165.201.4:port
PAT
104634
10.1.1.0/24
See the following commands for this example:
hostname(config)# access-list INSIDE extended permit ip 10.1.1.0 255.255.255.0 host
209.165.200.225
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-3
Chapter 18
Identifying Traffic with Access Lists
Access List Overview
hostname(config)# access-group INSIDE in interface inside
If you want to allow an outside host to access an inside host, you can apply an inbound access list on the
outside interface. You need to specify the translated address of the inside host in the access list because
that address is the address that can be used on the outside network (see Figure 18-2).
Figure 18-2
IP Addresses in Access Lists: NAT used for Destination Addresses
209.165.200.225
ACL
Permit from 209.165.200.225 to 209.165.201.5
Outside
10.1.1.34
209.165.201.5
Static NAT
104636
Inside
See the following commands for this example:
hostname(config)# access-list OUTSIDE extended permit ip host 209.165.200.225 host
209.165.201.5
hostname(config)# access-group OUTSIDE in interface outside
Cisco Security Appliance Command Line Configuration Guide
18-4
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Adding an Extended Access List
If you perform NAT on both interfaces, keep in mind the addresses that are visible to a given interface.
In Figure 18-3, an outside server uses static NAT so that a translated address appears on the inside
network.
Figure 18-3
IP Addresses in Access Lists: NAT used for Source and Destination Addresses
Static NAT
209.165.200.225
10.1.1.56
Outside
Inside
ACL
Permit from 10.1.1.0/24 to 10.1.1.56
10.1.1.0/24
209.165.201.4:port
PAT
104635
10.1.1.0/24
See the following commands for this example:
hostname(config)# access-list INSIDE extended permit ip 10.1.1.0 255.255.255.0 host
10.1.1.56
hostname(config)# access-group INSIDE in interface inside
Adding an Extended Access List
This section describes how to add an extended access list, and includes the following sections:
•
Extended Access List Overview, page 18-5
•
Allowing Broadcast and Multicast Traffic through the Transparent Firewall, page 18-6
•
Adding an Extended ACE, page 18-7
Extended Access List Overview
An extended access list is made up of one or more ACEs, in which you can specify the line number to
insert the ACE, source and destination addresses, and, depending on the ACE type, the protocol, the
ports (for TCP or UDP), or the ICMP type (for ICMP). You can identify all of these parameters within
the access-list command, or you can use object groups for each parameter. This section describes how
to identify the parameters within the command. To use object groups, see the “Simplifying Access Lists
with Object Grouping” section on page 18-12.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-5
Chapter 18
Identifying Traffic with Access Lists
Adding an Extended Access List
For information about logging options that you can add to the end of the ACE, see the “Logging Access
List Activity” section on page 18-21. For information about time range options, see “Scheduling
Extended Access List Activation” section on page 18-19.
For TCP and UDP connections for both routed and transparent mode, you do not need an access list to
allow returning traffic, because the security appliance allows all returning traffic for established,
bidirectional connections. For connectionless protocols such as ICMP, however, the security appliance
establishes unidirectional sessions, so you either need access lists to allow ICMP in both directions (by
applying access lists to the source and destination interfaces), or you need to enable the ICMP inspection
engine. The ICMP inspection engine treats ICMP sessions as bidirectional connections.
You can apply only one access list of each type (extended and EtherType) to each direction of an
interface. You can apply the same access lists on multiple interfaces. See Chapter 20, “Permitting or
Denying Network Access,” for more information about applying an access list to an interface.
Note
If you change the access list configuration, and you do not want to wait for existing connections to time
out before the new access list information is used, you can clear the connections using the clear
local-host command.
Allowing Broadcast and Multicast Traffic through the Transparent Firewall
In routed firewall mode, broadcast and multicast traffic is blocked even if you allow it in an access list,
including unsupported dynamic routing protocols and DHCP (unless you configure DHCP relay).
Transparent firewall mode can allow any IP traffic through. This feature is especially useful in multiple
context mode, which does not allow dynamic routing, for example.
Note
Because these special types of traffic are connectionless, you need to apply an extended access list to
both interfaces, so returning traffic is allowed through.
Table 18-2 lists common traffic types that you can allow through the transparent firewall.
Table 18-2
Transparent Firewall Special Traffic
Traffic Type
Protocol or Port
Notes
DHCP
UDP ports 67 and 68
If you enable the DHCP server, then the security
appliance does not pass DHCP packets.
EIGRP
Protocol 88
—
OSPF
Protocol 89
—
Multicast streams The UDP ports vary depending
on the application.
Multicast streams are always destined to a
Class D address (224.0.0.0 to 239.x.x.x).
RIP (v1 or v2)
—
UDP port 520
Cisco Security Appliance Command Line Configuration Guide
18-6
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Adding an Extended Access List
Adding an Extended ACE
When you enter the access-list command for a given access list name, the ACE is added to the end of
the access list unless you specify the line number.
To add an ACE, enter the following command:
hostname(config)# access-list access_list_name [line line_number] [extended]
{deny | permit} protocol source_address mask [operator port] dest_address mask
[operator port | icmp_type] [inactive]
Tip
Enter the access list name in upper case letters so the name is easy to see in the configuration. You might
want to name the access list for the interface (for example, INSIDE), or for the purpose for which it is
created (for example, NO_NAT or VPN).
Typically, you identify the ip keyword for the protocol, but other protocols are accepted. For a list of
protocol names, see the “Protocols and Applications” section on page C-11.
Enter the host keyword before the IP address to specify a single address. In this case, do not enter a mask.
Enter the any keyword instead of the address and mask to specify any address.
You can specify the source and destination ports only for the tcp or udp protocols. For a list of permitted
keywords and well-known port assignments, see the “TCP and UDP Ports” section on page C-11. DNS,
Discard, Echo, Ident, NTP, RPC, SUNRPC, and Talk each require one definition for TCP and one for
UDP. TACACS+ requires one definition for port 49 on TCP.
Use an operator to match port numbers used by the source or destination. The permitted operators are
as follows:
•
lt—less than
•
gt—greater than
•
eq—equal to
•
neq—not equal to
•
range—an inclusive range of values. When you use this operator, specify two port numbers, for
example:
range 100 200
You can specify the ICMP type only for the icmp protocol. Because ICMP is a connectionless protocol,
you either need access lists to allow ICMP in both directions (by applying access lists to the source and
destination interfaces), or you need to enable the ICMP inspection engine (see the “Adding an ICMP
Type Object Group” section on page 18-16). The ICMP inspection engine treats ICMP sessions as
stateful connections. To control ping, specify echo-reply (0) (security appliance to host) or echo (8)
(host to security appliance). See the “Adding an ICMP Type Object Group” section on page 18-16 for a
list of ICMP types.
When you specify a network mask, the method is different from the Cisco IOS software access-list
command. The security appliance uses a network mask (for example, 255.255.255.0 for a Class C mask).
The Cisco IOS mask uses wildcard bits (for example, 0.0.0.255).
To make an ACE inactive, use the inactive keyword. To reenable it, enter the entire ACE without the
inactive keyword. This feature lets you keep a record of an inactive ACE in your configuration to make
reenabling easier.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-7
Chapter 18
Identifying Traffic with Access Lists
Adding an EtherType Access List
To remove an ACE, enter the no access-list command with the entire command syntax string as it
appears in the configuration:
hostname(config)# no access-list access_list_name [line line_number] [extended]
{deny | permit} protocol source_address mask [operator port] dest_address mask
[operator port | icmp_type] [inactive]
If the entry that you are removing is the only entry in the access list, the entire access list is removed.
See the following examples:
The following access list allows all hosts (on the interface to which you apply the access list) to go
through the security appliance:
hostname(config)# access-list ACL_IN extended permit ip any any
The following sample access list prevents hosts on 192.168.1.0/24 from accessing the 209.165.201.0/27
network. All other addresses are permitted.
hostname(config)# access-list ACL_IN extended deny tcp 192.168.1.0 255.255.255.0
209.165.201.0 255.255.255.224
hostname(config)# access-list ACL_IN extended permit ip any any
If you want to restrict access to only some hosts, then enter a limited permit ACE. By default, all other
traffic is denied unless explicitly permitted.
hostname(config)# access-list ACL_IN extended permit ip 192.168.1.0 255.255.255.0
209.165.201.0 255.255.255.224
The following access list restricts all hosts (on the interface to which you apply the access list) from
accessing a website at address 209.165.201.29. All other traffic is allowed.
hostname(config)# access-list ACL_IN extended deny tcp any host 209.165.201.29 eq www
hostname(config)# access-list ACL_IN extended permit ip any any
Adding an EtherType Access List
Transparent firewall mode only
This section describes how to add an EtherType access list, and includes the following sections:
•
EtherType Access List Overview, page 18-8
•
Adding an EtherType ACE, page 18-10
EtherType Access List Overview
An EtherType access list is made up of one or more ACEs that specify an EtherType. This section
includes the following topics:
•
Supported EtherTypes, page 18-9
•
Implicit Permit of IP and ARPs Only, page 18-9
•
Implicit and Explicit Deny ACE at the End of an Access List, page 18-9
•
IPv6 Unsupported, page 18-9
•
Using Extended and EtherType Access Lists on the Same Interface, page 18-9
•
Allowing MPLS, page 18-10
Cisco Security Appliance Command Line Configuration Guide
18-8
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Adding an EtherType Access List
Supported EtherTypes
An EtherType ACE controls any EtherType identified by a 16-bit hexadecimal number.
EtherType access lists support Ethernet V2 frames.
802.3-formatted frames are not handled by the access list because they use a length field as opposed to
a type field.
BPDUs, which are handled by the access list, are the only exception: they are SNAP-encapsulated, and
the security appliance is designed to specifically handle BPDUs.
The security appliance receives trunk port (Cisco proprietary) BPDUs. Trunk BPDUs have VLAN
information inside the payload, so the security appliance modifies the payload with the outgoing VLAN
if you allow BPDUs.
Note
If you use failover, you must allow BPDUs on both interfaces with an EtherType access list to avoid
bridging loops.
Implicit Permit of IP and ARPs Only
IPv4 traffic is allowed through the transparent firewall automatically from a higher security interface to
a lower security interface, without an access list. ARPs are allowed through the transparent firewall in
both directions without an access list. ARP traffic can be controlled by ARP inspection.
However, to allow any traffic with EtherTypes other than IPv4 and ARP, you need to apply an EtherType
access list, even from a high security to a low security interface.
Because EtherTypes are connectionless, you need to apply the access list to both interfaces if you want
traffic to pass in both directions.
Implicit and Explicit Deny ACE at the End of an Access List
For EtherType access lists, the implicit deny at the end of the access list does not affect IP traffic or
ARPs; for example, if you allow EtherType 8037, the implicit deny at the end of the access list does not
now block any IP traffic that you previously allowed with an extended access list (or implicitly allowed
from a high security interface to a low security interface). However, if you explicitly deny all traffic with
an EtherType ACE, then IP and ARP traffic is denied.
IPv6 Unsupported
EtherType ACEs do not allow IPv6 traffic, even if you specify the IPv6 EtherType.
Using Extended and EtherType Access Lists on the Same Interface
You can apply only one access list of each type (extended and EtherType) to each direction of an
interface. You can also apply the same access lists on multiple interfaces.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-9
Chapter 18
Identifying Traffic with Access Lists
Adding an EtherType Access List
Allowing MPLS
If you allow MPLS, ensure that Label Distribution Protocol and Tag Distribution Protocol TCP
connections are established through the security appliance by configuring both MPLS routers connected
to the security appliance to use the IP address on the security appliance interface as the router-id for LDP
or TDP sessions. (LDP and TDP allow MPLS routers to negotiate the labels (addresses) used to forward
packets.)
On Cisco IOS routers, enter the appropriate command for your protocol, LDP or TDP. The interface is
the interface connected to the security appliance.
hostname(config)# mpls ldp router-id interface force
Or
hostname(config)# tag-switching tdp router-id interface force
Adding an EtherType ACE
To add an EtherType ACE, enter the following command:
hostname(config)# access-list access_list_name ethertype {permit | deny} {ipx | bpdu |
mpls-unicast | mpls-multicast | any | hex_number}
To remove an EtherType ACE, enter the no access-list command with the entire command syntax string
as it appears in the configuration:
ehostname(config)# no access-list access_list_name ethertype {permit | deny} {ipx | bpdu |
mpls-unicast | mpls-multicast | any | hex_number}
The hex_number is any EtherType that can be identified by a 16-bit hexadecimal number greater than or
equal to 0x600. See RFC 1700, “Assigned Numbers,” at http://www.ietf.org/rfc/rfc1700.txt for a list of
EtherTypes.
Note
If an EtherType access list is configured to deny all, all ethernet frames are discarded. Only physical
protocol traffic, such as auto-negotiation, is still allowed.
When you enter the access-list command for a given access list name, the ACE is added to the end of
the access list.
Tip
Enter the access_list_name in upper case letters so the name is easy to see in the configuration. You
might want to name the access list for the interface (for example, INSIDE), or for the purpose (for
example, MPLS or IPX).
For example, the following sample access list allows common EtherTypes originating on the inside
interface:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list ETHER ethertype permit ipx
access-list ETHER ethertype permit bpdu
access-list ETHER ethertype permit mpls-unicast
access-group ETHER in interface inside
The following access list allows some EtherTypes through the security appliance, but denies IPX:
hostname(config)# access-list ETHER ethertype deny ipx
Cisco Security Appliance Command Line Configuration Guide
18-10
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Adding a Standard Access List
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list ETHER ethertype permit 0x1234
access-list ETHER ethertype permit bpdu
access-list ETHER ethertype permit mpls-unicast
access-group ETHER in interface inside
access-group ETHER in interface outside
The following access list denies traffic with EtherType 0x1256, but allows all others on both interfaces:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list nonIP ethertype deny 1256
access-list nonIP ethertype permit any
access-group ETHER in interface inside
access-group ETHER in interface outside
Adding a Standard Access List
Single context mode only
Standard access lists identify the destination IP addresses of OSPF routes, and can be used in a route
map for OSPF redistribution. Standard access lists cannot be applied to interfaces to control traffic.
The following command adds a standard ACE. To add another ACE at the end of the access list, enter
another access-list command specifying the same access list name. Apply the access list using the
“Defining Route Maps” section on page 10-7.
To add an ACE, enter the following command:
hostname(config)# access-list access_list_name standard {deny | permit} {any | ip_address
mask}
The following sample access list identifies routes to 192.168.1.0/24:
hostname(config)# access-list OSPF standard permit 192.168.1.0 255.255.255.0
To remove an ACE, enter the no access-list command with the entire command syntax string as it
appears in the configuration:
hostname(config)# no access-list access_list_name standard {deny | permit} {any |
ip_address mask}
Adding a Webtype Access List
Webtype access lists are access lists that are added to a configuration that supports filtering for clientless
SSL VPN.
You can use the following wildcard characters to define more than one wildcard in the Webtype access
list entry:
•
Enter an asterisk “*” to match no characters or any number of characters.
•
Enter a question mark “?” to match any one character exactly.
•
Enter square brackets “[]” to create a range operator that matches any one character in a range.
To add an access list to the configuration that supports filtering for WebVPN, enter the following
command:
hostname(config)# access-list access_list_name webtype {deny
| permit} url [url_string | any]
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-11
Chapter 18
Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
To remove a Webtype access list, enter the no access-list command with the entire syntax string as it
appears in the configuration:
hostname(config)# access-list access_list_name webtype {deny
| permit} url [url_string | any]
The following scenario shows how to enforce a webtype access list to disable access to specific CIFS
shares.
In this scenario we have a root folder named “shares” that contains two sub-folders named
“Marketing_Reports” and “Sales_Reports.” We want to specifically deny access to the
“shares/Marketing_Reports” folder.
access-list CIFS_Avoid webtype deny url cifs://172.16.10.40/shares/Marketing_Reports.
However, due to the implicit “deny all,” the above access list makes all of the sub-folders inaccessible
(“shares/Sales_Reports” and “shares/Marketing_Reports”), including the root folder (“shares”).
To fix the problem, add a new access list to allow access to the root folder and the remaining sub-folders.
access-list CIFS_Allow webtype permit url cifs://172.16.10.40/shares*
For information about logging options that you can add to the end of the ACE, see the “Logging Access
List Activity” section on page 18-21.
Examples
The examples in this section show how to use wildcards in Webtype access lists.
•
The following example matches URLs such as http://www.cisco.com/ and http://wwz.caco.com/:
access-list test webtype permit url http://ww?.c*co*/
•
The following example matches URLs such as http://www.cisco.com and ftp://wwz.carrier.com:
access-list test webtype permit url *://ww?.c*co*/
•
The following example matches URLs such as http://www.cisco.com:80 and
https://www.cisco.com:81:
access-list test webtype permit url *://ww?.c*co*:8[01]/
The range operator “[]” in the preceding example specifies that either character 0 or 1 can occur.
•
The following example matches URLs such as http://www.google.com and http://www.boogie.com:
access-list test webtype permit url http://www.[a-z]oo?*/
The range operator “[]” in the preceding example specifies that any character in the range from a to
z can occur.
•
The following example matches URLs such as http://www.cisco.com/anything/crazy/url/ddtscgiz:
access-list test webtype permit url htt*://*/*cgi?*
Note
To match any http URL, you must enter http://*/* instead of the former method of entering http://*.
Simplifying Access Lists with Object Grouping
This section describes how to use object grouping to simplify access list creation and maintenance.
This section includes the following topics:
Cisco Security Appliance Command Line Configuration Guide
18-12
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
•
How Object Grouping Works, page 18-13
•
Adding Object Groups, page 18-13
•
Nesting Object Groups, page 18-16
•
Displaying Object Groups, page 18-18
•
Removing Object Groups, page 18-19
•
Using Object Groups with an Access List, page 18-17
How Object Grouping Works
By grouping like-objects together, you can use the object group in an ACE instead of having to enter an
ACE for each object separately. You can create the following types of object groups:
•
Protocol
•
Network
•
Service
•
ICMP type
For example, consider the following three object groups:
•
MyServices—Includes the TCP and UDP port numbers of the service requests that are allowed
access to the internal network
•
TrustedHosts—Includes the host and network addresses allowed access to the greatest range of
services and servers
•
PublicServers—Includes the host addresses of servers to which the greatest access is provided
After creating these groups, you could use a single ACE to allow trusted hosts to make specific service
requests to a group of public servers.
You can also nest object groups in other object groups.
Note
The ACE system limit applies to expanded access lists. If you use object groups in ACEs, the number of
actual ACEs that you enter is fewer, but the number of expanded ACEs is the same as without object
groups. In many cases, object groups create more ACEs than if you added them manually, because
creating ACEs manually leads you to summarize addresses more than an object group does. To view the
number of expanded ACEs in an access list, enter the show access-list access_list_name command.
Adding Object Groups
This section describes how to add object groups.
