Cisco ASA 5500 Series Configuration Guide using the CLI, 8.2

Cisco ASA 5500 Series Configuration Guide using the CLI, 8.2
Cisco ASA 5500 Series Configuration
Guide using the CLI
Software Version 8.2
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Text Part Number: OL-18970-03
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Cisco ASA 5500 Series Configuration Guide using the CLI
Copyright © 2010 Cisco Systems, Inc. All rights reserved.
C O N T E N T S
About This Guide
lix
Document Objectives
Audience
lix
lix
Related Documentation
lx
Document Conventions
lx
Obtaining Documentation, Obtaining Support, and Security Guidelines
PART
Getting Started and General Information
1
CHAPTER
lx
1
Introduction to the ASA
1-1
Supported Software, Models, and Modules
VPN Specifications
1-1
1-1
New Features 1-1
New Features in Version 8.2(5)
New Features in Version 8.2(4.4)
New Features in Version 8.2(4.1)
New Features in Version 8.2(4)
New Features in Version 8.2(3.9)
New Features in Version 8.2(3)
New Features in Version 8.2(2)
New Features in Version 8.2(1)
1-2
1-2
1-2
1-2
1-2
1-2
1-2
1-5
Firewall Functional Overview 1-10
Security Policy Overview 1-11
Permitting or Denying Traffic with Access Lists 1-11
Applying NAT 1-11
Protecting from IP Fragments 1-12
Using AAA for Through Traffic 1-12
Applying HTTP, HTTPS, or FTP Filtering 1-12
Applying Application Inspection 1-12
Sending Traffic to the Advanced Inspection and Prevention Security Services Module
Sending Traffic to the Content Security and Control Security Services Module 1-12
Applying QoS Policies 1-12
Applying Connection Limits and TCP Normalization 1-13
Enabling Threat Detection 1-13
1-12
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Firewall Mode Overview 1-13
Stateful Inspection Overview 1-13
VPN Functional Overview
Security Context Overview
CHAPTER
2
Getting Started
1-14
1-15
2-1
Factory Default Configurations 2-1
Restoring the Factory Default Configuration
ASA 5505 Default Configuration 2-2
ASA 5510 and Higher Default Configuration
Accessing the Command-Line Interface
2-2
2-3
2-4
Working with the Configuration 2-5
Saving Configuration Changes 2-5
Saving Configuration Changes in Single Context Mode 2-5
Saving Configuration Changes in Multiple Context Mode 2-6
Copying the Startup Configuration to the Running Configuration 2-7
Viewing the Configuration 2-7
Clearing and Removing Configuration Settings 2-8
Creating Text Configuration Files Offline 2-8
Applying Configuration Changes to Connections
CHAPTER
3
Managing Feature Licenses
2-9
3-1
Supported Feature Licenses Per Model 3-1
Licenses Per Model 3-1
License Notes 3-9
VPN License and Feature Compatibility 3-10
Information About Feature Licenses 3-10
Preinstalled License 3-11
Temporary, VPN Flex, and Evaluation Licenses 3-11
How the Temporary License Timer Works 3-11
How Multiple Licenses Interact 3-11
Failover and Temporary Licenses 3-13
Shared Licenses 3-13
Information About the Shared Licensing Server and Participants
Communication Issues Between Participant and Server 3-14
Information About the Shared Licensing Backup Server 3-14
Failover and Shared Licenses 3-15
Maximum Number of Participants 3-16
Licenses FAQ 3-17
3-13
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Guidelines and Limitations
3-18
Viewing Your Current License
Obtaining an Activation Key
Entering a New Activation Key
3-19
3-21
3-21
Upgrading the License for a Failover Pair 3-23
Upgrading the License for a Failover (No Reload Required) 3-23
Upgrading the License for a Failover (Reload Required) 3-24
Configuring a Shared License 3-25
Configuring the Shared Licensing Server 3-25
Configuring the Shared Licensing Backup Server (Optional)
Configuring the Shared Licensing Participant 3-27
Monitoring the Shared License 3-28
Feature History for Licensing
CHAPTER
4
3-26
3-30
Configuring the Transparent or Routed Firewall
4-1
Configuring the Firewall Mode 4-1
Information About the Firewall Mode 4-1
Information About Routed Firewall Mode 4-2
Information About Transparent Firewall Mode 4-2
Licensing Requirements for the Firewall Mode 4-4
Default Settings 4-4
Guidelines and Limitations 4-5
Setting the Firewall Mode 4-7
Feature History for Firewall Mode 4-8
Configuring ARP Inspection for the Transparent Firewall 4-8
Information About ARP Inspection 4-8
Licensing Requirements for ARP Inspection 4-9
Default Settings 4-9
Guidelines and Limitations 4-9
Configuring ARP Inspection 4-9
Task Flow for Configuring ARP Inspection 4-9
Adding a Static ARP Entry 4-10
Enabling ARP Inspection 4-10
Monitoring ARP Inspection 4-11
Feature History for ARP Inspection 4-11
Customizing the MAC Address Table for the Transparent Firewall
Information About the MAC Address Table 4-12
Licensing Requirements for the MAC Address Table 4-12
Default Settings 4-12
4-11
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Guidelines and Limitations 4-13
Configuring the MAC Address Table 4-13
Adding a Static MAC Address 4-13
Setting the MAC Address Timeout 4-14
Disabling MAC Address Learning 4-14
Monitoring the MAC Address Table 4-14
Feature History for the MAC Address Table 4-15
Firewall Mode Examples 4-15
How Data Moves Through the Security Appliance in Routed Firewall Mode
An Inside User Visits a Web Server 4-16
An Outside User Visits a Web Server on the DMZ 4-17
An Inside User Visits a Web Server on the DMZ 4-18
An Outside User Attempts to Access an Inside Host 4-19
A DMZ User Attempts to Access an Inside Host 4-20
How Data Moves Through the Transparent Firewall 4-21
An Inside User Visits a Web Server 4-22
An Inside User Visits a Web Server Using NAT 4-23
An Outside User Visits a Web Server on the Inside Network 4-24
An Outside User Attempts to Access an Inside Host 4-25
CHAPTER
5
Managing Multiple Context Mode
4-15
5-1
Information About Security Contexts 5-1
Common Uses for Security Contexts 5-2
Unsupported Features 5-2
Context Configuration Files 5-2
Context Configurations 5-2
System Configuration 5-2
Admin Context Configuration 5-3
How the Security Appliance Classifies Packets 5-3
Valid Classifier Criteria 5-3
Invalid Classifier Criteria 5-4
Classification Examples 5-5
Cascading Security Contexts 5-8
Management Access to Security Contexts 5-9
System Administrator Access 5-9
Context Administrator Access 5-10
Enabling or Disabling Multiple Context Mode 5-10
Backing Up the Single Mode Configuration 5-10
Enabling Multiple Context Mode 5-10
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Restoring Single Context Mode
5-11
Configuring Resource Management 5-11
Classes and Class Members Overview
Resource Limits 5-12
Default Class 5-13
Class Members 5-14
Configuring a Class 5-14
Configuring a Security Context
5-11
5-16
Automatically Assigning MAC Addresses to Context Interfaces
Information About MAC Addresses 5-21
Default MAC Address 5-21
Interaction with Manual MAC Addresses 5-21
Failover MAC Addresses 5-21
MAC Address Format 5-21
Enabling Auto-Generation of MAC Addresses 5-22
Viewing Assigned MAC Addresses 5-22
Viewing MAC Addresses in the System Configuration
Viewing MAC Addresses Within a Context 5-24
Changing Between Contexts and the System Execution Space
Managing Security Contexts 5-25
Removing a Security Context 5-25
Changing the Admin Context 5-26
Changing the Security Context URL 5-26
Reloading a Security Context 5-27
Reloading by Clearing the Configuration 5-27
Reloading by Removing and Re-adding the Context
Monitoring Security Contexts 5-28
Viewing Context Information 5-28
Viewing Resource Allocation 5-29
Viewing Resource Usage 5-32
Monitoring SYN Attacks in Contexts
CHAPTER
6
Configuring Interfaces
5-20
5-22
5-25
5-28
5-33
6-1
Information About Interfaces 6-1
ASA 5505 Interfaces 6-2
Understanding ASA 5505 Ports and Interfaces 6-2
Maximum Active VLAN Interfaces for Your License 6-2
VLAN MAC Addresses 6-4
Power Over Ethernet 6-4
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Monitoring Traffic Using SPAN 6-4
Auto-MDI/MDIX Feature 6-4
Security Levels 6-5
Dual IP Stack 6-5
Management Interface (ASA 5510 and Higher)
Licensing Requirements for Interfaces
Guidelines and Limitations
Default Settings
6-5
6-6
6-6
6-7
Starting Interface Configuration (ASA 5510 and Higher) 6-8
Task Flow for Starting Interface Configuration 6-9
Enabling the Physical Interface and Configuring Ethernet Parameters 6-9
Configuring a Redundant Interface 6-11
Configuring a Redundant Interface 6-11
Changing the Active Interface 6-14
Configuring VLAN Subinterfaces and 802.1Q Trunking 6-14
Assigning Interfaces to Contexts and Automatically Assigning MAC Addresses (Multiple Context
Mode) 6-15
Starting Interface Configuration (ASA 5505) 6-16
Task Flow for Starting Interface Configuration 6-16
Configuring VLAN Interfaces 6-16
Configuring and Enabling Switch Ports as Access Ports 6-17
Configuring and Enabling Switch Ports as Trunk Ports 6-19
Completing Interface Configuration (All Models) 6-22
Task Flow for Completing Interface Configuration 6-23
Entering Interface Configuration Mode 6-23
Configuring General Interface Parameters 6-24
Configuring the MAC Address 6-26
Configuring IPv6 Addressing 6-27
Allowing Same Security Level Communication
6-30
Enabling Jumbo Frame Support (ASA 5580 and 5585-X)
Monitoring Interfaces
6-32
Configuration Examples for Interfaces
Feature History for Interfaces
CHAPTER
7
6-31
6-32
6-33
Configuring DHCP and Dynamic DNS Services
Configuring DHCP Services 7-1
Information about DHCP 7-1
Licensing Requirements for DHCP
7-1
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Guidelines and Limitations 7-2
Configuring a DHCP Server 7-2
Enabling the DHCP Server 7-2
Configuring DHCP Options 7-3
Using Cisco IP Phones with a DHCP Server
Configuring DHCP Relay Services 7-6
Feature History for DHCP 7-7
7-5
Configuring DDNS Services 7-7
Information about DDNS 7-7
Licensing Requirements For DDNS 7-7
Configuring DDNS 7-8
Configuration Examples for DDNS 7-8
Example 1: Client Updates Both A and PTR RRs for Static IP Addresses 7-8
Example 2: Client Updates Both A and PTR RRs; DHCP Server Honors Client Update Request;
FQDN Provided Through Configuration 7-9
Example 3: Client Includes FQDN Option Instructing Server Not to Update Either RR; Server
Overrides Client and Updates Both RRs. 7-9
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 7-10
Example 5: Client Updates A RR; Server Updates PTR RR 7-10
Feature History for DDNS 7-11
CHAPTER
8
Configuring Basic Settings
8-1
Changing the Login Password
8-1
Changing the Enable Password
Setting the Hostname
8-2
8-2
Setting the Domain Name
8-3
Setting the Date and Time 8-3
Setting the Time Zone and Daylight Saving Time Date Range
Setting the Date and Time Using an NTP Server 8-5
Setting the Date and Time Manually 8-6
Configuring the DNS Server
8-4
8-6
Setting the Management IP Address for a Transparent Firewall 8-7
Information About the Management IP Address 8-7
Licensing Requirements for the Management IP Address for a Transparent Firewall
Guidelines and Limitations 8-8
Configuring the IPv4 Address 8-9
Configuring the IPv6 Address 8-9
Configuration Examples for the Management IP Address for a Transparent Firewall
8-8
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Feature History for the Management IP Address for a Transparent Firewall
CHAPTER
9
Using Modular Policy Framework
8-10
9-1
Information About Modular Policy Framework 9-1
Modular Policy Framework Supported Features 9-1
Supported Features for Through Traffic 9-2
Supported Features for Management Traffic 9-2
Information About Configuring Modular Policy Framework 9-2
Information About Inspection Policy Maps 9-4
Information About Layer 3/4 Policy Maps 9-5
Feature Directionality 9-5
Feature Matching Within a Policy Map 9-6
Order in Which Multiple Feature Actions are Applied 9-6
Incompatibility of Certain Feature Actions 9-8
Feature Matching for Multiple Policy Maps 9-8
Licensing Requirements for Modular Policy Framework
Guidelines and Limitations
9-9
9-9
Default Settings 9-10
Default Configuration 9-10
Default Class Maps 9-11
Default Inspection Policy Maps
9-11
Configuring Modular Policy Framework 9-12
Task Flow for Configuring Hierarchical Policy Maps 9-12
Identifying Traffic (Layer 3/4 Class Map) 9-13
Creating a Layer 3/4 Class Map for Through Traffic 9-13
Creating a Layer 3/4 Class Map for Management Traffic 9-15
Configuring Special Actions for Application Inspections (Inspection Policy Map)
Defining Actions in an Inspection Policy Map 9-17
Identifying Traffic in an Inspection Class Map 9-19
Creating a Regular Expression 9-21
Creating a Regular Expression Class Map 9-23
Defining Actions (Layer 3/4 Policy Map) 9-24
Applying Actions to an Interface (Service Policy) 9-25
Monitoring Modular Policy Framework
9-16
9-26
Configuration Examples for Modular Policy Framework 9-26
Applying Inspection and QoS Policing to HTTP Traffic 9-27
Applying Inspection to HTTP Traffic Globally 9-27
Applying Inspection and Connection Limits to HTTP Traffic to Specific Servers
Applying Inspection to HTTP Traffic with NAT 9-29
9-28
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Feature History for Modular Policy Framework
PART
Configuring Access Lists
2
CHAPTER
9-30
10
Information About Access Lists
Access List Types
10-1
10-1
Access Control Entry Order
10-2
Access Control Implicit Deny
10-3
IP Addresses Used for Access Lists When You Use NAT
Where to Go Next
CHAPTER
11
10-3
10-6
Adding an Extended Access List
11-1
Information About Extended Access Lists 11-1
Allowing Broadcast and Multicast Traffic through the Transparent Firewall
Licensing Requirements for Extended Access Lists
Guidelines and Limitations
Default Settings
11-4
11-7
Configuration Examples for Extended Access Lists
Feature History for Extended Access Lists
12
11-4
11-7
Monitoring Extended Access Lists
CHAPTER
11-2
11-2
Configuring Extended Access Lists 11-4
Task Flow for Configuring Extended Access Lists
Adding an Extended Access List 11-5
Adding Remarks to Access Lists 11-6
Deleting an Extended Access List Entry 11-6
What to Do Next
Adding an EtherType Access List
11-7
11-8
12-1
Information About EtherType Access Lists 12-1
Supported EtherTypes 12-1
Implicit Permit of IP and ARPs Only 12-2
Implicit and Explicit Deny ACE at the End of an Access List
Allowing MPLS 12-2
Licensing Requirements for EtherType Access Lists
Guidelines and Limitations
Default Settings
11-2
12-2
12-2
12-2
12-3
Configuring EtherType Access Lists
12-4
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Task Flow for Configuring EtherType Access Lists
Adding EtherType Access Lists 12-5
Adding Remarks to Access Lists 12-6
What to Do Next
12-6
Monitoring EtherType Access Lists
12-6
Configuration Examples for EtherType Access Lists
Feature History for EtherType Access Lists
CHAPTER
13
Adding a Standard Access List
12-7
12-7
13-1
Information About Standard Access Lists
13-1
Licensing Requirements for Standard Access Lists
Guidelines and Limitations
Default Settings
13-1
13-1
13-2
Adding a Standard Access List 13-3
Task Flow for Configuring Extended Access Lists
Adding a Standard Access List 13-3
Adding Remarks to Access Lists 13-4
What to Do Next
13-4
Configuration Examples for Standard Access Lists
Feature History for Standard Access Lists
14
Adding a Webtype Access List
Guidelines and Limitations
13-5
13-5
14-1
Licensing Requirements for Webtype Access Lists
Default Settings
13-3
13-4
Monitoring Access Lists
CHAPTER
12-4
14-1
14-1
14-2
Adding Webtype Access Lists 14-2
Task Flow for Configuring Webtype Access Lists 14-2
Adding Webtype Access Lists with a URL String 14-3
Adding Webtype Access Lists with an IP Address 14-4
Adding Remarks to Access Lists 14-5
What to Do Next
14-5
Monitoring Webtype Access Lists
14-5
Configuration Examples for Webtype Access Lists
Feature History for Webtype Access Lists
14-5
14-7
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CHAPTER
15
Adding an IPv6 Access List
15-1
Information About IPv6 Access Lists
15-1
Licensing Requirements for IPv6 Access Lists
Prerequisites for Adding IPv6 Access Lists
Guidelines and Limitations
Default Settings
15-1
15-2
15-2
15-3
Configuring IPv6 Access Lists 15-4
Task Flow for Configuring IPv6 Access Lists
Adding IPv6 Access Lists 15-5
Adding Remarks to Access Lists 15-6
Monitoring IPv6 Access Lists
15-7
Configuration Examples for IPv6 Access Lists
Where to Go Next
16
15-7
15-7
Feature History for IPv6 Access Lists
CHAPTER
15-4
Configuring Object Groups
15-7
16-1
Configuring Object Groups 16-1
Information About Object Groups 16-2
Licensing Requirements for Object Groups 16-2
Guidelines and Limitations for Object Groups 16-3
Adding Object Groups 16-4
Adding a Protocol Object Group 16-4
Adding a Network Object Group 16-5
Adding a Service Object Group 16-6
Adding an ICMP Type Object Group 16-7
Removing Object Groups 16-8
Monitoring Object Groups 16-8
Nesting Object Groups 16-9
Feature History for Object Groups 16-10
Using Object Groups with Access Lists 16-10
Information About Using Object Groups with Access Lists 16-10
Licensing Requirements for Using Object Groups with Access Lists 16-10
Guidelines and Limitations for Using Object Groups with Access Lists 16-11
Configuring Object Groups with Access Lists 16-11
Monitoring the Use of Object Groups with Access Lists 16-12
Configuration Examples for Using Object Groups with Access Lists 16-12
Feature History for Using Object Groups with Access Lists 16-13
Adding Remarks to Access Lists
16-13
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Scheduling Extended Access List Activation 16-14
Information About Scheduling Access List Activation 16-14
Licensing Requirements for Scheduling Access List Activation 16-14
Guidelines and Limitations for Scheduling Access List Activation 16-15
Configuring and Applying Time Ranges 16-15
Configuration Examples for Scheduling Access List Activation 16-16
Feature History for Scheduling Access Lis t Activation 16-17
CHAPTER
17
Configuring Logging for Access Lists
17-1
Configuring Logging for Access Lists 17-1
Information About Logging Access List Activity 17-1
Licensing Requirements for Access List Logging 17-2
Guidelines and Limitations 17-3
Default Settings 17-3
Configuring Access List Logging 17-3
Monitoring Access Lists 17-4
Configuration Examples for Access List Logging 17-4
Feature History for Access List Logging 17-5
Managing Deny Flows 17-5
Information About Managing Deny Flows 17-6
Licensing Requirements for Managing Deny Flows
Guidelines and Limitations 17-6
Default Settings 17-7
Managing Deny Flows 17-7
Monitoring Deny Flows 17-8
Feature History for Managing Deny Flows 17-8
PART
Configuring IP Routing
3
CHAPTER
17-6
18
Information About Routing
18-1
Information About Routing 18-1
Switching 18-1
Path Determination 18-2
Supported RouteTypes 18-2
How Routing Behaves Within the Adaptive Security Appliance
Egress Interface Selection Process 18-3
Next Hop Selection Process 18-4
Supported Internet Protocols for Routing
Information About the Routing Table
18-3
18-4
18-5
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Displaying the Routing Table 18-5
How the Routing Table is Populated 18-5
Backup Routes 18-7
How Forwarding Decisions are Made 18-7
Dynamic Routing and Failover 18-8
Information About IPv6 Support 18-8
Features that Support IPv6 18-8
IPv6-Enabled Commands 18-9
IPv6 Command Guidelines in Transparent Firewall Mode
Entering IPv6 Addresses in Commands 18-10
CHAPTER
19
Configuring Static and Default Routes
19-1
Information About Static and Default Routes
19-1
Licensing Requirements for Static and Default Routes
Guidelines and Limitations
19-2
19-2
Configuring Static and Default Routes 19-2
Configuring a Static Route 19-2
Configuring a Default Static Route 19-3
Limitations on Configuring a Default Static Route
Configuring IPv6 Default and Static Routes 19-4
Monitoring a Static or Default Route
Feature History for Static and Default Routes
20
Defining Route Maps
19-4
19-5
Configuration Examples for Static or Default Routes
CHAPTER
18-10
19-7
19-7
20-1
Overview 20-1
Permit and Deny Clauses 20-2
Match and Set Commands 20-2
Licensing Requirements for Route Maps
Guidelines and Limitations
Defining a Route Map
20-3
20-3
20-4
Customizing a Route Map 20-4
Defining a Route to Match a Specific Destination Address
Configuring the Metric Values for a Route Action 20-5
Configuration Example for Route Maps
Related Documents
20-4
20-6
20-6
Feature History for Route Maps
20-6
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CHAPTER
21
Configuring OSPF
Overview
21-1
21-1
Licensing Requirements for OSPF
Guidelines and Limitations
21-2
21-3
Configuring OSPF 21-3
Enabling OSPF 21-3
Restarting the OSPF Process
21-4
Customizing OSPF 21-4
Redistributing Routes Into OSPF 21-5
Generating a Default Route 21-6
Configuring Route Summarization When Redistributing Routes into OSPF
Configuring Route Summarization Between OSPF Areas 21-8
Configuring OSPF Interface Parameters 21-8
Configuring OSPF Area Parameters 21-11
Configuring OSPF NSSA 21-12
Defining Static OSPF Neighbors 21-13
Configuring Route Calculation Timers 21-13
Logging Neighbors Going Up or Down 21-14
Monitoring OSPF
21-7
21-15
Configuration Example for OSPF
Feature History for OSPF
21-16
21-17
Additional References 21-17
Related Documents 21-18
CHAPTER
22
Configuring RIP
22-1
Overview 22-1
Routing Update Process 22-1
RIP Routing Metric 22-2
RIP Stability Features 22-2
RIP Timers 22-2
Licensing Requirements for RIP
Guidelines and Limitations
22-2
22-2
Configuring RIP 22-3
Enabling RIP 22-3
Customizing RIP 22-3
Generating a Default Route 22-4
Configuring Interfaces for RIP 22-4
Disabling Route Summarization 22-5
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Filtering Networks in RIP 22-5
Redistributing Routes into the RIP Routing Process 22-6
Configuring RIP Send/Receive Version on an Interface 22-7
Enabling RIP Authentication 22-8
Monitoring RIP
22-8
Configuration Example for RIP
Feature History for RIP
22-9
22-10
Additional References 22-10
Related Documents 22-10
CHAPTER
23
Configuring EIGRP
Overview
23-1
23-1
Licensing Requirements for EIGRP
Guidelines and Limitations
23-2
23-2
Configuring EIGRP 23-3
Enabling EIGRP 23-3
Enabling EIGRP Stub Routing
Restarting the EIGRP Process
23-3
23-4
Customizing EIGRP 23-4
Configuring Interfaces for EIGRP 23-5
Configuring the Summary Aggregate Addresses on Interfaces
Changing the Interface Delay Value 23-6
Enabling EIGRP Authentication on an Interface 23-7
Defining an EIGRP Neighbor 23-8
Redistributing Routes Into EIGRP 23-9
Filtering Networks in EIGRP 23-10
Customizing the EIGRP Hello Interval and Hold Time 23-11
Disabling Automatic Route Summarization 23-12
Disabling EIGRP Split Horizon 23-13
Monitoring EIGRP
23-6
23-13
Configuration Example for EIGRP
Feature History for EIGRP
23-14
23-15
Additional References 23-15
Related Documents 23-15
CHAPTER
24
Configuring Multicast Routing
24-17
Information About Multicast Routing 24-17
Stub Multicast Routing 24-18
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PIM Multicast Routing 24-18
Multicast Group Concept 24-18
Licensing Requirements for Multicast Routing
Guidelines and Limitations
24-18
Enabling Multicast Routing
24-19
24-18
Customizing Multicast Routing 24-20
Configuring Stub Multicast Routing 24-20
Configuring a Static Multicast Route 24-20
Configuring IGMP Features 24-21
Disabling IGMP on an Interface 24-22
Configuring IGMP Group Membership 24-22
Configuring a Statically Joined IGMP Group 24-22
Controlling Access to Multicast Groups 24-23
Limiting the Number of IGMP States on an Interface 24-23
Modifying the Query Messages to Multicast Groups 24-24
Changing the IGMP Version 24-25
Configuring PIM Features 24-25
Enabling and Disabling PIM on an Interface 24-26
Configuring a Static Rendezvous Point Address 24-26
Configuring the Designated Router Priority 24-27
Filtering PIM Register Messages 24-28
Configuring PIM Message Intervals 24-28
Configuring a Multicast Boundary 24-28
Filtering PIM Neighbors 24-29
Supporting Mixed Bidirectional/Sparse-Mode PIM Networks
Configuration Example for Multicast Routing
24-29
24-30
Additional References 24-31
Related Documents 24-31
RFCs 24-31
CHAPTER
25
Configuring IPv6 Neighbor Discovery
25-1
Configuring Neighbor Solicitation Messages 25-1
Configuring Neighbor Solicitation Message Interval 25-1
Information About Neighbor Solicitation Messages 25-2
Licensing Requirements for Neighbor Solicitation Messages 25-3
Guidelines and Limitations for the Neighbor Solicitation Message Interval
Default Settings for the Neighbor Solicitation Message Interval 25-3
Configuring the Neighbor Solicitation Message Interval 25-3
Monitoring Neighbor Solicitation Message Intervals 25-4
25-3
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Feature History for Neighbor Solicitation Message Interval 25-4
Configuring the Neighbor Reachable Time 25-5
Information About Neighbor Reachable Time 25-5
Licensing Requirements for Neighbor Reachable Time 25-5
Guidelines and Limitations for Neighbor Reachable Time 25-5
Default Settings for Neighbor Reachable Time 25-6
Configuring Neighbor Reachable Time 25-6
Monitoring Neighbor Reachable Time 25-7
Feature History for Neighbor Reachable Time 25-7
Configuring Router Advertisement Messages 25-7
Information About Router Advertisement Messages 25-8
Configuring the Router Advertisement Transmission Interval 25-9
Licensing Requirements for Router Advertisement Transmission Interval 25-9
Guidelines and Limitations for Router Advertisement Transmission Interval 25-9
Default Settings for Router Advertisement Transmission Interval 25-10
Configuring Router Advertisement Transmission Interval 25-10
Monitoring Router Advertisement Transmission Interval 25-11
Feature History for Router Advertisement Transmission Interval 25-11
Configuring the Router Lifetime Value 25-12
Licensing Requirements for Router Advertisement Transmission Interval 25-12
Guidelines and Limitations for Router Advertisement Transmission Interval 25-12
Default Settings for Router Advertisement Transmission Interval 25-13
Configuring Router Advertisement Transmission Interval 25-13
Monitoring Router Advertisement Transmission Interval 25-14
Where to Go Next 25-14
Feature History for Router Advertisement Transmission Interval 25-14
Configuring the IPv6 Prefix 25-15
Licensing Requirements for IPv6 Prefixes 25-15
Guidelines and Limitations for IPv6 Prefixes 25-15
Default Settings for IPv6 Prefixes 25-16
Configuring IPv6 Prefixes 25-17
Monitoring IPv6 Prefixes 25-18
Additional References 25-18
Feature History for IPv6 Prefixes 25-19
Suppressing Router Advertisement Messages 25-19
Licensing Requirements for Suppressing Router Advertisement Messages 25-20
Guidelines and Limitations for Suppressing Router Advertisement Messages 25-20
Default Settings for Suppressing Router Advertisement Messages 25-20
Suppressing Router Advertisement Messages 25-21
Monitoring Router Advertisement Messages 25-21
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Feature History for Suppressing Router Advertisement Messages
25-22
Configuring a Static IPv6 Neighbor 25-22
Information About a Static IPv6 Neighbor 25-22
Licensing Requirements for Static IPv6 Neighbor 25-22
Guidelines and Limitations 25-22
Default Settings 25-23
Configuring a Static IPv6 Neighbor 25-24
Monitoring Neighbor Solicitation Messages 25-24
Feature History for Configuring a Static IPv6 Neighbor 25-25
PART
Configuring Network Address Translation
4
CHAPTER
26
Information About NAT
Introduction to NAT
NAT Types
26-1
26-1
26-2
NAT in Routed Mode
26-2
NAT in Transparent Mode
Policy NAT
26-3
26-5
NAT and Same Security Level Interfaces
26-8
Order of NAT Commands Used to Match Real Addresses
Mapped Address Guidelines
DNS and NAT
27
26-8
26-9
Where to Go Next
CHAPTER
26-8
26-11
Configuring NAT Control
27-1
Information About NAT Control 27-1
NAT Control and Inside Interfaces 27-1
NAT Control and Same Security Interfaces 27-2
NAT Control and Outside Dynamic NAT 27-2
NAT Control and Static NAT 27-3
Bypassing NAT When NAT Control is Enabled 27-3
Licensing Requirements
27-3
Prerequisites for NAT Control
Guidelines and Limitations
Default Settings
27-4
27-4
27-4
Configuring NAT Control
27-5
Monitoring NAT Control
27-5
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Configuration Examples for NAT Control
Feature History for NAT Control
CHAPTER
28
Configuring Static NAT
27-6
28-1
Information About Static NAT
28-1
Licensing Requirements for Static NAT
Guidelines and Limitations
Default Settings
27-5
28-2
28-2
28-3
Configuring Static NAT 28-4
Configuring Policy Static NAT 28-5
Configuring Regular Static NAT 28-8
Monitoring Static NAT
28-9
Configuration Examples for Static NAT 28-9
Typical Static NAT Examples 28-9
Example of Overlapping Networks 28-10
Additional References 28-11
Related Documents 28-11
Feature History for Static NAT
CHAPTER
29
28-11
Configuring Dynamic NAT and PAT
29-1
Information About Dynamic NAT and PAT 29-1
Information About Dynamic NAT 29-1
Information About PAT 29-4
Information About Implementing Dynamic NAT and PAT
Licensing Requirements for Dynamic NAT and PAT
Guidelines and Limitations
Default Settings
29-11
Monitoring Dynamic NAT and PAT
Feature History for Dynamic NAT and PAT
Configuring Static PAT
29-13
29-18
Configuration Examples for Dynamic NAT and PAT
30
29-10
29-11
Configuring Dynamic NAT or Dynamic PAT 29-13
Task Flow for Configuring Dynamic NAT and PAT
Configuring Policy Dynamic NAT 29-15
Configuring Regular Dynamic NAT 29-17
CHAPTER
29-5
29-18
29-19
30-1
Information About Static PAT
30-1
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Licensing Requirements for Static PAT
Prerequisites for Static PAT
Guidelines and Limitations
Default Settings
30-3
30-3
30-4
30-4
Configuring Static PAT 30-5
Configuring Policy Static PAT 30-5
Configuring Regular Static PAT 30-7
Monitoring Static PAT
30-9
Configuration Examples for Static PAT 30-9
Examples of Policy Static PAT 30-9
Examples of Regular Static PAT 30-9
Example of Redirecting Ports 30-10
Feature History for Static PAT
CHAPTER
31
Bypassing NAT
30-11
31-1
Configuring Identity NAT 31-1
Information About Identity NAT 31-2
Licensing Requirements for Identity NAT 31-2
Guidelines and Limitations for Identity NAT 31-2
Default Settings for Identity NAT 31-3
Configuring Identity NAT 31-4
Monitoring Identity NAT 31-5
Feature History for Identity NAT 31-5