This section includes the following topics:
•
Adding a Protocol Object Group, page 18-14
•
Adding a Network Object Group, page 18-14
•
Adding a Service Object Group, page 18-15
•
Adding an ICMP Type Object Group, page 18-16
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-13
Chapter 18
Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
Adding a Protocol Object Group
To add or change a protocol object group, perform the following steps. After you add the group, you can
add more objects as required by following this procedure again for the same group name and specifying
additional objects. You do not need to reenter existing objects; the commands you already set remain in
place unless you remove them with the no form of the command.
To add a protocol group, perform the following steps:
Step 1
To add a protocol group, enter the following command:
hostname(config)# object-group protocol grp_id
The grp_id is a text string up to 64 characters in length.
The prompt changes to protocol configuration mode.
Step 2
(Optional) To add a description, enter the following command:
hostname(config-protocol)# description text
The description can be up to 200 characters.
Step 3
To define the protocols in the group, enter the following command for each protocol:
hostname(config-protocol)# protocol-object protocol
The protocol is the numeric identifier of the specific IP protocol (1 to 254) or a keyword identifier (for
example, icmp, tcp, or udp). To include all IP protocols, use the keyword ip. For a list of protocols you
can specify, see the “Protocols and Applications” section on page C-11.
For example, to create a protocol group for TCP, UDP, and ICMP, enter the following commands:
hostname(config)# object-group protocol tcp_udp_icmp
hostname(config-protocol)# protocol-object tcp
hostname(config-protocol)# protocol-object udp
hostname(config-protocol)# protocol-object icmp
Adding a Network Object Group
To add or change a network object group, perform the following steps. After you add the group, you can
add more objects as required by following this procedure again for the same group name and specifying
additional objects. You do not need to reenter existing objects; the commands you already set remain in
place unless you remove them with the no form of the command.
Note
A network object group supports IPv4 and IPv6 addresses, depending on the type of access list. For more
information about IPv6 access lists, see “Configuring IPv6 Access Lists” section on page 13-6.
To add a network group, perform the following steps:
Step 1
To add a network group, enter the following command:
hostname(config)# object-group network grp_id
The grp_id is a text string up to 64 characters in length.
The prompt changes to network configuration mode.
Cisco Security Appliance Command Line Configuration Guide
18-14
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
Step 2
(Optional) To add a description, enter the following command:
hostname(config-network)# description text
The description can be up to 200 characters.
Step 3
To define the networks in the group, enter the following command for each network or address:
hostname(config-network)# network-object {host ip_address | ip_address mask}
For example, to create network group that includes the IP addresses of three administrators, enter the
following commands:
hostname(config)# object-group network admins
hostname(config-network)# description Administrator Addresses
hostname(config-network)# network-object host 10.1.1.4
hostname(config-network)# network-object host 10.1.1.78
hostname(config-network)# network-object host 10.1.1.34
Adding a Service Object Group
To add or change a service object group, perform the following steps. After you add the group, you can
add more objects as required by following this procedure again for the same group name and specifying
additional objects. You do not need to reenter existing objects; the commands you already set remain in
place unless you remove them with the no form of the command.
To add a service group, perform the following steps:
Step 1
To add a service group, enter the following command:
hostname(config)# object-group service grp_id {tcp | udp | tcp-udp}
The grp_id is a text string up to 64 characters in length.
Specify the protocol for the services (ports) you want to add, either tcp, udp, or tcp-udp keywords.
Enter tcp-udp keyword if your service uses both TCP and UDP with the same port number, for example,
DNS (port 53).
The prompt changes to service configuration mode.
Step 2
(Optional) To add a description, enter the following command:
hostname(config-service)# description text
The description can be up to 200 characters.
Step 3
To define the ports in the group, enter the following command for each port or range of ports:
hostname(config-service)# port-object {eq port | range begin_port end_port}
For a list of permitted keywords and well-known port assignments, see the “Protocols and Applications”
section on page C-11.
For example, to create service groups that include DNS (TCP/UDP), LDAP (TCP), and RADIUS (UDP),
enter the following commands:
hostname(config)# object-group service services1 tcp-udp
hostname(config-service)# description DNS Group
hostname(config-service)# port-object eq domain
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-15
Chapter 18
Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
hostname(config-service)#
hostname(config-service)#
hostname(config-service)#
hostname(config-service)#
object-group service services2 udp
description RADIUS Group
port-object eq radius
port-object eq radius-acct
hostname(config-service)# object-group service services3 tcp
hostname(config-service)# description LDAP Group
hostname(config-service)# port-object eq ldap
Adding an ICMP Type Object Group
To add or change an ICMP type object group, perform the following steps. After you add the group, you
can add more objects as required by following this procedure again for the same group name and
specifying additional objects. You do not need to reenter existing objects; the commands you already set
remain in place unless you remove them with the no form of the command.
To add an ICMP type group, perform the following steps:
Step 1
To add an ICMP type group, enter the following command:
hostname(config)# object-group icmp-type grp_id
The grp_id is a text string up to 64 characters in length.
The prompt changes to ICMP type configuration mode.
Step 2
(Optional) To add a description, enter the following command:
hostname(config-icmp-type)# description text
The description can be up to 200 characters.
Step 3
To define the ICMP types in the group, enter the following command for each type:
hostname(config-icmp-type)# icmp-object icmp_type
See the “ICMP Types” section on page C-15 for a list of ICMP types.
For example, to create an ICMP type group that includes echo-reply and echo (for controlling ping),
enter the following commands:
hostname(config)# object-group icmp-type ping
hostname(config-service)# description Ping Group
hostname(config-icmp-type)# icmp-object echo
hostname(config-icmp-type)# icmp-object echo-reply
Nesting Object Groups
To nest an object group within another object group of the same type, first create the group that you want
to nest according to the “Adding Object Groups” section on page 18-13. Then perform the following
steps:
Step 1
To add or edit an object group under which you want to nest another object group, enter the following
command:
Cisco Security Appliance Command Line Configuration Guide
18-16
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
hostname(config)# object-group {{protocol | network | icmp-type} grp_id | service grp_id
{tcp | udp | tcp-udp}}
Step 2
To add the specified group under the object group you specified in Step 1, enter the following command:
hostname(config-group_type)# group-object grp_id
The nested group must be of the same type.
You can mix and match nested group objects and regular objects within an object group.
For example, you create network object groups for privileged users from various departments:
hostname(config)# object-group network eng
hostname(config-network)# network-object host 10.1.1.5
hostname(config-network)# network-object host 10.1.1.9
hostname(config-network)# network-object host 10.1.1.89
hostname(config-network)# object-group network hr
hostname(config-network)# network-object host 10.1.2.8
hostname(config-network)# network-object host 10.1.2.12
hostname(config-network)# object-group network finance
hostname(config-network)# network-object host 10.1.4.89
hostname(config-network)# network-object host 10.1.4.100
You then nest all three groups together as follows:
hostname(config)# object-group network
hostname(config-network)# group-object
hostname(config-network)# group-object
hostname(config-network)# group-object
admin
eng
hr
finance
You only need to specify the admin object group in your ACE as follows:
hostname(config)# access-list ACL_IN extended permit ip object-group admin host
209.165.201.29
Using Object Groups with an Access List
To use object groups in an access list, replace the normal protocol (protocol), network
(source_address mask, etc.), service (operator port), or ICMP type (icmp_type) parameter with
object-group grp_id parameter.
For example, to use object groups for all available parameters in the access-list {tcp | udp} command,
enter the following command:
hostname(config)# access-list access_list_name [line line_number] [extended] {deny |
permit} {tcp | udp} object-group nw_grp_id [object-group svc_grp_id] object-group
nw_grp_id [object-group svc_grp_id] [log [[level] [interval secs] | disable | default]]
[inactive | time-range time_range_name]
You do not have to use object groups for all parameters; for example, you can use an object group for
the source address, but identify the destination address with an address and mask.
The following normal access list that does not use object groups restricts several hosts on the inside
network from accessing several web servers. All other traffic is allowed.
hostname(config)# access-list ACL_IN extended deny tcp host 10.1.1.4 host 209.165.201.29
eq www
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-17
Chapter 18
Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
hostname(config)#
eq www
hostname(config)#
eq www
hostname(config)#
eq www
hostname(config)#
eq www
hostname(config)#
eq www
hostname(config)#
eq www
hostname(config)#
eq www
hostname(config)#
eq www
hostname(config)#
hostname(config)#
access-list ACL_IN extended deny tcp host 10.1.1.78 host 209.165.201.29
access-list ACL_IN extended deny tcp host 10.1.1.89 host 209.165.201.29
access-list ACL_IN extended deny tcp host 10.1.1.4 host 209.165.201.16
access-list ACL_IN extended deny tcp host 10.1.1.78 host 209.165.201.16
access-list ACL_IN extended deny tcp host 10.1.1.89 host 209.165.201.16
access-list ACL_IN extended deny tcp host 10.1.1.4 host 209.165.201.78
access-list ACL_IN extended deny tcp host 10.1.1.78 host 209.165.201.78
access-list ACL_IN extended deny tcp host 10.1.1.89 host 209.165.201.78
access-list ACL_IN extended permit ip any any
access-group ACL_IN in interface inside
If you make two network object groups, one for the inside hosts, and one for the web servers, then the
configuration can be simplified and can be easily modified to add more hosts:
hostname(config)# object-group network denied
hostname(config-network)# network-object host 10.1.1.4
hostname(config-network)# network-object host 10.1.1.78
hostname(config-network)# network-object host 10.1.1.89
hostname(config-network)#
hostname(config-network)#
hostname(config-network)#
hostname(config-network)#
object-group network web
network-object host 209.165.201.29
network-object host 209.165.201.16
network-object host 209.165.201.78
hostname(config-network)# access-list ACL_IN extended deny tcp object-group denied
object-group web eq www
hostname(config)# access-list ACL_IN extended permit ip any any
hostname(config)# access-group ACL_IN in interface inside
Displaying Object Groups
To display a list of the currently configured object groups, enter the following command:
hostname(config)# show object-group [protocol | network | service | icmp-type | id grp_id]
If you enter the command without any parameters, the system displays all configured object groups.
The following is sample output from the show object-group command:
hostname# show object-group
object-group network ftp_servers
description: This is a group of FTP servers
network-object host 209.165.201.3
network-object host 209.165.201.4
object-group network TrustedHosts
network-object host 209.165.201.1
network-object 192.168.1.0 255.255.255.0
group-object ftp_servers
Cisco Security Appliance Command Line Configuration Guide
18-18
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Adding Remarks to Access Lists
Removing Object Groups
To remove an object group, enter one of the following commands.
Note
You cannot remove an object group or make an object group empty if it is used in an access list.
•
To remove a specific object group, enter the following command:
hostname(config)# no object-group grp_id
•
To remove all object groups of the specified type, enter the following command:
hostname(config)# clear object-group [protocol | network | services | icmp-type]
If you do not enter a type, all object groups are removed.
Adding Remarks to Access Lists
You can include remarks about entries in any access list, including extended, EtherType, and standard
access lists. The remarks make the access list easier to understand.
To add a remark after the last access-list command you entered, enter the following command:
hostname(config)# access-list access_list_name remark text
If you enter the remark before any access-list command, then the remark is the first line in the access list.
If you delete an access list using the no access-list access_list_name command, then all the remarks are
also removed.
The text can be up to 100 characters in length. You can enter leading spaces at the beginning of the text.
Trailing spaces are ignored.
For example, you can add remarks before each ACE, and the remark appears in the access list in this
location. Entering a dash (-) at the beginning of the remark helps set it apart from ACEs.
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list
access-list
access-list
access-list
OUT
OUT
OUT
OUT
remark extended
remark extended
this is the inside admin address
permit ip host 209.168.200.3 any
this is the hr admin address
permit ip host 209.168.200.4 any
Scheduling Extended Access List Activation
You can schedule each ACE to be activated at specific times of the day and week by applying a time
range to the ACE. This section includes the following topics:
•
Adding a Time Range, page 18-19
•
Applying the Time Range to an ACE, page 18-20
Adding a Time Range
To add a time range to implement a time-based access list, perform the following steps:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-19
Chapter 18
Identifying Traffic with Access Lists
Scheduling Extended Access List Activation
Step 1
Identify the time-range name by entering the following command:
hostname(config)# time-range name
Step 2
Specify the time range as either a recurring time range or an absolute time range.
Note
Users could experience a delay of approximately 80 to 100 seconds after the specified end time
for the ACL to become inactive. For example, if the specified end time is 3:50, because the end
time is inclusive, the command is picked up anywhere between 3:51:00 and 3:51:59. After the
command is picked up, the security appliance finishes any currently running task and then
services the command to deactivate the ACL.
Multiple periodic entries are allowed per time-range command. If a time-range command has both
absolute and periodic values specified, then the periodic commands are evaluated only after the
absolute start time is reached, and are not further evaluated after the absolute end time is reached.
•
Recurring time range:
hostname(config-time-range)# periodic days-of-the-week time to [days-of-the-week] time
You can specify the following values for days-of-the-week:
– monday, tuesday, wednesday, thursday, friday, saturday, and sunday.
– daily
– weekdays
– weekend
The time is in the format hh:mm. For example, 8:00 is 8:00 a.m. and 20:00 is 8:00 p.m.
•
Absolute time range:
hostname(config-time-range)# absolute start time date [end time date]
The time is in the format hh:mm. For example, 8:00 is 8:00 a.m. and 20:00 is 8:00 p.m.
The date is in the format day month year; for example, 1 january 2006.
The following is an example of an absolute time range beginning at 8:00 a.m. on January 1, 2006.
Because no end time and date are specified, the time range is in effect indefinitely.
hostname(config)# time-range for2006
hostname(config-time-range)# absolute start 8:00 1 january 2006
The following is an example of a weekly periodic time range from 8:00 a.m. to 6:00 p.m on weekdays.:
hostname(config)# time-range workinghours
hostname(config-time-range)# periodic weekdays 8:00 to 18:00
Applying the Time Range to an ACE
To apply the time range to an ACE, use the following command:
hostname(config)# access-list access_list_name [extended] {deny | permit}...[time-range
name]
Cisco Security Appliance Command Line Configuration Guide
18-20
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Logging Access List Activity
See the “Adding an Extended Access List” section on page 18-5 for complete access-list command
syntax.
Note
If you also enable logging for the ACE, use the log keyword before the time-range keyword. If you
disable the ACE using the inactive keyword, use the inactive keyword as the last keyword.
The following example binds an access list named “Sales” to a time range named “New_York_Minute.”
hostname(config)# access-list Sales line 1 extended deny tcp host 209.165.200.225 host
209.165.201.1 time-range New_York_Minute
Logging Access List Activity
This section describes how to configure access list logging for extended access lists and Webtype access
lists.
This section includes the following topics:
•
Access List Logging Overview, page 18-21
•
Configuring Logging for an Access Control Entry, page 18-22
•
Managing Deny Flows, page 18-23
Access List Logging Overview
By default, when traffic is denied by an extended ACE or a Webtype ACE, the security appliance
generates system message 106023 for each denied packet, in the following form:
%ASA|PIX-4-106023: Deny protocol src [interface_name:source_address/source_port] dst
interface_name:dest_address/dest_port [type {string}, code {code}] by access_group acl_id
If the security appliance is attacked, the number of system messages for denied packets can be very large.
We recommend that you instead enable logging using system message 106100, which provides statistics
for each ACE and lets you limit the number of system messages produced. Alternatively, you can disable
all logging.
Note
Only ACEs in the access list generate logging messages; the implicit deny at the end of the access list
does not generate a message. If you want all denied traffic to generate messages, add the implicit ACE
manually to the end of the access list, as follows.
hostname(config)# access-list TEST deny ip any any log
The log options at the end of the extended access-list command lets you to set the following behavior:
•
Enable message 106100 instead of message 106023
•
Disable all logging
•
Return to the default logging using message 106023
System message 106100 is in the following form:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-21
Chapter 18
Identifying Traffic with Access Lists
Logging Access List Activity
%ASA|PIX-n-106100: access-list acl_id {permitted | denied} protocol
interface_name/source_address(source_port) -> interface_name/dest_address(dest_port)
hit-cnt number ({first hit | number-second interval})
When you enable logging for message 106100, if a packet matches an ACE, the security appliance
creates a flow entry to track the number of packets received within a specific interval. The security
appliance generates a system message at the first hit and at the end of each interval, identifying the total
number of hits during the interval. At the end of each interval, the security appliance resets the hit count
to 0. If no packets match the ACE during an interval, the security appliance deletes the flow entry.
A flow is defined by the source and destination IP addresses, protocols, and ports. Because the source
port might differ for a new connection between the same two hosts, you might not see the same flow
increment because a new flow was created for the connection. See the “Managing Deny Flows” section
on page 18-23 to limit the number of logging flows.
Permitted packets that belong to established connections do not need to be checked against access lists;
only the initial packet is logged and included in the hit count. For connectionless protocols, such as
ICMP, all packets are logged even if they are permitted, and all denied packets are logged.
See the Cisco Security Appliance Logging Configuration and System Log Messages for detailed
information about this system message.
Configuring Logging for an Access Control Entry
To configure logging for an ACE, see the following information about the log option:
hostname(config)# access-list access_list_name [extended] {deny | permit}...[log [[level]
[interval secs] | disable | default]]
See the “Adding an Extended Access List” section on page 18-5 and “Adding a Webtype Access List”
section on page 18-11 for complete access-list command syntax.
If you enter the log option without any arguments, you enable system log message 106100 at the default
level (6) and for the default interval (300 seconds). See the following options:
•
level—A severity level between 0 and 7. The default is 6.
•
interval secs—The time interval in seconds between system messages, from 1 to 600. The default
is 300. This value is also used as the timeout value for deleting an inactive flow.
•
disable—Disables all access list logging.
•
default—Enables logging to message 106023. This setting is the same as having no log option.
For example, you configure the following access list:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list outside-acl permit ip host 1.1.1.1 any log 7 interval 600
access-list outside-acl permit ip host 2.2.2.2 any
access-list outside-acl deny ip any any log 2
access-group outside-acl in interface outside
When a packet is permitted by the first ACE of outside-acl, the security appliance generates the
following system message:
%ASA|PIX-7-106100: access-list outside-acl permitted tcp outside/1.1.1.1(12345) ->
inside/192.168.1.1(1357) hit-cnt 1 (first hit)
Although 20 additional packets for this connection arrive on the outside interface, the traffic does not
have to be checked against the access list, and the hit count does not increase.
Cisco Security Appliance Command Line Configuration Guide
18-22
OL-12172-04
Chapter 18
Identifying Traffic with Access Lists
Logging Access List Activity
If one more connection by the same host is initiated within the specified 10 minute interval (and the
source and destination ports remain the same), then the hit count is incremented by 1 and the following
message is displayed at the end of the 10 minute interval:
%ASA|PIX-7-106100: access-list outside-acl permitted tcp outside/1.1.1.1(12345)->
inside/192.168.1.1(1357) hit-cnt 2 (600-second interval)
When a packet is denied by the third ACE, the security appliance generates the following system
message:
%ASA|PIX-2-106100: access-list outside-acl denied ip outside/3.3.3.3(12345) ->
inside/192.168.1.1(1357) hit-cnt 1 (first hit)
20 additional attempts within a 5 minute interval (the default) result in the following message at the end
of 5 minutes:
%ASA|PIX-2-106100: access-list outside-acl denied ip outside/3.3.3.3(12345) ->
inside/192.168.1.1(1357) hit-cnt 21 (300-second interval)
Managing Deny Flows
When you enable logging for message 106100, if a packet matches an ACE, the security appliance
creates a flow entry to track the number of packets received within a specific interval. The security
appliance has a maximum of 32 K logging flows for ACEs. A large number of flows can exist
concurrently at any point of time. To prevent unlimited consumption of memory and CPU resources, the
security appliance places a limit on the number of concurrent deny flows; the limit is placed only on deny
flows (and not permit flows) because they can indicate an attack. When the limit is reached, the security
appliance does not create a new deny flow for logging until the existing flows expire.
For example, if someone initiates a DoS attack, the security appliance can create a large number of deny
flows in a short period of time. Restricting the number of deny flows prevents unlimited consumption of
memory and CPU resources.
When you reach the maximum number of deny flows, the security appliance issues system message
106100:
%ASA|PIX-1-106101: The number of ACL log deny-flows has reached limit (number).
To configure the maximum number of deny flows and to set the interval between deny flow alert
messages (106101), enter the following commands:
•
To set the maximum number of deny flows permitted per context before the security appliance stops
logging, enter the following command:
hostname(config)# access-list deny-flow-max number
The number is between 1 and 4096. 4096 is the default.
•
To set the amount of time between system messages (number 106101) that identify that the
maximum number of deny flows was reached, enter the following command:
hostname(config)# access-list alert-interval secs
The seconds are between 1 and 3600, and 300 is the default.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
18-23
Chapter 18
Identifying Traffic with Access Lists
Logging Access List Activity
Cisco Security Appliance Command Line Configuration Guide
18-24
OL-12172-04
CH A P T E R
19
Configuring NAT
This chapter describes Network Address Translation, and includes the following sections:
•
NAT Overview, page 19-1
•
Configuring NAT Control, page 19-18
•
Using Dynamic NAT and PAT, page 19-19
•
Using Static NAT, page 19-28
•
Using Static PAT, page 19-29
•
Bypassing NAT, page 19-32
•
NAT Examples, page 19-36
NAT Overview
This section describes how NAT works on the security appliance, and includes the following topics:
•
Introduction to NAT, page 19-1
•
NAT Control, page 19-5
•
NAT Types, page 19-6
•
Policy NAT, page 19-11
•
NAT and Same Security Level Interfaces, page 19-15
•
Order of NAT Commands Used to Match Real Addresses, page 19-16
•
Mapped Address Guidelines, page 19-16
•
DNS and NAT, page 19-17
Introduction to NAT
Address translation substitutes the real address in a packet with a mapped address that is routable on the
destination network. NAT is composed of two steps: the process by which a real address is translated
into a mapped address, and the process to undo translation for returning traffic.
The security appliance translates an address when a NAT rule matches the traffic. If no NAT rule
matches, processing for the packet continues. The exception is when you enable NAT control.
NAT control requires that packets traversing from a higher security interface (inside) to a lower security
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-1
Chapter 19
Configuring NAT
NAT Overview
interface (outside) match a NAT rule, or processing for the packet stops. See the “Security Level
Overview” section on page 8-1 for more information about security levels. See the “NAT Control”
section on page 19-5 for more information about NAT control.
Note
In this document, all types of translation are referred to as NAT. When describing NAT, the terms inside
and outside represent the security relationship between any two interfaces. The higher security level is
inside and the lower security level is outside. For example, interface 1 is at 60 and interface 2 is at 50;
therefore, interface 1 is “inside” and interface 2 is “outside.”
Some of the benefits of NAT are as follows:
•
You can use private addresses on your inside networks. Private addresses are not routable on the
Internet. See the “Private Networks” section on page C-2 for more information.
•
NAT hides the real addresses from other networks, so attackers cannot learn the real address of a
host.
•
You can resolve IP routing problems such as overlapping addresses.
See Table 26-1 on page 26-3 for information about protocols that do not support NAT.
NAT in Routed Mode
Figure 19-1 shows a typical NAT example in routed mode, with a private network on the inside. When
the inside host at 10.1.2.27 sends a packet to a web server, the real source address, 10.1.2.27, of the
packet is changed to a mapped address, 209.165.201.10. When the server responds, it sends the response
to the mapped address, 209.165.201.10, and the security appliance receives the packet. The security
appliance then changes the translation of the mapped address, 209.165.201.10 back to the real address,
10.1.2.27 before sending it to the host.
Figure 19-1
NAT Example: Routed Mode
Web Server
www.cisco.com
Outside
209.165.201.2
Originating
Packet
Security
Appliance
Translation
10.1.2.27
209.165.201.10
Responding
Packet
Undo Translation
209.165.201.10
10.1.2.27
10.1.2.1
10.1.2.27
130023
Inside
Cisco Security Appliance Command Line Configuration Guide
19-2
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
See the following commands for this example:
hostname(config)# nat (inside) 1 10.1.2.0 255.255.255.0
hostname(config)# global (outside) 1 209.165.201.1-209.165.201.15
NAT in Transparent Mode
Using NAT in transparent mode eliminates the need for the upstream or downstream routers to perform
NAT for their networks. For example, a transparent firewall security appliance is useful between two
VRFs so you can establish BGP neighbor relations between the VRFs and the global table. However,
NAT per VRF might not be supported. In this case, using NAT in transparent mode is essential.
NAT in transparent mode has the following requirements and limitations:
•
When the mapped addresses are not on the same network as the transparent firewall, then on the
upstream router, you need to add a static route for the mapped addresses that points to the
downstream router (through the security appliance).
•
If the real destination address is not directly-connected to the security appliance, then you also need
to add a static route on the security appliance for the real destination address that points to the
downstream router. Without NAT, traffic from the upstream router to the downstream router does not
need any routes on the security appliance because it uses the MAC address table. NAT, however,
causes the security appliance to use a route lookup instead of a MAC address lookup, so it needs a
static route to the downstream router.
•
The alias command is not supported.
•
Because the transparent firewall does not have any interface IP addresses, you cannot use interface
PAT.
•
ARP inspection is not supported. Moreover, if for some reason a host on one side of the firewall
sends an ARP request to a host on the other side of the firewall, and the initiating host real address
is mapped to a different address on the same subnet, then the real address remains visible in the ARP
request.
Figure 19-2 shows a typical NAT scenario in transparent mode, with the same network on the inside and
outside interfaces. The transparent firewall in this scenario is performing the NAT service so that the
upstream router does not have to perform NAT. When the inside host at 10.1.1.27 sends a packet to a web
server, the real source address of the packet, 10.1.1.27, is changed to a mapped address, 209.165.201.10.
When the server responds, it sends the response to the mapped address, 209.165.201.10, and the security
appliance receives the packet because the upstream router includes this mapped network in a static route
directed through the security appliance. The security appliance then undoes the translation of the
mapped address, 209.165.201.10 back to the real address, 10.1.1.1.27. Because the real address is
directly-connected, the security appliance sends it directly to the host. For host 192.168.1.2, the same
process occurs, except that the security appliance looks up the route in its route table, and sends the
packet to the downstream router at 10.1.1.3 based on the static route.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-3
Chapter 19
Configuring NAT
NAT Overview
Figure 19-2
NAT Example: Transparent Mode
www.example.com
Internet
Static route on router to
209.165.201.0/27 to downstream router
Source Addr Translation
10.1.1.75
209.165.201.15
Static route on security appliance for
192.168.1.1/24 to downstream router
10.1.1.2
Management IP
10.1.1.1
Security
appliance
10.1.1.75
10.1.1.3
Source Addr Translation
192.168.1.2
209.165.201.10
250261
192.168.1.1
Network 2
192.168.1.2
See the following commands for this example:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
route inside 192.168.1.0 255.255.255.0 10.1.1.3 1
nat (inside) 1 10.1.1.0 255.255.255.0
nat (inside) 1 192.168.1.0 255.255.255.0
global (outside) 1 209.165.201.1-209.165.201.15
Cisco Security Appliance Command Line Configuration Guide
19-4
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
NAT Control
NAT control requires that packets traversing from an inside interface to an outside interface match a NAT
rule; for any host on the inside network to access a host on the outside network, you must configure NAT
to translate the inside host address, as shown in Figure 19-3.
Figure 19-3
NAT Control and Outbound Traffic
Security
Appliance
10.1.1.1
209.165.201.1
NAT
Inside
132212
10.1.2.1 No NAT
Outside
Interfaces at the same security level are not required to use NAT to communicate. However, if you
configure dynamic NAT or PAT on a same security interface, then all traffic from the interface to a same
security interface or an outside interface must match a NAT rule, as shown in Figure 19-4.
Figure 19-4
NAT Control and Same Security Traffic
Security
Appliance
Security
Appliance
10.1.1.1 Dyn. NAT
10.1.1.1 No NAT
209.165.201.1
10.1.1.1
10.1.2.1 No NAT
Level 50
Level 50
Level 50
or
Outside
132215
Level 50
Similarly, if you enable outside dynamic NAT or PAT, then all outside traffic must match a NAT rule
when it accesses an inside interface (see Figure 19-5).
NAT Control and Inbound Traffic
Security
Appliance
Security
Appliance
209.165.202.129 Dyn. NAT
209.165.202.129 No NAT
Outside
209.165.202.129
10.1.1.50
209.165.200.240 No NAT
Inside
Outside
Inside
132213
Figure 19-5
Static NAT does not cause these restrictions.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-5
Chapter 19
Configuring NAT
NAT Overview
By default, NAT control is disabled; therefore, you do not need to perform NAT on any networks unless
you want to do so. If you upgraded from an earlier version of software, however, NAT control might be
enabled on your system. Even with NAT control disabled, you need to perform NAT on any addresses
for which you configure dynamic NAT. See the “Dynamic NAT and PAT Implementation” section on
page 19-19 for more information about how dynamic NAT is applied.
If you want the added security of NAT control but do not want to translate inside addresses in some cases,
you can apply a NAT exemption or identity NAT rule on those addresses. (See the “Bypassing NAT”
section on page 19-32 for more information).
To configure NAT control, see the “Configuring NAT Control” section on page 19-18.
Note
In multiple context mode, the packet classifier might rely on the NAT configuration to assign packets to
contexts if you do not enable unique MAC addresses for shared interfaces. See the “How the Security
Appliance Classifies Packets” section on page 4-3 for more information about the relationship between
the classifier and NAT.
NAT Types
This section describes the available NAT types, and includes the following topics:
•
Dynamic NAT, page 19-6
•
PAT, page 19-8
•
Static NAT, page 19-9
•
Static PAT, page 19-9
•
Bypassing NAT When NAT Control is Enabled, page 19-10
You can implement address translation as dynamic NAT, Port Address Translation, static NAT, static
PAT, or as a mix of these types. You can also configure rules to bypass NAT; for example, to enable NAT
control when you do not want to perform NAT.
Dynamic NAT
Dynamic NAT translates a group of real addresses to a pool of mapped addresses that are routable on the
destination network. The mapped pool may include fewer addresses than the real group. When a host
you want to translate accesses the destination network, the security appliance assigns the host an IP
address from the mapped pool. The translation is added only when the real host initiates the connection.
The translation is in place only for the duration of the connection, and a given user does not keep the
same IP address after the translation times out. For an example, see the timeout xlate command in the
Cisco Security Appliance Command Reference. Users on the destination network, therefore, cannot
initiate a reliable connection to a host that uses dynamic NAT, although the connection is allowed by an
access list, and the security appliance rejects any attempt to connect to a real host address directly. See
the “Static NAT” or “Static PAT” section for information on how to obtain reliable access to hosts.
Note
In some cases, a translation is added for a connection, although the session is denied by the security
appliance. This condition occurs with an outbound access list, a management-only interface, or a backup
interface in which the translation times out normally. For an example, see the show xlate command in
the Cisco Security Appliance Command Reference.
Cisco Security Appliance Command Line Configuration Guide
19-6
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
Figure 19-6 shows a remote host attempting to connect to the real address. The connection is denied,
because the security appliance only allows returning connections to the mapped address.
Figure 19-6
Remote Host Attempts to Connect to the Real Address
Web Server
www.example.com
Outside
209.165.201.2
Security
Appliance
Translation
10.1.2.27
209.165.201.10
10.1.2.27
10.1.2.1
132216
Inside
10.1.2.27
Figure 19-7 shows a remote host attempting to initiate a connection to a mapped address. This address
is not currently in the translation table; therefore, the security appliance drops the packet.
Figure 19-7
Remote Host Attempts to Initiate a Connection to a Mapped Address
Web Server
www.example.com
Outside
209.165.201.2
Security
Appliance
209.165.201.10
10.1.2.1
132217
Inside
10.1.2.27
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-7
Chapter 19
Configuring NAT
NAT Overview
Note
For the duration of the translation, a remote host can initiate a connection to the translated host if an
access list allows it. Because the address is unpredictable, a connection to the host is unlikely.
Nevertheless, in this case, you can rely on the security of the access list.
Dynamic NAT has these disadvantages:
•
If the mapped pool has fewer addresses than the real group, you could run out of addresses if the
amount of traffic is more than expected.
Use PAT if this event occurs often, because PAT provides over 64,000 translations using ports of a
single address.
•
You have to use a large number of routable addresses in the mapped pool; if the destination network
requires registered addresses, such as the Internet, you might encounter a shortage of usable
addresses.
The advantage of dynamic NAT is that some protocols cannot use PAT. PAT does not work with the
following:
•
IP protocols that do not have a port to overload, such as GRE version 0.
•
Some multimedia applications that have a data stream on one port, the control path on another port,
and are not open standard.
See the “When to Use Application Protocol Inspection” section on page 26-2 for more information about
NAT and PAT support.
PAT
PAT translates multiple real addresses to a single mapped IP address. Specifically, the security appliance
translates the real address and source port (real socket) to the mapped address and a unique port above
1024 (mapped socket). Each connection requires a separate translation, because the source port differs
for each connection. For example, 10.1.1.1:1025 requires a separate translation from 10.1.1.1:1026.
After the connection expires, the port translation also expires after 30 seconds of inactivity. The timeout
is not configurable. Users on the destination network cannot reliably initiate a connection to a host that
uses PAT (even if the connection is allowed by an access list). Not only can you not predict the real or
mapped port number of the host, but the security appliance does not create a translation at all unless the
translated host is the initiator. See the following “Static NAT” or “Static PAT” sections for reliable access
to hosts.
PAT lets you use a single mapped address, thus conserving routable addresses. You can even use the
security appliance interface IP address as the PAT address. PAT does not work with some multimedia
applications that have a data stream that is different from the control path. See the “When to Use
Application Protocol Inspection” section on page 26-2 for more information about NAT and PAT
support.
Note
For the duration of the translation, a remote host can initiate a connection to the translated host if an
access list allows it. Because the port address (both real and mapped) is unpredictable, a connection to
the host is unlikely. Nevertheless, in this case, you can rely on the security of the access list. However,
policy PAT does not support time-based ACLs.
Cisco Security Appliance Command Line Configuration Guide
19-8
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
Static NAT
Static NAT creates a fixed translation of real address(es) to mapped address(es).With dynamic NAT and
PAT, each host uses a different address or port for each subsequent translation. Because the mapped
address is the same for each consecutive connection with static NAT, and a persistent translation rule
exists, static NAT allows hosts on the destination network to initiate traffic to a translated host (if an
access list exists that allows it).
The main difference between dynamic NAT and a range of addresses for static NAT is that static NAT
allows a remote host to initiate a connection to a translated host (if an access list exists that allows it),
while dynamic NAT does not. You also need an equal number of mapped addresses as real addresses with
static NAT.
Static PAT
Static PAT is the same as static NAT, except that it lets you specify the protocol (TCP or UDP) and port
for the real and mapped addresses.
This feature lets you identify the same mapped address across many different static statements, provided
the port is different for each statement. You cannot use the same mapped address for multiple static NAT
statements.
For applications that require inspection for secondary channels (for example, FTP and VoIP), the
security appliance automatically translates the secondary ports.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-9
Chapter 19
Configuring NAT
NAT Overview
For example, if you want to provide a single address for remote users to access FTP, HTTP, and SMTP,
but these are all actually different servers on the real network, you can specify static PAT statements for
each server that uses the same mapped IP address, but different ports (see Figure 19-8).
Figure 19-8
Static PAT
Host
Undo Translation
209.165.201.3:21
10.1.2.27
Outside
Undo Translation
209.165.201.3:25
10.1.2.29
Undo Translation
209.165.201.3:80
10.1.2.28
Inside
SMTP server
10.1.2.29
HTTP server
10.1.2.28
130031
FTP server
10.1.2.27
See the following commands for this example:
hostname(config)# static (inside,outside) tcp 209.165.201.3 ftp 10.1.2.27 ftp netmask
255.255.255.255
hostname(config)# static (inside,outside) tcp 209.165.201.3 http 10.1.2.28 http netmask
255.255.255.255
hostname(config)# static (inside,outside) tcp 209.165.201.3 smtp 10.1.2.29 smtp netmask
255.255.255.255
You can also use static PAT to translate a well-known port to a non-standard port or vice versa. For
example, if inside web servers use port 8080, you can allow outside users to connect to port 80, and then
undo translation to the original port 8080. Similarly, to provide extra security, you can tell web users to
connect to non-standard port 6785, and then undo translation to port 80.
Bypassing NAT When NAT Control is Enabled
If you enable NAT control, then inside hosts must match a NAT rule when accessing outside hosts. If
you do not want to perform NAT for some hosts, then you can bypass NAT for those hosts or you can
disable NAT control. You might want to bypass NAT, for example, if you are using an application that
does not support NAT. See the “When to Use Application Protocol Inspection” section on page 26-2 for
information about inspection engines that do not support NAT.
You can configure traffic to bypass NAT using one of three methods. All methods achieve compatibility
with inspection engines. However, each method offers slightly different capabilities, as follows:
Cisco Security Appliance Command Line Configuration Guide
19-10
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
•
Identity NAT (nat 0 command)—When you configure identity NAT (which is similar to dynamic
NAT), you do not limit translation for a host on specific interfaces; you must use identity NAT for
connections through all interfaces. Therefore, you cannot choose to perform normal translation on
real addresses when you access interface A, but use identity NAT when accessing interface B.
Regular dynamic NAT, on the other hand, lets you specify a particular interface on which to translate
the addresses. Make sure that the real addresses for which you use identity NAT are routable on all
networks that are available according to your access lists.
For identity NAT, even though the mapped address is the same as the real address, you cannot initiate
a connection from the outside to the inside (even if the interface access list allows it). Use static
identity NAT or NAT exemption for this functionality.