Configuring Static Identity NAT 31-5
Information About Static Identity NAT 31-5
Licensing Requirements for Static Identity NAT 31-6
Guidelines and Limitations for Static Identity NAT 31-6
Default Settings for Static Identity NAT 31-7
Configuring Static Identity NAT 31-7
Configuring Policy Static Identity NAT 31-8
Configuring Regular Static Identity NAT 31-9
Monitoring Static Identity NAT 31-10
Feature History for Static Identity NAT 31-10
Configuring NAT Exemption 31-11
Information About NAT Exemption 31-11
Licensing Requirements for NAT Exemption 31-11
Guidelines and Limitations for NAT Exemption 31-12
Default Settings for NAT Exemption 31-12
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Configuring NAT Exemption 31-13
Monitoring NAT Exemption 31-13
Configuration Examples for NAT Exemption
Feature History for NAT Exemption 31-14
PART
Configuring High Availability
5
CHAPTER
31-13
32
Information About High Availability
32-1
Information About Failover and High Availability
32-1
Failover System Requirements 32-2
Hardware Requirements 32-2
Software Requirements 32-2
Licensing Requirements 32-3
Failover and Stateful Failover Links 32-3
Failover Link 32-3
Stateful Failover Link 32-4
Failover Interface Speed for Stateful Links
Avoiding Interrupted Failover Links 32-5
32-5
Active/Active and Active/Standby Failover 32-9
Determining Which Type of Failover to Use 32-9
Stateless (Regular) and Stateful Failover
Stateless (Regular) Failover 32-10
Stateful Failover 32-10
Transparent Firewall Mode Requirements
32-10
32-11
Auto Update Server Support in Failover Configurations
Auto Update Process Overview 32-12
Monitoring the Auto Update Process 32-13
32-12
Failover Health Monitoring 32-14
Unit Health Monitoring 32-15
Interface Monitoring 32-15
Failover Feature/Platform Matrix
Failover Times by Platform
32-16
32-16
Failover Messages 32-17
Failover System Messages
Debug Messages 32-17
SNMP 32-17
32-17
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33
Configuring Active/Standby Failover
33-1
Information About Active/Standby Failover 33-1
Active/Standby Failover Overview 33-1
Primary/Secondary Status and Active/Standby Status 33-2
Device Initialization and Configuration Synchronization 33-2
Command Replication 33-3
Failover Triggers 33-4
Failover Actions 33-4
Optional Active/Standby Failover Settings 33-5
Licensing Requirements for Active/Standby Failover
Prerequisites for Active/Standby Failover
Guidelines and Limitations
33-5
33-6
33-6
Configuring Active/Standby Failover 33-7
Task Flow for Configuring Active/Standby Failover 33-7
Configuring the Primary Unit 33-7
Configuring the Secondary Unit 33-10
Configuring Optional Active/Standby Failover Settings 33-11
Enabling HTTP Replication with Stateful Failover 33-11
Disabling and Enabling Interface Monitoring 33-12
Configuring the Interface Health Poll Time 33-12
Configuring Failover Criteria 33-13
Configuring Virtual MAC Addresses 33-13
Controlling Failover 33-15
Forcing Failover 33-15
Disabling Failover 33-15
Restoring a Failed Unit 33-15
Testing the Failover Functionality
Monitoring Active/Standby Failover
33-16
33-16
Feature History for Active/Standby Failover
CHAPTER
34
Configuring Active/Active Failover
33-16
34-1
Information About Active/Active Failover 34-1
Active/Active Failover Overview 34-1
Primary/Secondary Status and Active/Standby Status 34-2
Device Initialization and Configuration Synchronization 34-3
Command Replication 34-3
Failover Triggers 34-4
Failover Actions 34-5
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Optional Active/Active Failover Settings
34-6
Licensing Requirements for Active/Active Failover 34-6
Prerequisites for Active/Active Failover 34-7
Guidelines and Limitations
34-7
Configuring Active/Active Failover 34-8
Task Flow for Configuring Active/Active Failover 34-8
Configuring the Primary Failover Unit 34-8
Configuring the Secondary Failover Unit 34-11
Configuring Optional Active/Active Failover Settings 34-13
Configuring Failover Group Preemption 34-13
Enabling HTTP Replication with Stateful Failover 34-15
Disabling and Enabling Interface Monitoring 34-15
Configuring Interface Health Monitoring 34-16
Configuring Failover Criteria 34-17
Configuring Virtual MAC Addresses 34-17
Configuring Support for Asymmetrically Routed Packets 34-19
Remote Command Execution 34-22
Changing Command Modes 34-23
Security Considerations 34-24
Limitations of Remote Command Execution
34-24
Controlling Failover 34-24
Forcing Failover 34-24
Disabling Failover 34-25
Restoring a Failed Unit or Failover Group 34-25
Testing the Failover Functionality 34-25
Monitoring Active/Active Failover
34-26
Feature History for Active/Active Failover
PART
Configuring Access Control
6
CHAPTER
34-26
35
Permitting or Denying Network Access
35-1
Information About Inbound and Outbound Access Rules
Licensing Requirements for Access Rules
Prerequisites
35-1
35-2
35-3
Guidelines and Limitations
Default Settings
35-3
35-4
Applying an Access List to an Interface
35-4
Monitoring Permitting or Denying Network Access
35-5
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Configuration Examples for Permitting or Denying Network Access
Feature History for Permitting or Denying Network Access
CHAPTER
36
Configuring AAA Servers and the Local Database
35-6
35-7
36-1
AAA Overview 36-1
About Authentication 36-2
About Authorization 36-2
About Accounting 36-2
AAA Server and Local Database Support 36-3
Summary of Support 36-3
RADIUS Server Support 36-4
Authentication Methods 36-4
Attribute Support 36-4
RADIUS Authorization Functions 36-5
TACACS+ Server Support 36-5
RSA/SDI Server Support 36-5
RSA/SDI Version Support 36-5
Two-step Authentication Process 36-5
SDI Primary and Replica Servers 36-6
NT Server Support 36-6
Kerberos Server Support 36-6
LDAP Server Support 36-6
SSO Support for Clientless SSL VPN with HTTP Forms
Local Database Support 36-7
User Profiles 36-7
Fallback Support 36-7
Configuring the Local Database
36-6
36-8
Identifying AAA Server Groups and Servers
36-9
Configuring an LDAP Server 36-13
Authentication with LDAP 36-14
Authorization with LDAP for VPN 36-15
LDAP Attribute Mapping 36-16
Using Certificates and User Login Credentials
Using User Login Credentials 36-18
Using certificates 36-18
36-17
Differentiating User Roles Using AAA 36-19
Using Local Authentication 36-19
Using RADIUS Authentication 36-20
Using LDAP Authentication 36-20
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Using TACACS+ Authentication
CHAPTER
37
Configuring Management Access
Allowing Telnet Access
36-21
37-1
37-1
Allowing SSH Access 37-2
Configuring SSH Access 37-2
Using an SSH Client 37-3
Allowing HTTPS Access for ASDM 37-4
Enabling HTTPS Access 37-4
Accessing ASDM from Your PC 37-4
Configuring Management Access Over a VPN Tunnel
37-5
Configuring AAA for System Administrators 37-5
Configuring Authentication for CLI and ASDM Access 37-5
Configuring Authentication To Access Privileged EXEC Mode (the enable Command)
Configuring Authentication for the enable Command 37-6
Authenticating Users Using the Login Command 37-7
Limiting User CLI and ASDM Access with Management Authorization 37-7
Configuring Command Authorization 37-8
Command Authorization Overview 37-9
Configuring Local Command Authorization 37-11
Configuring TACACS+ Command Authorization 37-14
Configuring Command Accounting 37-18
Viewing the Current Logged-In User 37-18
Recovering from a Lockout 37-19
Configuring a Login Banner
CHAPTER
38
37-20
Applying AAA for Network Access
AAA Performance
37-6
38-1
38-1
Configuring Authentication for Network Access 38-1
Authentication Overview 38-2
One-Time Authentication 38-2
Applications Required to Receive an Authentication Challenge
Security Appliance Authentication Prompts 38-2
Static PAT and HTTP 38-3
Enabling Network Access Authentication 38-3
Enabling Secure Authentication of Web Clients 38-5
Authenticating Directly with the Security Appliance 38-6
Enabling Direct Authentication Using HTTP and HTTPS 38-6
Enabling Direct Authentication Using Telnet 38-7
38-2
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Configuring Authorization for Network Access 38-8
Configuring TACACS+ Authorization 38-8
Configuring RADIUS Authorization 38-9
Configuring a RADIUS Server to Send Downloadable Access Control Lists 38-10
Configuring a RADIUS Server to Download Per-User Access Control List Names 38-14
Configuring Accounting for Network Access
38-14
Using MAC Addresses to Exempt Traffic from Authentication and Authorization
CHAPTER
39
Applying Filtering Services
38-15
39-1
Configuring ActiveX Filtering 39-1
Information About ActiveX Filtering 39-2
Licensing Requirements for ActiveX Filtering
Configuring ActiveX Filtering 39-2
Configuration Examples for ActiveX Filtering
Feature History for ActiveX Filtering 39-3
39-2
39-3
Configuring Java Applet Filtering 39-3
Information About Java Applet Filtering 39-3
Licensing Requirements for Java Applet Filtering
Configuring Java Applet Filtering 39-4
Configuration Examples for Java Applet Filtering
Feature History for Java Applet Filtering 39-5
39-4
39-4
Configuring URLs and FTP Requests with an External Server
Information About URL Filtering 39-5
Licensing Requirements for URL Filtering 39-6
Identifying the Filtering Server 39-6
Buffering the Content Server Response 39-7
Caching Server Addresses 39-8
Filtering HTTP URLs 39-8
Configuring HTTP Filtering 39-8
Enabling Filtering of Long HTTP URLs 39-9
Truncating Long HTTP URLs 39-9
Exempting Traffic from Filtering 39-10
Filtering HTTPS URLs 39-10
Filtering FTP Requests 39-11
39-5
Viewing Filtering Statistics and Configuration 39-11
Viewing Filtering Server Statistics 39-11
Viewing Buffer Configuration and Statistics 39-12
Viewing Caching Statistics 39-13
Viewing Filtering Performance Statistics 39-13
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Viewing Filtering Configuration 39-14
Feature History for URL Filtering 39-14
PART
Configuring Application Inspection
7
CHAPTER
40
Getting Started With Application Layer Protocol Inspection
Information about Application Layer Protocol Inspection
How Inspection Engines Work 40-1
When to Use Application Protocol Inspection 40-2
Guidelines and Limitations
Default Settings
41
40-1
40-3
40-4
Configuring Application Layer Protocol Inspection
CHAPTER
40-1
Configuring Inspection of Basic Internet Protocols
40-6
41-1
DNS Inspection 41-1
How DNS Application Inspection Works 41-2
How DNS Rewrite Works 41-2
Configuring DNS Rewrite 41-3
Using the Static Command for DNS Rewrite 41-4
Using the Alias Command for DNS Rewrite 41-4
Configuring DNS Rewrite with Two NAT Zones 41-4
DNS Rewrite with Three NAT Zones 41-5
Configuring DNS Rewrite with Three NAT Zones 41-7
Configuring a DNS Inspection Policy Map for Additional Inspection Control
Verifying and Monitoring DNS Inspection 41-11
FTP Inspection 41-12
FTP Inspection Overview 41-12
Using the strict Option 41-12
Configuring an FTP Inspection Policy Map for Additional Inspection Control
Verifying and Monitoring FTP Inspection 41-17
HTTP Inspection 41-19
HTTP Inspection Overview 41-19
Configuring an HTTP Inspection Policy Map for Additional Inspection Control
ICMP Inspection
41-8
41-13
41-19
41-23
ICMP Error Inspection
41-24
Instant Messaging Inspection 41-24
IM Inspection Overview 41-24
Configuring an Instant Messaging Inspection Policy Map for Additional Inspection Control
41-24
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IP Options Inspection 41-27
IP Options Inspection Overview 41-28
Configuring an IP Options Inspection Policy Map for Additional Inspection Control
NetBIOS Inspection 41-29
NetBIOS Inspection Overview 41-29
Configuring a NetBIOS Inspection Policy Map for Additional Inspection Control
PPTP Inspection
CHAPTER
42
41-30
41-31
SMTP and Extended SMTP Inspection 41-32
SMTP and ESMTP Inspection Overview 41-32
Configuring an ESMTP Inspection Policy Map for Additional Inspection Control
TFTP Inspection
41-28
41-33
41-36
Configuring Inspection for Voice and Video Protocols
CTIQBE Inspection 42-1
CTIQBE Inspection Overview 42-1
Limitations and Restrictions 42-2
Verifying and Monitoring CTIQBE Inspection
42-1
42-2
H.323 Inspection 42-3
H.323 Inspection Overview 42-4
How H.323 Works 42-4
H.239 Support in H.245 Messages 42-5
ASA-Tandberg Interoperability with H.323 Inspection 42-5
Limitations and Restrictions 42-6
Configuring an H.323 Inspection Policy Map for Additional Inspection Control
Configuring H.323 and H.225 Timeout Values 42-9
Verifying and Monitoring H.323 Inspection 42-9
Monitoring H.225 Sessions 42-9
Monitoring H.245 Sessions 42-10
Monitoring H.323 RAS Sessions 42-11
MGCP Inspection 42-11
MGCP Inspection Overview 42-11
Configuring an MGCP Inspection Policy Map for Additional Inspection Control
Configuring MGCP Timeout Values 42-14
Verifying and Monitoring MGCP Inspection 42-14
RTSP Inspection 42-15
RTSP Inspection Overview 42-15
Using RealPlayer 42-16
Restrictions and Limitations 42-16
Configuring an RTSP Inspection Policy Map for Additional Inspection Control
42-6
42-13
42-16
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SIP Inspection 42-19
SIP Inspection Overview 42-19
SIP Instant Messaging 42-20
Configuring a SIP Inspection Policy Map for Additional Inspection Control
Configuring SIP Timeout Values 42-24
Verifying and Monitoring SIP Inspection 42-25
42-21
Skinny (SCCP) Inspection 42-25
SCCP Inspection Overview 42-26
Supporting Cisco IP Phones 42-26
Restrictions and Limitations 42-26
Configuring a Skinny (SCCP) Inspection Policy Map for Additional Inspection Control
Verifying and Monitoring SCCP Inspection 42-29
CHAPTER
43
Configuring Inspection of Database and Directory Protocols
ILS Inspection
43-2
Sun RPC Inspection 43-3
Sun RPC Inspection Overview 43-3
Managing Sun RPC Services 43-4
Verifying and Monitoring Sun RPC Inspection
44
43-1
43-1
SQL*Net Inspection
CHAPTER
43-4
Configuring Inspection for Management Application Protocols
44-1
DCERPC Inspection 44-1
DCERPC Overview 44-1
Configuring a DCERPC Inspection Policy Map for Additional Inspection Control
GTP Inspection 44-3
GTP Inspection Overview 44-4
Configuring a GTP Inspection Policy Map for Additional Inspection Control
Verifying and Monitoring GTP Inspection 44-8
44-2
44-5
RADIUS Accounting Inspection 44-9
RADIUS Accounting Inspection Overview 44-10
Configuring a RADIUS Inspection Policy Map for Additional Inspection Control
RSH Inspection
42-27
44-10
44-11
SNMP Inspection 44-11
SNMP Inspection Overview 44-11
Configuring an SNMP Inspection Policy Map for Additional Inspection Control
XDMCP Inspection
44-11
44-12
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PART
Configuring Unified Communications
8
CHAPTER
45
Information About Cisco Unified Communications Proxy Features
45-1
Information About the Adaptive Security Appliance in Cisco Unified Communications
TLS Proxy Applications in Cisco Unified Communications
45-2
Licensing for Cisco Unified Communications Proxy Features
CHAPTER
46
Configuring the Cisco Phone Proxy
45-1
45-4
46-1
Information About the Cisco Phone Proxy 46-1
Phone Proxy Functionality 46-1
Supported Cisco UCM and IP Phones for the Phone Proxy
Licensing Requirements for the Phone Proxy
46-3
46-4
Prerequisites for the Phone Proxy 46-5
Media Termination Instance Prerequisites 46-5
Certificates from the Cisco UCM 46-6
DNS Lookup Prerequisites 46-6
Cisco Unified Communications Manager Prerequisites 46-7
Access List Rules 46-7
NAT and PAT Prerequisites 46-7
Prerequisites for IP Phones on Multiple Interfaces 46-8
7960 and 7940 IP Phones Support 46-8
Cisco IP Communicator Prerequisites 46-9
Prerequisites for Rate Limiting TFTP Requests 46-10
Rate Limiting Configuration Example 46-10
About ICMP Traffic Destined for the Media Termination Address
End-User Phone Provisioning 46-11
Ways to Deploy IP Phones to End Users 46-11
Phone Proxy Guidelines and Limitations 46-12
General Guidelines and Limitations 46-12
Media Termination Address Guidelines and Limitations
46-11
46-13
Configuring the Phone Proxy 46-14
Task Flow for Configuring the Phone Proxy in a Non-secure Cisco UCM Cluster 46-14
Importing Certificates from the Cisco UCM 46-15
Task Flow for Configuring the Phone Proxy in a Mixed-mode Cisco UCM Cluster 46-16
Creating Trustpoints and Generating Certificates 46-17
Creating the CTL File 46-18
Using an Existing CTL File 46-20
Creating the TLS Proxy Instance for a Non-secure Cisco UCM Cluster 46-20
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Creating the TLS Proxy for a Mixed-mode Cisco UCM Cluster 46-21
Creating the Media Termination Instance 46-22
Creating the Phone Proxy Instance 46-23
Enabling the Phone Proxy with SIP and Skinny Inspection 46-25
Configuring Linksys Routers for UDP Port Forwarding 46-26
Configuring Your Router 46-26
Troubleshooting the Phone Proxy 46-27
Debugging Information from the Security Appliance 46-27
Debugging Information from IP Phones 46-31
IP Phone Registration Failure 46-32
TFTP Auth Error Displays on IP Phone Console 46-32
Configuration File Parsing Error 46-33
Configuration File Parsing Error: Unable to Get DNS Response 46-33
Non-configuration File Parsing Error 46-34
Cisco UCM Does Not Respond to TFTP Request for Configuration File 46-34
IP Phone Does Not Respond After the Security Appliance Sends TFTP Data 46-35
IP Phone Requesting Unsigned File Error 46-36
IP Phone Unable to Download CTL File 46-36
IP Phone Registration Failure from Signaling Connections 46-37
SSL Handshake Failure 46-39
Certificate Validation Errors 46-40
Media Termination Address Errors 46-40
Audio Problems with IP Phones 46-41
Saving SAST Keys 46-42
Configuration Examples for the Phone Proxy 46-43
Example 1: Nonsecure Cisco UCM cluster, Cisco UCM and TFTP Server on Publisher 46-43
Example 2: Mixed-mode Cisco UCM cluster, Cisco UCM and TFTP Server on Publisher 46-45
Example 3: Mixed-mode Cisco UCM cluster, Cisco UCM and TFTP Server on Different Servers 46-46
Example 4: Mixed-mode Cisco UCM cluster, Primary Cisco UCM, Secondary and TFTP Server on
Different Servers 46-47
Example 5: LSC Provisioning in Mixed-mode Cisco UCM cluster; Cisco UCM and TFTP Server on
Publisher 46-49
Example 6: VLAN Transversal 46-51
Feature History for the Phone Proxy
CHAPTER
47
46-53
Configuring the TLS Proxy for Encrypted Voice Inspection
47-1
Information about the TLS Proxy for Encrypted Voice Inspection 47-1
Decryption and Inspection of Unified Communications Encrypted Signaling
CTL Client Overview 47-3
47-2
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Licensing for the TLS Proxy
47-5
Prerequisites for the TLS Proxy for Encrypted Voice Inspection
47-6
Configuring the TLS Proxy for Encrypted Voice Inspection 47-6
Task flow for Configuring the TLS Proxy for Encrypted Voice Inspection
Creating Trustpoints and Generating Certificates 47-8
Creating an Internal CA 47-9
Creating a CTL Provider Instance 47-10
Creating the TLS Proxy Instance 47-11
Enabling the TLS Proxy Instance for Skinny or SIP Inspection 47-12
Monitoring the TLS Proxy
47-14
Feature History for the TLS Proxy for Encrypted Voice Inspection
CHAPTER
48
47-7
Configuring Cisco Mobility Advantage
47-16
48-1
Information about the Cisco Mobility Advantage Proxy Feature
Cisco Mobility Advantage Proxy Functionality 48-1
Mobility Advantage Proxy Deployment Scenarios 48-2
Mobility Advantage Proxy Using NAT/PAT 48-4
Trust Relationships for Cisco UMA Deployments 48-5
Licensing for the Mobility Advantage Proxy
48-1
48-6
Configuring Cisco Mobility Advantage 48-6
Task Flow for Configuring Cisco Mobility Advantage
Installing the Cisco UMA Server Certificate 48-7
Creating the TLS Proxy Instance 48-8
Enabling the TLS Proxy for MMP Inspection 48-9
Monitoring for Cisco Mobility Advantage Proxy
48-7
48-10
Configuration Examples for Cisco Mobility Advantage 48-11
Example 1: Cisco UMC/Cisco UMA Architecture – Security Appliance as Firewall with TLS Proxy
and MMP Inspection 48-11
Example 2: Cisco UMC/Cisco UMA Architecture – Security Appliance as TLS Proxy Only 48-12
Feature History for Cisco Mobility Advantage
CHAPTER
49
Configuring Cisco Unified Presence
48-14
49-1
Information About Cisco Unified Presence 49-1
Architecture for Cisco Unified Presence 49-1
Trust Relationship in the Presence Federation 49-3
Security Certificate Exchange Between Cisco UP and the Security Appliance
Licensing for Cisco Unified Presence
Configuring Cisco Unified Presence
49-4
49-4
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Task Flow for Configuring Cisco Unified Presence 49-5
Creating Trustpoints and Generating Certificates 49-6
Installing Certificates 49-7
Creating the TLS Proxy Instance 49-8
Enabling the TLS Proxy for SIP Inspection 49-9
Monitoring Cisco Unified Presence
49-10
Configuration Example for Cisco Unified Presence
Feature History for Cisco Unified Presence
PART
49-13
Configuring Advanced Connection Settings
9
CHAPTER
49-11
50
Configuring Threat Detection
50-1
Information About Threat Detection
50-1
Configuring Basic Threat Detection Statistics 50-1
Information About Basic Threat Detection Statistics 50-2
Guidelines and Limitations 50-2
Default Settings 50-3
Configuring Basic Threat Detection Statistics 50-4
Monitoring Basic Threat Detection Statistics 50-5
Feature History for Basic Threat Detection Statistics 50-6
Configuring Advanced Threat Detection Statistics 50-6
Information About Advanced Threat Detection Statistics 50-6
Guidelines and Limitations 50-6
Default Settings 50-7
Configuring Advanced Threat Detection Statistics 50-7
Monitoring Advanced Threat Detection Statistics 50-9
Feature History for Advanced Threat Detection Statistics 50-13
Configuring Scanning Threat Detection 50-13
Information About Scanning Threat Detection 50-14
Guidelines and Limitations 50-14
Default Settings 50-14
Configuring Scanning Threat Detection 50-15
Monitoring Shunned Hosts, Attackers, and Targets 50-16
Feature History for Scanning Threat Detection 50-16
Configuration Examples for Threat Detection
CHAPTER
51
Configuring TCP State Bypass
50-17
51-1
Information About TCP State Bypass
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Licensing Requirements for TCP State Bypass
Guidelines and Limitations
Default Settings
51-2
51-3
Configuring TCP State Bypass
51-3
Monitoring TCP State Bypass
51-4
Configuration Examples for TCP State Bypass
Feature History for TCP State Bypass
CHAPTER
52
Configuring TCP Normalization
52-1
Customizing the TCP Normalizer
52-1
52-1
Configuration Examples for TCP Normalization
53
51-4
51-5
Information About TCP Normalization
CHAPTER
51-2
Configuring Connection Limits and Timeouts
52-6
53-1
Information About Connection Limits 53-1
TCP Intercept 53-1
Disabling TCP Intercept for Management Packets for Clientless SSL Compatibility
Dead Connection Detection (DCD) 53-2
TCP Sequence Randomization 53-2
Configuring Connection Limits and Timeouts
53-3
Configuration Examples for Connection Limits and Timeouts
CHAPTER
54
Configuring the Botnet Traffic Filter
53-5
54-1
Information About the Botnet Traffic Filter 54-1
Botnet Traffic Filter Address Categories 54-2
Botnet Traffic Filter Actions for Known Addresses 54-2
Botnet Traffic Filter Databases 54-2
Information About the Dynamic Database 54-2
Information About the Static Database 54-3
Information About the DNS Reverse Lookup Cache and DNS Host Cache
How the Botnet Traffic Filter Works 54-4
Licensing Requirements for the Botnet Traffic Filter
Guidelines and Limitations
Default Settings
53-2
54-3
54-5
54-5
54-6
Configuring the Botnet Traffic Filter 54-6
Task Flow for Configuring the Botnet Traffic Filter
Configuring the Dynamic Database 54-7
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Adding Entries to the Static Database 54-8
Enabling DNS Snooping 54-9
Enabling Traffic Classification and Actions for the Botnet Traffic Filter
Blocking Botnet Traffic Manually 54-14
Searching the Dynamic Database 54-15
54-11
Monitoring the Botnet Traffic Filter 54-16
Botnet Traffic Filter Syslog Messaging 54-16
Botnet Traffic Filter Commands 54-16
Configuration Examples for the Botnet Traffic Filter
Recommended Configuration Example 54-18
Other Configuration Examples 54-19
Where to Go Next
54-20
Feature History for the Botnet Traffic Filter
CHAPTER
55
Configuring QoS
54-18
54-21
55-1
Information About QoS 55-1
Supported QoS Features 55-2
What is a Token Bucket? 55-2
Information About Policing 55-3
Information About Priority Queuing 55-3
Information About Traffic Shaping 55-4
How QoS Features Interact 55-4
DSCP and DiffServ Preservation 55-5
Licensing Requirements for QoS
Guidelines and Limitations
55-5
55-5
Configuring QoS 55-6
Determining the Queue and TX Ring Limits for a Standard Priority Queue 55-6
Configuring the Standard Priority Queue for an Interface 55-7
Configuring a Service Rule for Standard Priority Queuing and Policing 55-9
Configuring a Service Rule for Traffic Shaping and Hierarchical Priority Queuing
(Optional) Configuring the Hierarchical Priority Queuing Policy 55-12
Configuring the Service Rule 55-13
55-12
Monitoring QoS 55-15
Viewing QoS Police Statistics 55-15
Viewing QoS Standard Priority Statistics 55-16
Viewing QoS Shaping Statistics 55-16
Viewing QoS Standard Priority Queue Statistics 55-17
Feature History for QoS
55-18
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CHAPTER
56
Configuring Web Cache Services Using WCCP
Information About WCCP
56-1
Guidelines and Limitations
56-1
Enabling WCCP Redirection
Feature History for WCCP
CHAPTER
57
56-2
56-3
Preventing Network Attacks
Preventing IP Spoofing
57-1
57-1
Configuring the Fragment Size
57-2
Blocking Unwanted Connections
57-2
Configuring IP Audit for Basic IPS Support
PART
57-3
Configuring Applications on SSMs and SSCs
10
CHAPTER
56-1
58
Managing Services Modules
58-1
Information About Modules 58-1
Supported Applications 58-2
Information About Management Access 58-2
Sessioning to the Module 58-2
Using ASDM 58-2
Using SSH or Telnet 58-3
Other Uses for the Module Management Interface 58-3
Routing Considerations for Accessing the Management Interface
Guidelines and Limitations
Default Settings
58-3
58-3
58-4
Configuring the SSC Management Interface
Sessioning to the Module
58-4
58-6
Troubleshooting the Module 58-6
Installing an Image on the Module 58-7
Resetting the Password 58-8
Reloading or Resetting the Module 58-8
Shutting Down the Module 58-8
Monitoring SSMs and SSCs
Where to Go Next
58-9
58-11
Feature History for the Module
58-11
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59
Configuring the IPS Module
59-1
Information About the IPS Module 59-1
How the IPS Module Works with the Adaptive Security Appliance
Operating Modes 59-2
Using Virtual Sensors (ASA 5510 and Higher) 59-3
Differences Between Modules 59-4
Licensing Requirements for the IPS Module
Guidelines and Limitations
59-2
59-4
59-4
Configuring the IPS Module 59-5
IPS Module Task Overview 59-5
Configuring the Security Policy on the IPS Module 59-5
Assigning Virtual Sensors to a Security Context (ASA 5510 and Higher)
Diverting Traffic to the IPS Module 59-8
Monitoring the IPS Module
59-10
Configuration Examples for the IPS Module
Feature History for the IPS Module
CHAPTER
60
59-6
59-10
59-11
Configuring the Content Security and Control Application on the CSC SSM
60-1
Information About the CSC SSM 60-1
Determining What Traffic to Scan 60-3
Licensing Requirements for the CSC SSM
Prerequisites for the CSC SSM
Guidelines and Limitations
Default Settings
60-5
60-5
60-6
Configuring the CSC SSM 60-6
Before Configuring the CSC SSM
Diverting Traffic to the CSC SSM
Monitoring the CSC SSM
60-6
60-7
60-10
Configuration Examples for the CSC SSM
Additional References
60-12
Configuring VPN
11
CHAPTER
60-10
60-11
Feature History for the CSC SSM
PART
60-4
61
Configuring IPsec and ISAKMP
Tunneling Overview
IPsec Overview
61-1
61-1
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Configuring ISAKMP 61-2
ISAKMP Overview 61-2
Configuring ISAKMP Policies 61-5
Enabling ISAKMP on the Outside Interface 61-6
Disabling ISAKMP in Aggressive Mode 61-6
Determining an ID Method for ISAKMP Peers 61-6
Enabling IPsec over NAT-T 61-7
Using NAT-T 61-8
Enabling IPsec over TCP 61-8
Waiting for Active Sessions to Terminate Before Rebooting
Alerting Peers Before Disconnecting 61-9
61-9
Configuring Certificate Group Matching 61-9
Creating a Certificate Group Matching Rule and Policy 61-10
Using the Tunnel-group-map default-group Command 61-11
Configuring IPsec 61-11
Understanding IPsec Tunnels 61-11
Understanding Transform Sets 61-12
Defining Crypto Maps 61-12
Applying Crypto Maps to Interfaces 61-19
Using Interface Access Lists 61-19
Changing IPsec SA Lifetimes 61-22
Creating a Basic IPsec Configuration 61-22
Using Dynamic Crypto Maps 61-24
Providing Site-to-Site Redundancy 61-26
Viewing an IPsec Configuration 61-26
Clearing Security Associations
61-27
Clearing Crypto Map Configurations
Supporting the Nokia VPN Client
CHAPTER
62
Configuring L2TP over IPsec
61-27
61-28
62-1
Information About L2TP over IPsec 62-1
IPsec Transport and Tunnel Modes 62-2
Licensing Requirements for L2TP over IPsec
Prerequisites for Configuring L2TP over IPsec
Guidelines and Limitations
Configuring L2TP over IPsec
Guidelines and Limitations
62-3
62-3
62-4
62-4
62-4
Configuration Examples for L2TP over IPsec
62-7
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Feature History for L2TP over IPsec
CHAPTER
63
62-7
Setting General IPsec or SSL VPN Parameters
Configuring VPNs in Single, Routed Mode
63-1
63-1
Configuring IPsec or SSL VPN to Bypass ACLs
63-1
Permitting Intra-Interface Traffic (Hairpinning) 63-2
NAT Considerations for Intra-Interface Traffic 63-3
Setting Maximum Active IPsec or SSL VPN Sessions
63-4
Using Client Update to Ensure Acceptable IPsec Client Revision Levels
63-4
Understanding Load Balancing 63-6
Comparing Load Balancing to Failover 63-7
Load Balancing 63-7
Failover 63-7
Implementing Load Balancing 63-8
Prerequisites 63-8
Eligible Platforms 63-8
Eligible Clients 63-8
VPN Load Balancing Algorithm 63-9
VPN Load-Balancing Cluster Configurations 63-9
Some Typical Mixed Cluster Scenarios 63-10
Scenario 1: Mixed Cluster with No SSL VPN Connections 63-10
Scenario 2: Mixed Cluster Handling SSL VPN Connections 63-10
Configuring Load Balancing 63-11
Configuring the Public and Private Interfaces for Load Balancing 63-11
Configuring the Load Balancing Cluster Attributes 63-12
Enabling Redirection Using a Fully-qualified Domain Name 63-13
Monitoring Load Balancing 63-14
Frequently Asked Questions About Load Balancing 63-15
IP Address Pool Exhaustion 63-15
Unique IP Address Pools 63-15
Using Load Balancing and Failover on the Same Device 63-15
Load Balancing on Multiple Interfaces 63-15
Maximum Simultaneous Sessions for Load Balancing Clusters 63-15
Configuring VPN Session Limits
General Considerations
CHAPTER
64
63-16
63-17
Configuring Connection Profiles, Group Policies, and Users
Overview of Connection Profiles, Group Policies, and Users
64-1
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Connection Profiles 64-2
General Connection Profile Connection Parameters 64-3
IPSec Tunnel-Group Connection Parameters 64-4
Connection Profile Connection Parameters for SSL VPN Sessions
64-5
Configuring Connection Profiles 64-6
Maximum Connection Profiles 64-6
Default IPSec Remote Access Connection Profile Configuration 64-7
Configuring IPSec Tunnel-Group General Attributes 64-7
Configuring IPSec Remote-Access Connection Profiles 64-7
Specifying a Name and Type for the IPSec Remote Access Connection Profile 64-8
Configuring IPSec Remote-Access Connection Profile General Attributes 64-8
Configuring Double Authentication 64-12
Enabling IPv6 VPN Access 64-13
Configuring IPSec Remote-Access Connection Profile IPSec Attributes 64-14
Configuring IPSec Remote-Access Connection Profile PPP Attributes 64-16
Configuring LAN-to-LAN Connection Profiles 64-17
Default LAN-to-LAN Connection Profile Configuration 64-17
Specifying a Name and Type for a LAN-to-LAN Connection Profile 64-18
Configuring LAN-to-LAN Connection Profile General Attributes 64-18
Configuring LAN-to-LAN IPSec Attributes 64-19
Configuring Connection Profiles for Clientless SSL VPN Sessions 64-21
Specifying a Connection Profile Name and Type for Clientless SSL VPN Sessions 64-21
Configuring General Tunnel-Group Attributes for Clientless SSL VPN Sessions 64-21
Configuring Tunnel-Group Attributes for Clientless SSL VPN Sessions 64-24
Customizing Login Windows for Users of Clientless SSL VPN sessions 64-28
Configuring Microsoft Active Directory Settings for Password Management 64-29
Using Active Directory to Force the User to Change Password at Next Logon 64-30
Using Active Directory to Specify Maximum Password Age 64-31
Using Active Directory to Override an Account Disabled AAA Indicator 64-32
Using Active Directory to Enforce Minimum Password Length 64-33
Using Active Directory to Enforce Password Complexity 64-34
Configuring the Connection Profile for RADIUS/SDI Message Support for the AnyConnect
Client 64-35
AnyConnect Client and RADIUS/SDI Server Interaction 64-35
Configuring the Security Appliance to Support RADIUS/SDI Messages 64-36
Group Policies 64-37
Default Group Policy 64-38
Configuring Group Policies 64-39
Configuring an External Group Policy 64-40
Configuring an Internal Group Policy 64-40
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Configuring Group Policy Attributes 64-41
Configuring WINS and DNS Servers 64-41
Configuring VPN-Specific Attributes 64-42
Configuring Security Attributes 64-46
Configuring the Banner Message 64-48
Configuring IPSec-UDP Attributes 64-49
Configuring Split-Tunneling Attributes 64-49
Configuring Domain Attributes for Tunneling 64-51
Configuring Attributes for VPN Hardware Clients 64-52
Configuring Backup Server Attributes 64-56
Configuring Microsoft Internet Explorer Client Parameters 64-57
Configuring Network Admission Control Parameters 64-59
Configuring Address Pools 64-62
Configuring Firewall Policies 64-63
Supporting a Zone Labs Integrity Server 64-64
Overview of Integrity Server and Security Appliance Interaction 64-64
Configuring Integrity Server Support 64-65
Setting Up Client Firewall Parameters 64-65
Configuring Client Access Rules 64-67
Configuring Group-Policy Attributes for Clientless SSL VPN Sessions
Configuring User Attributes 64-79
Viewing the Username Configuration 64-80
Configuring Attributes for Specific Users 64-80
Setting a User Password and Privilege Level 64-80
Configuring User Attributes 64-81
Configuring VPN User Attributes 64-81
Configuring Clientless SSL VPN Access for Specific Users
CHAPTER
65
Configuring IP Addresses for VPNs
66
Configuring Remote Access IPsec VPNs
65-1
66-1
Information About Remote Access IPsec VPNs
66-1
Licensing Requirements for Remote Access IPsec VPNs
Guidelines and Limitations
64-85
65-1
Configuring an IP Address Assignment Method
Configuring Local IP Address Pools 65-2
Configuring AAA Addressing 65-2
Configuring DHCP Addressing 65-3
CHAPTER
64-69
66-2
66-2
Configuring Remote Access IPsec VPNs
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Configuring Interfaces 66-3
Configuring ISAKMP Policy and Enabling ISAKMP on the Outside Interface
Configuring an Address Pool 66-5
Adding a User 66-5
Creating a Transform Set 66-6
Defining a Tunnel Group 66-6
Creating a Dynamic Crypto Map 66-7
Creating a Crypto Map Entry to Use the Dynamic Crypto Map 66-8
Saving the Security Appliance Configuration 66-9
Configuration Examples for Remote Access IPsec VPNs
Feature History for Remote Access IPsec VPNs
CHAPTER
67
Configuring Network Admission Control
Overview
66-4
66-9
66-10
67-1
67-1
Uses, Requirements, and Limitations
67-2
Viewing the NAC Policies on the Security Appliance
Adding, Accessing, or Removing a NAC Policy
67-2
67-4
Configuring a NAC Policy 67-4
Specifying the Access Control Server Group 67-4
Setting the Query-for-Posture-Changes Timer 67-5
Setting the Revalidation Timer 67-5
Configuring the Default ACL for NAC 67-6
Configuring Exemptions from NAC 67-6
Assigning a NAC Policy to a Group Policy
67-7
Changing Global NAC Framework Settings 67-8
Changing Clientless Authentication Settings 67-8
Enabling and Disabling Clientless Authentication 67-8
Changing the Login Credentials Used for Clientless Authentication
Changing NAC Framework Session Attributes 67-10
CHAPTER
68
Configuring Easy VPN Services on the ASA 5505
68-1
Specifying the Client/Server Role of the Cisco ASA 5505
Specifying the Primary and Secondary Servers
Specifying the Mode 68-3
NEM with Multiple Interfaces
Comparing Tunneling Options
68-1
68-2
68-3
Configuring Automatic Xauth Authentication
Configuring IPSec Over TCP
67-9
68-4
68-4
68-5
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Specifying the Tunnel Group or Trustpoint
Specifying the Tunnel Group 68-7
Specifying the Trustpoint 68-7
Configuring Split Tunneling
68-6
68-8
Configuring Device Pass-Through
68-8
Configuring Remote Management
68-9
Guidelines for Configuring the Easy VPN Server 68-10
Group Policy and User Attributes Pushed to the Client
Authentication Options 68-12
CHAPTER
69
Configuring the PPPoE Client
PPPoE Client Overview
69-1
69-1
Configuring the PPPoE Client Username and Password
Enabling PPPoE
69-3
Monitoring and Debugging the PPPoE Client
70
69-2
69-3
Using PPPoE with a Fixed IP Address
CHAPTER
68-10
Clearing the Configuration
69-5
Using Related Commands
69-5
Configuring LAN-to-LAN IPsec VPNs
Summary of the Configuration
Configuring Interfaces
69-4
70-1
70-1
70-2
Configuring ISAKMP Policy and Enabling ISAKMP on the Outside Interface
Creating a Transform Set
Configuring an ACL
70-4
70-4
Defining a Tunnel Group
70-5
Creating a Crypto Map and Applying It To an Interface
Applying Crypto Maps to Interfaces 70-7
CHAPTER
71
70-2
Configuring Clientless SSL VPN
70-6
71-1
Getting Started 71-1
Observing Clientless SSL VPN Security Precautions 71-2
Understanding Clientless SSL VPN System Requirements 71-3
Understanding Features Not Supported in Clientless SSL VPN 71-4
Using SSL to Access the Central Site 71-5
Using HTTPS for Clientless SSL VPN Sessions 71-5
Configuring Clientless SSL VPN and ASDM Ports 71-5
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Configuring Support for Proxy Servers 71-6
Configuring SSL/TLS Encryption Protocols 71-7
Authenticating with Digital Certificates 71-8
Enabling Cookies on Browsers for Clientless SSL VPN 71-8
Managing Passwords 71-8
Using Single Sign-on with Clientless SSL VPN 71-9
Configuring SSO with HTTP Basic or NTLM Authentication 71-10
Configuring SSO Authentication Using SiteMinder 71-11
Configuring SSO Authentication Using SAML Browser Post Profile
Configuring SSO with the HTTP Form Protocol 71-16
Configuring SSO for Plug-ins 71-23
Configuring SSO with Macro Substitution 71-23
Authenticating with Digital Certificates 71-24
Creating and Applying Clientless SSL VPN Policies for Accessing Resources
Assigning Users to Group Policies 71-24
Using the Security Appliance Authentication Server 71-24
Using a RADIUS Server 71-25
Configuring Connection Profile Attributes for Clientless SSL VPN
71-13
71-24
71-25
Configuring Group Policy and User Attributes for Clientless SSL VPN
71-26
Configuring Browser Access to Plug-ins 71-27
Introduction to Browser Plug-Ins 71-27
Plug-in Requirements and Restrictions 71-28
Single Sign-On for Plug-ins 71-28
Preparing the Security Appliance for a Plug-in 71-28
Installing Plug-ins Redistributed by Cisco 71-29
Providing Access to Third-Party Plug-ins 71-31
Example: Providing Access to a Citrix Java Presentation Server
Viewing the Plug-ins Installed on the Security Appliance 71-32
71-31
Configuring Application Access 71-33
Configuring Smart Tunnel Access 71-33
About Smart Tunnels 71-33
Why Smart Tunnels? 71-34
Smart Tunnel Requirements, Restrictions, and Limitations 71-34
Adding Applications to Be Eligible for Smart Tunnel Access 71-35
Assigning a Smart Tunnel List 71-38
Configuring Smart Tunnel Auto Sign-on 71-39
Automating Smart Tunnel Access 71-40
Enabling and Disabling Smart Tunnel Access 71-41
Configuring Port Forwarding 71-41
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About Port Forwarding 71-42
Why Port Forwarding? 71-42
Port Forwarding Requirements and Restrictions 71-42
Configuring DNS for Port Forwarding 71-43
Adding Applications to Be Eligible for Port Forwarding 71-44
Assigning a Port Forwarding List 71-45
Automating Port Forwarding 71-46
Enabling and Disabling Port Forwarding 71-46
Application Access User Notes 71-47
Using Application Access on Vista 71-47
Closing Application Access to Prevent hosts File Errors 71-47
Recovering from hosts File Errors When Using Application Access
71-47
Configuring File Access 71-50
CIFS File Access Requirement 71-51
Adding Support for File Access 71-51
Ensuring Clock Accuracy for SharePoint Access
Using Clientless SSL VPN with PDAs
71-52
71-52
Using E-Mail over Clientless SSL VPN 71-53
Configuring E-mail Proxies 71-53
E-mail Proxy Certificate Authentication 71-54
Configuring Web E-mail: MS Outlook Web Access 71-54
Configuring Portal Access Rules
71-55
Optimizing Clientless SSL VPN Performance 71-55
Configuring Caching 71-56
Configuring Content Transformation 71-56
Configuring a Certificate for Signing Rewritten Java Content 71-56
Disabling Content Rewrite 71-57
Using Proxy Bypass 71-57
Configuring Application Profile Customization Framework 71-57
APCF Syntax 71-58
Clientless SSL VPN End User Setup 71-61
Defining the End User Interface 71-61
Viewing the Clientless SSL VPN Home Page 71-61
Viewing the Clientless SSL VPN Application Access Panel
Viewing the Floating Toolbar 71-62
Customizing Clientless SSL VPN Pages 71-63
How Customization Works 71-64
Exporting a Customization Template 71-64
Editing the Customization Template 71-64
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Importing a Customization Object 71-70
Applying Customizations to Connection Profiles, Group Policies and Users 71-70
Login Screen Advanced Customization 71-71
Customizing Help 71-75
Customizing a Help File Provided By Cisco 71-76
Creating Help Files for Languages Not Provided by Cisco 71-77
Importing a Help File to Flash Memory 71-77
Exporting a Previously Imported Help File from Flash Memory 71-78
Requiring Usernames and Passwords 71-78
Communicating Security Tips 71-78
Configuring Remote Systems to Use Clientless SSL VPN Features 71-79
Translating the Language of User Messages 71-83
Understanding Language Translation 71-84
Creating Translation Tables 71-85
Referencing the Language in a Customization Object 71-86
Changing a Group Policy or User Attributes to Use the Customization Object 71-88
Capturing Data
CHAPTER
72
71-88
Configuring AnyConnect VPN Client Connections
72-1
Information About AnyConnect VPN Client Connections
Licensing Requirements for AnyConnect Connections
72-1
72-2
Guidelines and Limitations 72-3
Remote PC System Requirements 72-3
Remote HTTPS Certificates Limitation 72-4
Configuring AnyConnect Connections 72-4
Configuring the Security Appliance to Web-Deploy the Client 72-4
Enabling Permanent Client Installation 72-6
Configuring DTLS 72-6
Prompting Remote Users 72-7
Enabling AnyConnect Client Profile Downloads 72-8
Enabling Additional AnyConnect Client Features 72-10
Enabling Start Before Logon 72-10
Translating Languages for AnyConnect User Messages 72-11
Understanding Language Translation 72-11
Creating Translation Tables 72-11
Configuring Advanced SSL VPN Features 72-13
Enabling Rekey 72-13
Enabling and Adjusting Dead Peer Detection 72-14
Enabling Keepalive 72-14
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Using Compression 72-15
Adjusting MTU Size 72-16
Monitoring SSL VPN Sessions 72-16
Logging Off SVC Sessions 72-16
Updating SSL VPN Client Images 72-17
Monitoring AnyConnect Connections
72-18
Feature History for AnyConnect Connections
CHAPTER
73
Configuring Digital Certificates
72-18
73-1
Information About Digital Certificates 73-1
Public Key Cryptography 73-2
Certificate Scalability 73-2
Key Pairs 73-2
Trustpoints 73-3
Certificate Enrollment 73-3
Revocation Checking 73-4
Supported CA Servers 73-4
CRLs 73-4
OCSP 73-5
The Local CA 73-6
The Local CA Server 73-6
Storage for Local CA Files 73-7
Licensing Requirements for Digital Certificates
Prerequisites for Certificates
Guidelines and Limitations
73-7
73-7
73-7
Configuring Digital Certificates 73-8
Configuring Key Pairs 73-9
Removing Key Pairs 73-9
Configuring Trustpoints 73-10
Configuring CRLs for a Trustpoint 73-13
Exporting a Trustpoint Configuration 73-15
Importing a Trustpoint Configuration 73-15
Configuring CA Certificate Map Rules 73-16
Obtaining Certificates Manually 73-17
Obtaining Certificates Automatically with SCEP
Enabling the Local CA Server 73-22
Configuring the Local CA Server 73-23
Customizing the Local CA Server 73-25
Debugging the Local CA Server 73-27
73-20
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Disabling the Local CA Server 73-27
Deleting the Local CA Server 73-28
Configuring Local CA Certificate Characteristics 73-28
Configuring the Issuer Name 73-29
Configuring the CA Certificate Lifetime 73-29
Configuring the User Certificate Lifetime 73-31
Configuring the CRL Lifetime 73-31
Configuring the Server Keysize 73-32
Setting Up External Local CA File Storage 73-33
Downloading CRLs 73-35
Storing CRLs 73-36
Setting Up Enrollment Parameters 73-37
Adding and Enrolling Users 73-38
Renewing Users 73-40
Restoring Users 73-41
Removing Users 73-41
Revoking Certificates 73-42
Maintaining the Local CA Certificate Database 73-42
Rolling Over Local CA Certificates 73-42
Archiving the Local CA Server Certificate and Keypair 73-43
Monitoring Digital Certificates
73-43
Feature History for Certificate Management
PART
Monitoring
12
CHAPTER
73-45
74
Configuring Logging
74-1
Information About Logging 74-1
Logging in Multiple Context Mode 74-2
Analyzing Syslog Messages 74-2
Syslog Message Format 74-2
Severity Levels 74-3
Message Classes and Range of Syslog IDs
Filtering Syslog Messages 74-3
Using Custom Message Lists 74-4
Licensing Requirements for Logging
Prerequisites for Logging
74-3
74-5
74-5
Guidelines and Limitations
74-5
Configuring Logging 74-5
Enabling Logging 74-6
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Sending Syslog Messages to an SNMP Server 74-6
Sending Syslog Messages to a Syslog Server 74-7
Sending Syslog Messages to the Console Port 74-8
Sending Syslog Messages to an E-mail Address 74-8
Sending Syslog Messages to ASDM 74-9
Sending Syslog Messages to a Telnet or SSH Session 74-9
Sending Syslog Messages to the Internal Log Buffer 74-10
Sending All Syslog Messages in a Class to a Specified Output Destination
Creating a Custom Message List 74-12
Enabling Secure Logging 74-13
Configuring the Logging Queue 74-13
Including the Device ID in Syslog Messages 74-14
Generating Syslog Messages in EMBLEM Format 74-15
Including the Date and Time in Syslog Messages 74-15
Disabling a Syslog Message 74-15
Changing the Severity Level of a Syslog Message 74-16
Limiting the Rate of Syslog Message Generation 74-16
Changing the Amount of Internal Flash Memory Available for Logs 74-17
Monitoring Logging
74-17
Configuration Examples for Logging
Feature History for Logging
CHAPTER
75
74-18
74-18
Configuring NetFlow Secure Event Logging (NSEL)
Information About NSEL 75-1
Using NSEL and Syslog Messages
Licensing Requirements for NSEL
Prerequisites for NSEL
75-1
75-2
75-3
75-3
Guidelines and Limitations
75-3
Configuring NSEL 75-4
Configuring NSEL Collectors 75-4
Configuring Flow-Export Actions Through Modular Policy Framework
Configuring Template Timeout Intervals 75-6
Delaying Flow-Create Events 75-6
Disabling and Reenabling NetFlow-related Syslog Messages 75-7
Clearing Runtime Counters 75-7
Monitoring NSEL
74-11
75-5
75-7
Configuration Examples for NSEL
Additional References
75-8
75-9
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76
Related Documents
RFCs 75-10
75-10
Feature History for NSEL
75-10
Configuring SNMP
76-1
Information about SNMP 76-1
SNMP Version 3 Overview 76-2
Security Models 76-2
SNMP Groups 76-2
SNMP Users 76-2
SNMP Hosts 76-2
Implementation Differences Between Adaptive Security Appliances and IOS
Licensing Requirements for SNMP
Prerequisites for SNMP
Guidelines and Limitations
76-3
76-3
76-3
Configuring SNMP 76-4
Enabling SNMP 76-5
Compiling Cisco Syslog MIB Files
Troubleshooting Tips 76-8
Interface Types and Examples
Monitoring SNMP
76-7
76-9
76-11
Configuration Examples for SNMP 76-12
Configuration Example for SNMP Versions 1 and 2c
Configuration Example for SNMP Version 3 76-12
Additional References 76-12
RFCs for SNMP Version 3
MIBs 76-13
Feature History for SNMP
CHAPTER
77
76-3
76-12
76-12
76-14
Configuring Anonymous Reporting and Smart Call Home
77-1
Information About Anonymous Reporting and Smart Call Home 77-1
Information About Anonymous Reporting 77-2
What is Sent to Cisco? 77-2
DNS Requirement 77-3
Anonymous Reporting and Smart Call Home Prompt 77-3
Information About Smart Call Home 77-4
Licensing Requirements for Anonymous Reporting and Smart Call Home
Prerequisites for Smart Call Home and Anonymous Reporting
77-4
77-5
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Guidelines and Limitations
77-5
Configuring Anonymous Reporting and Smart Call Home 77-6
Configuring Anonymous Reporting 77-6
Configuring Smart Call Home 77-7
Enabling Smart Call Home 77-7
Declaring and Authenticating a CA Trust Point 77-8
Configuring DNS 77-8
Subscribing to Alert Groups 77-9
Testing Call Home Communications 77-11
Optional Configuration Procedures 77-13
Monitoring Smart Call Home
77-19
Configuration Example for Smart Call Home
77-19
Feature History for Anonymous Reporting and Smart Call Home
PART
System Administration
13
CHAPTER
77-20
78
Managing Software and Configurations
78-1
Copying Files to a Local File System on a UNIX Server
Viewing Files in Flash Memory
78-1
78-1
Retrieving Files from Flash Memory
78-2
Removing Files from Flash Memory
78-2
Downloading Software or Configuration Files to Flash Memory 78-2
Downloading a File to a Specific Location 78-3
Downloading a File to the Startup or Running Configuration 78-4
Configuring the Application Image and ASDM Image to Boot
Configuring the File to Boot as the Startup Configuration
78-4
78-5
Performing Zero Downtime Upgrades for Failover Pairs 78-5
Upgrading an Active/Standby Failover Configuration 78-6
Upgrading and Active/Active Failover Configuration 78-7
Backing Up Configuration Files 78-7
Backing up the Single Mode Configuration or Multiple Mode System Configuration
Backing Up a Context Configuration in Flash Memory 78-8
Backing Up a Context Configuration within a Context 78-8
Copying the Configuration from the Terminal Display 78-9
Backing Up Additional Files Using the Export and Import Commands 78-9
Using a Script to Back Up and Restore Files 78-9
Prerequisites 78-10
Running the Script 78-10
78-8
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Sample Script
78-10
Configuring Auto Update Support 78-19
Configuring Communication with an Auto Update Server 78-19
Configuring Client Updates as an Auto Update Server 78-21
Viewing Auto Update Status 78-22
CHAPTER
79
Troubleshooting
79-1
Testing Your Configuration 79-1
Enabling ICMP Debug Messages and System Log Messages
Pinging Security Appliance Interfaces 79-2
Pinging Through the Security Appliance 79-4
Disabling the Test Configuration 79-6
Traceroute 79-6
Packet Tracer 79-6
Reloading the Security Appliance
79-2
79-7
Performing Password Recovery 79-7
Recovering Passwords for the ASA 5500 Series Adaptive Security Appliance
Recovering Passwords for the PIX 500 Series Security Appliance 79-8
Disabling Password Recovery 79-10
Resetting the Password on the SSM Hardware Module 79-10
Using the ROM Monitor to Load a Software Image
Erasing the Flash File System
79-7
79-11
79-12
Other Troubleshooting Tools 79-13
Viewing Debug Messages 79-13
Capturing Packets 79-13
Viewing the Crash Dump 79-13
Coredump 79-13
Common Problems
PART
Reference
14
APPENDIX
79-13
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
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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
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)
A-35
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Example 15: ASA 5505 Base License
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
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
APPENDIX
C
B-9
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
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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-6
Supported Cisco Attributes for LDAP Authorization D-6
Cisco AV Pair Attribute Syntax D-13
Cisco AV Pairs ACL Examples D-15
Active Directory/LDAP VPN Remote Access Authorization Use Cases
User-Based Attributes Policy Enforcement D-18
Placing LDAP users in a specific Group-Policy D-20
Enforcing Static IP Address Assignment for AnyConnect Tunnels
Enforcing Dial-in Allow or Deny Access D-25
Enforcing Logon Hours and Time-of-Day Rules D-28
D-16
D-22
Configuring an External RADIUS Server D-30
Reviewing the RADIUS Configuration Procedure D-30
Security Appliance RADIUS Authorization Attributes D-30
Security Appliance IETF RADIUS Authorization Attributes D-38
Configuring an External TACACS+ Server
APPENDIX
E
D-39
Configuring the Adaptive Security Appliance for Use with MARS E-1
Taskflow for Configuring MARS to Monitor Adaptive Security Appliances E-1
Enabling Administrative Access to MARS on the Adaptive Security Appliance E-2
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Adding an Adaptive 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 Syslog Messages E-5
Syslog Messages That Are Processed by MARS E-5
Configuring Specific Features E-7
GLOSSARY
INDEX
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About This Guide
This preface introduce the Cisco ASA 5500 Series Configuration Guide using the CLI, and includes the
following sections:
•
Document Objectives, page lix
•
Audience, page lix
•
Related Documentation, page lx
•
Document Conventions, page lx
•
Obtaining Documentation, Obtaining Support, and Security Guidelines, page lx
Document Objectives
The purpose of this guide is to help you configure the ASA 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 ASA by using ASDM, a web-based 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
This guide applies to the Cisco ASA 5500 series ASAs. Throughout this guide, the term “ASA” applies
generically to all supported models, unless specified otherwise. The PIX 500 security appliances are not
supported.
Audience
This guide is for network managers who perform any of the following tasks:
•
Manage network security
•
Install and configure firewalls/ASAs
•
Configure VPNs
•
Configure intrusion detection software
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About This Guide
Related Documentation
For more information, refer to Navigating the Cisco ASA 5500 Series Documentation at
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
•
Variables for which you must supply a value are shown in italic screen font.
boldface 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
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A R T
1
Getting Started and General Information
CH A P T E R
1
Introduction to the ASA
The ASA combines advanced stateful firewall and VPN concentrator functionality in one device, and for
some models, an integrated intrusion prevention module called the AIP SSM/SSC or an integrated
content security and control module called the CSC SSM. The ASA includes many advanced features,
such as multiple security contexts (similar to virtualized firewalls), transparent (Layer 2) firewall or
routed (Layer6 3) firewall operation, advanced inspection engines, IPSec VPN, SSL VPN, and clientless
SSL VPN support, and many more features.
This chapter includes the following sections:
•
Supported Software, Models, and Modules, page 1-1
•
VPN Specifications, page 1-1
•
New Features, page 1-1
•
Firewall Functional Overview, page 1-10
•
VPN Functional Overview, page 1-14
•
Security Context Overview, page 1-15
Supported Software, Models, and Modules
For a complete list of supported ASA software, models, and modules, see Cisco ASA 5500 Series
Hardware and Software Compatibility:
http://www.cisco.com/en/US/docs/security/asa/compatibility/asamatrx.html
VPN Specifications
See the Supported VPN Platforms, Cisco ASA 5500 Series at
http://www.cisco.com/en/US/docs/security/asa/compatibility/asa-vpn-compatibility.html
New Features
This section includes the following topics:
•
New Features in Version 8.2(5), page 1-2
•
New Features in Version 8.2(4.4), page 1-2
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Introduction to the ASA
New Features
Note
•
New Features in Version 8.2(4.1), page 1-2
•
New Features in Version 8.2(4), page 1-2
•
New Features in Version 8.2(3.9), page 1-2
•
New Features in Version 8.2(3), page 1-2
•
New Features in Version 8.2(2), page 1-2
•
New Features in Version 8.2(1), page 1-5
New, changed, and deprecated syslog messages are listed in Cisco ASA 5500 Series System Log
Messages.
New Features in Version 8.2(5)
New Features in Version 8.2(4.4)
New Features in Version 8.2(4.1)
New Features in Version 8.2(4)
New Features in Version 8.2(3.9)
New Features in Version 8.2(3)
New Features in Version 8.2(2)
Released: January 11, 2010
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New Features
Table 1-1 lists the new features forASA Version 8.2(2).
Table 1-1
New Features for ASA Version 8.2(2)
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.
Also available in Version 8.0(5).
Application Inspection Features
Inspection for
IP Options
You can now control which IP packets with specific IP options should be allowed through the ASA.
You can also clear IP options from an IP packet, and then allow it through the ASA. Previously, all
IP options were denied by default, except for some special cases.
Note
This inspection is enabled by default. The following command is added to the default global
service policy: inspect ip-options. Therefore, the ASA allows RSVP traffic that contains
packets with the Router Alert option (option 20) when the ASA is in routed mode.
The following commands were introduced: policy-map type inspect ip-options, inspect
ip-options, eool, nop.
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
ASA 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 IP
address is unknown and the ASA opens a pinhole through source IP address/port 0/0. By default,
this option is disabled.
The following command was introduced: ras-rcf-pinholes enable (under the policy-map type
inspect h323 > parameters commands).
Also available in Version 8.0(5).
Unified Communication Features
Mobility Proxy
application no longer
requires Unified
Communications Proxy
license
The Mobility Proxy no longer requires the UC Proxy license.
Interface Features
In multiple context
mode, auto-generated
MAC addresses now use
a user-configurable
prefix, and other
enhancements
The MAC address format was changed to allow use of 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.
Also available in Version 8.0(5).
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New Features
Table 1-1
New Features for ASA Version 8.2(2) (continued)
Feature
Description
Support for Pause
You can now enable pause (XOFF) frames for flow control.
Frames for Flow Control The following command was introduced: flowcontrol.
on the ASA 5580 10
Gigabit Ethernet
Interfaces
Firewall Features
Botnet Traffic Filter
Enhancements
The Botnet Traffic Filter now supports automatic blocking of blacklisted traffic based on the threat
level. You can also view the category and threat level of malware sites in statistics and reports.
Reporting was enhanced to show infected hosts. The 1 hour timeout for reports for top hosts was
removed; there is now no timeout.
The following commands were introduced or modified: dynamic-filter ambiguous-is-black,
dynamic-filter drop blacklist, show dynamic-filter statistics, show dynamic-filter reports
infected-hosts, and show dynamic-filter reports top.
Connection timeouts for The idle timeout was changed to apply to all protocols, not just TCP.
all protocols
The following command was modified: set connection timeout.
Routing Features
DHCP RFC
compatibility (rfc3011,
rfc3527) to resolve
routing issues
This enhancement introduces ASA 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 configured for VPN clients, you can now configure the ASA to send the Subnet
Selection option or the Link Selection option.
The following command was modified: dhcp-server [subnet-selection | link-selection].
Also available in Version 8.0(5).