•
Static identity NAT (static command)—Static identity NAT lets you specify the interface on which
you want to allow the real addresses to appear, so you can use identity NAT when you access
interface A, and use regular translation when you access interface B. Static identity NAT also lets
you use policy NAT, which identifies the real and destination addresses when determining the real
addresses to translate (see the “Policy NAT” section on page 19-11 for more information about
policy NAT). For example, you can use static identity NAT for an inside address when it accesses
the outside interface and the destination is server A, but use a normal translation when accessing the
outside server B.
•
NAT exemption (nat 0 access-list command)—NAT exemption allows both translated and remote
hosts to initiate connections. Like identity NAT, you do not limit translation for a host on specific
interfaces; you must use NAT exemption for connections through all interfaces. However,
NAT exemption does let you specify the real and destination addresses when determining the real
addresses to translate (similar to policy NAT), so you have greater control using NAT exemption.
However unlike policy NAT, NAT exemption does not consider the ports in the access list. NAT
exemption also does not support connection settings, such as maximum TCP connections.
Policy NAT
Policy NAT lets you identify real addresses for address translation by specifying the source and
destination addresses in an extended access list. You can also optionally specify the source and
destination ports. Regular NAT can only consider the source addresses, and not the destination. For
example, with policy NAT, you can translate the real address to mapped address A when it accesses
server A, but translate the real address to mapped address B when it accesses server B.
Note
Policy NAT does not support time-based ACLs.
For applications that require application inspection for secondary channels (for example, FTP and VoIP),
the policy specified in the policy NAT statement should include the secondary ports. When the ports
cannot be predicted, the policy should specify only the IP addresses for the secondary channel. With this
configuration, the security appliance translates the secondary ports.
Note
All types of NAT support policy NAT, except for NAT exemption. NAT exemption uses an access list to
identify the real addresses, but differs from policy NAT in that the ports are not considered. See the
“Bypassing NAT” section on page 19-32 for other differences. You can accomplish the same result as
NAT exemption using static identity NAT, which does support policy NAT.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-11
Chapter 19
Configuring NAT
NAT Overview
Figure 19-9 shows a host on the 10.1.2.0/24 network accessing two different servers. When the host
accesses the server at 209.165.201.11, the real address is translated to 209.165.202.129. When the host
accesses the server at 209.165.200.225, the real address is translated to 209.165.202.130. Consequently,
the host appears to be on the same network as the servers, which can help with routing.
Figure 19-9
Policy NAT with Different Destination Addresses
Server 1
209.165.201.11
Server 2
209.165.200.225
209.165.201.0/27
209.165.200.224/27
DMZ
Translation
10.1.2.27
209.165.202.129
Translation
10.1.2.27
209.165.202.130
Inside
Packet
Dest. Address:
209.165.201.11
10.1.2.27
Packet
Dest. Address:
209.165.200.225
130039
10.1.2.0/24
See the following commands for this example:
hostname(config)#
255.255.255.224
hostname(config)#
255.255.255.224
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list NET1 permit ip 10.1.2.0 255.255.255.0 209.165.201.0
access-list NET2 permit ip 10.1.2.0 255.255.255.0 209.165.200.224
nat (inside) 1 access-list NET1
global (outside) 1 209.165.202.129
nat (inside) 2 access-list NET2
global (outside) 2 209.165.202.130
Cisco Security Appliance Command Line Configuration Guide
19-12
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
Figure 19-10 shows the use of source and destination ports. The host on the 10.1.2.0/24 network accesses
a single host for both web services and Telnet services. When the host accesses the server for web
services, the real address is translated to 209.165.202.129. When the host accesses the same server for
Telnet services, the real address is translated to 209.165.202.130.
Figure 19-10
Policy NAT with Different Destination Ports
Web and Telnet server:
209.165.201.11
Internet
Translation
10.1.2.27:80
209.165.202.129
Translation
10.1.2.27:23
209.165.202.130
Inside
Web Packet
Dest. Address:
209.165.201.11:80
10.1.2.27
Telnet Packet
Dest. Address:
209.165.201.11:23
130040
10.1.2.0/24
See the following commands for this example:
hostname(config)# access-list WEB permit tcp 10.1.2.0 255.255.255.0 209.165.201.11
255.255.255.255 eq 80
hostname(config)# access-list TELNET permit tcp 10.1.2.0 255.255.255.0 209.165.201.11
255.255.255.255 eq 23
hostname(config)# nat (inside) 1 access-list WEB
hostname(config)# global (outside) 1 209.165.202.129
hostname(config)# nat (inside) 2 access-list TELNET
hostname(config)# global (outside) 2 209.165.202.130
For policy static NAT (and for NAT exemption, which also uses an access list to identify traffic), both
translated and remote hosts can originate traffic. For traffic originated on the translated network, the
NAT access list specifies the real addresses and the destination addresses, but for traffic originated on
the remote network, the access list identifies the real addresses and the source addresses of remote hosts
who are allowed to connect to the host using this translation.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-13
Chapter 19
Configuring NAT
NAT Overview
Figure 19-11 shows a remote host connecting to a translated host. The translated host has a policy static
NAT translation that translates the real address only for traffic to and from the 209.165.201.0/27
network. A translation does not exist for the 209.165.200.224/27 network, so the translated host cannot
connect to that network, nor can a host on that network connect to the translated host.
Figure 19-11
Policy Static NAT with Destination Address Translation
209.165.201.11
209.165.200.225
209.165.201.0/27
209.165.200.224/27
DMZ
No Translation
Undo Translation
10.1.2.27
209.165.202.128
Inside
10.1.2.27
130037
10.1.2.0/27
See the following commands for this example:
hostname(config)# access-list NET1 permit ip 10.1.2.0 255.255.255.224 209.165.201.0
255.255.255.224
hostname(config)# static (inside,outside) 209.165.202.128 access-list NET1
Note
For policy static NAT, in undoing the translation, the ACL in the static command is not used. If the
destination address in the packet matches the mapped address in the static rule, the static rule is used to
untranslate the address.
Note
Policy NAT does not support SQL*Net, but it is supported by regular NAT. See the “When to Use
Application Protocol Inspection” section on page 26-2 for information about NAT support for other
protocols.
You cannot use policy static NAT to translate different real addresses to the same mapped address. For
example, Figure 19-12 shows two inside hosts, 10.1.1.1 and 10.1.1.2, that you want to be translated to
209.165.200.225. When outside host 209.165.201.1 connects to 209.165.200.225, then the connection
goes to 10.1.1.1. When outside host 209.165.201.2 connects to the same mapped address,
209.165.200.225, you want the connection to go to 10.1.1.2. However, only one source address in the
access list can be used. Since the first ACE is for 10.1.1.1, then all inbound connections sourced from
209.165.201.1 and 209.165.201.2 and destined to 209.165.200.255 will have their destination address
translated to 10.1.1.1.
Cisco Security Appliance Command Line Configuration Guide
19-14
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
Figure 19-12
Real Addresses Cannot Share the Same Mapped Address
209.165.201.2
209.165.201.1
Outside
Undo Translation
209.165.200.225
10.1.1.1
No Undo Translation
209.165.200.225
10.1.1.2
10.1.1.1
10.1.1.2
242981
Inside
See the following commands for this example. (Although the second ACE in the example does allow
209.165.201.2 to connect to 209.165.200.225, it only allows 209.165.200.225 to be translated to
10.1.1.1.)
hostname(config)# static (in,out) 209.165.200.225 access-list policy-nat
hostname(config)# access-list policy-nat permit ip host 10.1.1.1 host 209.165.201.1
hostname(config)# access-list policy-nat permit ip host 10.1.1.2 host 209.165.201.2
NAT and Same Security Level Interfaces
NAT is not required between same security level interfaces even if you enable NAT control. You can
optionally configure NAT if desired. However, if you configure dynamic NAT when NAT control is
enabled, then NAT is required. See the “NAT Control” section on page 19-5 for more information. Also,
when you specify a group of IP address(es) for dynamic NAT or PAT on a same security interface, then
you must perform NAT on that group of addresses when they access any lower or same security level
interface (even when NAT control is not enabled). Traffic identified for static NAT is not affected.
See the “Allowing Communication Between Interfaces on the Same Security Level” section on page 8-7
to enable same security communication.
Note
The security appliance does not support VoIP inspection engines when you configure NAT on same
security interfaces. These inspection engines include Skinny, SIP, and H.323. See the “When to Use
Application Protocol Inspection” section on page 26-2 for supported inspection engines.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-15
Chapter 19
Configuring NAT
NAT Overview
Order of NAT Commands Used to Match Real Addresses
The security appliance matches real addresses to NAT commands in the following order:
1.
NAT exemption (nat 0 access-list)—In order, until the first match. Identity NAT is not included in
this category; it is included in the regular static NAT or regular NAT category. We do not recommend
overlapping addresses in NAT exemption statements because unexpected results can occur.
2.
Static NAT and Static PAT (regular and policy) (static)—In order, until the first match. Static
identity NAT is included in this category.
3.
Policy dynamic NAT (nat access-list)—In order, until the first match. Overlapping addresses are
allowed.
4.
Regular dynamic NAT (nat)—Best match. Regular identity NAT is included in this category. The
order of the NAT commands does not matter; the NAT statement that best matches the real address
is used. For example, you can create a general statement to translate all addresses (0.0.0.0) on an
interface. If you want to translate a subset of your network (10.1.1.1) to a different address, then you
can create a statement to translate only 10.1.1.1. When 10.1.1.1 makes a connection, the specific
statement for 10.1.1.1 is used because it matches the real address best. We do not recommend using
overlapping statements; they use more memory and can slow the performance of the security
appliance.
Mapped Address Guidelines
When you translate the real address to a mapped address, you can use the following mapped addresses:
•
Addresses on the same network as the mapped interface.
If you use addresses on the same network as the mapped interface (through which traffic exits the
security appliance), the security appliance uses proxy ARP to answer any requests for mapped
addresses, and thus intercepts traffic destined for a real address. This solution simplifies routing,
because the security appliance does not have to be the gateway for any additional networks.
However, this approach does put a limit on the number of available addresses used for translations.
For PAT, you can even use the IP address of the mapped interface.
•
Addresses on a unique network.
If you need more addresses than are available on the mapped interface network, you can identify
addresses on a different subnet. The security appliance uses proxy ARP to answer any requests for
mapped addresses, and thus intercepts traffic destined for a real address. If you use OSPF to
advertise mapped IP addresses that belong to a different subnet from the mapped interface, you need
to create a static route to the mapped addresses that are destined to the mapped interface IP, and then
redistribute this static route in OSPF. If the mapped interface is passive (not advertising routes) or
you are using static routing, then you need to add a static route on the upstream router that sends
traffic destined for the mapped addresses to the security appliance.
Cisco Security Appliance Command Line Configuration Guide
19-16
OL-12172-04
Chapter 19
Configuring NAT
NAT Overview
DNS and NAT
You might need to configure the security appliance to modify DNS replies by replacing the address in
the reply with an address that matches the NAT configuration. You can configure DNS modification
when you configure each translation.
For example, a DNS server is accessible from the outside interface. A server, ftp.cisco.com, is on the
inside interface. You configure the security appliance to statically translate the ftp.cisco.com real address
(10.1.3.14) to a mapped address (209.165.201.10) that is visible on the outside network (see
Figure 19-13). In this case, you want to enable DNS reply modification on this static statement so that
inside users who have access to ftp.cisco.com using the real address receive the real address from the
DNS server, and not the mapped address.
When an inside host sends a DNS request for the address of ftp.cisco.com, the DNS server replies with
the mapped address (209.165.201.10). The security appliance refers to the static statement for the inside
server and translates the address inside the DNS reply to 10.1.3.14. If you do not enable DNS reply
modification, then the inside host attempts to send traffic to 209.165.201.10 instead of accessing
ftp.cisco.com directly.
Figure 19-13
DNS Reply Modification
DNS Server
1
DNS Query
ftp.cisco.com?
2
Outside
DNS Reply
209.165.201.10
Security
Appliance
3
DNS Reply Modification
209.165.201.10
10.1.3.14
Inside
4
DNS Reply
10.1.3.14
ftp.cisco.com
10.1.3.14
Static Translation
on Outside to:
209.165.201.10
130021
User
5
FTP Request
10.1.3.14
See the following command for this example:
hostname(config)# static (inside,outside) 209.165.201.10 10.1.3.14 netmask 255.255.255.255
dns
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-17
Chapter 19
Configuring NAT
Configuring NAT Control
Note
If a user on a different network (for example, DMZ) also requests the IP address for ftp.cisco.com from
the outside DNS server, then the IP address in the DNS reply is also modified for this user, even though
the user is not on the Inside interface referenced by the static command.
Figure 19-14 shows a web server and DNS server on the outside. The security appliance has a static
translation for the outside server. In this case, when an inside user requests the address for ftp.cisco.com
from the DNS server, the DNS server responds with the real address, 209.165.20.10. Because you want
inside users to use the mapped address for ftp.cisco.com (10.1.2.56) you need to configure DNS reply
modification for the static translation.
Figure 19-14
DNS Reply Modification Using Outside NAT
ftp.cisco.com
209.165.201.10
Static Translation on Inside to:
10.1.2.56
DNS Server
7
FTP Request
209.165.201.10
1
DNS Query
ftp.cisco.com?
2
DNS Reply
209.165.201.10
3
Outside
6
Dest Addr. Translation
10.1.2.56
209.165.201.10
Security
Appliance
5
DNS Reply Modification
209.165.201.10
10.1.2.56
Inside
4
FTP Request
10.1.2.56
User
10.1.2.27
130022
DNS Reply
10.1.2.56
See the following command for this example:
hostname(config)# static (outside,inside) 10.1.2.56 209.165.201.10 netmask 255.255.255.255
dns
Configuring NAT Control
NAT control requires that packets traversing from an inside interface to an outside interface match a NAT
rule. See the “NAT Control” section on page 19-5 for more information.
To enable NAT control, enter the following command:
Cisco Security Appliance Command Line Configuration Guide
19-18
OL-12172-04
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
hostname(config)# nat-control
To disable NAT control, enter the no form of the command.
Using Dynamic NAT and PAT
This section describes how to configure dynamic NAT and PAT, and includes the following topics:
•
Dynamic NAT and PAT Implementation, page 19-19
•
Configuring Dynamic NAT or PAT, page 19-25
Dynamic NAT and PAT Implementation
For dynamic NAT and PAT, you first configure a nat command identifying the real addresses on a given
interface that you want to translate. Then you configure a separate global command to specify the
mapped addresses when exiting another interface (in the case of PAT, this is one address). Each nat
command matches a global command by comparing the NAT ID, a number that you assign to each
command (see Figure 19-15).
Figure 19-15
nat and global ID Matching
Web Server:
www.cisco.com
Outside
Global 1: 209.165.201.3209.165.201.10
Translation
10.1.2.27
209.165.201.3
NAT 1: 10.1.2.0/24
130027
Inside
10.1.2.27
See the following commands for this example:
hostname(config)# nat (inside) 1 10.1.2.0 255.255.255.0
hostname(config)# global (outside) 1 209.165.201.3-209.165.201.10
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-19
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
You can enter multiple nat commands using the same NAT ID on one or more interfaces; they all use the
same global command when traffic exits a given interface. For example, you can configure nat
commands for Inside and DMZ interfaces, both on NAT ID 1. Then you configure a global command on
the Outside interface that is also on ID 1. Traffic from the Inside interface and the DMZ interface share
a mapped pool or a PAT address when exiting the Outside interface (see Figure 19-16).
Figure 19-16
nat Commands on Multiple Interfaces
Web Server:
www.cisco.com
Translation
10.1.1.15
209.165.201.4
Outside
Global 1: 209.165.201.3209.165.201.10
NAT 1: 10.1.1.0/24
DMZ
Translation
10.1.2.27
209.165.201.3
10.1.1.15
NAT 1: 10.1.2.0/24
NAT 1: 192.168.1.0/24
Inside
Translation
192.168.1.5
209.165.201.5
10.1.2.27
250263
Network
2
192.168.1.5
See the following commands for this example:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
nat (inside) 1 10.1.2.0 255.255.255.0
nat (inside) 1 192.168.1.0 255.255.255.0
nat (dmz) 1 10.1.1.0 255.255.255.0
global (outside) 1 209.165.201.3-209.165.201.10
Cisco Security Appliance Command Line Configuration Guide
19-20
OL-12172-04
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
You can also enter a global command for each interface using the same NAT ID. If you enter a global
command for the Outside and DMZ interfaces on ID 1, then the Inside nat command identifies traffic to
be translated when going to both the Outside and the DMZ interfaces. Similarly, if you also enter a nat
command for the DMZ interface on ID 1, then the global command on the Outside interface is also used
for DMZ traffic. (See Figure 19-17).
Figure 19-17
global and nat Commands on Multiple Interfaces
Web Server:
www.cisco.com
Translation
10.1.1.15
209.165.201.4
Outside
Global 1: 209.165.201.3209.165.201.10
Security
Appliance
NAT 1: 10.1.1.0/24
Global 1: 10.1.1.23
Translation
10.1.2.27
209.165.201.3
DMZ
10.1.1.15
NAT 1: 10.1.2.0/24
Inside
130024
Translation
10.1.2.27
10.1.1.23:2024
10.1.2.27
See the following commands for this example:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
nat (inside) 1 10.1.2.0 255.255.255.0
nat (dmz) 1 10.1.1.0 255.255.255.0
global (outside) 1 209.165.201.3-209.165.201.10
global (dmz) 1 10.1.1.23
If you use different NAT IDs, you can identify different sets of real addresses to have different mapped
addresses. For example, on the Inside interface, you can have two nat commands on two different
NAT IDs. On the Outside interface, you configure two global commands for these two IDs. Then, when
traffic from Inside network A exits the Outside interface, the IP addresses are translated to pool A
addresses; while traffic from Inside network B are translated to pool B addresses (see Figure 19-18). If
you use policy NAT, you can specify the same real addresses for multiple nat commands, as long as the
the destination addresses and ports are unique in each access list.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-21
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
Figure 19-18
Different NAT IDs
Web Server:
www.cisco.com
Outside
Global 1: 209.165.201.3209.165.201.10
Global 2: 209.165.201.11
Security
Appliance
192.168.1.14
Translation
209.165.201.11:4567
NAT 1: 10.1.2.0/24
Translation
10.1.2.27
209.165.201.3
NAT 2: 192.168.1.0/24
10.1.2.27
130025
Inside
192.168.1.14
See the following commands for this example:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
nat (inside) 1 10.1.2.0 255.255.255.0
nat (inside) 2 192.168.1.0 255.255.255.0
global (outside) 1 209.165.201.3-209.165.201.10
global (outside) 2 209.165.201.11
You can enter multiple global commands for one interface using the same NAT ID; the security
appliance uses the dynamic NAT global commands first, in the order they are in the configuration, and
then uses the PAT global commands in order. You might want to enter both a dynamic NAT global
command and a PAT global command if you need to use dynamic NAT for a particular application, but
want to have a backup PAT statement in case all the dynamic NAT addresses are depleted. Similarly, you
might enter two PAT statements if you need more than the approximately 64,000 PAT sessions that a
single PAT mapped statement supports (see Figure 19-19).