High Availablility Features
IPv6 Support in Failover IPv6 is now supported in failover configurations. You can assign active and standby IPv6 addresses
Configurations
to interfaces and use IPv6 addresses for the failover and Stateful Failover interfaces.
The following commands were modified: failover interface ip, ipv6 address.
No notifications when
To distinguish between link up/down transitions during normal operation from link up/down
interfaces are brought up transitions during failover, no link up/link down traps are sent during a failover. Also, no syslog
or brought down during messages about link up/down transitions during failover are sent.
a switchover event
Also available in Version 8.0(5).
AAA Features
100 AAA Server Groups You can now configure up to 100 AAA server groups; the previous limit was 15 server groups.
The following command was modified: aaa-server.
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New Features
Table 1-1
New Features for ASA Version 8.2(2) (continued)
Feature
Description
Monitoring Features
Smart Call Home
Smart Call Home offers proactive diagnostics and real-time alerts on the ASA and provides higher
network availability and increased operational efficiency. Customers and TAC engineers get what
they need to resolve problems quickly when an issue is detected.
Note
Smart Call Home server Version 3.0(1) has limited support for the ASA. See the “Important
Notes” for more information.
The following commands were introduced: call-home, call-home send alert-group, call-home
test, call-home send, service call-home, show call-home, show call-home registered-module
status.
New Features in Version 8.2(1)
Released: May 6, 2009
Table 1-2 lists the new features for ASA Version 8.2(1).
Hi
Table 1-2
New Features for ASA Version 8.2(1)
Feature
Description
Remote Access Features
One Time Password
Support for ASDM
Authentication
ASDM now supports administrator authentication using one time passwords (OTPs) supported by
RSA SecurID (SDI). This feature addresses security concerns about administrators authenticating
with static passwords.
New session controls for ASDM users include the ability to limit the session time and the idle time.
When the password used by the ASDM administrator times out, ASDM prompts the administrator
to re-authenticate.
The following commands were introduced: http server idle-timeout and http server
session-timeout. The http server idle-timeout default is 20 minutes, and can be increased up to a
maximum of 1440 minutes.
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New Features
Table 1-2
New Features for ASA Version 8.2(1) (continued)
Feature
Description
Pre-fill Username from
Certificate
The pre-fill username feature enables the use of a username extracted from a certificate for
username/password authentication. With this feature enabled, the username is “pre-filled” on the
login screen, with the user being prompted only for the password. To use this feature, you must
configure both the pre-fill username and the username-from-certificate commands in
tunnel-group configuration mode.
The double-authentication feature is compatible with the pre-fill username feature, as the pre-fill
username feature can support extracting a primary username and a secondary username from the
certificate to serve as the usernames for double authentication when two usernames are required.
When configuring the pre-fill username feature for double authentication, the administrator uses
the following new tunnel-group general-attributes configuration mode commands:
Double Authentication
•
secondary-pre-fill-username—Enables username extraction for Clientless or AnyConnect
client connection.
•
secondary-username-from-certificate—Allows for extraction of a few standard DN fields
from a certificate for use as a username.
The double authentication feature implements two-factor authentication for remote access to the
network, in accordance with the Payment Card Industry Standards Council Data Security Standard.
This feature requires that the user enter two separate sets of login credentials at the login page. For
example, the primary authentication might be a one-time password, and the secondary
authentication might be a domain (Active Directory) credential. If either authentication fails, the
connection is denied.
Both the AnyConnect VPN client and Clientless SSL VPN support double authentication. The
AnyConnect client supports double authentication on Windows computers (including supported
Windows Mobile devices and Start Before Logon), Mac computers, and Linux computers. The
IPsec VPN client, SVC client, cut-through-proxy authentication, hardware client authentication,
and management authentication do not support double authentication.
Double authentication requires the following new tunnel-group general-attributes configuration
mode commands:
•
secondary-authentication-server-group—Specifies the secondary AAA server group, which
cannot be an SDI server group.
•
secondary-username-from-certificate—Allows for extraction of a few standard DN fields
from a certificate for use as a username.
•
secondary-pre-fill-username—Enables username extraction for Clientless or AnyConnect
client connection.
•
authentication-attr-from-server—Specifies which authentication server authorization
attributes are applied to the connection.
•
authenticated-session-username—Specifies which authentication username is associated
with the session.
Note
The RSA/SDI authentication server type cannot be used as the secondary
username/password credential. It can only be used for primary authentication.
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New Features
Table 1-2
New Features for ASA Version 8.2(1) (continued)
Feature
Description
AnyConnect Essentials
AnyConnect Essentials is a separately licensed SSL VPN client, entirely configured on the ASA,
that provides the full AnyConnect capability, with the following exceptions:
•
No CSD (including HostScan/Vault/Cache Cleaner)
•
No clientless SSL VPN
•
Optional Windows Mobile Support
The AnyConnect Essentials client provides remote end users running Microsoft Windows Vista,
Windows Mobile, Windows XP or Windows 2000, Linux, or Macintosh OS X, with the benefits of
a Cisco SSL VPN client.
To configure AnyConnect Essentials, the administrator uses the following command:
anyconnect-essentials—Enables the AnyConnect Essentials feature. If this feature is disabled
(using the no form of this command), the SSL Premium license is used. This feature is enabled by
default.
Note
This license cannot be used at the same time as the shared SSL VPN premium license.
Disabling Cisco Secure When enabled, Cisco Secure Desktop automatically runs on all computers that make SSL VPN
Desktop per Connection connections to the ASA. This new feature lets you exempt certain users from running Cisco Secure
Profile
Desktop on a per connection profile basis. It prevents the detection of endpoint attributes for these
sessions, so you might need to adjust the Dynamic Access Policy (DAP) configuration.
CLI: [no] without-csd command
Note
“Connect Profile” in ASDM is also known as “Tunnel Group” in the CLI. Additionally, the
group-url command is required for this feature. If the SSL VPN session uses
connection-alias, this feature will not take effect.
Certificate
Authentication Per
Connection Profile
Previous versions supported certificate authentication for each ASA interface, so users received
certificate prompts even if they did not need a certificate. With this new feature, users receive a
certificate prompt only if the connection profile configuration requires a certificate. This feature is
automatic; the ssl certificate authentication command is no longer needed, but the ASA retains it
for backward compatibility.
EKU Extensions for
Certificate Mapping
This feature adds the ability to create certificate maps that look at the Extended Key Usage
extension of a client certificate and use these values in determining what connection profile the
client should use. If the client does not match that profile, it uses the default group. The outcome
of the connection then depends on whether or not the certificate is valid and the authentication
settings of the connection profile.
The following command was introduced: extended-key-usage.
SSL VPN SharePoint
Support for Win 2007
Server
Clientless SSL VPN sessions now support Microsoft Office SharePoint Server 2007.
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New Features
Table 1-2
New Features for ASA Version 8.2(1) (continued)
Feature
Description
Shared license for SSL
VPN sessions
You can purchase a shared license with a large number of SSL VPN sessions and share the sessions
as needed among a group of ASAs by configuring one of the ASAs as a shared license server, and
the rest as clients. The following commands were introduced: license-server commands (various),
show shared license.
Note
This license cannot be used at the same time as the AnyConnect Essentials license.
Firewall Features
TCP state bypass
If you have asymmetric routing configured on upstream routers, and traffic alternates between two
ASAs, then you can configure TCP state bypass for specific traffic. The following command was
introduced: set connection advanced tcp-state-bypass.
Per-Interface IP
Addresses for the
Media-Termination
Instance Used by the
Phone Proxy
In Version 8.0(4), you configured a global media-termination address (MTA) on the ASA. In
Version 8.2, you can now configure MTAs for individual interfaces (with a minimum of two
MTAs). As a result of this enhancement, the old CLI has been deprecated. You can continue to use
the old configuration if desired. However, if you need to change the configuration at all, only the
new configuration method is accepted; you cannot later restore the old configuration.
Displaying the CTL File The Cisco Phone Proxy feature includes the show ctl-file command, which shows the contents of
for the Phone Proxy
the CTL file used by the phone proxy. Using the show ctl-file command is useful for debugging
when configuring the phone proxy instance.
This command is not supported in ASDM.
Clearing Secure-phone
Entries from the Phone
Proxy Database
The Cisco Phone Proxy feature includes the clear phone-proxy secure-phones command, which
clears the secure-phone entries in the phone proxy database. Because secure IP phones always
request a CTL file upon bootup, the phone proxy creates a database that marks the IP phones as
secure. The entries in the secure phone database are removed after a specified configured timeout
(via the timeout secure-phones command). Alternatively, you can use the clear phone-proxy
secure-phones command to clear the phone proxy database without waiting for the configured
timeout.
This command is not supported in ASDM.
H.239 Message Support In this release, the ASA supports the H.239 standard as part of H.323 application inspection. H.239
is a standard that provides the ability for H.300 series endpoints to open an additional video channel
in H.323 Application
Inspection
in a single call. In a call, an endpoint (such as a video phone), sends a channel for video and a
channel for data presentation. The H.239 negotiation occurs on the H.245 channel. The ASA opens
a pinhole for the additional media channel. The endpoints use open logical channel message (OLC)
to signal a new channel creation. The message extension is part of H.245 version 13. The decoding
and encoding of the telepresentation session is enabled by default. H.239 encoding and decoding
is preformed by ASN.1 coder.
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Table 1-2
New Features for ASA Version 8.2(1) (continued)
Feature
Description
Processing H.323
Endpoints When the
Endpoints Do Not Send
OLCAck
H.323 application inspection has been enhanced to process common H.323 endpoints. The
enhancement affects endpoints using the extendedVideoCapability OLC with the H.239 protocol
identifier. Even when an H.323 endpoint does not send OLCAck after receiving an OLC message
from a peer, the ASA propagates OLC media proposal information into the media array and opens
a pinhole for the media channel (extendedVideoCapability).
IPv6 in transparent
firewall mode
Transparent firewall mode now participates in IPv6 routing. Prior to this release, the ASA could
not pass IPv6 traffic in transparent mode. You can now configure an IPv6 management address in
transparent mode, create IPv6 access lists, and configure other IPv6 features; the ASA recognizes
and passes IPv6 packets.
All IPv6 functionality is supported unless specifically noted.
Botnet Traffic Filter
Malware is malicious software that is installed on an unknowing host. Malware that attempts
network activity such as sending private data (passwords, credit card numbers, key strokes, or
proprietary data) can be detected by the Botnet Traffic Filter when the malware starts a connection
to a known bad IP address. The Botnet Traffic Filter checks incoming and outgoing connections
against a dynamic database of known bad domain names and IP addresses, and then logs any
suspicious activity. You can also supplement the dynamic database with a static database by
entering IP addresses or domain names in a local “blacklist” or “whitelist.”
Note
This feature requires the Botnet Traffic Filter license. See the following licensing document
for more information:
http://www.cisco.com/en/US/docs/security/asa/asa82/license/license82.html
The following commands were introduced: dynamic-filter commands (various), and the inspect
dns dynamic-filter-snoop keyword.
AIP SSC card for the
ASA 5505
The AIP SSC offers IPS for the ASA 5505 ASA. Note that the AIP SSM does not support virtual
sensors. The following commands were introduced: allow-ssc-mgmt, hw-module module ip, and
hw-module module allow-ip.
IPv6 support for IPS
You can now send IPv6 traffic to the AIP SSM or SSC when your traffic class uses the match any
command, and the policy map specifies the ips command.
Management Features
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Firewall Functional Overview
Table 1-2
New Features for ASA Version 8.2(1) (continued)
Feature
Description
SNMP version 3 and
encryption
This release provides DES, 3DES, or AES encryption and support for SNMP Version 3, the most
secure form of the supported security models. This version allows you to configure authentication
characteristics by using the User-based Security Model (USM).
The following commands were introduced:
•
show snmp engineid
•
show snmp group
•
show snmp-server group
•
show snmp-server user
•
snmp-server group
•
snmp-server user
The following command was modified:
•
NetFlow
snmp-server host
This feature was introduced in Version 8.1(1) for the ASA 5580; this version introduces the feature
to the other platforms. The new NetFlow feature enhances the ASA logging capabilities by logging
flow-based events through the NetFlow protocol.
Routing Features
Multicast NAT
The ASA now offers Multicast NAT support for group addresses.
Troubleshooting Features
Coredump functionality A coredump is a snapshot of the running program when the program has terminated abnormally.
Coredumps are used to diagnose or debug errors and save a crash for later or off-site analysis. Cisco
TAC may request that users enable the coredump feature to troubleshoot application or system
crashes on the ASA.
To enable coredump, use the coredump enable command.
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.
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Firewall Functional Overview
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 ASA 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 1-11
•
Firewall Mode Overview, page 1-13
•
Stateful Inspection Overview, page 1-13
Security Policy Overview
A security policy determines which traffic is allowed to pass through the firewall to access another
network. By default, the ASA 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 1-11
•
Applying NAT, page 1-11
•
Protecting from IP Fragments, page 1-12
•
Using AAA for Through Traffic, page 1-12
•
Applying HTTP, HTTPS, or FTP Filtering, page 1-12
•
Applying Application Inspection, page 1-12
•
Sending Traffic to the Advanced Inspection and Prevention Security Services Module, page 1-12
•
Sending Traffic to the Content Security and Control Security Services Module, page 1-12
•
Applying QoS Policies, page 1-12
•
Applying Connection Limits and TCP Normalization, page 1-13
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.
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Protecting from IP Fragments
The ASA 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 ASA.
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 ASA also sends accounting information to a RADIUS or TACACS+ server.
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 ASA 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 ASA 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 ASA 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.
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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 ASA 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.
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 ASA 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 ASA to send system log messages about an attacker or you can automatically shun
the host.
Firewall Mode Overview
The ASA runs in two different firewall modes:
•
Routed
•
Transparent
In routed mode, the ASA is considered to be a router hop in the network.
In transparent mode, the ASA acts like a “bump in the wire,” or a “stealth firewall,” and is not considered
a router hop. The ASA 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 ASA 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.
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VPN Functional Overview
A stateful firewall like the ASA, however, takes into consideration the state of a packet:
•
Is this a new connection?
If it is a new connection, the ASA 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
– Performing route lookups
– Allocating NAT translations (xlates)
– Establishing sessions in the “fast 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 ASA 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 ASA 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 ASA uses tunneling protocols to negotiate
security parameters, create and manage tunnels, encapsulate packets, transmit or receive them through
the tunnel, and unencapsulate them. The ASA 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 ASA invokes various standard
protocols to accomplish these functions.
The ASA performs the following functions:
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•
Establishes tunnels
•
Negotiates tunnel parameters
•
Authenticates users
•
Assigns user addresses
•
Encrypts and decrypts data
•
Manages security keys
•
Manages data transfer across the tunnel
•
Manages data transfer inbound and outbound as a tunnel endpoint or router
The ASA invokes various standard protocols to accomplish these functions.
Security Context Overview
You can partition a single ASA 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 ASA 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 ASA. 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.
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2
Getting Started
This chapter describes how to get started with your ASA. This chapter includes the following sections:
•
Factory Default Configurations, page 2-1
•
Accessing the Command-Line Interface, page 2-4
•
Working with the Configuration, page 2-5
•
Applying Configuration Changes to Connections, page 2-9
Factory Default Configurations
The factory default configuration is the configuration applied by Cisco to new ASAs.
For the ASA 5510 and higher ASAs, 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 ASA is ready to use in your network immediately.
The factory default configuration is available only for routed firewall mode and single context mode. See
Chapter 5, “Managing Multiple Context Mode,” for more information about multiple context mode. See
Chapter 4, “Configuring the Transparent or Routed Firewall,” for more information about routed and
transparent firewall mode.
Note
In addition to the image files and the (hidden) default configuration, the following folders and files are
standard in flash memory: log/, crypto_archive/, and coredumpinfo/coredump.cfg. The date on these
files may not match the date of the image files in flash memory. These files aid in potential
troubleshooting; they do not indicate that a failure has occurred.
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
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Factory Default Configurations
Restoring the Factory Default Configuration
This section describes how to restore the factory default configuration.
Detailed Steps
Step 1
Command
Purpose
configure factory-default [ip_address
[mask]]
Restores the factory default configuration.
Example:
hostname(config)# configure
factory-default 10.1.1.1 255.255.255.0
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.
Note
Step 2
write memory
Example:
active(config)# write memory
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 ASA 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 ASA does not boot.
Saves the default configuration to Flash memory. This 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.
What to Do Next
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.
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Factory Default Configurations
•
The DHCP server is enabled on the ASA, 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
interface Ethernet 0/1
switchport access vlan 1
interface Ethernet 0/2
switchport access vlan 1
interface Ethernet 0/3
switchport access vlan 1
interface Ethernet 0/4
switchport access vlan 1
interface Ethernet 0/5
switchport access vlan 1
interface Ethernet 0/6
switchport access vlan 1
interface Ethernet 0/7
switchport access vlan 1
interface vlan2
nameif outside
ip address dhcp setroute
interface vlan1
nameif inside
ip address 192.168.1.1 255.255.255.0
security-level 100
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 ASA, 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 management 0/0
ip address 192.168.1.1 255.255.255.0
nameif management
security-level 100
asdm logging informational 100
asdm history enable
http server enable
http 192.168.1.0 255.255.255.0 management
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Accessing the Command-Line Interface
dhcpd
dhcpd
dhcpd
dhcpd
address 192.168.1.2-192.168.1.254 management
lease 3600
ping_timeout 750
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 37, “Configuring Management
Access.” If your system is already in multiple context mode, then accessing the console port places you
in the system execution space. See Chapter 5, “Managing Multiple Context Mode,” for more information
about multiple context mode.
Note
If you want to use ASDM to configure the ASA instead of the command-line interface, you can connect
to the default management address of 192.168.1.1 (if your ASA includes a factory default configuration.
See the “Factory Default Configurations” section on page 2-1.). On the 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. 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 ASA 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 8-2 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
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Working with the Configuration
The prompt changes to the following:
hostname(config)#
To exit global configuration mode, enter the exit, quit, or end command.
Working with the Configuration
This section describes how to work with the configuration. The ASA 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 78, “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 5, “Managing Multiple Context Mode.”
This section includes the following topics:
•
Saving Configuration Changes, page 2-5
•
Copying the Startup Configuration to the Running Configuration, page 2-7
•
Viewing the Configuration, page 2-7
•
Clearing and Removing Configuration Settings, page 2-8
•
Creating Text Configuration Files Offline, page 2-8
Saving Configuration Changes
This section describes how to save your configuration, and includes the following topics:
•
Saving Configuration Changes in Single Context Mode, page 2-5
•
Saving Configuration Changes in Multiple Context Mode, page 2-6
Saving Configuration Changes in Single Context Mode
To save the running configuration to the startup configuration, enter the following command:
Command
Purpose
write memory
Saves the running configuration to the startup configuration.
Example:
hostname# write memory
Note
The copy running-config startup-config command is equivalent
to the write memory command.
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Working with the Configuration
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 2-6
•
Saving All Context Configurations at the Same Time, page 2-6
Saving Each Context and System Separately
To save the system or context configuration, enter the following command within the system or context:
Command
Purpose
write memory
Saves the running configuration to the startup configuration.
Example:
hostname# write memory
For multiple context mode, context startup configurations can reside on
external servers. In this case, the ASA 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.
Note
The copy running-config startup-config command is equivalent
to the write memory command.
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:
Command
Purpose
write memory all [/noconfirm]
Saves the running configuration to the startup configuration for all contexts
and the system configuration.
Example:
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 ASA saves the system configuration and each
context. Context startup configurations can reside on external servers. In
this case, the ASA 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 ASA 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
•
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
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Working with the Configuration
•
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 the following options.
Command
Purpose
copy startup-config running-config
Merges the startup 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.
reload
Reloads the ASA, which loads the startup configuration and discards the
running configuration.
clear configure all
copy startup-config running-config
Loads the startup configuration and discards the running configuration
without requiring a reload.
Viewing the Configuration
The following commands let you view the running and startup configurations.
Command
Purpose
show running-config
Views the running configuration.
show running-config command
Views the running configuration of a specific command.
show startup-config
Views the startup configuration.
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Working with the Configuration
Clearing and Removing Configuration Settings
To erase settings, enter one of the following commands.
Command
Purpose
clear configure configurationcommand
[level2configurationcommand]
Clears all the configuration for a specified 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
no configurationcommand
[level2configurationcommand] qualifier
Disables the specific parameters or options of a command. 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
write erase
Erases the startup configuration.
clear configure all
Erases the running configuration.
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. The context configuration files are not erased, and
remain in their original location.
Creating Text Configuration Files Offline
This guide describes how to use the CLI to configure the ASA; 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 ASA internal Flash memory. See Chapter 78,
“Managing Software and Configurations,” for information on downloading the configuration file to the
ASA.
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.”
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Applying Configuration Changes to Connections
Applying Configuration Changes to Connections
When you make security policy changes to the configuration, all new connections use the new security
policy. Existing connections continue to use the policy that was configured at the time of the connection
establishment. To ensure that all connections use the new policy, you need to disconnect the current
connections so they can reconnect using the new policy. To disconnect connections, enter one of the
following commands:
Command
Purpose
clear local-host [ip_address] [all]
This command reinitalizes per-client run-time states such as connection
limits and embryonic limits. As a result, this command removes any
connection that uses those limits. See the show local-host all command to
view all current connections per host.
With no arguments, this command clears all affected through-the-box
connections. To also clear to-the-box connections (including your current
management session), use the all keyword. To clear connections to and
from a particular IP address, use the ip_address argument.
clear conn [all] [protocol {tcp | udp}]
[address src_ip[-src_ip] [netmask mask]]
[port src_port[-src_port]] [address
dest_ip[-dest_ip] [netmask mask]] [port
dest_port[-dest_port]]
This command terminates connections in any state. See the show conn
command to view all current connections.
clear xlate [arguments]
This command clears dynamic NAT sessions; static sessions are not
affected. As a result, it removes any connections using those NAT sessions.
With no arguments, this command clears all through-the-box connections.
To also clear to-the-box connections (including your current management
session), use the all keyword. To clear specific connections based on the
source IP address, destination IP address, port, and/or protocol, you can
specify the desired options.
With no arguments, this command clears all NAT sessions. See the Cisco
ASA 5500 Series Command Reference for more information about the
arguments available.
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3
Managing Feature Licenses
A license specifies the options that are enabled on a given ASA. 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:
•
Supported Feature Licenses Per Model, page 3-1
•
Information About Feature Licenses, page 3-10
•
Guidelines and Limitations, page 3-18
•
Viewing Your Current License, page 3-19
•
Obtaining an Activation Key, page 3-21
•
Entering a New Activation Key, page 3-21
•
Upgrading the License for a Failover Pair, page 3-23
•
Configuring a Shared License, page 3-25
•
Feature History for Licensing, page 3-30
Supported Feature Licenses Per Model
This section describes the licenses available for each model as well as important notes about licenses.
This section includes the following topics:
•
Licenses Per Model, page 3-1
•
License Notes, page 3-9
•
VPN License and Feature Compatibility, page 3-10
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
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Supported Feature Licenses Per Model
•
ASA 5540, Table 3-4 on page 3-5
•
ASA 5550, Table 3-5 on page 3-6
•
ASA 5580, Table 3-6 on page 3-7
•
ASA 5585-X, Table 3-7 on page 3-8
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 Clientless 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
Security Plus
Firewall Licenses
Botnet Traffic Filter1
Disabled
Optional temporary license:
Available
Disabled
Firewall Conns, Concurrent 10 K
25 K
GTP/GPRS
No support
No support
2
2
Unified Comm. Sessions
1
Optional license: 24
Optional temporary license:
Available
Optional license: 24
2
VPN Licenses
Adv. Endpoint Assessment
AnyConnect Essentials
1
AnyConnect Mobile1
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
AnyConnect Premium SSL 2
VPN (sessions)1
IPSec VPN (sessions)
1
VPN Load Balancing
Optional Permanent licenses:
10
2
25
Optional Permanent licenses:
10
25
10 (max. 25 combined IPSec and SSL VPN)
25 (max. 25 combined IPSec and SSL VPN)
No support
No support
General Licenses
Encryption
Base (DES)
Failover
No support
Active/Standby (no stateful failover)
No support
No support
Security Contexts
Users, concurrent
3
10
4
Opt. lic.: Strong (3DES/AES)
Optional licenses:
50
Base (DES)
10 4
Unlimited
Opt. lic.: Strong (3DES/AES)
Optional licenses:
50
VLANs/Zones, Maximum
3 (2 regular zones and 1 restricted zone)
20
VLAN Trunk, Maximum
No support
8 trunks
Unlimited
1. See the “License Notes” section.
2. See the “VPN License and Feature Compatibility” section.
3. In routed mode, hosts on the inside (Business and Home VLANs) count towards the limit when they communicate with the outside (Internet VLAN),
including when the inside initiates a connection to the outside as well as when the outside initiates a connection to the inside. Note that even when the
outside initiates a connection to the inside, outside hosts are not counted towards the limit; only the inside hosts count. 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 outside 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 host limits.
4. 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.
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Table 3-2
ASA 5510 Adaptive Security Appliance License Features
ASA 5510
Base License
Security Plus
Firewall Licenses
Botnet Traffic Filter1
Disabled
Optional temporary license:
Available
Disabled
Firewall Conns, Concurrent 50 K
130 K
GTP/GPRS
No support
No support
2
2
Unified Comm. Sessions
1
Optional licenses:
24
50
100
Optional temporary license:
Available
Optional licenses:
24
50
100
2
VPN Licenses
Adv. Endpoint Assessment
AnyConnect Essentials
AnyConnect Mobile
1
1
AnyConnect Premium SSL
VPN (sessions)
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
2
Optional Permanent licenses:
10
25
50
100
2
250
10
25
50
100
250
Optional Shared licenses: Participant or
Server. For the Server, these licenses are
available:1
Optional Shared licenses: Participant or
Server. For the Server, these licenses are
available:1
500-50,000 in
increments of 500
500-50,000 in
increments of 500
50,000-545,000 in
increments of 1000
Optional FLEX license: 250
50,000-545,000 in
increments of 1000
Optional FLEX license: 250
1
250 (max. 250 combined IPSec and SSL VPN) 250 (max. 250 combined IPSec and SSL VPN)
1
No support
IPSec VPN (sessions)
VPN Load Balancing
Optional Permanent licenses:
Supported
General Licenses
Encryption
Base (DES)
Opt. lic.: Strong (3DES/AES)
Base (DES)
Opt. lic.: Strong (3DES/AES)
Failover
No support
Active/Standby or Active/Active1
Interface Speed
All: Fast Ethernet
Ethernet 0/0 and 0/1: Gigabit Ethernet3
Ethernet 0/2, 0/3, and 0/4: Fast Ethernet
Security Contexts
No support
2
Optional licenses:
5
VLANs, Maximum
50
100
1. See the “License Notes” section.
2. See the “VPN License and Feature Compatibility” section.
3. Although the Ethernet 0/0 and 0/1 ports are Gigabit Ethernet, they are still identified as “Ethernet” in the software.
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Table 3-3
ASA 5520 Adaptive Security Appliance License Features
ASA 5520
Base License
Firewall Licenses
Botnet Traffic Filter1
Disabled
Optional temporary license: Available
Firewall Conns, Concurrent 280 K
GTP/GPRS
Disabled
Unified Communications
Proxy Sessions1
2
Optional license: Available
Optional licenses:
24
50
100
250
500
750
1000
500
750
2
VPN Licenses
Adv. Endpoint Assessment
AnyConnect Essentials
AnyConnect Mobile
1
1
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
AnyConnect Premium SSL 2
VPN (sessions)
Optional Permanent licenses:
10
25
50
100
250
Optional Shared licenses: Participant or Server. For the Server, these licenses are available:1
500-50,000 in increments of 500
50,000-545,000 in increments of 1000
Optional FLEX licenses:
250
750 (max. 750 combined IPSec and SSL VPN)
1
Supported
IPSec VPN (sessions)
VPN Load Balancing
750
1
General Licenses
Encryption
Base (DES)
Failover
Active/Standby or Active/Active 1
Security Contexts
2
Optional licenses:
5
VLANs, Maximum
Optional license: Strong (3DES/AES)
10
20
150
1. See the “License Notes” section.
2. See the “VPN License and Feature Compatibility” section.
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Supported Feature Licenses Per Model
Table 3-4
ASA 5540 Adaptive Security Appliance License Features
ASA 5540
Base License
Firewall Licenses
Botnet Traffic Filter1
Disabled
Optional temporary license: Available
Firewall Conns, Concurrent 400 K
GTP/GPRS
Disabled
Unified Communications
Proxy Sessions1
2
Optional license: Available
Optional licenses:
24
50
100
250
500
750
1000
2000
500
750
1000
2
VPN Licenses
Adv. Endpoint Assessment
Disabled
Optional license: Available
AnyConnect Essentials1
Disabled
Optional license: Available
Disabled
Optional license: Available
AnyConnect Mobile
1
AnyConnect Premium SSL
VPN (sessions)
2
Optional Permanent licenses:
10
25
50
100
250
2500
Optional Shared licenses: Participant or Server. For the Server, these licenses are available:1
500-50,000 in increments of 500
50,000-545,000 in increments of 1000
Optional FLEX licenses:
250
IPSec VPN (sessions)1
VPN Load Balancing
1
750
1000
2500
5000 (max. 5000 combined IPSec and SSL VPN)
Supported
General Licenses
Encryption
Base (DES)
Failover
Active/Standby or Active/Active1
Security Contexts
2
Optional licenses:
5
VLANs, Maximum
Optional license: Strong (3DES/AES)
10
20
50
200
1. See the “License Notes” section.
2. See the “VPN License and Feature Compatibility” section.
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Table 3-5
ASA 5550 Adaptive Security Appliance License Features
ASA 5550
Base License
Firewall Licenses
Botnet Traffic Filter1
Disabled
Optional temporary license: Available
Firewall Conns, Concurrent 650 K
GTP/GPRS
Disabled
Unified Communications
Proxy Sessions1
2
Optional license: Available
Optional licenses:
24
50
100
250
500
750
1000
2000
3000
500
750
1000
2500
2
VPN Licenses
Adv. Endpoint Assessment
Disabled
Optional license: Available
AnyConnect Essentials1
Disabled
Optional license: Available
Disabled
Optional license: Available
AnyConnect Mobile
1
AnyConnect Premium SSL 2
VPN (sessions)
Optional Permanent licenses:
10
25
50
100
250
5000
Optional Shared licenses: Participant or Server. For the Server, these licenses are available:1
500-50,000 in increments of 500
50,000-545,000 in increments of 1000
Optional FLEX licenses:
250
IPSec VPN (sessions)1
VPN Load Balancing
1
750
1000
2500
5000
5000 (max. 5000 combined IPSec and SSL VPN)
Supported
General Licenses
Encryption
Base (DES)
Failover
Active/Standby or Active/Active1
Security Contexts
2
Optional licenses:
5
VLANs, Maximum
Optional license: Strong (3DES/AES)
10
20
50
250
1. See the “License Notes” section.
2. See the “VPN License and Feature Compatibility” section.
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Table 3-6
ASA 5580 Adaptive Security Appliance License Features
ASA 5580
Base License
Firewall Licenses
Botnet Traffic Filter1
Disabled
Optional temporary license: Available
Firewall Conns, Concurrent 5580-20: 1,000 K
5580-40: 2,000 K
GTP/GPRS
Disabled
Unified Communications
Proxy Sessions1
2
Optional license: Available
Optional licenses:
24
50
100
250
500
750
1000
2000
3000
5000
500
750
1000
2500
5000
100002
VPN Licenses3
Adv. Endpoint Assessment
AnyConnect Essentials
AnyConnect Mobile
1
1
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
AnyConnect Premium SSL 2
VPN (sessions)
Optional Permanent licenses:
10
25
50
100
250
Optional Shared licenses: Participant or Server. For the Server, these licenses are available:1
500-50,000 in increments of 500
50,000-545,000 in increments of 1000
Optional FLEX licenses:
250
1000
2500
5000
5000 (max. 5000 combined IPSec and SSL VPN)
1
Supported
IPSec VPN (sessions)
VPN Load Balancing
750
1
General Licenses
Encryption
Base (DES)
Failover
Active/Standby or Active/Active 1
Security Contexts
2
Optional licenses:
5
VLANs, Maximum
Optional license: Strong (3DES/AES)
10
20
50
250
1. See the “License Notes” section.
2. With the 10,000-session license, the total combined sessions can be 10,000, but the maximum number of Phone Proxy sessions is 5000.
3. See the “VPN License and Feature Compatibility” section.
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Table 3-7
ASA 5585-X Adaptive Security Appliance License Features
ASA 5585-X
Base License
Firewall Licenses
Botnet Traffic Filter1
Disabled
Optional temporary license: Available
Firewall Conns, Concurrent 5585-X with SSP-10: 750 K
5585-X with SSP-20: 1,000 K
5585-X with SSP-40: 2,000 K
5585-X with SSP-60: 2,000 K
GTP/GPRS
Disabled
Unified Communications
Proxy Sessions1
2
Optional license: Available
Optional licenses:
24
50
100
250
500
750
1000
2000
3000
5000
100002
500
750
1000
2500
5000
10000
VPN Licenses3
Adv. Endpoint Assessment
AnyConnect Essentials
AnyConnect Mobile
1
1
Disabled
Optional license: Available
Disabled
Optional license: Available
Disabled
Optional license: Available
AnyConnect Premium SSL 2
VPN (sessions)
Optional Permanent licenses:
10
25
50
100
250
Optional Shared licenses: Participant or Server. For the Server, these licenses are available:1
500-50,000 in increments of 500
50,000-545,000 in increments of 1000
Optional FLEX licenses:
250
1000
2500
5000
5000 (max. 5000 combined IPSec and SSL VPN)
1
Supported
IPSec VPN (sessions)
VPN Load Balancing
750
1
General Licenses
Encryption
Base (DES)
Failover
Active/Standby or Active/Active1
10 GE I/O for SSP-10 and
SSP-204
Disabled; fiber ifcs run at 1 GE
Security Contexts
2
Optional license: Available; fiber ifcs run at 10 GE
Optional licenses:
5
VLANs, Maximum
Optional license: Strong (3DES/AES)
10
20
50
250
1. See the “License Notes” section.
2. With the 10,000-session license, the total combined sessions can be 10,000, but the maximum number of Phone Proxy sessions is 5000.
3. See the “VPN License and Feature Compatibility” section.
4. The ASA 5585-X with SSP-40 and -60 support 10-Gigabit Ethernet speeds by default.
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License Notes
Table 3-8 lists footnotes for the tables in the “Licenses Per Model” section on page 3-1.
Table 3-8
License Notes
License
Notes
Active/Active failover
You cannot use Active/Active failover and VPN; if you want to use VPN, use Active/Standby
failover.
AnyConnect Essentials
This license enables AnyConnect VPN client access to the adaptive security appliance. This
license does not support deploy browser-based SSL VPN access or Cisco Secure Desktop. For
these features, activate an AnyConnect Premium SSL VPN license instead of the AnyConnect
Essentials license.
Note
With the AnyConnect Essentials license, VPN users can use a Web browser to log in, and
download and start (WebLaunch) the AnyConnect client.
The AnyConnect client software offers the same set of client features, whether it is enabled by
this license or an AnyConnect Premium SSL VPN license.
The AnyConnect Essentials license cannot be active at the same time as the following licenses on
a given adaptive security appliance: AnyConnect Premium SSL VPN license (all types) or the
Advanced Endpoint Assessment license. You can, however, run AnyConnect Essentials and
AnyConnect Premium SSL VPN licenses on different adaptive security appliances in the same
network.
By default, the ASA uses the AnyConnect Essentials license, but you can disable it to use other
licenses by using the no anyconnect-essentials command.
AnyConnect Mobile
This license provides access to the AnyConnect Client for touch-screen mobile devices running
Windows Mobile 5.0, 6.0, and 6.1. We recommend using this license if you want to support
mobile access to AnyConnect 2.3 and later versions. This license requires activation of one of the
following licenses to specify the total number SSL VPN sessions permitted: AnyConnect
Essentials or AnyConnect Premium SSL VPN.
AnyConnect Premium
SSL VPN Shared
A shared license lets the ASA act as a shared license server for multiple client ASAs. The shared
license pool is large, but the maximum number of sessions used by each individual ASA cannot
exceed the maximum number listed for permanent licenses.
Botnet Traffic Filter
Requires a Strong Encryption (3DES/AES) License to download the dynamic database.
Combined IPSec and SSL
VPN sessions
•
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 ASA, so be sure to size your network
appropriately.
•
If you start a clientless SSL VPN session and then start an AnyConnect client session from
the portal, 1 session is used in total. However, if you start the AnyConnect client first (from
a standalone client, for example) and then log into the clientless SSL VPN portal, then 2
sessions are used.
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Table 3-8
License Notes
License
Notes
Unified Communications
Proxy sessions
Phone Proxy, Mobility Advantage 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, so 2 UC Proxy sessions are used.
Note
VPN load balancing
In Version 8.2(2) and later, Mobility Advantage Proxy no longer requires the UC Proxy
license.
Requires a Strong Encryption (3DES/AES) License.
VPN License and Feature Compatibility
Table 3-9 shows how the VPN licenses and features can combine.
Table 3-9
VPN License and Feature Compatibility
Enable one of the following licenses: 1
Supported with:
AnyConnect Essentials
AnyConnect Premium SSL VPN
AnyConnect Mobile
Yes
Yes
Advanced Endpoint Assessment
No
Yes
AnyConnect Premium SSL VPN Shared No
Yes
Client-based SSL VPN
Yes
Yes
Browser-based (clientless) SSL VPN
No
Yes
IPsec VPN
Yes
Yes
VPN Load Balancing
Yes
Yes
Cisco Secure Desktop
No
Yes
1. You can only have one license type active, either the AnyConnect Essentials license or the AnyConnect Premium license. By
default, the ASA includes an AnyConnect Premium license for 2 sessions. If you install the AnyConnect Essentials license,
then it is used by default. See the no anyconnect-essentials command to enable the Premium license instead.
Information About Feature Licenses
A license specifies the options that are enabled on a given ASA. It is represented by an activation key
that 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 section includes the following topics:
•
Preinstalled License, page 3-11
•
Temporary, VPN Flex, and Evaluation Licenses, page 3-11
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•
Shared Licenses, page 3-13
•
Licenses FAQ, page 3-17
Preinstalled License
By default, your ASA 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 3-19 section to determine which licenses you have installed.
Temporary, VPN Flex, and Evaluation Licenses
In addition to permanent licenses, you can purchase a temporary 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, or you might order a Botnet Traffic Filter temporary license that
is valid for 1 year.
This section includes the following topics:
•
How the Temporary License Timer Works, page 3-11
•
How Multiple Licenses Interact, page 3-11
•
Failover and Temporary Licenses, page 3-13
How the Temporary License Timer Works
Note
•
The timer for the temporary license starts counting down when you activate it on the ASA.
•
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 ASA, then the timer continues to count
down. If you intend to leave the ASA 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 ASA, 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 ASA 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.
How Multiple Licenses Interact
•
When you activate a temporary license, then features from both permanent and temporary licenses
are merged to form the running license. Note that the ASA only uses the highest value from each
license for each feature; the values are not added together. The ASA displays any resolved conflicts
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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 you install a new permanent license, and it is a downgrade from the temporary license,
then you need to reload the ASA to disable the temporary license and restore the permanent
license. Until you reload, the temporary license continues to count down.
If you reactivate the already installed permanent license, you do not need to reload the ASA;
the temporary license does not continue to count down, and there is 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 ASA 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
3.
+
Base + 10 SSL conns
50 contexts
=
25 SSL conns
Base + 10 SSL conns
Merged Key
=
VPN Flex Key
Base + 10 SSL conns + +
50 contexts
Base + 25 SSL conns
Permanent Key
Evaluation Key
+
Merged Key
4.
=
Permanent Key
Permanent Key
Base + 10 SSL conns
25 SSL conns
Merged Key
Base + 10 SSL conns +
50 contexts
New Merged Key
=
Base + 25 SSL conns
251137
Figure 3-1
1.
In example 1 in the above figure, you apply a temporary key with 25 SSL sessions; because the VPN
Flex value is greater than the permanent key value of 10 sessions, the resulting running key is a
merged key that uses the VPN Flex value of 25 sessions, and not a combined total of 35 sessions.
2.
In example 2 above, the merged key from example 1 is replaced by the permanent key, and the VPN
Flex license is disabled. The running key defaults to the permanent key value of 10 sessions.
3.
In example 3 above, an evaluation license including 50 contexts is applied to the permanent key, so
the resulting running key is a merged key that includes all the features of the permanent key plus the
50 context license.
4.
In example 4 above, the merged key from example 3 has the VPN Flex key applied. Because the
ASA can only use one temporary key at a time, the VPN flex key replaces the evaluation key, so the
end result is the same as the merged key from example 1.
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Failover and Temporary Licenses
With failover, identical licenses are required. For failover purposes, temporary and permanent licenses
appear to be identical, so you can have a permanent license on one unit and a temporary license on the
other unit. This functionality is useful in an emergency situation; for example, if one of your units fails,
and you have an extra unit, you can install the extra unit while the other one is repaired. If you do not
normally use the extra unit for SSL VPN, then a VPN Flex license is a perfect solution while the other
unit is being repaired.
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 permanent failover installation; when the temporary
license expires, failover will no longer work.
Shared Licenses
A shared license lets you purchase a large number of SSL VPN sessions and share the sessions as needed
amongst a group of ASAs by configuring one of the ASAs as a shared licensing server, and the rest as
shared licensing participants. This section describes how a shared license works, and includes the
following topics:
•
Information About the Shared Licensing Server and Participants, page 3-13
•
Communication Issues Between Participant and Server, page 3-14
•
Information About the Shared Licensing Backup Server, page 3-14
•
Failover and Shared Licenses, page 3-15
•
Maximum Number of Participants, page 3-16
Information About the Shared Licensing Server and Participants
The following steps describe how shared licenses operate:
1.
Decide which ASA should be the shared licensing server, and purchase the shared licensing server
license using that device serial number.
2.
Decide which ASAs should be shared licensing participants, including the shared licensing backup
server, and obtain a shared licensing participant license for each device, using each device serial
number.
3.
(Optional) Designate a second ASA as a shared licensing backup server. You can only specify one
backup server.
Note
The shared licensing backup server only needs a participant license.
4.
Configure a shared secret on the shared licensing server; any participants with the shared secret can
use the shared license.
5.
When you configure the ASA as a participant, it registers with the shared licensing server by sending
information about itself, including the local license and model information.
Note
The participant needs to be able to communicate with the server over the IP network; it does
not have to be on the same subnet.
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6.
The shared licensing server responds with information about how often the participant should poll
the server.
7.
When a participant uses up the sessions of the local license, it sends a request to the shared licensing
server for additional sessions in 50-session increments.
8.
The shared licensing server responds with a shared license. The total sessions used by a participant
cannot exceed the maximum sessions for the platform model.
Note
The shared licensing server can also participate in the shared license pool. It does not need
a participant license as well as the server license to participate.
a. If there are not enough sessions left in the shared license pool for the participant, then the server
responds with as many sessions as available.
b. The participant continues to send refresh messages requesting more sessions until the server can
adequately fulfill the request.
9.
Note
When the load is reduced on a participant, it sends a message to the server to release the shared
sessions.
The ASA uses SSL between the server and participant to encrypt all communications.
Communication Issues Between Participant and Server
See the following guidelines for communication issues between the participant and server:
•
If a participant fails to send a refresh after 3 times the refresh interval, then the server releases the
sessions back into the shared license pool.
•
If the participant cannot reach the license server to send the refresh, then the participant can continue
to use the shared license it received from the server for up to 24 hours.
•
If the participant is still not able to communicate with a license server after 24 hours, then the
participant releases the shared license, even if it still needs the sessions. The participant leaves
existing connections established, but cannot accept new connections beyond the license limit.
•
If a participant reconnects with the server before 24 hours expires, but after the server expired the
participant sessions, then the participant needs to send a new request for the sessions; the server
responds with as many sessions as can be reassigned to that participant.
Information About the Shared Licensing Backup Server
The shared licensing backup server must register successfully with the main shared licensing server
before it can take on the backup role. When it registers, the main shared licensing server syncs server
settings as well as the shared license information with the backup, including a list of registered
participants and the current license usage. The main server and backup server sync the data at 10 second
intervals. After the initial sync, the backup server can successfully perform backup duties, even after a
reload.
When the main server goes down, the backup server takes over server operation. The backup server can
operate for up to 30 continuous days, after which the backup server stops issuing sessions to participants,
and existing sessions time out. Be sure to reinstate the main server within that 30-day period.
Critical-level syslog messages are sent at 15 days, and again at 30 days.
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When the main server comes back up, it syncs with the backup server, and then takes over server
operation.
When the backup server is not active, it acts as a regular participant of the main shared licensing server.
Note
When you first launch the main shared licensing server, the backup server can only operate
independently for 5 days. The operational limit increases day-by-day, until 30 days is reached. Also, if
the main server later goes down for any length of time, the backup server operational limit decrements
day-by-day. When the main server comes back up, the backup server starts to increment again
day-by-day. For example, if the main server is down for 20 days, with the backup server active during
that time, then the backup server will only have a 10-day limit left over. The backup server “recharges”
up to the maximum 30 days after 20 more days as an inactive backup. This recharging function is
implemented to discourage misuse of the shared license.
Failover and Shared Licenses
This section describes how shared licenses interact with failover, and includes the following topics:
•
“Failover and Shared License Servers” section on page 3-15
•
“Failover and Shared License Participants” section on page 3-16
Failover and Shared License Servers
This section describes how the main server and backup server interact with failover. Because the shared
licensing server is also performing normal duties as the ASA, including performing functions such as
being a VPN gateway and firewall, then you might need to configure failover for the main and backup
shared licensing servers for increased reliability.
Note
The backup server mechanism is separate from, but compatible with, failover.
Shared licenses are supported only in single context mode, so Active/Active failover is not supported.
Both main shared licensing server units in the failover pair need to have the same license. So if you
purchase a 10,000 session shared license for the primary main server unit, you must also purchase a
10,000 session shared license for the standby main server unit. Because the standby unit does not pass
traffic when it is in a standby state, the total number of sessions remains at 10,000 in this example, not
a combined 20,000 sessions.
For Active/Standby failover, the primary unit acts as the main shared licensing server, and the standby
unit acts as the main shared licensing server after failover; because both units need to have the same
license, both units can act as the main licensing server. The standby unit does not act as the backup
shared licensing server. Instead, you can have a second pair of units acting as the backup server, if
desired.
For example, you have a network with 2 failover pairs. Pair #1 includes the main licensing server. Pair
#2 includes the backup server. When the primary unit from Pair #1 goes down, the standby unit
immediately becomes the new main licensing server. The backup server from Pair #2 never gets used.
Only if both units in Pair #1 go down does the backup server in Pair #2 come into use as the shared
licensing server. If Pair #1 remains down, and the primary unit in Pair #2 goes down, then the standby
unit in Pair #2 comes into use as the shared licensing server (see Figure 3-2).
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Figure 3-2
Failover and Shared License Servers
Key
Blue=Shared license
server in use
Failover Pair #1
Failover Pair #2
(Active)=Active
failover unit
Main (Standby)
Failover Pair #1
2. Primary main Main (Failed)
server fails over:
Main (Active)
Failover Pair #1
3. Both main Main (Failed)
servers fail:
Main (Failed)
Failover Pair #1
4. Both main servers and Main (Failed)
primary backup fail:
Main (Failed)
Backup (Active)
Backup (Standby)
Failover Pair #2
Backup (Active)
Backup (Standby)
Failover Pair #2
Backup (Active)
Backup (Standby)
Failover Pair #2
Backup (Failed)
Backup (Active)
251356
1. Normal Main (Active)
operation:
The standby backup server shares the same operating limits as the primary backup server; if the standby
unit becomes active, it continues counting down where the primary unit left off. See the “Information
About the Shared Licensing Backup Server” section on page 3-14 for more information.
Failover and Shared License Participants
For participant pairs, both units register with the shared licensing server using separate participant IDs.
The active unit syncs its participant ID with the standby unit. The standby unit uses this ID to generate
a transfer request when it switches to the active role. This transfer request is used to move the shared
sessions from the previously active unit to the new active unit.
Maximum Number of Participants
The ASA does not limit the number of participants for the shared license; however, a very large shared
network could potentially affect the performance on the licensing server. In this case, you can increase
the delay between participant refreshes, or you can create two shared networks.
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Licenses FAQ
Q. Can I activate multiple temporary licenses, for example, VPN Flex and Botnet Traffic Filter?
A. No. You can only use one temporary license at a time. The last license you activate is the one in use.
In the case of evaluation licenses that group multiple features into one activation key, then multiple
features are supported at the same time. But temporary licenses for sale by Cisco are limited to one
feature per activation key.
Q. Can I “stack” temporary licenses so that when the time limit runs out, it will automatically use the
next license?
A. No. You can install multiple temporary licenses, but only the last activated license is active. When
the active license expires, you need to manually activate the new one. Be sure to activate it shortly
before the old one expires so you do not lose functionality. (Any remaining time on the old license
remains unused; for example, if you use 10 months of a 12-month license, and activate a new
12-month license, then the remaining 2 months of the first license goes unused unless you later
reactivate it. We recommend that you activate the new license as close as possible to the end of the
old license to maximize the license usage.)
Q. Can I install a new permanent license while maintaining an active temporary license?
A. No. The temporary license will be deactivated when you apply a permanent license. You have to
activate the permanent license, and then reactivate the temporary license to be able to use the new
permanent license along with the temporary license. This will cause temporary loss of functionality
for the features reliant on the temporary license.
Q. For failover, can I use a shared licensing server as the primary unit, and the shared licensing backup
server as the secondary unit?
A. No. The secondary unit must also have a shared licensing server license. The backup server, which
has a participant license, can be in a separate failover pair of two backup servers.
Q. Do I need to buy the same licenses for the secondary unit in a failover pair? Even for a shared
licensing server?
A. Yes. Both units need the same licenses. For a shared licensing server, you need to buy the same
shared licensing server license for both units. Note: In Active/Standby failover, for licenses that
specify the number of sessions, the sessions for both units are not added to each other; only the
active unit sessions can be used. For example, for a shared SSL VPN license, you need to purchase
a 10,000 user session for both the active and the standby unit; the total number of sessions is 10,000,
not 20,000 combined.
Q. Can I use a VPN Flex or permanent SSL VPN license in addition to a shared SSL VPN license?
A. Yes. The shared license is used only after the sessions from the locally installed license (VPN Flex
or permanent) are used up. Note: On the shared licensing server, the permanent SSL VPN license is
not used; you can however use a VPN Flex license at the same time as the shared licensing server
license. In this case, the VPN Flex license sessions are available for local SSL VPN sessions only;
they cannot be added to the shared licensing pool for use by participants.
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Guidelines and Limitations
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.
•
Shared licenses are not supported in multiple context mode.
Firewall Mode Guidelines
All license types are available in both routed and transparent mode.
Failover Guidelines
•
You must have the same licenses activated on the primary and secondary units.
Note
•
For failover purposes, there is no distinction between permanent and temporary licenses as
long as the feature set is the same between the two units. See the “Failover and Temporary
Licenses” section on page 3-13 for more information.
Shared licenses are not supported in Active/Active mode. See the “Failover and Shared Licenses”
section on page 3-15 for more information.
Upgrade Guidelines
Your activation key remains compatible if you upgrade to Version 8.2 or later, and also if you later
downgrade. After you upgrade, if you activate additional feature licenses that were introduced before
8.2, then the activation key continues to be compatible with earlier versions if you downgrade. However
if you activate feature licenses that were introduced in 8.2 or later, then the activation key is not
backwards compatible. If you have an incompatible license key, then see the following guidelines:
•
If you previously entered an activation key in an earlier version, then the ASA uses that key (without
any of the new licenses you activated in Version 8.2 or later).
•
If you have a new system and do not have an earlier activation key, then you need to request a new
activation key compatible with the earlier version.
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. (You may be able to purchase a larger license at an upgrade
price, for example from 25 sessions to 75 sessions; this kind of upgrade should be distinguished
from adding two separate licenses together).
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Viewing Your Current License
•
Although you can activate all license types, some features are incompatible with each other; for
example, multiple context mode and VPN. In the case of the AnyConnect Essentials license, the
license is incompatible with the following licenses: full SSL VPN license, shared SSL VPN license,
and Advanced Endpoint Assessment license. By default, the AnyConnect Essentials license is used
instead of the above licenses, but you can disable the AnyConnect Essentials license in the
configuration to restore use of the other licenses using the no anyconnect-essentials command.
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.
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 with 2 SSL VPN peers (in bold), an active temporary license with 5000 SSL VPN peers
(in bold), the merged running license with the SSL VPN peers taken from the temporary license (in
bold), 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
: 2
SSL VPN Peers
: 2
Total VPN Peers
: 250
Shared License
: Enabled
Shared SSL VPN Peers
: 5000
AnyConnect for Mobile
: Disabled
AnyConnect for Linksys phone : Disabled
AnyConnect Essentials
: Disabled
Advanced Endpoint Assessment : Disabled
UC Phone Proxy Sessions
: 24
Total UC Proxy Sessions
: 24
Botnet Traffic Filter
: Enabled
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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
: Enabled
Security Contexts
: 2
GTP/GPRS
: Disabled
SSL VPN Peers
: 5000
Total VPN Peers
: 250
Shared License
: Enabled
Shared SSL VPN Peers
: 10000
AnyConnect for Mobile
: Disabled
AnyConnect for Linksys phone : Disabled
AnyConnect Essentials
: Disabled
Advanced Endpoint Assessment : Disabled
UC Phone Proxy Sessions
: 24
Total UC Proxy Sessions
: 24
Botnet Traffic Filter
: Enabled
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
Inside Hosts
: Unlimited
Failover
: Active/Active
VPN-DES
: Enabled
VPN-3DES-AES
: Enabled
Security Contexts
: 2
GTP/GPRS
: Disabled
SSL VPN Peers
: 5000
Total VPN Peers
: 250
Shared License
: Enabled
Shared SSL VPN Peers
: 10000
AnyConnect for Mobile
: Disabled
AnyConnect for Linksys phone : Disabled
AnyConnect Essentials
: Disabled
Advanced Endpoint Assessment : Disabled
UC Phone Proxy Sessions
: 24
Total UC Proxy Sessions
: 24
Botnet Traffic Filter
: Enabled
This platform has an ASA 5540 VPN Premium license.
This is a Shared SSL VPN License server.
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)
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Obtaining an Activation Key
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 ASA by entering the following command.
hostname# show activation-key
Step 2
If you are not already registered with Cisco.com, create an account.
Step 3
Go to the following licensing website:
http://www.cisco.com/go/license
Step 4
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 ASA
•
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 5
If you have additional Product Authorization Keys, repeat Step 4 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
This section describes how to enter a new activation key.
Prerequisites
•
Before entering the activation key, ensure that the image in Flash memory and the running image are
the same by entering the show activation-key command. You can do this by reloading the ASA
before entering the new activation key.
•
If you are already in multiple context mode, enter the activation key in the system execution space.
•
Some licenses require you to reload the ASA after you activate them. Table 3-10 lists the licenses
that require reloading.
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Managing Feature Licenses
Entering a New Activation Key
Table 3-10
License Reloading Requirements
Model
License Action Requiring Reload
ASA 5505 and ASA 5510
Changing between the Base and Security Plus
license.
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
ASA; the next time you reload, the
permanent license is restored.
Limitations and Restrictions
Your activation key remains compatible if you upgrade to Version 8.2 or later, and also if you later
downgrade. After you upgrade, if you activate additional feature licenses that were introduced before
8.2, then the activation key continues to be compatible with earlier versions if you downgrade. However
if you activate feature licenses that were introduced in 8.2 or later, then the activation key is not
backwards compatible. If you have an incompatible license key, then see the following guidelines:
•
If you previously entered an activation key in an earlier version, then the ASA uses that key (without
any of the new licenses you activated in Version 8.2 or later).
•
If you have a new system and do not have an earlier activation key, then you need to request a new
activation key compatible with the earlier version.
Detailed Steps
Step 1
Command
Purpose
activation-key key
Applies an activation key to the ASA. 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# activation-key 0xd11b3d48
0xa80a4c0a 0x48e0fd1c 0xb0443480
0x843fc490
Step 2
reload
Example:
hostname# reload
You can enter one permanent key, and multiple temporary keys.
The last temporary key entered is the active one. See the
“Temporary, VPN Flex, and Evaluation Licenses” section on
page 3-11 for more information. To change the running activation
key, enter the activation-key command with a new key value.
(Might be required.) Reloads the ASA. Some licenses require you
to reload the ASA after entering the new activation key. See
Table 3-10 on page 3-22 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.
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Managing Feature Licenses
Upgrading the License for a Failover Pair
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 3-10 on page 3-22 for more information
about licenses requiring a reload. This section includes the following topics:
•
Upgrading the License for a Failover (No Reload Required), page 3-23
•
Upgrading the License for a Failover (Reload Required), page 3-24
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 3-10 on
page 3-22 for more information about licenses requiring a reload. This procedure ensures that there is
no downtime.
Prerequisites
Before you upgrade the license, be sure that both units are operating correctly, the Failover LAN
interface is up, and there is not an imminent failover event; for example, monitored interfaces are
operating normally.
On each unit, enter the show failover command to view the failover status and the monitored interface
status.
Detailed Steps
Command
Purpose
On the active unit:
Step 1
no failover
Example:
active(config)# no failover
Step 2
activation-key key
Example:
active(config)# activation-key 0xd11b3d48
0xa80a4c0a 0x48e0fd1c 0xb0443480
0x843fc490
Disables failover on the active unit. The standby unit remains in a
pseudo-standby state. Deactivating failover on the active unit
prevents the standby unit from attempting to become active during
the period when the licenses do not match.
Installs the new license on the active unit. Make sure this license
is for the active unit serial number.
On the standby unit:
Step 3
activation-key key
Example:
standby# activation-key 0xc125727f
0x903de1ee 0x8c838928 0x92dc84d4
0x003a2ba0
Installs the new license on the standby unit. Make sure this license
is for the standby unit serial number.
On the active unit:
Step 4
failover
Reenables failover.
Example:
active(config)# failover
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Upgrading the License for a Failover Pair
Upgrading the License for a Failover (Reload Required)
Use the following procedure if your new license requires you to reload. See Table 3-10 on page 3-22 for
more information about licenses requiring a reload. Reloading the failover pair causes a loss of
connectivity during the reload.
Prerequisites
Before you upgrade the license, be sure that both units are operating correctly, the Failover LAN
interface is up, and there is not an imminent failover event; for example, monitored interfaces are
operating normally.
On each unit, enter the show failover command to view the failover status and the monitored interface
status.
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 a
pseudo-standby state. Deactivating failover on the active unit
prevents the standby unit from attempting to become active during
the period when the licenses do not match.
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 3-23 instead of this procedure.
On the standby unit:
Step 3
activation-key key
Installs the new license on the standby unit.
Example:
standby# activation-key 0xc125727f
0x903de1ee 0x8c838928 0x92dc84d4
0x003a2ba0
Step 4
reload
Reloads the standby unit.
Example:
standby# reload
On the active unit:
Step 5
reload
Example:
active(config)# reload
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.
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Chapter 3
Managing Feature Licenses
Configuring a Shared License
Configuring a Shared License
This section describes how to configure the shared licensing server and participants. For more
information about shared licenses, see the “Shared Licenses” section on page 3-13.
This section includes the following topics:
•
Configuring the Shared Licensing Server, page 3-25
•
Configuring the Shared Licensing Backup Server (Optional), page 3-26
•
Configuring the Shared Licensing Participant, page 3-27
•
Monitoring the Shared License, page 3-28
Configuring the Shared Licensing Server
This section describes how to configure the ASA to be a shared licensing server.
Prerequisites
The server must have a shared licensing server key.
Detailed Steps
Step 1
Command
Purpose
license-server secret secret
Sets the shared secret, a string between 4 and 128 ASCII
characters. Any participant with this secret can use the licensing
server.
Example:
hostname(config)# license-server secret
farscape
Step 2
(Optional)
license-server refresh-interval seconds
Sets the refresh interval between 10 and 300 seconds; this value
is provided to participants to set how often they should
communicate with the server. The default is 30 seconds.
Example:
hostname(config)# license-server
refresh-interval 100
Step 3
(Optional)
license-server port port
Sets the port on which the server listens for SSL connections from
participants, between 1 and 65535. The default is TCP port
50554.
Example:
hostname(config)# license-server port
40000
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Configuring a Shared License
Step 4
Command
Purpose
(Optional)
Identifies the backup server IP address and serial number. If the
backup server is part of a failover pair, identify the standby unit
serial number as well. You can only identify 1 backup server and
its optional standby unit.
license-server backup address backup-id
serial_number [ha-backup-id
ha_serial_number]
Example:
hostname(config)# license-server backup
10.1.1.2 backup-id JMX0916L0Z4
ha-backup-id JMX1378N0W3
Step 5
license-server enable interface_name
Example:
hostname(config)# license-server enable
inside
Enables this unit to be the shared licensing server. Specify the
interface on which participants contact the server. You can repeat
this command for as many interfaces as desired.
Examples
The following example sets the shared secret, changes the refresh interval and port, configures a backup
server, and enables this unit as the shared licensing server on the inside interface and dmz interface.
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
JMX1378N0W3
hostname(config)#
hostname(config)#
license-server
license-server
license-server
license-server
secret farscape
refresh-interval 100
port 40000
backup 10.1.1.2 backup-id JMX0916L0Z4 ha-backup-id
license-server enable inside
license-server enable dmz
What to Do Next
See the “Configuring the Shared Licensing Backup Server (Optional)” section on page 3-26 , or the
“Configuring the Shared Licensing Participant” section on page 3-27.
Configuring the Shared Licensing Backup Server (Optional)
This section enables a shared license participant to act as the backup server if the main server goes down.
Prerequisites
The backup server must have a shared licensing participant key.
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Detailed Steps
Step 1
Command
Purpose
license-server address address secret
secret [port port]
Identifies the shared licensing server IP address and shared secret.
If you changed the default port in the server configuration, set the
port for the backup server to match.
Example:
hostname(config)# license-server address
10.1.1.1 secret farscape
Step 2
license-server backup enable
interface_name
Example:
hostname(config)# license-server backup
enable inside
Enables this unit to be the shared licensing backup server. Specify
the interface on which participants contact the server. You can
repeat this command for as many interfaces as desired.
Examples
The following example identifies the license server and shared secret, and enables this unit as the backup
shared license server on the inside interface and dmz interface.
hostname(config)# license-server address 10.1.1.1 secret farscape
hostname(config)# license-server backup enable inside
hostname(config)# license-server backup enable dmz
What to Do Next
See the “Configuring the Shared Licensing Participant” section on page 3-27.
Configuring the Shared Licensing Participant
This section configures a shared licensing participant to communicate with the shared licensing server .