Cisco Security Appliance Command Line Configuration Guide
19-22
OL-12172-04
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
Figure 19-19
NAT and PAT Together
Web Server:
www.cisco.com
Translation
10.1.2.27
209.165.201.3
Outside
Global 1: 209.165.201.3209.165.201.4
Global 1: 209.165.201.5
10.1.2.29
Translation
209.165.201.5:6096
Translation
10.1.2.28
209.165.201.4
NAT 1: 10.1.2.0/24
Inside
10.1.2.29
130026
10.1.2.27
10.1.2.28
See the following commands for this example:
hostname(config)# nat (inside) 1 10.1.2.0 255.255.255.0
hostname(config)# global (outside) 1 209.165.201.3-209.165.201.4
hostname(config)# global (outside) 1 209.165.201.5
For outside NAT (from outside to inside), you need to use the outside keyword in the nat command. If
you also want to translate the same traffic when it accesses an outside interface (for example, traffic on
a DMZ is translated when accessing the Inside and the Outside interfaces), then you must configure a
separate nat command without the outside option. In this case, you can identify the same addresses in
both statements and use the same NAT ID (see Figure 19-20). Note that for outside NAT (DMZ interface
to Inside interface), the inside host uses a static command to allow outside access, so both the source
and destination addresses are translated.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-23
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
Figure 19-20
Outside NAT and Inside NAT Combined
Outside
Translation
10.1.1.15
209.165.201.4
Global 1: 209.165.201.3209.165.201.10
Outside NAT 1: 10.1.1.0/24
NAT 1: 10.1.1.0/24
DMZ
10.1.1.15
Global 1: 10.1.2.3010.1.2.40 Static to DMZ: 10.1.2.27
10.1.1.5
Translation
10.1.1.15
10.1.2.30
Inside
10.1.2.27
130038
Undo Translation
10.1.1.5
10.1.2.27
See the following commands for this example:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
nat (dmz) 1 10.1.1.0 255.255.255.0 outside
nat (dmz) 1 10.1.1.0 255.255.255.0
static (inside,dmz) 10.1.1.5 10.1.2.27 netmask 255.255.255.255
global (outside) 1 209.165.201.3-209.165.201.4
global (inside) 1 10.1.2.30-1-10.1.2.40
When you specify a group of IP address(es) in a nat command, then you must perform NAT on that group
of addresses when they access any lower or same security level interface; you must apply a global
command with the same NAT ID on each interface, or use a static command. NAT is not required for
that group when it accesses a higher security interface, because to perform NAT from outside to inside,
you must create a separate nat command using the outside keyword. If you do apply outside NAT, then
the NAT requirements preceding come into effect for that group of addresses when they access all higher
security interfaces. Traffic identified by a static command is not affected.
Cisco Security Appliance Command Line Configuration Guide
19-24
OL-12172-04
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
Configuring Dynamic NAT or PAT
This section describes how to configure dynamic NAT or dynamic PAT. The configuration for dynamic
NAT and PAT are almost identical; for NAT you specify a range of mapped addresses, and for PAT you
specify a single address.
Figure 19-21 shows a typical dynamic NAT scenario. Only translated hosts can create a NAT session,
and responding traffic is allowed back. The mapped address is dynamically assigned from a pool defined
by the global command.
Figure 19-21
Dynamic NAT
Security
Appliance
209.165.201.1
10.1.1.2
209.165.201.2
130032
10.1.1.1
Inside Outside
Figure 19-22 shows a typical dynamic PAT scenario. Only translated hosts can create a NAT session, and
responding traffic is allowed back. The mapped address defined by the global command is the same for
each translation, but the port is dynamically assigned.
Figure 19-22
Dynamic PAT
209.165.201.1:2020
10.1.1.1:1026
209.165.201.1:2021
10.1.1.2:1025
209.165.201.1:2022
Inside Outside
130034
Security
Appliance
10.1.1.1:1025
For more information about dynamic NAT, see the “Dynamic NAT” section on page 19-6. For more
information about PAT, see the “PAT” section on page 19-8.
Note
If you change the NAT configuration, and you do not want to wait for existing translations to time out
before the new NAT information is used, you can clear the translation table using the clear xlate
command. However, clearing the translation table disconnects all current connections that use
translations.
To configure dynamic NAT or PAT, perform the following steps:
Step 1
To identify the real addresses that you want to translate, enter one of the following commands:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-25
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
•
Policy NAT:
hostname(config)# nat (real_interface) nat_id access-list acl_name [dns] [outside]
[norandomseq] [[tcp] tcp_max_conns [emb_limit]] [udp udp_max_conns]
You can identify overlapping addresses in other nat commands. For example, you can identify
10.1.1.0 in one command, but 10.1.1.1 in another. The traffic is matched to a policy NAT command
in order, until the first match, or for regular NAT, using the best match.
The options for this command are as follows:
– access-list acl_name—Identify the real addresses and destination addresses using an extended
access list. Create the extended access list using the access-list extended command (see the
“Adding an Extended Access List” section on page 18-5). This access list should include only
permit ACEs. You can optionally specify the real and destination ports in the access list using
the eq operator. Policy NAT considers the inactive and time-range keywords, but it does not
support ACL with all inactive and time-range ACEs.
– nat_id—An integer between 1 and 65535. The NAT ID should match a global command NAT
ID. See the “Dynamic NAT and PAT Implementation” section on page 19-19 for more
information about how NAT IDs are used. 0 is reserved for NAT exemption. (See the
“Configuring NAT Exemption” section on page 19-35 for more information about NAT
exemption.)
– dns—If your nat command includes the address of a host that has an entry in a DNS server, and
the DNS server is on a different interface from a client, then the client and the DNS server need
different addresses for the host; one needs the mapped address and one needs the real address.
This option rewrites the address in the DNS reply to the client. The translated host needs to be
on the same interface as either the client or the DNS server. Typically, hosts that need to allow
access from other interfaces use a static translation, so this option is more likely to be used with
the static command. (See the “DNS and NAT” section on page 19-17 for more information.)
– outside—If this interface is on a lower security level than the interface you identify by the
matching global statement, then you must enter outside to identify the NAT instance as
outside NAT.
– norandomseq, tcp tcp_max_conns, udp udp_max_conns, and emb_limit—These keywords set
connection limits. However, we recommend using a more versatile method for setting
connection limits; see the “Configuring Connection Limits and Timeouts” section on
page 24-17.
•
Regular NAT:
hostname(config)# nat (real_interface) nat_id real_ip [mask [dns] [outside]
[norandomseq] [[tcp] tcp_max_conns [emb_limit]] [udp udp_max_conns]]
The nat_id argument is an integer between 1 and 2147483647. The NAT ID must match a global
command NAT ID. See the “Dynamic NAT and PAT Implementation” section on page 19-19 for
more information about how NAT IDs are used. 0 is reserved for identity NAT. See the “Configuring
Identity NAT” section on page 19-32 for more information about identity NAT.
See the preceding policy NAT command for information about other options.
Step 2
To identify the mapped address(es) to which you want to translate the real addresses when they exit a
particular interface, enter the following command:
hostname(config)# global (mapped_interface) nat_id {mapped_ip[-mapped_ip] | interface}
This NAT ID should match a nat command NAT ID. The matching nat command identifies the addresses
that you want to translate when they exit this interface.
Cisco Security Appliance Command Line Configuration Guide
19-26
OL-12172-04
Chapter 19
Configuring NAT
Using Dynamic NAT and PAT
You can specify a single address (for PAT) or a range of addresses (for NAT). The range can go across
subnet boundaries if desired. For example, you can specify the following “supernet”:
192.168.1.1-192.168.2.254
For example, to translate the 10.1.1.0/24 network on the inside interface, enter the following command:
hostname(config)# nat (inside) 1 10.1.1.0 255.255.255.0
hostname(config)# global (outside) 1 209.165.201.1-209.165.201.30
To identify a pool of addresses for dynamic NAT as well as a PAT address for when the NAT pool is
exhausted, enter the following commands:
hostname(config)# nat (inside) 1 10.1.1.0 255.255.255.0
hostname(config)# global (outside) 1 209.165.201.5
hostname(config)# global (outside) 1 209.165.201.10-209.165.201.20
To translate the lower security dmz network addresses so they appear to be on the same network as the
inside network (10.1.1.0), for example, to simplify routing, enter the following commands:
hostname(config)# nat (dmz) 1 10.1.2.0 255.255.255.0 outside dns
hostname(config)# global (inside) 1 10.1.1.45
To identify a single real address with two different destination addresses using policy NAT, enter the
following commands (see Figure 19-9 on page 19-12 for a related figure):
hostname(config)#
255.255.255.224
hostname(config)#
255.255.255.224
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list NET1 permit ip 10.1.2.0 255.255.255.0 209.165.201.0
access-list NET2 permit ip 10.1.2.0 255.255.255.0 209.165.200.224
nat (inside) 1 access-list NET1 tcp 0 2000 udp 10000
global (outside) 1 209.165.202.129
nat (inside) 2 access-list NET2 tcp 1000 500 udp 2000
global (outside) 2 209.165.202.130
To identify a single real address/destination address pair that use different ports using policy NAT, enter
the following commands (see Figure 19-10 on page 19-13 for a related figure):
hostname(config)# access-list WEB permit tcp 10.1.2.0 255.255.255.0 209.165.201.11
255.255.255.255 eq 80
hostname(config)# access-list TELNET permit tcp 10.1.2.0 255.255.255.0 209.165.201.11
255.255.255.255 eq 23
hostname(config)# nat (inside) 1 access-list WEB
hostname(config)# global (outside) 1 209.165.202.129
hostname(config)# nat (inside) 2 access-list TELNET
hostname(config)# global (outside) 2 209.165.202.130
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-27
Chapter 19
Configuring NAT
Using Static NAT
Using Static NAT
This section describes how to configure a static translation.
Figure 19-23 shows a typical static NAT scenario. The translation is always active so both translated and
remote hosts can originate connections, and the mapped address is statically assigned by the static
command.
Figure 19-23
Static NAT
10.1.1.1
209.165.201.1
10.1.1.2
209.165.201.2
Inside Outside
130035
Security
Appliance
You cannot use the same real or mapped address in multiple static commands between the same two
interfaces unless you use static PAT (see the “Using Static PAT” section on page 19-29). Do not use a
mapped address in the static command that is also defined in a global command for the same mapped
interface.
For more information about static NAT, see the “Static NAT” section on page 19-9.
Note
If you remove a static command, existing connections that use the translation are not affected. To remove
these connections, enter the clear local-host command.
You cannot clear static translations from the translation table with the clear xlate command; you must
remove the static command instead. Only dynamic translations created by the nat and global commands
can be removed with the clear xlate command.
To configure static NAT, enter one of the following commands.
•
For policy static NAT, enter the following command:
hostname(config)# static (real_interface,mapped_interface) {mapped_ip | interface}
access-list acl_name [dns] [norandomseq] [[tcp] tcp_max_conns [emb_limit]]
[udp udp_max_conns]
Identify the real addresses and destination/source addresses using an extended access list. Create the
extended access list using the access-list extended command (see the “Adding an Extended Access
List” section on page 18-5). The first address in the access list is the real address; the second address
is either the source or destiniation address, depending on where the traffic originates. For example,
to translate the real address 10.1.1.1 to the mapped address 192.168.1.1 when 10.1.1.1 sends traffic
to the 209.165.200.224 network, the access-list and static commands are:
hostname(config)# access-list TEST extended ip host 10.1.1.1 209.165.200.224
255.255.255.224
hostname(config)# static (inside,outside) 192.168.1.1 access-list TEST
Cisco Security Appliance Command Line Configuration Guide
19-28
OL-12172-04
Chapter 19
Configuring NAT
Using Static PAT
In this case, the second address is the destination address. However, the same configuration is used
for hosts to originate a connection to the mapped address. For example, when a host on the
209.165.200.224/27 network initiates a connection to 192.168.1.1, then the second address in the
access list is the source address.
This access list should include only permit ACEs. You can optionally specify the real and
destination ports in the access list using the eq operator. Policy NAT does not consider the inactive
or time-range keywords; all ACEs are considered to be active for policy NAT configuration. See the
“Policy NAT” section on page 19-11 for more information.
If you specify a network for translation (for example, 10.1.1.0 255.255.255.0), then the security
appliance translates the .0 and .255 addresses. If you want to prevent access to these addresses, be
sure to configure an access list to deny access.
See the “Configuring Dynamic NAT or PAT” section on page 19-25 for information about the other
options.
•
To configure regular static NAT, enter the following command:
hostname(config)# static (real_interface,mapped_interface) {mapped_ip | interface}
real_ip [netmask mask] [dns] [norandomseq] [[tcp] tcp_max_conns [emb_limit]]
[udp udp_max_conns]
See the “Configuring Dynamic NAT or PAT” section on page 19-25 for information about the
options.
For example, the following policy static NAT example shows a single real address that is translated to
two mapped addresses depending on the destination address (see Figure 19-9 on page 19-12 for a related
figure):
hostname(config)#
hostname(config)#
255.255.255.224
hostname(config)#
hostname(config)#
access-list NET1 permit ip host 10.1.2.27 209.165.201.0 255.255.255.224
access-list NET2 permit ip host 10.1.2.27 209.165.200.224
static (inside,outside) 209.165.202.129 access-list NET1
static (inside,outside) 209.165.202.130 access-list NET2
The following command maps an inside IP address (10.1.1.3) to an outside IP address (209.165.201.12):
hostname(config)# static (inside,outside) 209.165.201.12 10.1.1.3 netmask 255.255.255.255
The following command maps the outside address (209.165.201.15) to an inside address (10.1.1.6):
hostname(config)# static (outside,inside) 10.1.1.6 209.165.201.15 netmask 255.255.255.255
The following command statically maps an entire subnet:
hostname(config)# static (inside,dmz) 10.1.1.0 10.1.2.0 netmask 255.255.255.0
Using Static PAT
This section describes how to configure a static port translation. Static PAT lets you translate the real IP
address to a mapped IP address, as well as the real port to a mapped port. You can choose to translate
the real port to the same port, which lets you translate only specific types of traffic, or you can take it
further by translating to a different port.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-29
Chapter 19
Configuring NAT
Using Static PAT
Figure 19-24 shows a typical static PAT scenario. The translation is always active so both translated and
remote hosts can originate connections, and the mapped address and port is statically assigned by the
static command.
Figure 19-24
Static PAT
10.1.1.1:23
209.165.201.1:23
10.1.1.2:8080
209.165.201.2:80
Inside Outside
130044
Security
Appliance
For applications that require application inspection for secondary channels (for example, FTP and VoIP),
the security appliance automatically translates the secondary ports.
Do not use a mapped address in the static command that is also defined in a global command for the
same mapped interface.
For more information about static PAT, see the “Static PAT” section on page 19-9.
Note
If you remove a static command, existing connections that use the translation are not affected. To remove
these connections, enter the clear local-host command.
You cannot clear static translations from the translation table with the clear xlate command; you must
remove the static command instead. Only dynamic translations created by the nat and global commands
can be removed with the clear xlate command.
To configure static PAT, enter one of the following commands.
•
For policy static PAT, enter the following command:
hostname(config)# static (real_interface,mapped_interface) {tcp | udp}
{mapped_ip | interface} mapped_port access-list acl_name [dns] [norandomseq]
[[tcp] tcp_max_conns [emb_limit]] [udp udp_max_conns]
Identify the real addresses and destination/source addresses using an extended access list. Create the
extended access list using the access-list extended command (see the “Adding an Extended Access
List” section on page 18-5). The protocol in the access list must match the protocol you set in this
command. For example, if you specify tcp in the static command, then you must specify tcp in the
access list. Specify the port using the eq operator.
The first address in the access list is the real address; the second address is either the source or
destiniation address, depending on where the traffic originates. For example, to translate the real
address 10.1.1.1/Telnet to the mapped address 192.168.1.1/Telnet when 10.1.1.1 sends traffic to the
209.165.200.224 network, the access-list and static commands are:
hostname(config)# access-list TEST extended tcp host 10.1.1.1 eq telnet
209.165.200.224 255.255.255.224
hostname(config)# static (inside,outside) tcp 192.168.1.1 telnet access-list TEST
Cisco Security Appliance Command Line Configuration Guide
19-30
OL-12172-04
Chapter 19
Configuring NAT
Using Static PAT
In this case, the second address is the destination address. However, the same configuration is used
for hosts to originate a connection to the mapped address. For example, when a host on the
209.165.200.224 network initiates a Telnet connection to 192.168.1.1, then the second address in
the access list is the source address.
This access list should include only permit ACEs. Policy NAT does not consider the inactive or
time-range keywords; all ACEs are considered to be active for policy NAT configuration. See the
“Policy NAT” section on page 19-11 for more information.
If you specify a network for translation (for example, 10.1.1.0 255.255.255.0), then the security
appliance translates the .0 and .255 addresses. If you want to prevent access to these addresses, be
sure to configure an access list to deny access.
See the “Configuring Dynamic NAT or PAT” section on page 19-25 for information about the other
options.
•
To configure regular static PAT, enter the following command:
hostname(config)# static (real_interface,mapped_interface) {tcp | udp} {mapped_ip |
interface} mapped_port real_ip real_port [netmask mask] [dns] [norandomseq] [[tcp]
tcp_max_conns [emb_limit]] [udp udp_max_conns]
See the “Configuring Dynamic NAT or PAT” section on page 19-25 for information about the
options.
Note
When configuring static PAT with FTP, you need to add entries for both TCP ports 20 and 21. You must
specify port 20 so that the source port for the active transfer is not modified to another port, which may
interfere with other devices that perform NAT on FTP traffic.