Prerequisites
The participant must have a shared licensing participant key.
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Configuring a Shared License
Detailed Steps
Step 1
Command
Purpose
license-server address address secret
secret [port port]
Identifies the shared licensing server IP address and shared secret.
If you changed the default port in the server configuration, set the
port for the participant to match.
Example:
hostname(config)# license-server address
10.1.1.1 secret farscape
Step 2
(Optional)
If you configured a backup server, enter the backup server
address.
license-server backup address address
Example:
hostname(config)# license-server backup
address 10.1.1.2
Examples
The following example sets the license server IP address and shared secret, as well as the backup license
server IP address:
hostname(config)# license-server address 10.1.1.1 secret farscape
hostname(config)# license-server backup address 10.1.1.2
Monitoring the Shared License
To monitor the shared license, enter one of the following commands.
Command
Purpose
show shared license [detail | client
[hostname] | backup]
Shows shared license statistics. Optional keywords ar available only for
the licensing server: the detail keyword shows statistics per participant.
To limit the display to one participant, use the client keyword. The
backup keyword shows information about the backup server.
To clear the shared license statistics, enter the clear shared license
command.
show activation-key
Shows the licenses installed on the ASA. The show version command
also shows license information.
show vpn-sessiondb
Shows license information about VPN sessions.
Examples
The following is sample output from the show shared license command on the license participant:
hostname> show shared license
Primary License Server : 10.3.32.20
Version
: 1
Status
: Inactive
Shared license utilization:
SSLVPN:
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Configuring a Shared License
Total for network :
Available
:
Utilized
:
This device:
Platform limit
:
Current usage
:
High usage
:
Messages Tx/Rx/Error:
Registration
: 0
Get
: 0
Release
: 0
Transfer
: 0
5000
5000
0
250
0
0
/
/
/
/
0
0
0
0
/
/
/
/
0
0
0
0
The following is sample output from the show shared license detail command on the license server:
hostname> show shared license detail
Backup License Server Info:
Device ID
: ABCD
Address
: 10.1.1.2
Registered
: NO
HA peer ID
: EFGH
Registered
: NO
Messages Tx/Rx/Error:
Hello
: 0 / 0 / 0
Sync
: 0 / 0 / 0
Update
: 0 / 0 / 0
Shared license utilization:
SSLVPN:
Total for network :
Available
:
Utilized
:
This device:
Platform limit
:
Current usage
:
High usage
:
Messages Tx/Rx/Error:
Registration
: 0 / 0
Get
: 0 / 0
Release
: 0 / 0
Transfer
: 0 / 0
500
500
0
250
0
0
/
/
/
/
0
0
0
0
Client Info:
Hostname
: 5540-A
Device ID
: XXXXXXXXXXX
SSLVPN:
Current usage
: 0
High
: 0
Messages Tx/Rx/Error:
Registration
: 1 / 1 / 0
Get
: 0 / 0 / 0
Release
: 0 / 0 / 0
Transfer
: 0 / 0 / 0
...
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Feature History for Licensing
Feature History for Licensing
Table 3-11 lists the release history for this feature.
Table 3-11
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
7.1(1)
SSL VPN licenses were introduced.
Increased SSL VPN Licenses
7.2(1)
A 5000-user SSL VPN license was introduced for the ASA
5550 and above.
Increased interfaces for the Base license on the 7.2(2)
ASA 5510
For the Base license on the ASA 5510, the maximum
number of interfaces was increased from 3 plus a
management interface to unlimited interfaces.
Increased VLANs
The maximum number of VLANs for the Security Plus
license on the ASA 5505 ASA 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.
7.2(2)
VLAN limits were also increased for the ASA 5510 ASA
(from 10 to 50 for the Base license, and from 25 to 100 for
the Security Plus license), the ASA 5520 adaptive security
appliance (from 100 to 150), the ASA 5550 adaptive
security appliance (from 200 to 250).
Gigabit Ethernet Support for the ASA 5510
Security Plus License
7.2(3)
The ASA 5510 ASA now supports Gigabit Ethernet (1000
Mbps) for the Ethernet 0/0 and 0/1 ports with the Security
Plus license. In the Base license, they continue to be used as
Fast Ethernet (100 Mbps) ports. Ethernet 0/2, 0/3, and 0/4
remain as Fast Ethernet ports for both licenses.
Note
The interface names 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.
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Feature History for Licensing
Table 3-11
Feature History for Licensing (continued)
Feature Name
Releases
Feature Information
Advanced Endpoint Assessment License
8.0(2)
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 ASA 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.
VPN Load Balancing for the ASA 5510
8.0(2)
VPN load balancing is now supported on the ASA 5510
Security Plus license.
AnyConnect for Mobile License
8.0(3)
The AnyConnect for Mobile license lets Windows mobile
devices connect to the ASA using the AnyConnect client.
VPN Flex and Evaluation Licenses
8.0(4)/8.1(2)
Support for temporary licenses was introduced. VPN Flex
licenses provide temporary support for extra SSL VPN
sessions.
Increased VLANs for the ASA 5580
8.1(2)
The number of VLANs supported on the ASA 5580 are
increased from 100 to 250.
Unified Communications Proxy Sessions
license
8.0(4)
The UC Proxy sessions license was introduced. This feature
is not available in Version 8.1.
Botnet Traffic Filter License
8.2(1)
The Botnet Traffic Filter license was introduced. The
Botnet Traffic Filter protects against malware network
activity by tracking connections to known bad domains and
IP addresses.
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Feature History for Licensing
Table 3-11
Feature History for Licensing (continued)
Feature Name
Releases
Feature Information
AnyConnect Essentials License
8.2(1)
This license enables AnyConnect VPN client access to the
adaptive security appliance. This license does not support
browser-based SSL VPN access or Cisco Secure Desktop.
For these features, activate an AnyConnect Premium SSL
VPN license instead of the AnyConnect Essentials license.
Note
With the AnyConnect Essentials license, VPN users
can use a Web browser to log in, and download and
start (WebLaunch) the AnyConnect client.
The AnyConnect client software offers the same set of
client features, whether it is enabled by this license or an
AnyConnect Premium SSL VPN license.
The AnyConnect Essentials license cannot be active at the
same time as the following licenses on a given adaptive
security appliance: AnyConnect Premium SSL VPN license
(all types) or the Advanced Endpoint Assessment license.
You can, however, run AnyConnect Essentials and
AnyConnect Premium SSL VPN licenses on different
adaptive security appliances in the same network.
By default, the ASA uses the AnyConnect Essentials
license, but you can disable it to use other licenses by using
the no anyconnect-essentials command.
Shared Licenses for SSL VPN
8.2(1)
Shared licenses for SSL VPN were introduced. Multiple
ASAs can share a pool of SSL VPN sessions on an
as-needed basis.
Mobility Proxy application no longer requires
Unified Communications Proxy license
8.2(2)
The Mobility Proxy no longer requires the UC Proxy
license.
10 GE I/O license for the ASA 5585-X with
SSP-20
8.2(3)
We introduced the 10 GE I/O license for the ASA 5585-X
with SSP-20 to enable 10-Gigabit Ethernet speeds for the
fiber ports. The SSP-60 supports 10-Gigabit Ethernet
speeds by default.
10 GE I/O license for the ASA 5585-X with
SSP-10
8.2(4)
We introduced the 10 GE I/O license for the ASA 5585-X
with SSP-10 to enable 10-Gigabit Ethernet speeds for the
fiber ports. The SSP-40 supports 10-Gigabit Ethernet
speeds by default.
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CH A P T E R
4
Configuring the Transparent or Routed Firewall
This chapter describes how to configure the firewall mode, routed or transparent, and how to customize
transparent firewall operation.
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 ASA.
This chapter includes the following sections:
•
Configuring the Firewall Mode, page 4-1
•
Configuring ARP Inspection for the Transparent Firewall, page 4-8
•
Customizing the MAC Address Table for the Transparent Firewall, page 4-11
•
Firewall Mode Examples, page 4-15
Configuring the Firewall Mode
This section describes routed and transparent firewall mode, and how to set the mode. This section
includes the following topics:
•
Information About the Firewall Mode, page 4-1
•
Licensing Requirements for the Firewall Mode, page 4-4
•
Default Settings, page 4-4
•
Guidelines and Limitations, page 4-5
•
Setting the Firewall Mode, page 4-7
•
Feature History for Firewall Mode, page 4-8
Information About the Firewall Mode
This section describes routed and transparent firewall mode, and includes the following topics:
•
Information About Routed Firewall Mode, page 4-2
•
Information About Transparent Firewall Mode, page 4-2
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Configuring the Transparent or Routed Firewall
Configuring the Firewall Mode
Information About Routed Firewall Mode
In routed mode, the ASA 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.
The ASA 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, EIGRP, 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 ASA for extensive routing needs.
Information About Transparent Firewall Mode
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 4-2
•
Allowing Layer 3 Traffic, page 4-2
•
Allowed MAC Addresses, page 4-2
•
Passing Traffic Not Allowed in Routed Mode, page 4-3
•
BPDU Handling, page 4-3
•
MAC Address vs. Route Lookups, page 4-3
•
Using the Transparent Firewall in Your Network, page 4-4
Transparent Firewall Network
The ASA 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 and IPv6 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 Chapter 11, “Adding an Extended Access List,” or Chapter 15, “Adding
an IPv6 Access List,” 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
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Configuring the Transparent or Routed Firewall
Configuring the Firewall Mode
•
Appletalk multicast MAC addresses from 0900.0700.0000 to 0900.07FF.FFFF
Passing Traffic Not Allowed in Routed Mode
In routed mode, some types of traffic cannot pass through the ASA 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 ASA does not pass CDP packets 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 ASA.
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.
BPDU Handling
To prevent loops using the spanning tree protocol, BPDUs are passed by default. To block BPDUs, you
need to configure an EtherType access list to deny them. If you are using failover, you might want to
block BPDUs to prevent the switch port from going into a blocking state when the topology changes.
See the “Transparent Firewall Mode Requirements” section on page 32-11 for more information.
MAC Address vs. Route Lookups
When the ASA runs in transparent mode, the outgoing interface of a packet is determined by performing
a MAC address lookup instead of a route lookup.
Route lookups, however, are necessary for the following traffic types:
•
Traffic originating on the ASA—For example, if your syslog server is located on a remote network,
you must use a static route so the ASA can reach that subnet.
•
Voice over IP (VoIP) traffic with inspection enabled, and the endpoint is at least one hop away from
the ASA—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 ASA for the H.323 gateway for successful call completion.
•
VoIP or DNS traffic with NAT and inspection enabled—To successfully translate the IP address
inside VoIP and DNS packets, the ASA needs to perform a route lookup. Unless the host is on a
directly-connected network, then you need to add a static route on the ASA for the real host address
that is embedded in the packet.
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Using the Transparent Firewall in Your Network
Figure 4-1 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 4-1
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
Licensing Requirements for the Firewall Mode
The following table shows the licensing requirements for this feature.
Model
License Requirement
All models
Base License.
Default Settings
The default mode is routed mode.
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Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
•
The firewall mode is set for the entire system and all contexts; you cannot set the mode individually
for each context.
•
For multiple context mode, set the mode in the system execution space.
•
When you change modes, the ASA clears the running configuration because many commands are
not supported for both modes. 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 might 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.
Transparent Firewall Guidelines
Follow these guidelines when planning your transparent firewall network:
•
For IPv4, a management IP address is required for both management traffic and for traffic to pass
through the ASA. 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 ASA uses this IP address as the source address for
packets originating on the ASA, 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).
For IPv6, at a minimum you need to configure link-local addresses for each interface for through
traffic. For full functionality, including the ability to manage the ASA, you need to configure a
global IP address for the device.
You can configure an IP address (both IPv4 and IPv6) for the Management 0/0 or Management 0/1
management-only interface. This IP address can be on a separate subnet from the main management
IP address.
•
The transparent ASA 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.
Note
•
In transparent firewall mode, the management interface updates the MAC address table in
the same manner as a data interface; therefore you should not connect both a management
and a data interface to the same switch unless you configure one of the switch ports as a
routed port (by default Cisco Catalyst switches share a MAC address for all VLAN switch
ports). Otherwise, if traffic arrives on the management interface from the
physically-connected switch, then the ASA updates the MAC address table to use the
management interface to access the switch, instead of the data interface. This action causes
a temporary traffic interruption; the ASA will not re-update the MAC address table for
packets from the switch to the data interface for at least 30 seconds for security reasons.
Each directly connected network must be on the same subnet.
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•
Do not specify the ASA management IP address as the default gateway for connected devices;
devices need to specify the router on the other side of the ASA 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.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
•
When you change modes, the ASA clears the running configuration because many commands are
not supported for both modes. The startup configuration remains unchanged. If you reload without
saving, then the startup configuration is loaded, and the mode reverts back to the original setting.
See the “Setting the Firewall Mode” section on page 4-7 for information about backing up your
configuration file.
•
If you download a text configuration to the ASA that changes the mode with the
firewall transparent command, be sure to put the command at the top of the configuration; the ASA
changes the mode as soon as it reads the command and then continues reading the configuration you
downloaded. If the command appears later in the configuration, the ASA clears all the preceding
lines in the configuration. See the “Downloading Software or Configuration Files to Flash Memory”
section on page 78-2 for information about downloading text files.
Unsupported Features in Transparent Mode
Table 4-1 lists the features are not supported in transparent mode.
Table 4-1
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 ASA.
You can also allow dynamic routing protocols through the ASA using
an extended access list.
Multicast IP routing
You can allow multicast traffic through the ASA by allowing it in an
extended access list.
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Table 4-1
Unsupported Features in Transparent Mode
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 ASA. You can pass VPN traffic through the
security appliance using an extended access list, but it does not
terminate non-management connections. SSL VPN is also not
supported.
Setting the Firewall Mode
This section describes how to change the firewall mode.
Note
We recommend that you set the firewall mode before you perform any other configuration because
changing the firewall mode clears the running configuration.
Prerequisites
When you change modes, the ASA clears the running configuration (see the “Guidelines and
Limitations” section on page 4-5 for more information).
•
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 78-7.
•
Use the CLI at the console port to change the mode. If you use any other type of session, including
the ASDM Command Line Interface tool or SSH, you will be disconnected when the configuration
is cleared, and you will have to reconnect to the ASA using the console port in any case.
Detailed Steps
Command
Purpose
firewall transparent
Sets the firewall mode to transparent. Enter this command in the system
execution space for multiple context mode. To change the mode to routed,
enter the no firewall transparent command.
Example:
hostname(config)# firewall transparent
This command also appears in each context configuration for informational
purposes only; you cannot enter this command in a context.
Note
You are not prompted to confirm the firewall mode change; the
change occurs immediately.
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Configuring ARP Inspection for the Transparent Firewall
Feature History for Firewall Mode
Table 4-2 lists the release history for this feature.
Table 4-2
Feature History for Firewall Mode
Feature Name
Transparent firewall mode
Releases
Feature Information
7.0(1)
A transparent firewall 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.
The following commands were introduced: firewall
transparent, show firewall.
Configuring ARP Inspection for the Transparent Firewall
This section describes ARP inspection and how to enable it, and includes the following topics:
•
Information About ARP Inspection, page 4-8
•
Licensing Requirements for ARP Inspection, page 4-9
•
Default Settings, page 4-9
•
Guidelines and Limitations, page 4-9
•
Configuring ARP Inspection, page 4-9
•
Monitoring ARP Inspection, page 4-11
•
Feature History for ARP Inspection, page 4-11
Information About ARP Inspection
By default, all ARP packets are allowed through the ASA. You can control the flow of ARP packets by
enabling ARP inspection.
When you enable ARP inspection, the ASA compares the MAC address, IP address, and source interface
in all ARP packets to static entries in the ARP table, and takes the following actions:
•
If the IP address, MAC address, and source interface match an ARP entry, the packet is passed
through.
•
If there is a mismatch between the MAC address, the IP address, or the interface, then the ASA drops
the packet.
•
If the ARP packet does not match any entries in the static ARP table, then you can set the ASA to
either forward the packet out all interfaces (flood), or to drop the packet.
Note
The dedicated management interface, if present, never floods packets even if this parameter
is set to flood.
ARP inspection prevents malicious users from impersonating other hosts or routers (known as ARP
spoofing). ARP spoofing can enable a “man-in-the-middle” attack. For example, a host sends an
ARP request to the gateway router; the gateway router responds with the gateway router MAC address.
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The attacker, however, sends another ARP response to the host with the attacker MAC address instead
of the router MAC address. The attacker can now intercept all the host traffic before forwarding it on to
the router.
ARP inspection ensures that an attacker cannot send an ARP response with the attacker MAC address,
so long as the correct MAC address and the associated IP address are in the static ARP table.
Licensing Requirements for ARP Inspection
The following table shows the licensing requirements for this feature.
Model
License Requirement
All models
Base License.
Default Settings
By default, all ARP packets are allowed through the ASA.
If you enable ARP inspection, the default setting is to flood non-matching packets.
Guidelines and Limitations
Context Mode Guidelines
•
Supported in single and multiple context mode.
•
In multiple context mode, configure ARP inspection within each context.
Firewall Mode Guidelines
Supported only in transparent firewall mode. Routed mode is not supported.
Configuring ARP Inspection
This section describes how to configure ARP inspection, and includes the following topics:
•
Task Flow for Configuring ARP Inspection, page 4-9
•
Adding a Static ARP Entry, page 4-10
•
Enabling ARP Inspection, page 4-10
Task Flow for Configuring ARP Inspection
Follow these steps to configure ARP Inspection:
Step 1
Add static ARP entries according to the “Adding a Static ARP Entry” section on page 4-10. ARP
inspection compares ARP packets with static ARP entries in the ARP table, so static ARP entries are
required for this feature.
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Step 2
Enable ARP inspection according to the “Enabling ARP Inspection” section on page 4-10.
Adding a Static ARP Entry
ARP inspection compares ARP packets with static ARP entries in the ARP table. Although hosts identify
a packet destination by an IP address, the actual delivery of the packet on Ethernet relies on the Ethernet
MAC address. When a router or host wants to deliver a packet on a directly connected network, it sends
an ARP request asking for the MAC address associated with the IP address, and then delivers the packet
to the MAC address according to the ARP response. The host or router keeps an ARP table so it does not
have to send ARP requests for every packet it needs to deliver. The ARP table is dynamically updated
whenever ARP responses are sent on the network, and if an entry is not used for a period of time, it times
out. If an entry is incorrect (for example, the MAC address changes for a given IP address), the entry
times out before it can be updated.
Note
The transparent firewall uses dynamic ARP entries in the ARP table for traffic to and from the ASA,
such as management traffic.
Detailed Steps
Command
Purpose
arp interface_name ip_address mac_address
Adds a static ARP entry.
Example:
hostname(config)# arp outside 10.1.1.1
0009.7cbe.2100
Examples
For example, to allow ARP responses from the router at 10.1.1.1 with the MAC address 0009.7cbe.2100
on the outside interface, enter the following command:
hostname(config)# arp outside 10.1.1.1 0009.7cbe.2100
What to Do Next
Enable ARP inspection according to the “Enabling ARP Inspection” section on page 4-10.
Enabling ARP Inspection
This section describes how to enable ARP inspection.
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Detailed Steps
Command
Purpose
arp-inspection interface_name enable
[flood | no-flood]
Enables ARP inspection.
Example:
hostname(config)# arp-inspection outside
enable no-flood
The flood keyword forwards non-matching ARP packets out all interfaces,
and no-flood drops non-matching packets.
Note
The default setting is to flood non-matching packets. To restrict
ARP through the ASA to only static entries, then set this command
to no-flood.
Examples
For example, to enable ARP inspection on the outside interface, and to drop all non-matching ARP
packets, enter the following command:
hostname(config)# arp-inspection outside enable no-flood
Monitoring ARP Inspection
To monitor ARP inspection, perform the following task:
Command
Purpose
show arp-inspection
Shows the current settings for ARP inspection on all interfaces.
Feature History for ARP Inspection
Table 4-2 lists the release history for this feature.
Table 4-3
Feature History for ARP Inspection
Feature Name
ARP inspection
Releases
Feature Information
7.0(1)
ARP inspection compares the MAC address, IP address, and
source interface in all ARP packets to static entries in the
ARP table.
The following commands were introduced: arp,
arp-inspection, and show arp-inspection.
Customizing the MAC Address Table for the Transparent
Firewall
This section describes the MAC address table, and includes the following topics:
•
Information About the MAC Address Table, page 4-12
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•
Licensing Requirements for the MAC Address Table, page 4-12
•
Default Settings, page 4-12
•
Guidelines and Limitations, page 4-13
•
Configuring the MAC Address Table, page 4-13
•
Monitoring the MAC Address Table, page 4-14
•
Feature History for the MAC Address Table, page 4-15
Information About the MAC Address Table
The ASA learns and builds a MAC address table in a similar way as a normal bridge or switch: when a
device sends a packet through the ASA, the ASA adds the MAC address to its table. The table associates
the MAC address with the source interface so that the ASA knows to send any packets addressed to the
device out the correct interface.
The ASA 5505 adaptive security appliance includes a built-in switch; the switch MAC address table
maintains the MAC address-to-switch port mapping for traffic within each VLAN. This section discusses
the bridge MAC address table, which maintains the MAC address-to-VLAN interface mapping for traffic
that passes between VLANs.
Because the ASA is a firewall, if the destination MAC address of a packet is not in the table, the ASA
does not flood the original packet on all interfaces as a normal bridge does. Instead, it generates the
following packets for directly connected devices or for remote devices:
•
Packets for directly connected devices—The ASA generates an ARP request for the destination IP
address, so that the ASA can learn which interface receives the ARP response.
•
Packets for remote devices—The ASA generates a ping to the destination IP address so that the ASA
can learn which interface receives the ping reply.
The original packet is dropped.
Licensing Requirements for the MAC Address Table
The following table shows the licensing requirements for this feature.
Model
License Requirement
All models
Base License.
Default Settings
The default timeout value for dynamic MAC address table entries is 5 minutes.
By default, each interface automatically learns the MAC addresses of entering traffic, and the ASA adds
corresponding entries to the MAC address table.
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Guidelines and Limitations
Context Mode Guidelines
•
Supported in single and multiple context mode.
•
In multiple context mode, configure the MAC address table within each context.
Firewall Mode Guidelines
Supported only in transparent firewall mode. Routed mode is not supported.
Additional Guidelines
In transparent firewall mode, the management interface updates the MAC address table in the same
manner as a data interface; therefore you should not connect both a management and a data interface to
the same switch unless you configure one of the switch ports as a routed port (by default Cisco Catalyst
switches share a MAC address for all VLAN switch ports). Otherwise, if traffic arrives on the
management interface from the physically-connected switch, then the ASA updates the MAC address
table to use the management interface to access the switch, instead of the data interface. This action
causes a temporary traffic interruption; the ASA will not re-update the MAC address table for packets
from the switch to the data interface for at least 30 seconds for security reasons.
Configuring the MAC Address Table
This section describes how you can customize the MAC address table, and includes the following
sections:
•
Adding a Static MAC Address, page 4-13
•
Setting the MAC Address Timeout, page 4-14
•
Disabling MAC Address Learning, page 4-14
Adding a Static MAC Address
Normally, MAC addresses are added to the MAC address table dynamically as traffic from a particular
MAC address enters an interface. You can add static MAC addresses to the MAC address table if desired.
One benefit to adding static entries is to guard against MAC spoofing. If a client with the same
MAC address as a static entry attempts to send traffic to an interface that does not match the static entry,
then the ASA drops the traffic and generates a system message. When you add a static ARP entry (see
the “Adding a Static ARP Entry” section on page 4-10), a static MAC address entry is automatically
added to the MAC address table.
To add a static MAC address to the MAC address table, enter the following command:
Command
Purpose
mac-address-table static interface_name
mac_address
Adds a static MAC address entry.
The interface_name is the source interface.
Example:
hostname(config)# mac-address-table static
inside 0009.7cbe.2100
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Setting the MAC Address Timeout
The default timeout value for dynamic MAC address table entries is 5 minutes, but you can change the
timeout. To change the timeout, enter the following command:
Command
Purpose
mac-address-table aging-time timeout_value
Sets the MAC address entry timeout.
Example:
hostname(config)# mac-address-table
aging-time 10
The timeout_value (in minutes) is between 5 and 720 (12 hours). 5 minutes
is the default.
Disabling MAC Address Learning
By default, each interface automatically learns the MAC addresses of entering traffic, and the ASA adds
corresponding entries to the MAC address table. You can disable MAC address learning if desired,
however, unless you statically add MAC addresses to the table, no traffic can pass through the ASA.
To disable MAC address learning, enter the following command:
Command
Purpose
mac-learn interface_name disable
Disables MAC address learning.
Example:
hostname(config)# mac-learn inside disable
The no form of this command reenables MAC address learning. The clear
configure mac-learn command reenables MAC address learning on all
interfaces.
Monitoring the MAC Address Table
You can view the entire MAC address table (including static and dynamic entries for both interfaces), or
you can view the MAC address table for an interface. To view the MAC address table, enter the following
command:
Command
Purpose
show mac-address-table [interface_name]
Shows the MAC address table.
Examples
The following is sample output from the show mac-address-table command that shows the entire table:
hostname# show mac-address-table
interface
mac address
type
Time Left
----------------------------------------------------------------------outside
0009.7cbe.2100
static
inside
0010.7cbe.6101
static
inside
0009.7cbe.5101
dynamic
10
The following is sample output from the show mac-address-table command that shows the table for the
inside interface:
hostname# show mac-address-table inside
interface
mac address
type
Time Left
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----------------------------------------------------------------------inside
0010.7cbe.6101
static
inside
0009.7cbe.5101
dynamic
10
Feature History for the MAC Address Table
Table 4-2 lists the release history for this feature.
Table 4-4
Feature History for the MAC Address Table
Feature Name
MAC address table
Releases
Feature Information
7.0(1)
Transparent firewall mode uses a MAC address table.
The following commands were introduced:
mac-address-table static, mac-address-table aging-time,
mac-learn disable, and show mac-address-table.
Firewall Mode Examples
This section includes examples of how traffic moves through the ASA, and includes the following topics:
•
How Data Moves Through the Security Appliance in Routed Firewall Mode, page 4-15
•
How Data Moves Through the Transparent Firewall, page 4-21
How Data Moves Through the Security Appliance in Routed Firewall Mode
This section describes how data moves through the ASA in routed firewall mode, and includes the
following topics:
•
An Inside User Visits a Web Server, page 4-16
•
An Outside User Visits a Web Server on the DMZ, page 4-17
•
An Inside User Visits a Web Server on the DMZ, page 4-18
•
An Outside User Attempts to Access an Inside Host, page 4-19
•
A DMZ User Attempts to Access an Inside Host, page 4-20
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An Inside User Visits a Web Server
Figure 4-2 shows an inside user accessing an outside web server.
Figure 4-2
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 ASA (see Figure 4-2):
1.
The user on the inside network requests a web page from www.example.com.
2.
The ASA receives the packet and because it is a new session, the ASA verifies that the packet is
allowed according to the terms of the security policy (access lists, filters, AAA).
For multiple context mode, the ASA 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.
3.
The ASA 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 ASA then records that a session is established and forwards the packet from the outside
interface.
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5.
When www.example.com responds to the request, the packet goes through the ASA, and because
the session is already established, the packet bypasses the many lookups associated with a new
connection. The ASA performs NAT by translating the global destination address to the local user
address, 10.1.2.27.
6.
The ASA forwards the packet to the inside user.
An Outside User Visits a Web Server on the DMZ
Figure 4-3 shows an outside user accessing the DMZ web server.
Figure 4-3
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 ASA (see Figure 4-3):
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.
2.
The ASA receives the packet and because it is a new session, the ASA verifies that the packet is
allowed according to the terms of the security policy (access lists, filters, AAA).
For multiple context mode, the ASA 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 ASA translates the destination address to the local address 10.1.1.3.
4.
The ASA then adds a session entry to the fast path and forwards the packet from the DMZ interface.
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5.
When the DMZ web server responds to the request, the packet goes through the ASA and because
the session is already established, the packet bypasses the many lookups associated with a new
connection. The ASA performs NAT by translating the local source address to 209.165.201.3.
6.
The ASA forwards the packet to the outside user.
An Inside User Visits a Web Server on the DMZ
Figure 4-4 shows an inside user accessing the DMZ web server.
Figure 4-4
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
The following steps describe how data moves through the ASA (see Figure 4-4):
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 ASA receives the packet and because it is a new session, the ASA verifies that the packet is
allowed according to the terms of the security policy (access lists, filters, AAA).
For multiple context mode, the ASA 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 ASA 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.
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Firewall Mode Examples
5.
The ASA forwards the packet to the inside user.
An Outside User Attempts to Access an Inside Host
Figure 4-5 shows an outside user attempting to access the inside network.
Figure 4-5
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
The following steps describe how data moves through the ASA (see Figure 4-5):
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 ASA receives the packet and because it is a new session, the ASA verifies if the packet is
allowed according to the security policy (access lists, filters, AAA).
3.
The packet is denied, and the ASA drops the packet and logs the connection attempt.
If the outside user is attempting to attack the inside network, the ASA employs many technologies
to determine if a packet is valid for an already established session.
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A DMZ User Attempts to Access an Inside Host
Figure 4-6 shows a user in the DMZ attempting to access the inside network.
Figure 4-6
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 ASA (see Figure 4-6):
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 ASA receives the packet and because it is a new session, the ASA verifies if the packet is
allowed according to the security policy (access lists, filters, AAA).
The packet is denied, and the ASA drops the packet and logs the connection attempt.
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Firewall Mode Examples
How Data Moves Through the Transparent Firewall
Figure 4-7 shows a typical transparent firewall implementation with an inside network that contains a
public web server. The ASA 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 4-7
Typical Transparent Firewall Data Path
www.example.com
Internet
209.165.201.2
Management IP
209.165.201.6
Host
209.165.201.3
92412
209.165.200.230
Web Server
209.165.200.225
This section describes how data moves through the ASA, and includes the following topics:
•
An Inside User Visits a Web Server, page 4-22
•
An Inside User Visits a Web Server Using NAT, page 4-23
•
An Outside User Visits a Web Server on the Inside Network, page 4-24
•
An Outside User Attempts to Access an Inside Host, page 4-25
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An Inside User Visits a Web Server
Figure 4-8 shows an inside user accessing an outside web server.
Figure 4-8
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 ASA (see Figure 4-8):
1.
The user on the inside network requests a web page from www.example.com.
2.
The ASA 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 ASA first classifies the packet according to a unique interface.
3.
The ASA records that a session is established.
4.
If the destination MAC address is in its table, the ASA forwards the packet out of the outside
interface. The destination MAC address is that of the upstream router, 209.186.201.2.
If the destination MAC address is not in the ASA table, the ASA attempts to discover the MAC
address by sending an ARP request or 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 ASA forwards the packet to the inside user.
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An Inside User Visits a Web Server Using NAT
Figure 4-8 shows an inside user accessing an outside web server.
Figure 4-9
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 ASA (see Figure 4-8):
1.
The user on the inside network requests a web page from www.example.com.
2.
The ASA 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 ASA first classifies the packet according to a unique interface.
3.
The ASA 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 ASA.
4.
The ASA then records that a session is established and forwards the packet from the outside
interface.
5.
If the destination MAC address is in its table, the ASA forwards the packet out of the outside
interface. The destination MAC address is that of the upstream router, 10.1.2.1.
If the destination MAC address is not in the ASA table, the ASA 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 ASA performs NAT by translating the mapped address to the real address, 10.1.2.27.
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An Outside User Visits a Web Server on the Inside Network
Figure 4-10 shows an outside user accessing the inside web server.
Figure 4-10
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 ASA (see Figure 4-10):
1.
A user on the outside network requests a web page from the inside web server.
2.
The ASA 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 ASA first classifies the packet according to a unique interface.
3.
The ASA records that a session is established.
4.
If the destination MAC address is in its table, the ASA forwards the packet out of the inside
interface. The destination MAC address is that of the downstream router, 209.165.201.1.
If the destination MAC address is not in the ASA table, the ASA 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 ASA forwards the packet to the outside user.
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An Outside User Attempts to Access an Inside Host
Figure 4-11 shows an outside user attempting to access a host on the inside network.
Figure 4-11
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 ASA (see Figure 4-11):
1.
A user on the outside network attempts to reach an inside host.
2.
The ASA 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 ASA first classifies the packet according to a unique interface.
3.
The packet is denied because there is no access list permitting the outside host, and the ASA drops
the packet.
4.
If the outside user is attempting to attack the inside network, the ASA employs many technologies
to determine if a packet is valid for an already established session.
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5
Managing Multiple Context Mode
This chapter describes how to configure multiple security contexts on the ASA, and includes the
following sections:
•
Information About Security Contexts, page 5-1
•
Enabling or Disabling Multiple Context Mode, page 5-10
•
Configuring Resource Management, page 5-11
•
Configuring a Security Context, page 5-16
•
Automatically Assigning MAC Addresses to Context Interfaces, page 5-20
•
Changing Between Contexts and the System Execution Space, page 5-25
•
Managing Security Contexts, page 5-25
•
Monitoring Security Contexts, page 5-28
Information About Security Contexts
You can partition a single ASA 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 ASA 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 5-2
•
Unsupported Features, page 5-2
•
Context Configuration Files, page 5-2
•
How the Security Appliance Classifies Packets, page 5-3
•
Cascading Security Contexts, page 5-8
•
Management Access to Security Contexts, page 5-9
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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 ASA, 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 ASA.
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
•
Phone Proxy
•
QoS
Context Configuration Files
This section describes how the ASA implements multiple context mode configurations and includes the
following sections:
•
Context Configurations, page 5-2
•
System Configuration, page 5-2
•
Admin Context Configuration, page 5-3
Context Configurations
The ASA 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.
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
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settings for the ASA. 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 ASA must be classified, so that the ASA can determine to which context to
send a packet. This section includes the following topics:
Note
•
Valid Classifier Criteria, page 5-3
•
Invalid Classifier Criteria, page 5-4
•
Classification Examples, page 5-5
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 5-3
•
Unique MAC Addresses, page 5-3
•
NAT Configuration, page 5-4
Unique Interfaces
If only one context is associated with the ingress interface, the ASA 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.
Unique MAC Addresses
If multiple contexts share an interface, then the classifier uses the interface MAC address. The ASA 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
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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 the MAC Address” section
on page 6-26), or you can automatically generate MAC addresses (see the “Automatically Assigning
MAC Addresses to Context Interfaces” section on page 5-20).
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.
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Classification Examples
Figure 5-1 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 5-1
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
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Figure 5-2 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 5-2
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 5-3 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.
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Figure 5-3
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
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For transparent firewalls, you must use unique interfaces. Figure 5-4 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 5-4
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.
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Figure 5-5 shows a gateway context with two contexts behind the gateway.
Figure 5-5
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 ASA 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 5-9
•
Context Administrator Access, page 5-10
System Administrator Access
You can access the ASA as a system administrator in two ways:
•
Access the ASA 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 37, “Configuring Management 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
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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 37, “Configuring Management Access,” to enable Telnet, SSH, and SDM access and to
configure management authentication.
Enabling or Disabling Multiple Context Mode
Your ASA 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.
This section includes the following topics:
•
Backing Up the Single Mode Configuration, page 5-10
•
Enabling Multiple Context Mode, page 5-10
•
Restoring Single Context Mode, page 5-11
Backing Up the Single Mode Configuration
When you convert from single mode to multiple mode, the ASA 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 ASA 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 ASA automatically adds an entry for the admin context
to the system configuration with the name “admin.”
To enable multiple mode, enter the following command:
hostname(config)# mode multiple
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You are prompted to reboot the ASA.
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 ASA; 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 ASA 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 ASA reboots.
Configuring Resource Management
By default, all security contexts have unlimited access to the resources of the ASA, 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 5-11
•
Configuring a Class, page 5-14
Classes and Class Members Overview
The ASA 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 5-12
•
Default Class, page 5-13
•
Class Members, page 5-14
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Resource Limits
When you create a class, the ASA does not set aside a portion of the resources for each context assigned
to the class; rather, the ASA 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 ASA 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 5-6.)
Figure 5-6
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
ASA, then the performance of the ASA might be impaired.
The ASA 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 5-7.) Setting
unlimited access is similar to oversubscribing the ASA, except that you have less control over how much
you oversubscribe the system.
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Figure 5-7
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.
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Figure 5-8 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 5-8
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.
Guidelines
Table 5-1 lists the resource types and the limits. See also the show resource types command.
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Table 5-1
Resource Names and Limits
Rate or
Resource Name Concurrent
Minimum and
Maximum Number
per Context
System Limit1
Description
mac-addresses Concurrent
N/A
65,535
For transparent firewall mode, the number of
MAC addresses allowed in the MAC address
table.
conns
N/A
Concurrent connections: TCP or UDP connections between any two
See the “Supported
hosts, including connections between one
Feature Licenses Per
host and multiple other hosts.
Model” section on
page 3-1 for the
connection limit for your
platform.
Concurrent
or Rate
Rate: N/A
inspects
Rate
N/A
N/A
Application inspections.
hosts
Concurrent
N/A
N/A
Hosts that can connect through the ASA.
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.
Detailed Steps
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 5-1) to be unlimited, enter the following command:
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hostname(config-resmgmt)# limit-resource all 0
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 5-1 for
resources for which you can set the rate per second and which to not have a system limit.
Examples
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
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)#
gold
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.
Prerequisites
•
Configure physical interface parameters, VLAN subinterfaces, and redundant interfaces according
to the “Starting Interface Configuration (ASA 5510 and Higher)” section on page 6-8.
•
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.
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Detailed 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.
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
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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
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 ASA 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 ASA 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
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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
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 5-26 for more information about
changing the URL.
For example, enter the following command:
hostname(config-ctx)# config-url ftp://joe:[email protected]/configlets/test.cfg
Step 5
(Optional) To assign the context to a resource class, enter the following command:
hostname(config-ctx)# member class_name
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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 a Security Context (ASA 5510 and
Higher)” section on page 59-6 for detailed information about virtual sensors
Examples
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
hostname(config-ctx)#
hostname(config-ctx)#
hostname(config-ctx)#
hostname(config-ctx)#
int3-int8
hostname(config-ctx)#
hostname(config-ctx)#
context sample
allocate-interface gigabitethernet0/1.200 int1
allocate-interface gigabitethernet0/1.212 int2
allocate-interface gigabitethernet0/1.230-gigabitethernet0/1.235
config-url ftp://user1:[email protected]/configlets/test.cfg
member gold
config-url ftp://user1:[email protected]/configlets/sample.cfg
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 5-21
•
Default MAC Address, page 5-21
•
Failover MAC Addresses, page 5-21
•
MAC Address Format, page 5-21
•
Enabling Auto-Generation of MAC Addresses, page 5-22
•
Viewing Assigned MAC Addresses, page 5-22
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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 5-3 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 MAC Address” section on page 6-26 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.
Failover MAC Addresses
For use with failover, the ASA 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 ASA 5500 Series
Command Reference.
MAC Address Format
The ASA 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 ASA. 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 ASA converts 77 into the
hexadecimal value 004D (yyxx). When used in the MAC address, the prefix is reversed (xxyy) to match
the ASA native form:
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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.
Guidelines
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 ASA 5500 Series Command Reference.
Detailed Steps
Command
Purpose
mac-address auto prefix prefix
Automatically assign private MAC addresses to each context interface.
Example:
hostname(config)# mac-address auto prefix
19
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 ASA uses unique MAC addresses, so you can have
multiple ASAs on a network segment, for example. See the “MAC Address
Format” section for more information about how the prefix is used.
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 5-22
•
Viewing MAC Addresses Within a Context, page 5-24
Viewing MAC Addresses in the System Configuration
This section describes how to view MAC addresses in the system configuration.
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Guidelines
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.
Detailed Steps
Command
Purpose
show running-config all context [name]
Shows the assigned MAC addresses from the system execution space.
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.
Examples
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
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
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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
This section describes how to view MAC addresses within a context.
Detailed Steps
Command
Purpose
show interface | include (Interface)|(MAC)
Shows the MAC address in use by each interface within the context.
Examples
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.
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Changing Between Contexts and the System Execution Space
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.
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 5-25
•
Changing the Admin Context, page 5-26
•
Changing the Security Context URL, page 5-26
•
Reloading a Security Context, page 5-27
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
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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
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 ASA 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
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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
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 5-27
•
Reloading by Removing and Re-adding the Context, page 5-28
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
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The ASA copies the configuration from the URL specified in the system configuration. You cannot
change the URL from within a context.
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 5-20
2.
“Configuring a Security Context” section on page 5-16
Monitoring Security Contexts
This section describes how to view and monitor context information, and includes the following topics:
•
Viewing Context Information, page 5-28
•
Viewing Context Information, page 5-28
•
Viewing Resource Allocation, page 5-29
•
Viewing Resource Usage, page 5-32
•
Monitoring SYN Attacks in Contexts, page 5-33
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 5-2 shows each field description.
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Table 5-2
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 ASA loads the context configuration.
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 ASA 5500 Series 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 5-32 for more information about actual resource usage.
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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
SSH
35
Telnet
35
Xlates
91749
All
unlimited
% of Avail
N/A
N/A
N/A
30.50%
N/A
35.00%
35.00%
N/A
Table 5-3 shows each field description.
Table 5-3
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 ASA 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
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
all
CA
unlimited
unlimited
10000
5000
unlimited
6000
3000
1500
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
unlimited
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Hosts
SSH
Telnet
Xlates
mac-addresses
gold
silver
bronze
All Contexts:
1
1
0
3
C
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
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
200000
100000
50000
unlimited
unlimited
26214
13107
200000
100000
20.00%
10.00%
300000
30.00%
26214
N/A
26214
N/A
5
5
10
5
5
5
10
5
unlimited
unlimited
23040
11520
65535
65535
6553
3276
5
10
5.00%
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 5-4 shows each field description.
Table 5-4
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 ASA 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 ASA converts the percentage to an absolute
number for this display.
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Table 5-4
show resource allocation detail Fields
Field
Description
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.
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 5-1 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
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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
Current
Peak
Limit
Denied
Syslogs [rate]
1743
2132
N/A
0
Conns
584
763
280000(S)
0
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
Context
Summary
Summary
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 ASA 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
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a connection is crossed, the ASA acts as a proxy for the server and generates a SYN-ACK response to
the client SYN request. When the ASA 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
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
Current
0/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
Average
0/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
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
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
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chunk:route
chunk:static
tcp-intercept-rate
globals
np-statics
statics
nats
ace-rules
console-access-rul
fixup-rules
memory
chunk:channels
chunk:dbgtrace
chunk:fixup
chunk:ip-users
chunk:list-elem
chunk:list-hdr
chunk:route
block:16384
block:2048
2
1
16056
1
3
1
1
2
2
14
232695716
17
3
15
4
1014
1
1
510
32
2
1
16254
1
3
1
1
2
2
15
232020648
20
3
15
4
1014
1
1
885
34
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
unlimited
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
c1
c1
c1
c1
c1
c1
c1
c1
c1
c1
system
system
system
system
system
system
system
system
system
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
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Chapter 5
Managing Multiple Context Mode
Monitoring Security Contexts
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CH A P T E R
6
Configuring Interfaces
This chapter describes how to configure interfaces, including Ethernet parameters, switch ports (for the
ASA 5505), VLAN subinterfaces, and IP addressing.
The procedure to configure interfaces varies depending on several factors: the ASA 5505 vs. other
models; routed vs. transparent mode; and single vs. multiple mode. This chapter describes how to
configure interfaces for each of these variables.
Note
If your ASA has the default factory configuration, many interface parameters are already configured.
This chapter assumes you do not have a factory default configuration, or that if you have a default
configuration, that you need to change the configuration. For information about the factory default
configurations, see the “Factory Default Configurations” section on page 2-1.
This chapter includes the following sections:
•
Information About Interfaces, page 6-1
•
Licensing Requirements for Interfaces, page 6-6
•
Guidelines and Limitations, page 6-6
•
Default Settings, page 6-7
•
Starting Interface Configuration (ASA 5510 and Higher), page 6-8
•
Starting Interface Configuration (ASA 5505), page 6-16
•
Completing Interface Configuration (All Models), page 6-22
•
Allowing Same Security Level Communication, page 6-30
•
Enabling Jumbo Frame Support (ASA 5580 and 5585-X), page 6-31
•
Monitoring Interfaces, page 6-32
•
Configuration Examples for Interfaces, page 6-32
•
Feature History for Interfaces, page 6-33
Information About Interfaces
This section describes ASA interfaces, and includes the following topics:
•
ASA 5505 Interfaces, page 6-2
•
Auto-MDI/MDIX Feature, page 6-4
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Information About Interfaces
•
Security Levels, page 6-5
•
Dual IP Stack, page 6-5
•
Management Interface (ASA 5510 and Higher), page 6-5
ASA 5505 Interfaces
This section describes the ports and interfaces of the ASA 5505 ASA, and includes the following topics:
•
Understanding ASA 5505 Ports and Interfaces, page 6-2
•
Maximum Active VLAN Interfaces for Your License, page 6-2
•
VLAN MAC Addresses, page 6-4
•
Power Over Ethernet, page 6-4
Understanding ASA 5505 Ports and Interfaces
The ASA 5505 ASA supports a built-in switch. There are two kinds of ports and interfaces that you need
to configure:
•
Physical switch ports—The ASA has 8 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 6-4 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 ASA applies
the security policy to the traffic and routes or bridges between the two VLANs.
Maximum Active VLAN Interfaces for Your License
In transparent firewall mode, you can configure the following VLANs depending on your license:
•
Base license—2 active VLANs.
•
Security Plus license—3 active VLANs, one of which must be for failover.
In routed mode, you can configure the following VLANs depending on your license: Base license
Note
•
Base license—3 active VLANs. The third VLAN can only be configured to initiate traffic to one
other VLAN. See Figure 6-1 for more information.
•
Security Plus license—20 active VLANs.
An active VLAN is a VLAN with a nameif command configured.
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With the Base license, the third VLAN can only be configured to initiate traffic to one other VLAN. See
Figure 6-1 for an example network where the Home VLAN can communicate with the Internet, but
cannot initiate contact with Business.
Figure 6-1
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. You can configure the backup interface to
not pass through traffic unless the route through the primary interface fails. You can configure trunk
ports to accommodate multiple VLANs per port.
Note
The ASA 5505 ASA supports Active/Standby failover, but not Stateful failover.
See Figure 6-2 for an example network.
Figure 6-2
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
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VLAN MAC Addresses
•
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. See the “Configuring the MAC Address” section on page 6-26.
•
Transparent firewall mode—Each VLAN has a unique MAC address. You can override the generated
MAC addresses if desired by manually assigning MAC addresses. See the “Configuring the MAC
Address” section on page 6-26.
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 ASA 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 enable the port using the no shutdown command. See the “Configuring and
Enabling Switch Ports as Access Ports” section on page 6-17 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.
See the switchport monitor command in the Cisco ASA 5500 Series Command Reference for more
information.
Auto-MDI/MDIX Feature
For RJ-45 interfaces, 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.
For the ASA 5510 and higher, 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.
For the ASA 5505, you cannot disable Auto-MDI/MDIX.
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Security Levels
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 Same Security Level Communication”
section on page 6-30 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 Same Security Level
Communication” section on page 6-30), 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
ASA.
•
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.
Dual IP Stack
The ASA 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.
Management Interface (ASA 5510 and Higher)
The management interface is a Fast Ethernet interface designed for management traffic only, and is
specified as management slot/port in commands. You can, however, use it for through traffic if desired
(see the management-only command). In transparent firewall mode, you can use the management
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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.
Note
In transparent firewall mode, the management interface updates the MAC address table in the same
manner as a data interface; therefore you should not connect both a management and a data interface to
the same switch unless you configure one of the switch ports as a routed port (by default Cisco Catalyst
switches share a MAC address for all VLAN switch ports). Otherwise, if traffic arrives on the
management interface from the physically-connected switch, then the ASA updates the MAC address
table to use the management interface to access the switch, instead of the data interface. This action
causes a temporary traffic interruption; the ASA will not re-update the MAC address table for packets
from the switch to the data interface for at least 30 seconds for security reasons.
Licensing Requirements for Interfaces
The following table shows the licensing requirements for VLANs:
Model
License Requirement
ASA 5505
Base License: 3 (2 regular zones and 1 restricted zone that can only communicate with 1 other zone)
Security Plus License: 20
ASA 5510
Base License: 50
Security Plus License: 100
ASA 5520
Base License: 150
ASA 5540
Base License: 200
ASA 5550
Base License: 250
ASA 5580
Base License: 250
ASA 5585-X
Base License: 250
The following table shows the licensing requirements for VLAN trunks:
Model
License Requirement
ASA 5505
Base License: None.
Security Plus License: 8.
All other models
N/A
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
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Default Settings
Context Mode Guidelines
In multiple context mode, configure the physical interfaces in the system execution space according to
the “Starting Interface Configuration (ASA 5510 and Higher)” section on page 6-8.
Then, configure the logical interface parameters in the context execution space according to the
“Completing Interface Configuration (All Models)” section on page 6-22.
Firewall Mode Guidelines
•
Transparent firewall mode allows only two interfaces to pass through traffic; however, on the ASA
5510 and higher ASA, you can use the Management 0/0 or 0/1 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.
•
Intra-interface communication is only available in routed firewall mode. Inter-interface
communication is available for both routed and transparent mode.
Failover Guidelines
Do not finish configuring failover interfaces with the procedures in “Completing Interface Configuration
(All Models)” section on page 6-22. See the “Configuring Active/Standby Failover” section on
page 33-7 or the “Configuring Active/Active Failover” section on page 34-8 to configure the failover and
state links. In multiple context mode, failover interfaces are configured in the system configuration.
IPv6 Guidelines
Supports IPv6.
In transparent mode on a per interface basis, you can only configure the link-local address; you configure
the global address as the management address for the entire unit, but not per interface. Because
configuring the management global IP address automatically configures the link-local addresses per
interface, the only IPv6 configuration you need to perform is to set the management IP address according
to the “Configuring the IPv6 Address” section on page 8-9.
Model Guidelines
Subinterfaces are not available for the ASA 5505 ASA.
Default Settings
This section lists default settings for interfaces if you do not have a factory default configuration. For
information about the factory default configurations, see the “Factory Default Configurations” section
on page 2-1.
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 ASA 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.
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Starting Interface Configuration (ASA 5510 and Higher)
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 and switch ports—Disabled.
•
Redundant Interfaces—Enabled. However, for traffic to pass through the redundant interface, the
member physical interfaces must also be enabled.
•
Subinterfaces or VLANs—Enabled. However, for traffic to pass through the subinterface, the
physical interface must also be enabled.
Default Speed and Duplex
•
By default, the speed and duplex for copper (RJ-45) interfaces are set to auto-negotiate.
•
The fiber interface for the ASA 5550 and the 4GE SSM 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.
•
For fiber interfaces for the ASA 5580 and ASA 5585-X, the speed is set for automatic link
negotiation.
Default Connector Type
The ASA 5550 ASA and the 4GE SSM for the ASA 5510 and higher ASA include two connector types:
copper RJ-45 and fiber SFP. RJ-45 is the default. You can configure the ASA to use the fiber SFP
connectors.
Default MAC Addresses
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.
Starting Interface Configuration (ASA 5510 and Higher)
This section includes tasks for starting your interface configuration for the ASA 5510 and higher.
Note
For multiple context mode, complete all tasks in this section in the system execution space. To change
from the context to the system execution space, enter the changeto system command.
For ASA 5505 configuration, see the “Starting Interface Configuration (ASA 5505)” section on
page 6-16.
This section includes the following topics:
•
Task Flow for Starting Interface Configuration, page 6-9
•
Configuring a Redundant Interface, page 6-11
•
Enabling the Physical Interface and Configuring Ethernet Parameters, page 6-9
•
Configuring VLAN Subinterfaces and 802.1Q Trunking, page 6-14
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Starting Interface Configuration (ASA 5510 and Higher)
•
Assigning Interfaces to Contexts and Automatically Assigning MAC Addresses (Multiple Context
Mode), page 6-15
Task Flow for Starting Interface Configuration
To start configuring interfaces, perform the following steps:
Step 1
(Multiple context mode) Complete all tasks in this section in the system execution space. To change from
the context to the system execution space, enter the changeto system command.
Step 2
Enable the physical interface, and optionally change Ethernet parameters. See the “Enabling the Physical
Interface and Configuring Ethernet Parameters” section on page 6-9.
Physical interfaces are disabled by default.
Step 3
(Optional) Configure redundant interface pairs. See the “Configuring a Redundant Interface” section on
page 6-11.
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.
Step 4
(Optional) Configure VLAN subinterfaces. See the “Configuring VLAN Subinterfaces and 802.1Q
Trunking” section on page 6-14.
Step 5
(Multiple context mode only) Assign interfaces to contexts and automatically assign unique MAC
addresses to context interfaces. See the “Assigning Interfaces to Contexts and Automatically Assigning
MAC Addresses (Multiple Context Mode)” section on page 6-15.
Step 6
Complete the interface configuration according to the “Completing Interface Configuration (All
Models)” section on page 6-22.
Enabling the Physical Interface and Configuring Ethernet Parameters
This section describes how to:
•
Enable the physical interface
•
Set a specific speed and duplex (if available)
•
Enable pause frames for flow control.
Prerequisites
For multiple context mode, complete this procedure in the system execution space. To change from the
context to the system execution space, enter the changeto system command.
Detailed 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.
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The physical interface types include the following:
•
ethernet
•
gigabitethernet
•
tengigabitethernet
•
management
Enter the type followed by slot/port, for example, gigabitethernet0/1 or ethernet 0/1.
To view the interfaces available on your ASA, enter the show interface command.
Step 2
(Optional) To set the media type to SFP, if available for your model, 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 set the speed, enter the following command:
hostname(config-if)# speed {auto | 10 | 100 | 1000 | nonegotiate}
For copper interfaces, the default setting is auto.
For SFP interfaces, the default setting is no speed nonegotiate, which sets the speed to the maximum
speed and enables link negotiation for flow-control parameters and remote fault information. The
nonegotiate keyword is the only keyword available for SFP interfaces. The speed nonegotiate
command disables link negotiation.
Step 4
(Optional) To set the duplex for copper interfaces, enter the following command:
hostname(config-if)# duplex {auto | full | half}
The auto setting is the default.
Step 5
(Optional) To enable pause (XOFF) frames for flow control, enter the following command:
hostname(config-if)# flowcontrol send on [low_water high_water pause_time] [noconfirm]
If you have a traffic burst, dropped packets can occur if the burst exceeds the buffering capacity of the
FIFO buffer on the NIC and the receive ring buffers. Enabling pause frames for flow control can alleviate
this issue. Pause (XOFF) and XON frames are generated automatically by the NIC hardware based on
the FIFO buffer usage. A pause frame is sent when the buffer usage exceeds the high-water mark.
For 10 GigabitEthernet interfaces, the default high_water value is 128 KB; you can set it between 0 and
511. After a pause is sent, an XON frame can be sent when the buffer usage is reduced below the
low-water mark. By default, the low_water value is 64 KB; you can set it between 0 and 511. The link
partner can resume traffic after receiving an XON, or after the XOFF expires, as controlled by the timer
value in the pause frame.
(8.2(5) and later) For 1 GigabitEthernet interfaces, the default high_water value is 16 KB; you can set it
between 0 and 47. By default, the low_water value is 24 KB; you can set it between 0 and 47.
The default pause_time value is 26624; you can set it between 0 and 65535. Each pause time unit is the
amount of time to transmit 64 bytes, so the time per unit depends on your link speed. If the buffer usage
is consistently above the high-water mark, pause frames are sent repeatedly, controlled by the pause
refresh threshold value.
When you use this command, you see the following warning:
Changing flow-control parameters will reset the interface. Packets may be lost during the
reset.
Proceed with flow-control changes?
To change the parameters without being prompted, use the noconfirm keyword.
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Note
Step 6
Only flow control frames defined in 802.3x are supported. Priority-based flow control is not
supported.
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.
What to Do Next
Optional Tasks:
•
Configure redundant interface pairs. See the “Configuring a Redundant Interface” section on
page 6-11.
•
Configure VLAN subinterfaces. See the “Configuring VLAN Subinterfaces and 802.1Q Trunking”
section on page 6-14.
Required Tasks:
•
For multiple context mode, assign interfaces to contexts and automatically assign unique MAC
addresses to context interfaces. See the “Assigning Interfaces to Contexts and Automatically
Assigning MAC Addresses (Multiple Context Mode)” section on page 6-15.
•
For single context mode, complete the interface configuration. See the “Completing Interface
Configuration (All Models)” section on page 6-22.
Configuring a Redundant Interface
A logical redundant interface consists of a pair of physical interfaces: an active and a standby interface.
When the active interface fails, the standby interface becomes active and starts passing traffic. You can
configure a redundant interface to increase the ASA reliability. This feature is separate from device-level
failover, but you can configure redundant interfaces as well as failover if desired.
This section describes how to configure redundant interfaces, and includes the following topics:
•
Configuring a Redundant Interface, page 6-11
•
Changing the Active Interface, page 6-14
Configuring a Redundant Interface
This section describes how to create a redundant interface. By default, redundant interfaces are enabled.
Guidelines and Limitations
•
You can configure up to 8 redundant interface pairs.
•
All ASA configuration refers to the logical redundant interface instead of the member physical
interfaces.
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•
Redundant interface delay values are configurable, but by default the ASA will inherit the default
delay values based on the physical type of its member interfaces.
•
The only configuration available to physical interfaces that are part of a redundant interface pair are
physical parameters (set in the “Enabling the Physical Interface and Configuring Ethernet
Parameters” section on page 6-9), 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.
For failover, 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 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 the MAC Address” section on page 6-26 or the “Assigning Interfaces to Contexts and
Automatically Assigning MAC Addresses (Multiple Context Mode)” section on page 6-15). When the
active interface fails over to the standby, the same MAC address is maintained so that traffic is not
disrupted.
Prerequisites
Caution
•
Both member interfaces must be of the same physical type. For example, both must be Ethernet.
•
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.
•
For multiple context mode, complete this procedure in the system execution space. To change from
the context to the system execution space, enter the changeto system command.
If you are using a physical interface already in your configuration, removing the name will clear any
configuration that refers to the interface.
Detailed Steps
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:
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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 “Enabling the Physical Interface and Configuring Ethernet Parameters” 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.
The Add Redundant Interface dialog box appears.
You return to the Interfaces pane.
Examples
The following example creates two redundant interfaces:
hostname(config)# interface redundant 1
hostname(config-if)# member-interface gigabitethernet
hostname(config-if)# member-interface gigabitethernet
hostname(config-if)# interface redundant 2
hostname(config-if)# member-interface gigabitethernet
hostname(config-if)# member-interface gigabitethernet
0/0
0/1
0/2
0/3
What to Do Next
Optional Task:
•
Configure VLAN subinterfaces. See the “Configuring VLAN Subinterfaces and 802.1Q Trunking”
section on page 6-14.
Required Tasks:
•
For multiple context mode, assign interfaces to contexts and automatically assign unique MAC
addresses to context interfaces. See the “Assigning Interfaces to Contexts and Automatically
Assigning MAC Addresses (Multiple Context Mode)” section on page 6-15.
•
For single context mode, complete the interface configuration. See the “Completing Interface
Configuration (All Models)” section on page 6-22.
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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
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 ASAs. This feature is particularly useful in multiple context mode so that you can
assign unique interfaces to each context.
Guidelines and Limitations
•
Maximum subinterfaces—To determine how many VLAN subinterfaces are allowed for your
platform, see the “Licensing Requirements for Interfaces” section on page 6-6.
•
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 “Completing Interface Configuration (All
Models)” section on page 6-22 for more information about completing the interface configuration.
Prerequisites
For multiple context mode, complete this procedure in the system execution space. To change from the
context to the system execution space, enter the changeto system command.
Detailed Steps
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)#
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See the “Enabling Jumbo Frame Support (ASA 5580 and 5585-X)” 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 ASA changes
the old ID.
What to Do Next
•
For multiple context mode, assign interfaces to contexts and automatically assign unique MAC
addresses to context interfaces. See the “Assigning Interfaces to Contexts and Automatically
Assigning MAC Addresses (Multiple Context Mode)” section on page 6-15.
•
For single context mode, complete the interface configuration. See the “Completing Interface
Configuration (All Models)” section on page 6-22.
Assigning Interfaces to Contexts and Automatically Assigning MAC Addresses
(Multiple Context Mode)
To complete the configuration of interfaces in the system execution space, perform the following tasks
that are documented in Chapter 5, “Managing Multiple Context Mode”:
•
To assign interfaces to contexts, see the “Configuring a Security Context” section on page 5-16 .
•
(Optional) To automatically assign unique MAC addresses to context interfaces, see the
“Automatically Assigning MAC Addresses to Context Interfaces” section on page 5-20.
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. Alternatively, you can manually assign MAC addresses within the context
according to the “Configuring the MAC Address” section on page 6-26.
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What to Do Next
Complete the interface configuration. See the “Completing Interface Configuration (All Models)”
section on page 6-22.
Starting Interface Configuration (ASA 5505)
This section includes tasks for starting your interface configuration for the ASA 5505 ASA, including
creating VLAN interfaces and assigning them to switch ports. See the “Understanding ASA 5505 Ports
and Interfaces” section on page 6-2 for more information.
For ASA 5510 and higher configuration, see the “Starting Interface Configuration (ASA 5510 and
Higher)” section on page 6-8.
This section includes the following topics:
•
Task Flow for Starting Interface Configuration, page 6-16
•
Configuring VLAN Interfaces, page 6-16
•
Configuring and Enabling Switch Ports as Access Ports, page 6-17
•
Configuring and Enabling Switch Ports as Trunk Ports, page 6-19
Task Flow for Starting Interface Configuration
To configure interfaces in single mode, perform the following steps:
Step 1
Configure VLAN interfaces. See the “Configuring VLAN Interfaces” section on page 6-16.
Step 2
Configure and enable switch ports as access ports. See the “Configuring and Enabling Switch Ports as
Access Ports” section on page 6-17.
Step 3
(Optional for Security Plus licenses) Configure and enable switch ports as trunk ports. See the
“Configuring and Enabling Switch Ports as Trunk Ports” section on page 6-19.
Step 4
Complete the interface configuration according to the “Completing Interface Configuration (All
Models)” section on page 6-22.
Configuring VLAN Interfaces
This section describes how to configure VLAN interfaces. For more information about ASA 5505
interfaces, see the “ASA 5505 Interfaces” section on page 6-2.
Detailed Steps
Step 1
To add a VLAN interface, enter the following command:
hostname(config)# interface vlan number
Where the number is between 1 and 4090.
For example, enter the following command:
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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) To allow this interface to be the third VLAN by limiting it from initiating
contact to one other VLAN, enter 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 ASA does not allow
three fully functioning VLAN interfaces with the Base license on the ASA 5505 ASA.