For example, for Telnet traffic initiated from hosts on the 10.1.3.0 network to the security appliance
outside interface (10.1.2.14), you can redirect the traffic to the inside host at 10.1.1.15 by entering the
following commands:
hostname(config)# access-list TELNET permit tcp host 10.1.1.15 eq telnet 10.1.3.0
255.255.255.0
hostname(config)# static (inside,outside) tcp 10.1.2.14 telnet access-list TELNET
For HTTP traffic initiated from hosts on the 10.1.3.0 network to the security appliance outside interface
(10.1.2.14), you can redirect the traffic to the inside host at 10.1.1.15 by entering:
hostname(config)# access-list HTTP permit tcp host 10.1.1.15 eq http 10.1.3.0
255.255.255.0
hostname(config)# static (inside,outside) tcp 10.1.2.14 http access-list HTTP
To redirect Telnet traffic from the security appliance outside interface (10.1.2.14) to the inside host at
10.1.1.15, enter the following command:
hostname(config)# static (inside,outside) tcp 10.1.2.14 telnet 10.1.1.15 telnet netmask
255.255.255.255
If you want to allow the preceding real Telnet server to initiate connections, though, then you need to
provide additional translation. For example, to translate all other types of traffic, enter the following
commands. The original static command provides translation for Telnet to the server, while the nat and
global commands provide PAT for outbound connections from the server.
hostname(config)# static (inside,outside) tcp 10.1.2.14 telnet 10.1.1.15 telnet netmask
255.255.255.255
hostname(config)# nat (inside) 1 10.1.1.15 255.255.255.255
hostname(config)# global (outside) 1 10.1.2.14
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-31
Chapter 19
Configuring NAT
Bypassing NAT
If you also have a separate translation for all inside traffic, and the inside hosts use a different mapped
address from the Telnet server, you can still configure traffic initiated from the Telnet server to use the
same mapped address as the static statement that allows Telnet traffic to the server. You need to create
a more exclusive nat statement just for the Telnet server. Because nat statements are read for the best
match, more exclusive nat statements are matched before general statements. The following example
shows the Telnet static statement, the more exclusive nat statement for initiated traffic from the Telnet
server, and the statement for other inside hosts, which uses a different mapped address.
hostname(config)#
255.255.255.255
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
static (inside,outside) tcp 10.1.2.14 telnet 10.1.1.15 telnet netmask
nat (inside) 1 10.1.1.15 255.255.255.255
global (outside) 1 10.1.2.14
nat (inside) 2 10.1.1.0 255.255.255.0
global (outside) 2 10.1.2.78
To translate a well-known port (80) to another port (8080), enter the following command:
hostname(config)# static (inside,outside) tcp 10.1.2.45 80 10.1.1.16 8080 netmask
255.255.255.255
Bypassing NAT
This section describes how to bypass NAT. You might want to bypass NAT when you enable NAT control.
You can bypass NAT using identity NAT, static identity NAT, or NAT exemption. See the “Bypassing
NAT When NAT Control is Enabled” section on page 19-10 for more information about these methods.
This section includes the following topics:
•
Configuring Identity NAT, page 19-32
•
Configuring Static Identity NAT, page 19-33
•
Configuring NAT Exemption, page 19-35
Configuring Identity NAT
Identity NAT translates the real IP address to the same IP address. Only “translated” hosts can create
NAT translations, and responding traffic is allowed back.
Figure 19-25 shows a typical identity NAT scenario.
Figure 19-25
Identity NAT
209.165.201.1
209.165.201.1
209.165.201.2
209.165.201.2
Inside Outside
130033
Security
Appliance
Cisco Security Appliance Command Line Configuration Guide
19-32
OL-12172-04
Chapter 19
Configuring NAT
Bypassing NAT
Note
If you change the NAT configuration, and you do not want to wait for existing translations to time out
before the new NAT information is used, you can clear the translation table using the clear xlate
command. However, clearing the translation table disconnects all current connections that use
translations.
To configure identity NAT, enter the following command:
hostname(config)# nat (real_interface) 0 real_ip [mask [dns] [outside] [norandomseq]
[[tcp] tcp_max_conns [emb_limit]] [udp udp_max_conns]
See the “Configuring Dynamic NAT or PAT” section on page 19-25 for information about the options.
For example, to use identity NAT for the inside 10.1.1.0/24 network, enter the following command:
hostname(config)# nat (inside) 0 10.1.1.0 255.255.255.0
Configuring Static Identity NAT
Static identity NAT translates the real IP address to the same IP address. The translation is always active,
and both “translated” and remote hosts can originate connections. Static identity NAT lets you use
regular NAT or policy NAT. Policy NAT lets you identify the real and destination addresses when
determining the real addresses to translate (see the “Policy NAT” section on page 19-11 for more
information about policy NAT). For example, you can use policy static identity NAT for an inside address
when it accesses the outside interface and the destination is server A, but use a normal translation when
accessing the outside server B.
Figure 19-26 shows a typical static identity NAT scenario.
Figure 19-26
Static Identity NAT
Security
Appliance
209.165.201.1
209.165.201.2
209.165.201.2
Inside Outside
Note
130036
209.165.201.1
If you remove a static command, existing connections that use the translation are not affected. To remove
these connections, enter the clear local-host command.
You cannot clear static translations from the translation table with the clear xlate command; you must
remove the static command instead. Only dynamic translations created by the nat and global commands
can be removed with the clear xlate command.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-33
Chapter 19
Configuring NAT
Bypassing NAT
To configure static identity NAT, enter one of the following commands:
•
To configure policy static identity NAT, enter the following command:
hostname(config)# static (real_interface,mapped_interface) real_ip access-list acl_id
[dns] [norandomseq] [[tcp] tcp_max_conns [emb_limit]] [udp udp_max_conns]
Create the extended access list using the access-list extended command (see the “Adding an
Extended Access List” section on page 18-5). This access list should include only permit ACEs.
Make sure the source address in the access list matches the real_ip in this command. Policy NAT
does not consider the inactive or time-range keywords; all ACEs are considered to be active for
policy NAT configuration. See the “Policy NAT” section on page 19-11 for more information.
See the “Configuring Dynamic NAT or PAT” section on page 19-25 for information about the other
options.
•
To configure regular static identity NAT, enter the following command:
hostname(config)# static (real_interface,mapped_interface) real_ip real_ip [netmask
mask] [dns] [norandomseq] [[tcp] tcp_max_conns [emb_limit]] [udp udp_max_conns]
Specify the same IP address for both real_ip arguments.
See the “Configuring Dynamic NAT or PAT” section on page 19-25 for information about the other
options.
For example, the following command uses static identity NAT for an inside IP address (10.1.1.3) when
accessed by the outside:
hostname(config)# static (inside,outside) 10.1.1.3 10.1.1.3 netmask 255.255.255.255
The following command uses static identity NAT for an outside address (209.165.201.15) when accessed
by the inside:
hostname(config)# static (outside,inside) 209.165.201.15 209.165.201.15 netmask
255.255.255.255
The following command statically maps an entire subnet:
hostname(config)# static (inside,dmz) 10.1.2.0 10.1.2.0 netmask 255.255.255.0
The following static identity policy NAT example shows a single real address that uses identity NAT
when accessing one destination address, and a translation when accessing another:
hostname(config)#
hostname(config)#
255.255.255.224
hostname(config)#
hostname(config)#
access-list NET1 permit ip host 10.1.2.27 209.165.201.0 255.255.255.224
access-list NET2 permit ip host 10.1.2.27 209.165.200.224
static (inside,outside) 10.1.2.27 access-list NET1
static (inside,outside) 209.165.202.130 access-list NET2
Cisco Security Appliance Command Line Configuration Guide
19-34
OL-12172-04
Chapter 19
Configuring NAT
Bypassing NAT
Configuring NAT Exemption
NAT exemption exempts addresses from translation and allows both real and remote hosts to originate
connections. NAT exemption lets you specify the real and destination addresses when determining the
real traffic to exempt (similar to policy NAT), so you have greater control using NAT exemption than
identity NAT. However unlike policy NAT, NAT exemption does not consider the ports in the access list.
Use static identity NAT to consider ports in the access list.
Figure 19-27 shows a typical NAT exemption scenario.
Figure 19-27
NAT Exemption
Security
Appliance
209.165.201.1
209.165.201.2
209.165.201.2
Inside Outside
Note
130036
209.165.201.1
If you remove a NAT exemption configuration, existing connections that use NAT exemption are not
affected. To remove these connections, enter the clear local-host command.
To configure NAT exemption, enter the following command:
hostname(config)# nat (real_interface) 0 access-list acl_name [outside]
Create the extended access list using the access-list extended command (see the “Adding an Extended
Access List” section on page 18-5). This access list can include both permit ACEs and deny ACEs. Do
not specify the real and destination ports in the access list; NAT exemption does not consider the ports.
NAT exemption considers the inactive and time-range keywords, but it does not support ACL with all
inactive and time-range ACEs.
By default, this command exempts traffic from inside to outside. If you want traffic from outside to
inside to bypass NAT, then add an additional nat command and enter outside to identify the NAT
instance as outside NAT. You might want to use outside NAT exemption if you configure dynamic NAT
for the outside interface and want to exempt other traffic.
For example, to exempt an inside network when accessing any destination address, enter the following
command:
hostname(config)# access-list EXEMPT permit ip 10.1.2.0 255.255.255.0 any
hostname(config)# nat (inside) 0 access-list EXEMPT
To use dynamic outside NAT for a DMZ network, and exempt another DMZ network, enter the following
command:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
nat (dmz) 1 10.1.2.0 255.255.255.0 outside dns
global (inside) 1 10.1.1.45
access-list EXEMPT permit ip 10.1.3.0 255.255.255.0 any
nat (dmz) 0 access-list EXEMPT
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-35
Chapter 19
Configuring NAT
NAT Examples
To exempt an inside address when accessing two different destination addresses, enter the following
commands:
hostname(config)# access-list NET1 permit ip 10.1.2.0 255.255.255.0 209.165.201.0
255.255.255.224
hostname(config)# access-list NET1 permit ip 10.1.2.0 255.255.255.0 209.165.200.224
255.255.255.224
hostname(config)# nat (inside) 0 access-list NET1
NAT Examples
This section describes typical scenarios that use NAT solutions, and includes the following topics:
•
Overlapping Networks, page 19-36
•
Redirecting Ports, page 19-38
Overlapping Networks
In Figure 19-28, the security appliance connects two private networks with overlapping address ranges.
Figure 19-28
Using Outside NAT with Overlapping Networks
192.168.100.2
192.168.100.2
outside
inside
192.168.100.0/24
192.168.100.3
10.1.1.1
dmz
192.168.100.0/24
192.168.100.3
130029
192.168.100.1
10.1.1.2
Two networks use an overlapping address space (192.168.100.0/24), but hosts on each network must
communicate (as allowed by access lists). Without NAT, when a host on the inside network tries to access
a host on the overlapping DMZ network, the packet never makes it past the security appliance, which
sees the packet as having a destination address on the inside network. Moreover, if the destination
address is being used by another host on the inside network, that host receives the packet.
To solve this problem, use NAT to provide non-overlapping addresses. If you want to allow access in
both directions, use static NAT for both networks. If you only want to allow the inside interface to access
hosts on the DMZ, then you can use dynamic NAT for the inside addresses, and static NAT for the DMZ
addresses you want to access. This example shows static NAT.
To configure static NAT for these two interfaces, perform the following steps. The 10.1.1.0/24 network
on the DMZ is not translated.
Cisco Security Appliance Command Line Configuration Guide
19-36
OL-12172-04
Chapter 19
Configuring NAT
NAT Examples
Step 1
Translate 192.168.100.0/24 on the inside to 10.1.2.0/24 when it accesses the DMZ by entering the
following command:
hostname(config)# static (inside,dmz) 10.1.2.0 192.168.100.0 netmask 255.255.255.0
Step 2
Translate the 192.168.100.0/24 network on the DMZ to 10.1.3.0/24 when it accesses the inside by
entering the following command:
hostname(config)# static (dmz,inside) 10.1.3.0 192.168.100.0 netmask 255.255.255.0
Step 3
Configure the following static routes so that traffic to the dmz network can be routed correctly by the
security appliance:
hostname(config)# route dmz 192.168.100.128 255.255.255.128 10.1.1.2 1
hostname(config)# route dmz 192.168.100.0 255.255.255.128 10.1.1.2 1
The security appliance already has a connected route for the inside network. These static routes allow
the security appliance to send traffic for the 192.168.100.0/24 network out the DMZ interface to the
gateway router at 10.1.1.2. (You need to split the network into two because you cannot create a static
route with the exact same network as a connected route.) Alternatively, you could use a more broad route
for the DMZ traffic, such as a default route.
If host 192.168.100.2 on the DMZ network wants to initiate a connection to host 192.168.100.2 on the
inside network, the following events occur:
1.
The DMZ host 192.168.100.2 sends the packet to IP address 10.1.2.2.
2.
When the security appliance receives this packet, the security appliance translates the source address
from 192.168.100.2 to 10.1.3.2.
3.
Then the security appliance translates the destination address from 10.1.2.2 to 192.168.100.2, and
the packet is forwarded.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-37
Chapter 19
Configuring NAT
NAT Examples
Redirecting Ports
Figure 19-29 shows an example of a network configuration in which the port redirection feature might
be useful.
Figure 19-29
Port Redirection Using Static PAT
Telnet Server
10.1.1.6
209.165.201.5
FTP Server
10.1.1.3
10.1.1.1
Web Server
10.1.1.5
209.165.201.25
Inside
209.165.201.15
130030
Web Server
10.1.1.7
Outside
In the configuration described in this section, port redirection occurs for hosts on external networks as
follows:
•
Telnet requests to IP address 209.165.201.5 are redirected to 10.1.1.6.
•
FTP requests to IP address 209.165.201.5 are redirected to 10.1.1.3.
•
HTTP request to an security appliance outside IP address 209.165.201.25 are redirected to 10.1.1.5.
•
HTTP port 8080 requests to PAT address 209.165.201.15 are redirected to 10.1.1.7 port 80.
To implement this configuration, perform the following steps:
Step 1
Configure PAT for the inside network by entering the following commands:
hostname(config)# nat (inside) 1 0.0.0.0 0.0.0.0 0 0
hostname(config)# global (outside) 1 209.165.201.15
Step 2
Redirect Telnet requests for 209.165.201.5 to 10.1.1.6 by entering the following command:
hostname(config)# static (inside,outside) tcp 209.165.201.5 telnet 10.1.1.6 telnet netmask
255.255.255.255
Step 3
Redirect FTP requests for IP address 209.165.201.5 to 10.1.1.3 by entering the following command:
hostname(config)# static (inside,outside) tcp 209.165.201.5 ftp 10.1.1.3 ftp netmask
255.255.255.255
Step 4
Redirect HTTP requests for the security appliance outside interface address to 10.1.1.5 by entering the
following command:
hostname(config)# static (inside,outside) tcp interface www 10.1.1.5 www netmask
255.255.255.255
Cisco Security Appliance Command Line Configuration Guide
19-38
OL-12172-04
Chapter 19
Configuring NAT
NAT Examples
Step 5
Redirect HTTP requests on port 8080 for PAT address 209.165.201.15 to 10.1.1.7 port 80 by entering
the following command:
hostname(config)# static (inside,outside) tcp 209.165.201.15 8080 10.1.1.7 www netmask
255.255.255.255
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
19-39
Chapter 19
Configuring NAT
NAT Examples
Cisco Security Appliance Command Line Configuration Guide
19-40
OL-12172-04
CH A P T E R
20
Permitting or Denying Network Access
This chapter describes how to control network access through the security appliance using access lists.
To create an extended access lists or an EtherType access list, see Chapter 18, “Identifying Traffic with
Access Lists.”
Note
You use ACLs to control network access in both routed and transparent firewall modes. In transparent
mode, you can use both extended ACLs (for Layer 3 traffic) and EtherType ACLs (for Layer 2 traffic).
To access the security appliance interface for management access, you do not need an access list
allowing the host IP address. You only need to configure management access according to Chapter 42,
“Managing System Access.”
This chapter includes the following sections:
•
Inbound and Outbound Access List Overview, page 20-1
•
Applying an Access List to an Interface, page 20-2
Inbound and Outbound Access List Overview
By default, all traffic from a higher-security interface to a lower-security interface is allowed. Access
lists let you either allow traffic from lower-security interfaces, or restrict traffic from higher-security
interfaces.
The security appliance supports two types of access lists:
Note
•
Inbound—Inbound access lists apply to traffic as it enters an interface.
•
Outbound—Outbound access lists apply to traffic as it exits an interface.
“Inbound” and “outbound” refer to the application of an access list on an interface, either to traffic
entering the security appliance on an interface or traffic exiting the security appliance on an interface.
These terms do not refer to the movement of traffic from a lower security interface to a higher security
interface, commonly known as inbound, or from a higher to lower interface, commonly known as
outbound.
An outbound access list is useful, for example, if you want to allow only certain hosts on the inside
networks to access a web server on the outside network. Rather than creating multiple inbound access
lists to restrict access, you can create a single outbound access list that allows only the specified hosts
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
20-1
Chapter 20
Permitting or Denying Network Access
Applying an Access List to an Interface
(see Figure 20-1). See the “IP Addresses Used for Access Lists When You Use NAT” section on
page 18-3 for information about NAT and IP addresses. The outbound access list prevents any other hosts
from reaching the outside network.
Figure 20-1
Outbound Access List
Web Server:
209.165.200.225
Security
appliance
Outside
ACL Outbound
Permit HTTP from 209.165.201.4, 209.165.201.6,
and 209.165.201.8 to 209.165.200.225
Deny all others
ACL Inbound
Permit from any to any
10.1.1.14
HR
ACL Inbound
Permit from any to any
209.165.201.4
Static NAT
10.1.2.67
209.165.201.6
Static NAT
Eng
ACL Inbound
Permit from any to any
10.1.3.34
209.165.201.8
Static NAT
132210
Inside
See the following commands for this example:
hostname(config)# access-list OUTSIDE extended permit tcp host 209.165.201.4
host 209.165.200.225 eq www
hostname(config)# access-list OUTSIDE extended permit tcp host 209.165.201.6
host 209.165.200.225 eq www
hostname(config)# access-list OUTSIDE extended permit tcp host 209.165.201.8
host 209.165.200.225 eq www
hostname(config)# access-group OUTSIDE out interface outside
Applying an Access List to an Interface
To apply an extended access list to the inbound or outbound direction of an interface, enter the following
command:
hostname(config)# access-group access_list_name {in | out} interface interface_name
[per-user-override]
You can apply one access list of each type (extended and EtherType) to both directions of the interface.
You can also apply an IPv4 and an IPv6 ACL to an interface at the same time and in the same direction.
See the “Inbound and Outbound Access List Overview” section on page 20-1 for more information about
access list directions.
Cisco Security Appliance Command Line Configuration Guide
20-2
OL-12172-04
Chapter 20
Permitting or Denying Network Access
Applying an Access List to an Interface
The per-user-override keyword allows dynamic access lists that are downloaded for user authorization
to override the access list assigned to the interface. For example, if the interface access list denies all
traffic from 10.0.0.0, but the dynamic access list permits all traffic from 10.0.0.0, then the dynamic
access list overrides the interface access list for that user. See the “Configuring RADIUS Authorization”
section for more information about per-user access lists. The per-user-override keyword is only
available for inbound access lists.
For connectionless protocols, you need to apply the access list to the source and destination interfaces
if you want traffic to pass in both directions.
The following example illustrates the commands required to enable access to an inside web server with
the IP address 209.165.201.12 (this IP address is the address visible on the outside interface after NAT):
hostname(config)# access-list ACL_OUT extended permit tcp any host 209.165.201.12 eq www
hostname(config)# access-group ACL_OUT in interface outside
You also need to configure NAT for the web server.
The following access lists allow any hosts to communicate between the inside and hr networks, but only
specific hosts (209.168.200.3 and 209.168.200.4) to access the outside network, as shown in the last line
below:
hostname(config)# access-list ANY extended permit ip any any
hostname(config)# access-list OUT extended permit ip host 209.168.200.3 any
hostname(config)# access-list OUT extended permit ip host 209.168.200.4 any
hostname(config)# access-group ANY in interface inside
hostname(config)# access-group ANY in interface hr
hostname(config)# access-group OUT out interface outside
For example, the following sample access list allows common EtherTypes originating on the inside
interface:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list ETHER ethertype permit ipx
access-list ETHER ethertype permit bpdu
access-list ETHER ethertype permit mpls-unicast
access-group ETHER in interface inside
The following access list allows some EtherTypes through the security appliance, but denies all others:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list ETHER ethertype permit 0x1234
access-list ETHER ethertype permit bpdu
access-list ETHER ethertype permit mpls-unicast
access-group ETHER in interface inside
access-group ETHER in interface outside
The following access list denies traffic with EtherType 0x1256 but allows all others on both interfaces:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list nonIP ethertype deny 1256
access-list nonIP ethertype permit any
access-group ETHER in interface inside
access-group ETHER in interface outside
The following example uses object groups to permit specific traffic on the inside interface:
!
hostname
hostname
hostname
hostname
hostname
hostname
(config)# object-group service myaclog
(config-service)# service-object tcp source range 2000 3000
(config-service)# service-object tcp source range 3000 3010 destinatio$
(config-service)# service-object ipsec
(config-service)# service-object udp destination range 1002 1006
(config-service)# service-object icmp echo
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
20-3
Chapter 20
Permitting or Denying Network Access
Applying an Access List to an Interface
hostname(config)# access-list outsideacl extended permit object-group myaclog interface
inside any
Cisco Security Appliance Command Line Configuration Guide
20-4
OL-12172-04
CH A P T E R
21
Applying AAA for Network Access
This chapter describes how to enable AAA (pronounced “triple A”) for network access.
For information about AAA for management access, see the “Configuring AAA for System
Administrators” section on page 42-5.
This chapter includes the following sections:
•
AAA Performance, page 21-1
•
Configuring Authentication for Network Access, page 21-1
•
Configuring Authorization for Network Access, page 21-8
•
Configuring Accounting for Network Access, page 21-14
•
Using MAC Addresses to Exempt Traffic from Authentication and Authorization, page 21-16
AAA Performance
The security appliance uses “cut-through proxy” to significantly improve performance compared to a
traditional proxy server. The performance of a traditional proxy server suffers because it analyzes every
packet at the application layer of the OSI model. The security appliance cut-through proxy challenges a
user initially at the application layer and then authenticates against standard AAA servers or the local
database. After the security appliance authenticates the user, it shifts the session flow, and all traffic
flows directly and quickly between the source and destination while maintaining session state
information.
Configuring Authentication for Network Access
This section includes the following topics:
•
Authentication Overview, page 21-2
•
Enabling Network Access Authentication, page 21-3
•
Enabling Secure Authentication of Web Clients, page 21-5
•
Authenticating Directly with the Security Appliance, page 21-6
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-1
Chapter 21
Applying AAA for Network Access
Configuring Authentication for Network Access
Authentication Overview
The security appliance lets you configure network access authentication using AAA servers. This section
includes the following topics:
•
One-Time Authentication, page 21-2
•
Applications Required to Receive an Authentication Challenge, page 21-2
•
Security Appliance Authentication Prompts, page 21-2
•
Static PAT and HTTP, page 21-3
•
Enabling Network Access Authentication, page 21-3
One-Time Authentication
A user at a given IP address only needs to authenticate one time for all rules and types, until the
authentication session expires. (See the timeout uauth command in the Cisco Security Appliance
Command Reference for timeout values.) For example, if you configure the security appliance to
authenticate Telnet and FTP, and a user first successfully authenticates for Telnet, then as long as the
authentication session exists, the user does not also have to authenticate for FTP.
Applications Required to Receive an Authentication Challenge
Although you can configure the security appliance to require authentication for network access to any
protocol or service, users can authenticate directly with HTTP, HTTPS, Telnet, or FTP only. A user must
first authenticate with one of these services before the security appliance allows other traffic requiring
authentication.
The authentication ports that the security appliance supports for AAA are fixed:
•
Port 21 for FTP
•
Port 23 for Telnet
•
Port 80 for HTTP
•
Port 443 for HTTPS
Security Appliance Authentication Prompts
For Telnet and FTP, the security appliance generates an authentication prompt.
For HTTP, the security appliance uses basic HTTP authentication by default, and provides an
authentication prompt. You can optionally configure the security appliance to redirect users to an
internal web page where they can enter their username and password (configured with the aaa
authentication listener command).
For HTTPS, the security appliance generates a custom login screen. You can optionally configure the
security appliance to redirect users to an internal web page where they can enter their username and
password (configured with the aaa authentication listener command).
Redirection is an improvement over the basic method because it provides an improved user experience
when authenticating, and an identical user experience for HTTP and HTTPS in both Easy VPN and
firewall modes. It also supports authenticating directly with the security appliance.
Cisco Security Appliance Command Line Configuration Guide
21-2
OL-12172-04
Chapter 21
Applying AAA for Network Access
Configuring Authentication for Network Access
You might want to continue to use basic HTTP authentication if: you do not want the security appliance
to open listening ports; if you use NAT on a router and you do not want to create a translation rule for
the web page served by the security appliance; basic HTTP authentication might work better with your
network. For example non-browser applications, like when a URL is embedded in email, might be more
compatible with basic authentication.
After you authenticate correctly, the security appliance redirects you to your original destination. If the
destination server also has its own authentication, the user enters another username and password. If you
use basic HTTP authentication and need to enter another username and password for the destination
server, then you need to configure the virtual http command.
Note
If you use HTTP authentication, by default the username and password are sent from the client to the
security appliance in clear text; in addition, the username and password are sent on to the destination
web server as well. See the “Enabling Secure Authentication of Web Clients” section on page 21-5 for
information to secure your credentials.
For FTP, a user has the option of entering the security appliance username followed by an at sign (@)
and then the FTP username (name1@name2). For the password, the user enters the security appliance
password followed by an at sign (@) and then the FTP password (password1@password2). For example,
enter the following text.
name> jamiec@patm
password> letmein@he110
This feature is useful when you have cascaded firewalls that require multiple logins. You can separate
several names and passwords by multiple at signs (@).
Static PAT and HTTP
For HTTP authentication, the security appliance checks real ports when static PAT is configured. If it
detects traffic destined for real port 80, regardless of the mapped port, the security appliance intercepts
the HTTP connection and enforces authentication.
For example, assume that outside TCP port 889 is translated to port 80 (www) and that any relevant
access lists permit the traffic:
static (inside,outside) tcp 10.48.66.155 889 192.168.123.10 www netmask 255.255.255.255
Then when users try to access 10.48.66.155 on port 889, the security appliance intercepts the traffic and
enforces HTTP authentication. Users see the HTTP authentication page in their web browsers before the
security appliance allows HTTP connection to complete.
If the local port is different than port 80, as in the following example:
static (inside,outside) tcp 10.48.66.155 889 192.168.123.10 111 netmask 255.255.255.255
Then users do not see the authentication page. Instead, the security appliance sends to the web browser
an error message indicating that the user must be authenticated prior using the requested service.
Enabling Network Access Authentication
To enable network access authentication, perform the following steps:
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-3
Chapter 21
Applying AAA for Network Access
Configuring Authentication for Network Access
Step 1
Using the aaa-server command, identify your AAA servers. If you have already identified your AAA
servers, continue to the next step.
For more information about identifying AAA servers, see the “Identifying AAA Server Groups and
Servers” section on page 14-9.
Step 2
Using the access-list command, create an access list that identifies the source addresses and destination
addresses of traffic you want to authenticate. For steps, see the “Adding an Extended Access List”
section on page 18-5.
The permit ACEs mark matching traffic for authentication, while deny entries exclude matching traffic
from authentication. Be sure to include the destination ports for either HTTP, HTTPS, Telnet, or FTP in
the access list because the user must authenticate with one of these services before other services are
allowed through the security appliance.
Step 3
To configure authentication, enter the following command:
hostname(config)# aaa authentication match acl_name interface_name server_group
Where acl_name is the name of the access list you created in Step 2, interface_name is the name of the
interface as specified with the nameif command, and server_group is the AAA server group you created
in Step 1.
Note
Step 4
You can alternatively use the aaa authentication include command (which identifies traffic within the
command). However, you cannot use both methods in the same configuration. See the Cisco Security
Appliance Command Reference for more information.
(Optional) To enable the redirection method of authentication for HTTP or HTTPS connections, enter
the following command:
hostname(config)# aaa authentication listener http[s] interface_name
redirect
[port portnum]
where the interface_name argument is the interface on which you want to enable listening ports.
The port portnum argument specifies the port number that the security appliance listens on; the defaults
are 80 (HTTP) and 443 (HTTPS). You can use any port number and retain the same functionality, but be
sure your direct authentication users know the port number; redirected traffic is sent to the correct port
number automatically, but direct authenticators must specify the port number manually.
Enter this command separately for HTTP and for HTTPS.
Step 5
(Optional) If you are using the local database for network access authentication and you want to limit
the number of consecutive failed login attempts that the security appliance allows any given user account
(with the exception of users with a privilege level of 15; this feature does not affect level 15 users), use
the following command:
hostname(config)# aaa local authentication attempts max-fail number
Where number is between 1 and 16.
For example:
hostname(config)# aaa local authentication attempts max-fail 7
Tip
To clear the lockout status of a specific user or all users, use the clear aaa local user lockout command.
Cisco Security Appliance Command Line Configuration Guide
21-4
OL-12172-04
Chapter 21
Applying AAA for Network Access
Configuring Authentication for Network Access
For example, the following commands authenticate all inside HTTP traffic and SMTP traffic:
hostname(config)# aaa-server AuthOutbound protocol tacacs+
hostname(config-aaa-server-group)# exit
hostname(config)# aaa-server AuthOutbound (inside) host 10.1.1.1
hostname(config-aaa-server-host)# key TACPlusUauthKey
hostname(config-aaa-server-host)# exit
hostname(config)# access-list MAIL_AUTH extended permit tcp any any eq smtp
hostname(config)# access-list MAIL_AUTH extended permit tcp any any eq www
hostname(config)# aaa authentication match MAIL_AUTH inside AuthOutbound
hostname(config)# aaa authentication listener http inside redirect
The following commands authenticate Telnet traffic from the outside interface to a particular server
(209.165.201.5):
hostname(config)# aaa-server AuthInbound protocol tacacs+
hostname(config-aaa-server-group)# exit
hostname(config)# aaa-server AuthInbound (inside) host 10.1.1.1
hostname(config-aaa-server-host)# key TACPlusUauthKey
hostname(config-aaa-server-host)# exit
hostname(config)# access-list TELNET_AUTH extended permit tcp any host 209.165.201.5 eq
telnet
hostname(config)# aaa authentication match TELNET_AUTH outside AuthInbound
Enabling Secure Authentication of Web Clients
If you use HTTP authentication, by default the username and password are sent from the client to the
security appliance in clear text; in addition, the username and password are sent on to the destination
web server as well. The security appliance provides several methods of securing HTTP authentication:
•
Enable the redirection method of authentication for HTTP—Use the aaa authentication listener
command with the redirect keyword. This method prevents the authentication credentials from
continuing to the destination server. See the “Security Appliance Authentication Prompts” section
on page 21-2 for more information about the redirection method versus the basic method.
•
Enable virtual HTTP—Use the virtual http command to let you authenticate separately with the
security appliance and with the HTTP server. Even if the HTTP server does not need a second
authentication, this command achieves the effect of stripping the basic authentication credentials
from the HTTP GET request.
•
Enable the exchange of usernames and passwords between a web client and the security appliance
with HTTPS—Use the aaa authentication secure-http-client command to enable the exchange of
usernames and passwords between a web client and the security appliance with HTTPS. This is the
only method that protects credentials between the client and the security appliance, as well as
between the security appliance and the destination server. You can use this method alone, or in
conjunction with either of the other methods so you can maximize your security.
After enabling this feature, when a user requires authentication when using HTTP, the security
appliance redirects the HTTP user to an HTTPS prompt. After you authenticate correctly, the
security appliance redirects you to the original HTTP URL.
Secured web-client authentication has the following limitations:
– A maximum of 16 concurrent HTTPS authentication sessions are allowed. If all 16 HTTPS
authentication processes are running, a new connection requiring authentication will not
succeed.
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-5
Chapter 21
Applying AAA for Network Access
Configuring Authentication for Network Access
– When uauth timeout 0 is configured (the uauth timeout is set to 0), HTTPS authentication
might not work. If a browser initiates multiple TCP connections to load a web page after HTTPS
authentication, the first connection is let through, but the subsequent connections trigger
authentication. As a result, users are continuously presented with an authentication page, even
if the correct username and password are entered each time. To work around this, set the uauth
timeout to 1 second with the timeout uauth 0:0:1 command. However, this workaround opens
a 1-second window of opportunity that might allow non-authenticated users to go through the
firewall if they are coming from the same source IP address.
– Because HTTPS authentication occurs on the SSL port 443, users must not configure an
access-list command statement to block traffic from the HTTP client to HTTP server on port
443. Furthermore, if static PAT is configured for web traffic on port 80, it must also be
configured for the SSL port. In the following example, the first line configures static PAT for
web traffic and the second line must be added to support the HTTPS authentication
configuration.
static (inside,outside) tcp 10.132.16.200 www 10.130.16.10 www
static (inside,outside) tcp 10.132.16.200 443 10.130.16.10 443
Authenticating Directly with the Security Appliance
If you do not want to allow HTTP, HTTPS, Telnet, or FTP through the security appliance but want to
authenticate other types of traffic, you can authenticate with the security appliance directly using HTTP,
HTTPS, or Telnet.
This section includes the following topics:
•
Enabling Direct Authentication Using HTTP and HTTPS, page 21-6
•
Enabling Direct Authentication Using Telnet, page 21-7
Enabling Direct Authentication Using HTTP and HTTPS
If you enabled the redirect method of HTTP and HTTPS authentication in the “Enabling Network Access
Authentication” section on page 21-3, then you also automatically enabled direct authentication.
If you want to continue to use basic HTTP authentication, but want to enable direct authentication for
HTTP and HTTPS, then enter the following command:
hostname(config)# aaa authentication listener http[s] interface_name
[port portnum]
where the interface_name argument is the interface on which you want to enable direct authentication.
The port portnum argument specifies the port number that the security appliance listens on; the defaults
are 80 (HTTP) and 443 (HTTPS).
Enter this command separately for HTTP and for HTTPS.
If the destination HTTP server requires authentication in addition to the security appliance, then the
virtual http command lets you authenticate separately with the security appliance (via a AAA server)
and with the HTTP server. Without virtual HTTP, the same username and password you used to
authenticate with the security appliance is sent to the HTTP server; you are not prompted separately for
the HTTP server username and password. Assuming the username and password is not the same for the
AAA and HTTP servers, then the HTTP authentication fails.
Cisco Security Appliance Command Line Configuration Guide
21-6
OL-12172-04
Chapter 21
Applying AAA for Network Access
Configuring Authentication for Network Access
This command redirects all HTTP connections that require AAA authentication to the virtual HTTP
server on the security appliance. The security appliance prompts for the AAA server username and
password. After the AAA server authenticates the user, the security appliance redirects the HTTP
connection back to the original server, but it does not include the AAA server username and password.
Because the username and password are not included in the HTTP packet, the HTTP server prompts the
user separately for the HTTP server username and password.
For inbound users (from lower security to higher security), you must also include the virtual HTTP
address as a destination interface in the access list applied to the source interface. Moreover, you must
add a static command for the virtual HTTP IP address, even if NAT is not required (using the no
nat-control command). An identity NAT command is typically used (where you translate the address to
itself).
For outbound users, there is an explicit permit for traffic, but if you apply an access list to an inside
interface, be sure to allow access to the virtual HTTP address. A static statement is not required.
Note
Do not set the timeout uauth command duration to 0 seconds when using the virtual http command,
because this setting prevents HTTP connections to the real web server.
You can authenticate directly with the security appliance at the following URLs when you enable AAA
for the interface:
http://interface_ip[:port]/netaccess/connstatus.html
https://interface_ip[:port]/netaccess/connstatus.html
Enabling Direct Authentication Using Telnet
Although you can configure network access authentication for any protocol or service (see the aaa
authentication match or aaa authentication include command), you can authenticate directly with
HTTP, Telnet, or FTP only. A user must first authenticate with one of these services before other traffic
that requires authentication is allowed through. If you do not want to allow HTTP, Telnet, or FTP through
the security appliance, but want to authenticate other types of traffic, you can configure virtual Telnet;
the user Telnets to a given IP address configured on the security appliance, and the security appliance
provides a Telnet prompt.
To configure a virtual Telnet server, enter the following command:
hostname(config)# virtual telnet ip_address
where the ip_address argument sets the IP address for the virtual Telnet server. Make sure this address
is an unused address that is routed to the security appliance.
You must configure authentication for Telnet access to the virtual Telnet address as well as the other
services you want to authenticate using the authentication match or aaa authentication include
command.
When an unauthenticated user connects to the virtual Telnet IP address, the user is challenged for a
username and password, and then authenticated by the AAA server. Once authenticated, the user sees
the message “Authentication Successful.” Then, the user can successfully access other services that
require authentication.
For inbound users (from lower security to higher security), you must also include the virtual Telnet
address as a destination interface in the access list applied to the source interface. Moreover, you must
add a static command for the virtual Telnet IP address, even if NAT is not required (using the no
nat-control command). An identity NAT command is typically used (where you translate the address to
itself).
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-7
Chapter 21
Applying AAA for Network Access
Configuring Authorization for Network Access
For outbound users, there is an explicit permit for traffic, but if you apply an access list to an inside
interface, be sure to allow access to the virtual Telnet address. A static statement is not required.
To logout from the security appliance, reconnect to the virtual Telnet IP address; you are prompted to
log out.
This example shows how to enable virtual Telnet along with AAA authentication for other services:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
telnet
hostname(config)#
hostname(config)#
hostname(config)#
255.255.255.255
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
virtual telnet 209.165.202.129
access-list ACL-IN extended permit tcp any host 209.165.200.225 eq smtp
access-list ACL-IN remark This is the SMTP server on the inside
access-list ACL-IN extended permit tcp any host 209.165.202.129 eq
access-list ACL-IN remark This is the virtual Telnet address
access-group ACL-IN in interface outside
static (inside, outside) 209.165.202.129 209.165.202.129 netmask
access-list AUTH extended permit tcp any host 209.165.200.225 eq smtp
access-list AUTH remark This is the SMTP server on the inside
access-list AUTH extended permit tcp any host 209.165.202.129 eq telnet
access-list AUTH remark This is the virtual Telnet address
aaa authentication match AUTH outside tacacs+
Configuring Authorization for Network Access
After a user authenticates for a given connection, the security appliance can use authorization to further
control traffic from the user.
This section includes the following topics:
•
Configuring TACACS+ Authorization, page 21-8
•
Configuring RADIUS Authorization, page 21-10
Configuring TACACS+ Authorization
You can configure the security appliance to perform network access authorization with TACACS+. You
identify the traffic to be authorized by specifying access lists that authorization rules must match.
Alternatively, you can identify the traffic directly in authorization rules themselves.
Tip
Using access lists to identify traffic to be authorized can greatly reduced the number of authorization
commands you must enter. This is because each authorization rule you enter can specify only one source
and destination subnet and service, whereas an access list can include many entries.
Authentication and authorization statements are independent; however, any unauthenticated traffic
matched by an authorization statement will be denied. For authorization to succeed, a user must first
authenticate with the security appliance. Because a user at a given IP address only needs to authenticate
one time for all rules and types, if the authentication session hasn’t expired, authorization can occur even
if the traffic is matched by an authentication statement.
Cisco Security Appliance Command Line Configuration Guide
21-8
OL-12172-04
Chapter 21
Applying AAA for Network Access
Configuring Authorization for Network Access
After a user authenticates, the security appliance checks the authorization rules for matching traffic. If
the traffic matches the authorization statement, the security appliance sends the username to the
TACACS+ server. The TACACS+ server responds to the security appliance with a permit or a deny for
that traffic, based on the user profile. The security appliance enforces the authorization rule in the
response.
See the documentation for your TACACS+ server for information about configuring network access
authorizations for a user.
To configure TACACS+ authorization, perform the following steps:
Step 1
Enable authentication. For more information, see the “Enabling Network Access Authentication” section
on page 21-3. If you have already enabled authentication, continue to the next step.
Step 2
Using the access-list command, create an access list that identifies the source addresses and destination
addresses of traffic you want to authorize. For steps, see the “Adding an Extended Access List” section
on page 18-5.
The permit ACEs mark matching traffic for authorization, while deny entries exclude matching traffic
from authorization. The access list you use for authorization matching should contain rules that are equal
to or a subset of the rules in the access list used for authentication matching.
Note
Step 3
If you have configured authentication and want to authorize all the traffic being authenticated,
you can use the same access list you created for use with the aaa authentication match
command.
To enable authorization, enter the following command:
hostname(config)# aaa authorization match acl_name interface_name server_group
where acl_name is the name of the access list you created in Step 2, interface_name is the name of the
interface as specified with the nameif command or by default, and server_group is the AAA server group
you created when you enabled authentication.
Note
Alternatively, you can use the aaa authorization include command (which identifies traffic
within the command) but you cannot use both methods in the same configuration. See the Cisco
Security Appliance Command Reference for more information.
The following commands authenticate and authorize inside Telnet traffic. Telnet traffic to servers other
than 209.165.201.5 can be authenticated alone, but traffic to 209.165.201.5 requires authorization.
hostname(config)# access-list TELNET_AUTH extended permit tcp any any eq telnet
hostname(config)# access-list SERVER_AUTH extended permit tcp any host 209.165.201.5 eq
telnet
hostname(config)# aaa-server AuthOutbound protocol tacacs+
hostname(config-aaa-server-group)# exit
hostname(config)# aaa-server AuthOutbound (inside) host 10.1.1.1
hostname(config-aaa-server-host)# key TACPlusUauthKey
hostname(config-aaa-server-host)# exit
hostname(config)# aaa authentication match TELNET_AUTH inside AuthOutbound
hostname(config)# aaa authorization match SERVER_AUTH inside AuthOutbound
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-9
Chapter 21
Applying AAA for Network Access
Configuring Authorization for Network Access
Configuring RADIUS Authorization
When authentication succeeds, the RADIUS protocol returns user authorizations in the access-accept
message sent by a RADIUS server. For more information about configuring authentication, see the
“Configuring Authentication for Network Access” section on page 21-1.
When you configure the security appliance to authenticate users for network access, you are also
implicitly enabling RADIUS authorizations; therefore, this section contains no information about
configuring RADIUS authorization on the security appliance. It does provide information about how the
security appliance handles access list information received from RADIUS servers.
You can configure a RADIUS server to download an access list to the security appliance or an access list
name at the time of authentication. The user is authorized to do only what is permitted in the
user-specific access list.
Note
If you have used the access-group command to apply access lists to interfaces, be aware of the following
effects of the per-user-override keyword on authorization by user-specific access lists:
•
Without the per-user-override keyword, traffic for a user session must be permitted by both the
interface access list and the user-specific access list.
•
With the per-user-override keyword, the user-specific access list determines what is permitted.
For more information, see the access-group command entry in the Cisco Security Appliance Command
Reference.
This section includes the following topics:
•
Configuring a RADIUS Server to Send Downloadable Access Control Lists, page 21-10
•
Configuring a RADIUS Server to Download Per-User Access Control List Names, page 21-14
Configuring a RADIUS Server to Send Downloadable Access Control Lists
This section describes how to configure Cisco Secure ACS or a third-party RADIUS server, and includes
the following topics:
•
About the Downloadable Access List Feature and Cisco Secure ACS, page 21-10
•
Configuring Cisco Secure ACS for Downloadable Access Lists, page 21-12
•
Configuring Any RADIUS Server for Downloadable Access Lists, page 21-13
•
Converting Wildcard Netmask Expressions in Downloadable Access Lists, page 21-14
About the Downloadable Access List Feature and Cisco Secure ACS
Downloadable access lists is the most scalable means of using Cisco Secure ACS to provide the
appropriate access lists for each user. It provides the following capabilities:
•
Unlimited access list size—Downloadable access lists are sent using as many RADIUS packets as
required to transport the full access list from Cisco Secure ACS to the security appliance.
•
Simplified and centralized management of access lists—Downloadable access lists enable you to
write a set of access lists once and apply it to many user or group profiles and distribute it to many
security appliances.
Cisco Security Appliance Command Line Configuration Guide
21-10
OL-12172-04
Chapter 21
Applying AAA for Network Access
Configuring Authorization for Network Access
This approach is most useful when you have very large access list sets that you want to apply to more
than one Cisco Secure ACS user or group; however, its ability to simplify Cisco Secure ACS user and
group management makes it useful for access lists of any size.
The security appliance receives downloadable access lists from Cisco Secure ACS using the following
process:
1.
The security appliance sends a RADIUS authentication request packet for the user session.
2.
If Cisco Secure ACS successfully authenticates the user, Cisco Secure ACS returns a RADIUS
access-accept message that contains the internal name of the applicable downloadable access list.
The Cisco IOS cisco-av-pair RADIUS VSA (vendor 9, attribute 1) contains the following
attribute-value pair to identify the downloadable access list set:
ACS:CiscoSecure-Defined-ACL=acl-set-name
where acl-set-name is the internal name of the downloadable access list, which is a combination of
the name assigned to the access list by the Cisco Secure ACS administrator and the date and time
that the access list was last modified.
3.
The security appliance examines the name of the downloadable access list and determines if it has
previously received the named downloadable access list.
– If the security appliance has previously received the named downloadable access list,
communication with Cisco Secure ACS is complete and the security appliance applies the
access list to the user session. Because the name of the downloadable access list includes the
date and time it was last modified, matching the name sent by Cisco Secure ACS to the name of
an access list previous downloaded means that the security appliance has the most recent
version of the downloadable access list.
– If the security appliance has not previously received the named downloadable access list, it may
have an out-of-date version of the access list or it may not have downloaded any version of the
access list. In either case, the security appliance issues a RADIUS authentication request using
the downloadable access list name as the username in the RADIUS request and a null password
attribute. In a cisco-av-pair RADIUS VSA, the request also includes the following
attribute-value pairs:
AAA:service=ip-admission
AAA:event=acl-download
In addition, the security appliance signs the request with the Message-Authenticator attribute
(IETF RADIUS attribute 80).
4.
Upon receipt of a RADIUS authentication request that has a username attribute containing the name
of a downloadable access list, Cisco Secure ACS authenticates the request by checking the
Message-Authenticator attribute. If the Message-Authenticator attribute is missing or incorrect,
Cisco Secure ACS ignores the request. The presence of the Message-Authenticator attribute
prevents malicious use of a downloadable access list name to gain unauthorized network access. The
Message-Authenticator attribute and its use are defined in RFC 2869, RADIUS Extensions,
available at http://www.ietf.org.
5.
If the access list required is less than approximately 4 KB in length, Cisco Secure ACS responds
with an access-accept message containing the access list. The largest access list that can fit in a
single access-accept message is slightly less than 4 KB because some of the message must be other
required attributes.
Cisco Secure ACS sends the downloadable access list in a cisco-av-pair RADIUS VSA. The access
list is formatted as a series of attribute-value pairs that each contain an ACE and are numbered
serially:
ip:inacl#1=ACE-1
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-11
Chapter 21
Applying AAA for Network Access
Configuring Authorization for Network Access
ip:inacl#2=ACE-2
.
.
.
ip:inacl#n=ACE-n
An example of an attribute-value pair follows:
ip:inacl#1=permit tcp 10.1.0.0 255.0.0.0 10.0.0.0 255.0.0.0
6.
If the access list required is more than approximately 4 KB in length, Cisco Secure ACS responds
with an access-challenge message that contains a portion of the access list, formatted as described
above, and an State attribute (IETF RADIUS attribute 24), which contains control data used by
Cisco Secure ACS to track the progress of the download. Cisco Secure ACS fits as many complete
attribute-value pairs into the cisco-av-pair RADIUS VSA as it can without exceeding the maximum
RADIUS message size.
The security appliance stores the portion of the access list received and responds with another
access-request message containing the same attributes as the first request for the downloadable
access list plus a copy of the State attribute received in the access-challenge message.
This repeats until Cisco Secure ACS sends the last of the access list in an access-accept message.
Configuring Cisco Secure ACS for Downloadable Access Lists
You can configure downloadable access lists on Cisco Secure ACS as a shared profile component and
then assign the access list to a group or to an individual user.
The access list definition consists of one or more security appliance commands that are similar to the
extended access-list command (see the “Adding an Extended Access List” section on page 18-5), except
without the following prefix:
access-list acl_name extended
The following example is a downloadable access list definition on Cisco Secure ACS version 3.3:
+--------------------------------------------+
| Shared profile Components
|
|
|
|
Downloadable IP ACLs Content
|
|
|
| Name:
acs_ten_acl
|
|
|
|
ACL Definitions
|
|
|
| permit tcp any host 10.0.0.254
|
| permit udp any host 10.0.0.254
|
| permit icmp any host 10.0.0.254
|
| permit tcp any host 10.0.0.253
|
| permit udp any host 10.0.0.253
|
| permit icmp any host 10.0.0.253
|
| permit tcp any host 10.0.0.252
|
| permit udp any host 10.0.0.252
|
| permit icmp any host 10.0.0.252
|
| permit ip any any
|
+--------------------------------------------+
For more information about creating downloadable access lists and associating them with users, see the
user guide for your version of Cisco Secure ACS.
On the security appliance, the downloaded access list has the following name:
#ACSACL#-ip-acl_name-number
Cisco Security Appliance Command Line Configuration Guide
21-12
OL-12172-04
Chapter 21
Applying AAA for Network Access
Configuring Authorization for Network Access
The acl_name argument is the name that is defined on Cisco Secure ACS (acs_ten_acl in the preceding
example), and number is a unique version ID generated by Cisco Secure ACS.
The downloaded access list on the security appliance consists of the following lines:
access-list
access-list
access-list
access-list
access-list
access-list
access-list
access-list
access-list
access-list
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
#ACSACL#-ip-asa-acs_ten_acl-3b5385f7
permit
permit
permit
permit
permit
permit
permit
permit
permit
permit
tcp any host 10.0.0.254
udp any host 10.0.0.254
icmp any host 10.0.0.254
tcp any host 10.0.0.253
udp any host 10.0.0.253
icmp any host 10.0.0.253
tcp any host 10.0.0.252
udp any host 10.0.0.252
icmp any host 10.0.0.252
ip any any
Configuring Any RADIUS Server for Downloadable Access Lists
You can configure any RADIUS server that supports Cisco IOS RADIUS VSAs to send user-specific
access lists to the security appliance in a Cisco IOS RADIUS cisco-av-pair VSA (vendor 9, attribute 1).
In the cisco-av-pair VSA, configure one or more ACEs that are similar to the access-list extended
command (see the “Adding an Extended Access List” section on page 18-5), except that you replace the
following command prefix:
access-list acl_name extended
with the following text:
ip:inacl#nnn=
The nnn argument is a number in the range from 0 to 999999999 that identifies the order of the command
statement to be configured on the security appliance. If this parameter is omitted, the sequence value is
0, and the order of the ACEs inside the cisco-av-pair RADIUS VSA is used.
The following example is an access list definition as it should be configured for a cisco-av-pair VSA on
a RADIUS server:
ip:inacl#1=permit tcp 10.1.0.0 255.0.0.0 10.0.0.0 255.0.0.0
ip:inacl#99=deny tcp any any
ip:inacl#2=permit udp 10.1.0.0 255.0.0.0 10.0.0.0 255.0.0.0
ip:inacl#100=deny udp any any
ip:inacl#3=permit icmp 10.1.0.0 255.0.0.0 10.0.0.0 255.0.0.0
For information about making unique per user the access lists that are sent in the cisco-av-pair attribute,
see the documentation for your RADIUS server.
On the security appliance, the downloaded access list name has the following format:
AAA-user-username
The username argument is the name of the user that is being authenticated.
The downloaded access list on the security appliance consists of the following lines. Notice the order
based on the numbers identified on the RADIUS server.
access-list
access-list
access-list
access-list
access-list
AAA-user-bcham34-79AD4A08
AAA-user-bcham34-79AD4A08
AAA-user-bcham34-79AD4A08
AAA-user-bcham34-79AD4A08
AAA-user-bcham34-79AD4A08
permit tcp 10.1.0.0 255.0.0.0 10.0.0.0 255.0.0.0
permit udp 10.1.0.0 255.0.0.0 10.0.0.0 255.0.0.0
permit icmp 10.1.0.0 255.0.0.0 10.0.0.0 255.0.0.0
deny tcp any any
deny udp any any
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-13
Chapter 21
Applying AAA for Network Access
Configuring Accounting for Network Access
Downloaded access lists have two spaces between the word “access-list” and the name. These spaces
serve to differentiate a downloaded access list from a local access list. In this example, “79AD4A08” is
a hash value generated by the security appliance to help determine when access list definitions have
changed on the RADIUS server.
Converting Wildcard Netmask Expressions in Downloadable Access Lists
If a RADIUS server provides downloadable access lists to Cisco VPN 3000 series concentrators as well
as to the security appliance, you may need the security appliance to convert wildcard netmask
expressions to standard netmask expressions. This is because Cisco VPN 3000 series concentrators
support wildcard netmask expressions but the security appliance only supports standard netmask
expressions. Configuring the security appliance to convert wildcard netmask expressions helps minimize
the effects of these differences upon how you configure downloadable access lists on your RADIUS
servers. Translation of wildcard netmask expressions means that downloadable access lists written for
Cisco VPN 3000 series concentrators can be used by the security appliance without altering the
configuration of the downloadable access lists on the RADIUS server.
You configure access list netmask conversion on a per-server basis, using the acl-netmask-convert
command, available in the aaa-server configuration mode. For more information about configuring a
RADIUS server, see “Identifying AAA Server Groups and Servers” section on page 14-9. For more
information about the acl-netmask-convert command, see the Cisco Security Appliance Command
Reference.
Configuring a RADIUS Server to Download Per-User Access Control List Names
To download a name for an access list that you already created on the security appliance from the
RADIUS server when a user authenticates, configure the IETF RADIUS filter-id attribute (attribute
number 11) as follows:
filter-id=acl_name
Note
In Cisco Secure ACS, the value for filter-id attributes are specified in boxes in the HTML interface,
omitting filter-id= and entering only acl_name.
For information about making unique per user the filter-id attribute value, see the documentation for your
RADIUS server.
See the “Adding an Extended Access List” section on page 18-5 to create an access list on the security
appliance.
Configuring Accounting for Network Access
The security appliance can send accounting information to a RADIUS or TACACS+ server about any
TCP or UDP traffic that passes through the security appliance. If that traffic is also authenticated, then
the AAA server can maintain accounting information by username. If the traffic is not authenticated, the
AAA server can maintain accounting information by IP address. Accounting information includes when
sessions start and stop, username, the number of bytes that pass through the security appliance for the
session, the service used, and the duration of each session.
To configure accounting, perform the following steps:
Cisco Security Appliance Command Line Configuration Guide
21-14
OL-12172-04
Chapter 21
Applying AAA for Network Access
Configuring Accounting for Network Access
Step 1
If you want the security appliance to provide accounting data per user, you must enable authentication.
For more information, see the “Enabling Network Access Authentication” section on page 21-3. If you
want the security appliance to provide accounting data per IP address, enabling authentication is not
necessary and you can continue to the next step.
Step 2
Using the access-list command, create an access list that identifies the source addresses and destination
addresses of traffic you want accounted. For steps, see the “Adding an Extended Access List” section on
page 18-5.
The permit ACEs mark matching traffic for authorization, while deny entries exclude matching traffic
from authorization.
Note
Step 3
If you have configured authentication and want accounting data for all the traffic being
authenticated, you can use the same access list you created for use with the aaa authentication
match command.
To enable accounting, enter the following command:
hostname(config)# aaa accounting match acl_name interface_name server_group
where the acl_name argument is the access list name set in the access-list command.
The interface_name argument is the interface name set in the nameif command.
The server_group argument is the server group name set in the aaa-server command.
Note
Alternatively, you can use the aaa accounting include command (which identifies traffic within
the command) but you cannot use both methods in the same configuration. See the Cisco
Security Appliance Command Reference for more information.
The following commands authenticate, authorize, and account for inside Telnet traffic. Telnet traffic to
servers other than 209.165.201.5 can be authenticated alone, but traffic to 209.165.201.5 requires
authorization and accounting.
hostname(config)# aaa-server AuthOutbound protocol tacacs+
hostname(config-aaa-server-group)# exit
hostname(config)# aaa-server AuthOutbound (inside) host 10.1.1.1
hostname(config-aaa-server-host)# key TACPlusUauthKey
hostname(config-aaa-server-host)# exit
hostname(config)# access-list TELNET_AUTH extended permit tcp any any eq telnet
hostname(config)# access-list SERVER_AUTH extended permit tcp any host 209.165.201.5 eq
telnet
hostname(config)# aaa authentication match TELNET_AUTH inside AuthOutbound
hostname(config)# aaa authorization match SERVER_AUTH inside AuthOutbound
hostname(config)# aaa accounting match SERVER_AUTH inside AuthOutbound
Cisco Security Appliance Command Line Configuration Guide
OL-12172-04
21-15
Chapter 21
Applying AAA for Network Access
Using MAC Addresses to Exempt Traffic from Authentication and Authorization
Using MAC Addresses to Exempt Traffic from Authentication
and Authorization
The security appliance can exempt from authentication and authorization any traffic from specific MAC
addresses. For example, if the security appliance authenticates TCP traffic originating on a particular
network but you want to allow unauthenticated TCP connections from a specific server, you would use
a MAC exempt rule to exempt from authentication and authorization any traffic from the server specified
by