Note
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.
What to Do Next
Configure the switch ports. See the “Configuring and Enabling Switch Ports as Access Ports” section on
page 6-17 and the “Configuring and Enabling Switch Ports as Trunk Ports” section on page 6-19.
Configuring and Enabling Switch Ports as Access Ports
By default (with no configuration), all switch ports are shut down, and assigned to VLAN 1. To assign
a switch port to a single VLAN, configure it as an access port. To create a trunk port to carry multiple
VLANs, see the “Configuring and Enabling Switch Ports as Trunk Ports” section on page 6-19. If you
have a factory default configuration, see the “ASA 5505 Default Configuration” section on page 2-2to
check if you want to change the default interface settings according to this procedure.
For more information about ASA 5505 interfaces, see the “ASA 5505 Interfaces” section on page 6-2.
Caution
The ASA 5505 ASA does not support Spanning Tree Protocol for loop detection in the network.
Therefore you must ensure that any connection with the ASA does not end up in a network loop.
Detailed Steps
Step 1
To specify the switch port you want to configure, enter the following command:
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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. See the “Configuring VLAN Interfaces” section
on page 6-16 to configure the VLAN interface that you want to assign to this switch port. To view
configured VLANs,
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}
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, enter the following command:
hostname(config-if)# no shutdown
To disable the switch port, enter the shutdown command.
Examples
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
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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
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
What to Do Next
If you want to configure a switch port as a trunk port, see the “Configuring and Enabling Switch Ports
as Trunk Ports” section on page 6-19.
To complete the interface configuration, see the “Completing Interface Configuration (All Models)”
section on page 6-22.
Configuring and Enabling Switch Ports as Trunk Ports
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.
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To create an access port, where an interface is assigned to only one VLAN, see the “Configuring and
Enabling Switch Ports as Access Ports” section on page 6-17.
For more information about ASA 5505 interfaces, see the “ASA 5505 Interfaces” section on page 6-2.
Detailed 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:
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
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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, enter the following command:
hostname(config-if)# no shutdown
To disable the switch port, enter the shutdown command.
Examples
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)#
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)# interface vlan 400
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hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
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
What to Do Next
To complete the interface configuration, see the “Completing Interface Configuration (All Models)”
section on page 6-22.
Completing Interface Configuration (All Models)
This section includes tasks to complete the interface configuration for all models.
Note
For multiple context mode, complete the tasks in this section in the context execution space. Enter the
changeto context name command to change to the context you want to configure.
This section includes the following topics:
•
Entering Interface Configuration Mode, page 6-23
•
Configuring General Interface Parameters, page 6-24
•
Configuring the MAC Address, page 6-26
•
Configuring IPv6 Addressing, page 6-27
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Task Flow for Completing Interface Configuration
Step 1
Complete the procedures in the “Starting Interface Configuration (ASA 5510 and Higher)” section on
page 6-8 or the “Starting Interface Configuration (ASA 5505)” section on page 6-16.
Step 2
(Multiple context mode) Enter the changeto context name command to change to the context you want
to configure.
Step 3
Enter interface configuration mode. See the “Entering Interface Configuration Mode” section on
page 6-23.
Step 4
Configure general interface parameters, including the interface name, security level, and IPv4 address.
See the “Configuring General Interface Parameters” section on page 6-24.
For transparent mode, you do not configure IP addressing per interface, except for the management-only
interface (see the “Information About the Management Interface” section on page 6-24). You do need to
configure the other parameters in this section, however. To set the global management address for
transparent mode, see the “Configuring the IPv4 Address” section on page 8-9.
Step 5
(Optional) Configure the MAC address. See the “Configuring the MAC Address” section on page 6-26.
Step 6
(Optional) Configure IPv6 addressing. See the “Configuring IPv6 Addressing” section on page 6-27
For transparent mode, you do not configure IP addressing per interface, except for the management-only
interface (see the “Information About the Management Interface” section on page 6-24). To set the
global management address for transparent mode, see the “Configuring the IPv6 Address” section on
page 8-9 .
Entering Interface Configuration Mode
The procedures in this section are performed in interface configuration mode.
Prerequisites
For multiple context mode, complete this procedure in the context execution space. Enter the changeto
context name command to change to the context you want to configure.
Detailed Steps
If you are not already in interface configuration mode, enter the mode by using the interface command.
•
For the ASA 5510 and higher:
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.
See the “Enabling Jumbo Frame Support (ASA 5580 and 5585-X)” section for a description of the
physical interface ID.
Append the subinterface ID to the physical or redundant interface ID separated by a period (.).
In multiple context mode, enter the mapped_name if one was assigned using the allocate-interface
command.
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•
For the ASA 5505:
hostname(config)# interface vlan number
hostname(config-if)#
Configuring General Interface Parameters
This procedure describes how to set the name, security level, IPv4 address and other options.
For the ASA 5510 and higher, you must configure interface parameters for the following interface types:
•
Physical interfaces
•
VLAN subinterfaces
•
Redundant interfaces
For the ASA 5505, you must configure interface parameters for the following interface types:
•
VLAN interfaces
Guidelines and Limitations
•
For the ASA 5550 ASA, 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.
•
For information about security levels, see the “Security Levels” section on page 6-5.
•
If you are using failover, do not use this procedure to name interfaces that you are reserving for
failover and Stateful Failover communications. See the “Configuring Active/Standby Failover”
section on page 33-7 or the “Configuring Active/Active Failover” section on page 34-8 to configure
the failover and state links.
•
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 ASA or context. The exception is for the Management 0/0 or 0/1 management-only interface,
which does not pass through traffic. To set the transparent firewall mode whole ASA or context
management IP address, see the “Setting the Management IP Address for a Transparent Firewall”
section on page 8-7. To set the IP address of the Management 0/0 or 0/1 interface or subinterface,
use this procedure.
Restrictions
PPPoE is not supported in multiple context mode or transparent firewall mode.
Information About the Management Interface
The ASA 5510 and higher ASA includes a dedicated management interface called Management 0/0 or
Management 0/1, depending on your model, which is meant to support traffic to the ASA. However, you
can configure any interface to be a management-only interface. Also, for Management 0/0 or 0/1, you
can disable management-only mode so the interface can pass through traffic just like any other interface.
Transparent firewall mode allows only two interfaces to pass through traffic; however, on the ASA 5510
and higher ASA, you can use the Management 0/0 or 0/1 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.
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Prerequisites
•
Complete the procedures in the “Starting Interface Configuration (ASA 5510 and Higher)” section
on page 6-8 or the “Starting Interface Configuration (ASA 5505)” section on page 6-16.
•
In multiple context mode, complete this procedure in the context execution space. To change from
the system to a context configuration, enter the changeto context name command.
•
Enter interface configuration mode according to the “Entering Interface Configuration Mode”
section on page 6-23.
Detailed Steps
Step 1
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 2
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 3
To set the IP address, enter one of the following commands.
Note
For use with failover, you must set the IP address and standby address manually; DHCP and
PPPoE are not supported.
In transparent firewall mode, do not set the IP address for each interface, but rather set it for the
whole ASA or context. The exception is for the Management 0/0 or 0/1 management-only
interface, which does not pass through traffic.
•
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 the “Configuring Active/Standby
Failover” section on page 33-7 or the “Configuring Active/Active Failover” section on page 34-8 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 ASA 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 69, “Configuring the PPPoE Client.”
PPPoE is not supported in multiple context mode.
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Completing Interface Configuration (All Models)
Step 4
(Optional) To set an interface to management-only mode so that it does not pass through traffic, enter
the following command:
hostname(config-if)# management-only
See the “Information About the Management Interface” section on page 6-24 for more information.
What to Do Next
•
(Optional) Configure the MAC address. See the “Configuring the MAC Address” section on
page 6-26.
•
(Optional) Configure IPv6 addressing. See the “Configuring IPv6 Addressing” section on page 6-27
Configuring the MAC Address
This section describes how to configure MAC addresses for interfaces.
Information About MAC Addresses
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 ASA 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 5-3 for more
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 5-20 to automatically generate MAC addresses. If you automatically
generate MAC addresses, you can use this procedure to override the generated address.
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.
Prerequisites
Enter interface configuration mode according to the “Entering Interface Configuration Mode” section on
page 6-23.
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Detailed Steps
Command
Purpose
mac-address mac_address
[standby mac_address]
Assigns a private MAC address to this interface. 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.
Example:
The first two bytes of a manual MAC address cannot be A2 if you also want
to use auto-generated MAC addresses.
hostname(config-if)# mac-address
000C.F142.4CDE standby 000C.F142.4CDF
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.
What to Do Next
(Optional) Configure IPv6 addressing. See the “Configuring IPv6 Addressing” section on page 6-27
Configuring IPv6 Addressing
This section describes how to configure IPv6 addressing. For more information about IPv6, see the
“Information About IPv6 Support” section on page 18-8 and the “IPv6 Addresses” section on page C-5 .
For transparent mode, use this section for the Management 0/0 or 0/1 interface. To configure the global
IPv6 management address for transparent mode, see the “Configuring the IPv6 Address” section on
page 8-9 .
Information About IPv6 Addressing
When you configure an IPv6 address on an interface, you can assign one or several IPv6 addresses to the
interface at one time, such as an IPv6 link-local address and a global address. However, at a minimum,
you must configure a link-local address.
Every IPv6-enabled interface must include at least one link-local address. When you configure a global
address, a link-local addresses is automatically configured on the interface, so you do not also need to
specifically configure a link-local address. These link-local addresses can only be used to communicate
with other hosts on the same physical link.
Note
If you want to only configure the link-local addresses, see the ipv6 enable (to auto-configure) or ipv6
address link-local (to manually configure) command in the Cisco ASA 5500 Series Command
Reference.
When IPv6 is used over Ethernet networks, the Ethernet MAC address can be used to generate the 64-bit
interface ID for the host. This is called the EUI-64 address. Because MAC addresses use 48 bits,
additional bits must be inserted to fill the 64 bits required. The last 64 bits are used for the interface ID.
For example, FE80::/10 is a link-local unicast IPv6 address type in hexadecimal format.
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Completing Interface Configuration (All Models)
Information About Duplicate Address Detection
During the stateless autoconfiguration process, duplicate address detection (DAD) 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.
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 ASA uses neighbor solicitation messages to perform duplicate address detection. By default, the
number of times an interface performs duplicate address detection is 1.
Information About Modified EUI-64 Interface IDs
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 ASA can enforce this requirement for hosts
attached to the local link.
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.
Prerequisites
Enter interface configuration mode according to the “Entering Interface Configuration Mode” section on
page 6-23.
Restrictions
The ASA does not support IPv6 anycast addresses.
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Completing Interface Configuration (All Models)
Detailed Steps
Command
Step 1
Do one of the following:
ipv6 address autoconfig
Example:
hostname(config-if)# ipv6 address
autoconfig
ipv6 address ipv6-prefix/prefix-length
[eui-64]
Example:
hostname(config-if)# ipv6 address
2001:0DB8::BA98:0:3210/48
Step 2
(Optional)
ipv6 nd suppress-ra
Example:
hostname(config-if)# ipv6 nd suppress-ra
Step 3
(Optional)
ipv6 nd dad attempts value
Example:
hostname(config-if)# ipv6 nd dad attempts
3
Step 4
Purpose
(Optional)
ipv6 nd ns-interval value
Example:
hostname(config-if)# ipv6 nd ns-interval
2000
Enables 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.
Assigns a global address to the interface. When you assign a
global address, the link-local address is automatically created for
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.
See the “IPv6 Addresses” section on page C-5 for more
information about IPv6 addressing.
Suppresses 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
ASA to supply the IPv6 prefix (for example, the outside
interface).
Changes the number of duplicate address detection attempts. The
value argument can be any value from 0 to 600. Setting the value
argument to 0 disables duplicate address detection on the
interface.
By default, the number of times an interface performs duplicate
address detection is 1. See the “Information About Duplicate
Address Detection” section on page 6-28 for more information.
Changes the neighbor solicitation message interval. When you
configure an interface to send out more than one duplicate address
detection attempt with the ipv6 nd dad attempts command, this
command configures the interval at which the neighbor
solicitation messages are sent out. By default, they are sent out
once every 1000 milliseconds. The value argument can be from
1000 to 3600000 milliseconds.
Note
Step 5
(Optional)
Changing this value changes it for all neighbor
solicitation messages sent out on the interface, not just
those used for duplicate address detection.
ipv6 enforce-eui64 if_name
Enforces the use of Modified EUI-64 format interface identifiers
in IPv6 addresses on a local link.
Example:
hostname(config)# ipv6 enforce-eui64
inside
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.
See the “Information About Modified EUI-64 Interface IDs”
section on page 6-28 for more information.
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Configuring Interfaces
Allowing Same Security Level Communication
Allowing Same Security Level Communication
By default, interfaces on the same security level cannot communicate with each other, and packets
cannot enter and exit the same interface. This section describes how to enable inter-interface
communication when interfaces are on the same security level, and how to enable intra-interface
communication.
Information About Inter-Interface Communication
Allowing interfaces on the same security level to communicate with each other 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).
•
You want traffic to flow freely between all same security interfaces without access lists.
If you enable same security interface communication, you can still configure interfaces at different
security levels as usual.
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 26-8 for more information on NAT
and same security level interfaces.
Information About Intra-Interface Communication
Intra-interface communication might be useful for VPN traffic that enters an interface, but is then routed
out the same interface. The VPN traffic might be unencrypted in this case, or it might be reencrypted for
another VPN connection. For example, if you have a hub and spoke VPN network, where the security
appliance is the hub, and remote VPN networks are spokes, for one spoke to communicate with another
spoke, traffic must go into the security appliance and then out again to the other spoke.
Note
All traffic allowed by this feature is still subject to firewall rules. Be careful not to create an asymmetric
routing situation that can cause return traffic not to traverse the ASA.
Restrictions
Intra-interface communication is only available in routed firewall mode. Inter-interface communication
is available for both routed and transparent mode.
Detailed Steps
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
(Routed mode only) To enable communication between hosts connected to the same interface, enter the
following command:
hostname(config)# same-security-traffic permit intra-interface
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Enabling Jumbo Frame Support (ASA 5580 and 5585-X)
To disable these settings, use the no form of the command.
Enabling Jumbo Frame Support (ASA 5580 and 5585-X)
A jumbo frame is an Ethernet packet larger than the standard maximum of 1518 bytes (including Layer
2 header and FCS), up to 9216 bytes. You can enable support for jumbo frames for all interfaces by
increasing the amount of memory to process Ethernet frames. Assigning more memory for jumbo frames
might limit the maximum use of other features, such as access lists.
Note
Other platform models do not support jumbo frames.
Prerequisites
In multiple context mode, set this option in the system execution space.
Detailed Steps
To enable jumbo frame support for the ASA 5580 and 5585-X ASA, enter the following command:
hostname(config)# jumbo-frame reservation
To disable jumbo frames, use the no form of this command.
Note
Changes in this setting require you to reboot the security appliance.
Be sure to set the MTU for each interface that needs to transmit jumbo frames to a higher value than the
default 1500; for example, set the value to 9000 using the mtu command. In multiple context mode, set
the MTU within each context.
Examples
The following example enables jumbo frame reservation, saves the configuration, and reloads the ASA:
hostname(config)# jumbo-frame reservation
WARNING: this command will take effect after the running-config is saved
and the system has been rebooted. Command accepted.
hostname(config)# write memory
Building configuration...
Cryptochecksum: 718e3706 4edb11ea 69af58d0 0a6b7cb5
70291 bytes copied in 3.710 secs (23430 bytes/sec)
[OK]
hostname(config)# reload
Proceed with reload? [confirm] Y
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Configuring Interfaces
Monitoring Interfaces
Monitoring Interfaces
To monitor interfaces, enter one of the following commands:
Command
Purpose
show interface
Displays interface statistics.
show interface ip brief
Displays interface IP addresses and status.
Configuration Examples for Interfaces
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
hostname/contextA(config-if)# nameif inside
hostname/contextA(config-if)# security-level 100
hostname/contextA(config-if)# ip address 10.1.2.1 255.255.255.0
hostname/contextA(config-if)# mac-address 030C.F142.4CDE standby 040C.F142.4CDE
hostname/contextA(config-if)# no shutdown
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
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Feature History for Interfaces
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
Feature History for Interfaces
Table 6-1 lists the release history for this feature.
Table 6-1
Feature History for Interfaces
Feature Name
Releases
Feature Information
Increased VLANs
7.0(5)
Increased the following limits:
•
ASA5510 Base license VLANs from 0 to 10.
•
ASA5510 Security Plus license VLANs from 10 to 25.
•
ASA5520 VLANs from 25 to 100.
•
ASA5540 VLANs from 100 to 200.
Increased interfaces for the Base license on the 7.2(2)
ASA 5510
For the Base license on the ASA 5510, the maximum
number of interfaces was increased from 3 plus a
management interface to unlimited interfaces.
Increased VLANs
The maximum number of VLANs for the Security Plus
license on the ASA 5505 ASA 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.
7.2(2)
VLAN limits were also increased for the ASA 5510 ASA
(from 10 to 50 for the Base license, and from 25 to 100 for
the Security Plus license), the ASA 5520 ASA (from 100 to
150), the ASA 5550 ASA (from 200 to 250).
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Feature History for Interfaces
Table 6-1
Feature History for Interfaces (continued)
Feature Name
Releases
Feature Information
Gigabit Ethernet Support for the ASA 5510
Security Plus License
7.2(3)
The ASA 5510 ASA now supports GE (Gigabit Ethernet)
for port 0 and 1 with the Security Plus license. 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.
Native VLAN support for the ASA 5505
7.2(4)/8.0(4)
You can now include the native VLAN in an ASA 5505
trunk port using the switchport trunk native vlan
command.
Gigabit Ethernet Support for the ASA 5510
Base License
7.2(4)/8.0(4)
The ASA 5510 ASA now supports GE (Gigabit Ethernet)
for port 0 and 1 in the Base license (support was previously
added for the Security Plus license). 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.
Jumbo packet support for the ASA 5580
8.1(1)
The Cisco ASA 5580 supports jumbo frames when you
enter the jumbo-frame reservation command. A jumbo
frame is an Ethernet packet larger than the standard
maximum of 1518 bytes (including Layer 2 header and
FCS), up to 9216 bytes. You can enable support for jumbo
frames for all interfaces by increasing the amount of
memory to process Ethernet frames. Assigning more
memory for jumbo frames might limit the maximum use of
other features, such as access lists.
In ASDM, see Configuration > Device Setup > Interfaces >
Add/Edit Interface > Advanced.
Increased VLANs for the ASA 5580
8.1(2)
The number of VLANs supported on the ASA 5580 are
increased from 100 to 250.
Support for Pause Frames for Flow Control on
the ASA 5580 10 Gigabit Ethernet Interfaces
8.2(2)
You can now enable pause (XOFF) frames for flow control.
This feature is also supported for the ASA 5585-X.
The following command was introduced: flowcontrol.
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7
Configuring DHCP and Dynamic DNS Services
This chapter describes how to configure the DHCP server and dynamic DNS (DDNS) update methods.
This chapter includes the following topics:
•
Configuring DHCP Services, page 7-1
•
Configuring DDNS Services, page 7-7
Configuring DHCP Services
This section includes the following topics:
•
Information about DHCP, page 7-1
•
Licensing Requirements for DHCP, page 7-1
•
Guidelines and Limitations, page 7-2
•
Configuring a DHCP Server, page 7-2
•
Configuring DHCP Relay Services, page 7-6
Information about DHCP
DHCP provides network configuration parameters, such as IP addresses, to DHCP clients. The ASA can
provide a DHCP server or DHCP relay services to DHCP clients attached to ASA 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.
Licensing Requirements for DHCP
Table 7-1 lists the license requirements for DHCP.
Table 7-1
License Requirements
Model
License Requirement
All models
Base License.
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Configuring DHCP and Dynamic DNS Services
Configuring DHCP Services
For the Cisco ASA 5505 Adaptive Security Appliance, the maximum number of DHCP client addresses
varies depending on the license:
Note
•
If the Host limit is 10 hosts, we limit the DHCP pool to 32 addresses.
•
If the Host limit is 50 hosts, we limit the DHCP pool to 128 addresses.
•
If the Host limit is unlimited, we limit the DHCP pool to 256 addresses.
By default the Cisco ASA 5505 Adaptive Security Appliance comes with a 10-user license.
Guidelines and Limitations
Use the following guidelines to configure the DHCP server:
•
You can configure a DHCP server on each interface of the ASA. 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.
•
The ASA does not support QIP DHCP servers for use with DHCP Proxy.
•
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.
•
You can add up to four DHCP relay servers per interface; however, there is a limit of ten DHCP relay
servers total that can be configured on the ASA. You must add at least one dhcprelay server
command to the ASA configuration before you can enter the dhcprelay enable command. You
cannot configure a DHCP client on an interface that has a DHCP relay server configured
Configuring a DHCP Server
This section describes how to configure DHCP server provided by the ASA. This section includes the
following topics:
•
Enabling the DHCP Server, page 7-2
•
Configuring DHCP Options, page 7-3
•
Using Cisco IP Phones with a DHCP Server, page 7-5
Enabling the DHCP Server
The ASA 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.
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Configuring DHCP Services
Note
The ASA 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.
To enable the DHCP server on a given ASA interface, perform the following steps:
Enter the following command to define the address pool:
Step 1
Command
Purpose
dhcpd address ip_address-ip_address
interface_name
Create a DHCP address pool. The ASA 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.
Example:
hostname(config)# dhcpd address
10.0.1.101-10.0.1.110 inside
Step 2
dhcpd dns dns1 [dns2]
The address pool must be on the same subnet as the ASA
interface.
(Optional) Specifies the IP address(es) of the DNS server(s).
Example:
hostname(config)# dhcpd dns 209.165.201.2
209.165.202.129
Step 3
dhcpd wins wins1 [wins2]
(Optional) Specifies the IP address(es) of the WINS server(s).
You can specify up to two WINS servers.
Example:
hostname(config)# dhcpd wins 209.165.201.5
Step 4
dhcpd lease lease_length
Example:
hostname(config)# dhcpd lease 3000
Step 5
dhcpd domain domain_name
(Optional) Change the lease length to be granted to the client.
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 0 to 1,048,575. The default value is 3600 seconds.
(Optional) Configures the domain name.
Example:
hostname(config)# dhcpd domain example.com
Step 6
dhcpd ping_timeout milliseconds
(Optional) Configures the DHCP ping timeout value. To avoid
address conflicts, the ASA 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
dhcpd option 3 ip gateway_ip
(Transparent Firewall Mode) Defines a default gateway that is
sent to DHCP clients. 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
dhcpd enable interface_name
Enables the DHCP daemon within the ASA to listen for DHCP
client requests on the enabled interface
Configuring DHCP Options
You can configure the ASA to send information for the DHCP options listed in RFC 2132. The DHCP
options fall into one of three categories:
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The ASA supports all three categories of DHCP options. To configure a DHCP option, do one of the
following:
Options that return an IP address
Command
Purpose
dhcpd option code ip addr_1 [addr_2]
Configures a DHCP option that returns one or two IP addresses.
Options that return a text string
Command
Purpose
dhcpd option code ascii text
Configures a DHCP option that returns one or two IP addresses.
Options that return a hexadecimal value
.
Command
Purpose
dhcpd option code hex value
Configures a DHCP option that returns a hexadecimal value.
Note
The ASA 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 ASA 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 7-2 shows the DHCP options that are not supported by the dhcpd option command.
Table 7-2
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
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Table 7-2
Unsupported DHCP Options
Option Code
Description
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 7-5 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 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 ASA DHCP
server provides values for both options in the response if they are configured on the ASA.
You can configure the ASA 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:
Command
Purpose
dhcpd option number value
Provides information for DHCP requests that include an option number as
specified in RFC-2132
Command
Purpose
dhcpd option 66 ascii server_name
Provides the IP address or name of a TFTP server for option 66
Command
Purpose
dhcpd option 150 ip server_ip1
[server_ip2]
Provides the IP address or names of one or two TFTP servers for option 150
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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.
Command
Purpose
dhcpd option 3 ip router_ip1
Sets the default route
Configuring DHCP Relay Services
A DHCP relay agent allows the ASA 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:
Note
•
The relay agent cannot be enabled if the DHCP server feature is also enabled.
•
DHCP clients must be directly connected to the ASA 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 ASA in transparent firewall
mode only allows ARP traffic through; all other traffic requires an access list. To allow DHCP
requests and replies through the ASA 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.
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
Command
Purpose
dhcprelay server ip_address if_name
Set the IP address of a DHCP server on a different interface from
the DHCP client.
Example:
hostname(config)# dhcprelay server
201.168.200.4
Step 2
dhcprelay enable interface
You can use this command up to 4 times to identify up to 4
servers.
Enables DHCP relay on the interface connected to the clients.
Example:
hostname(config)# dhcprelay enable inside
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Command
Purpose
Step 3
dhcprelay timeout seconds
(Optional) Set the number of seconds allowed for relay address
negotiation.
Step 4
dhcprelay setroute interface_name
(Optional) Change the first default router address in the packet
sent from the DHCP server to the address of the ASA interface.
Example:
hostname(config)# dhcprelay setroute
inside
This action allows the client to set its default route to point to the
ASA even if the DHCP server specifies a different router.
If there is no default router option in the packet, the ASA adds one
containing the interface address.
Feature History for DHCP
Table 7-3 lists the release history for this feature.
Table 7-3
Feature History for DHCP
Feature Name
Releases
Feature Information
DHCP
7.0(1)
This feature was introduced.
Configuring DDNS Services
This section includes the following topics:
•
Information about DDNS, page 7-7
•
Licensing Requirements For DDNS, page 7-7
•
Configuring DDNS, page 7-8
•
Configuration Examples for DDNS, page 7-8
•
Feature History for DDNS, page 7-11
Information about DDNS
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.
Licensing Requirements For DDNS
Table 7-4 lists the license requirements for DDNS.
Table 7-4
License Requirements
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Configuring DDNS Services
Model
License Requirement
All models
Base License.
Configuring DDNS
This section describes examples for configuring the ASA 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
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 ASA 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.
Configuration Examples for DDNS
The following examples present these common scenarios:
•
Example 1: Client Updates Both A and PTR RRs for Static IP Addresses, page 7-8
•
Example 2: Client Updates Both A and PTR RRs; DHCP Server Honors Client Update Request;
FQDN Provided Through Configuration, page 7-9
•
Example 3: Client Includes FQDN Option Instructing Server Not to Update Either RR; Server
Overrides Client and Updates Both RRs., page 7-9
•
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 7-10
•
Example 5: Client Updates A RR; Server Updates PTR RR, page 7-10
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:
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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:
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 ASA 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
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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
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
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Step 3
To configure the DHCP server, enter the following commands:
hostname(config-if)# dhcpd update dns
hostname(config-if)# dhcpd domain example.com
Feature History for DDNS
Table 7-5 lists the release history for this feature.
Table 7-5
Feature History for DDNS
Feature Name
Releases
Feature Information
DHCP
7.0(1)
This feature was introduced.
DDNS
7.0(1)
This feature was introduced.
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8
Configuring Basic Settings
This chapter describes how to configure basic settings on your ASA that are typically required for a
functioning configuration. This chapter includes the following sections:
•
Changing the Login Password, page 8-1
•
Changing the Enable Password, page 8-2
•
Setting the Hostname, page 8-2
•
Setting the Domain Name, page 8-3
•
Setting the Date and Time, page 8-3
•
Configuring the DNS Server, page 8-6
•
Setting the Management IP Address for a Transparent Firewall, page 8-7
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:
Command
Purpose
{passwd | password} password
Changes the 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.
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Changing the Enable Password
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:
Command
Purpose
enable password password
Changes the enable 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.
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 ASA, 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.
Command
Purpose
hostname name
Specifies the hostname for the ASA or for a context.
Example:
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.
hostname(config)# hostname farscape
farscape(config)#
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Setting the Domain Name
Setting the Domain Name
The ASA 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.
Command
Purpose
domain-name name
Specifies the domain name for the ASA.
Example:
For example, to set the domain as example.com.
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.
This section includes the following topics:
•
Setting the Time Zone and Daylight Saving Time Date Range, page 8-4
•
Setting the Date and Time Using an NTP Server, page 8-5
•
Setting the Date and Time Manually, page 8-6
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Setting the Date and Time
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
Command
Purpose
clock timezone zone
[-]hours [minutes]
Sets the time zone.
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
Do one of the following 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:
clock summer-time zone
date {day month | month
day} year hh:mm {day
month | month day} year
hh:mm [offset]
Sets the start and end dates for daylight saving time as a specific date in a specific year.
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.
clock summer-time zone
recurring [week weekday
month hh:mm week weekday
month hh:mm] [offset]
Specifies 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.
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.
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.
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Setting the Date and Time
Setting the Date and Time Using an NTP Server
To obtain the date and time from an NTP server, perform the following steps:S
Command
Purpose
Step 1
ntp authenticate
Enables authentication with an NTP server.
Step 2
ntp trusted-key key_id
Specifies an authentication key ID to be a trusted key, which is required for
authentication with an NTP server.
Where the key_id is between 1 and 4294967295. You can enter multiple
trusted keys for use with multiple servers.
Step 3
ntp authentication-key key_id
md5 key
Sets a key to authenticate with an NTP server.
Where key_id is the ID you set in Step 2 using the ntp trusted-key
command, and key is a string up to 32 characters in length.
Step 4
ntp server ip_address [key
key_id] [source interface_name]
[prefer]
Identifies an NTP server.
Where the key_id is the ID you set in Step 2 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 ASA uses the more accurate one. For example, the ASA uses a
server of stratum 2 over a server of stratum 3 that is preferred.
You can identify multiple servers; the ASA uses the most accurate server.
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Setting the Date and Time Manually
Command
Purpose
clock set hh:mm:ss {month day | day month}
year
Sets the date time manually.
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.
Configuring the DNS Server
Some ASA features require use of a DNS server to access external servers by domain name; for example,
the Botnet Traffic Filter feature requires a DNS server to access the dynamic database server and to
resolve entries in the static database. Other features, such as the ping or traceroute command, let you
enter a name that you want to PING for traceroute, and the ASA can resolve the name by communicating
with a DNS server. Many SSL VPN and certificate commands also support names.
Note
The ASA has limited support for using the DNS server, depending on the feature. For example, most
commands require you to enter an IP address and can only use a name when you manually configure the
name command to associate a name with an IP address and enable use of the names using the names
command.
For information about dynamic DNS, see the “Configuring DDNS” section on page 7-8.
Prerequisites
Make sure you configure the appropriate routing for any interface on which you enable DNS domain
lookup so you can reach the DNS server. See the “Information About Routing” section on page 18-1 for
more information about routing.
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Detailed Steps
Step 1
Command
Purpose
dns domain-lookup interface_name
Enables the ASA to send DNS requests to a DNS server to perform a
name lookup for supported commands.
Example:
hostname(config)# dns domain-lookup
inside
Step 2
dns server-group DefaultDNS
Example:
hostname(config)# dns server-group
DefaultDNS
Step 3
name-server ip_address [ip_address2]
[...] [ip_address6]
Example:
hostname(config-dns-server-group)#
name-server 10.1.1.5 192.168.1.67
209.165.201.6
Specifies the DNS server group that the ASA uses for from-the-box
requests.
Other DNS server groups can be configured for VPN tunnel groups.
See the tunnel-group command in the Cisco ASA 5500 Series
Command Reference for more information.
Specifies one or more DNS servers. You can enter all 6 IP addresses
in the same command, separated by spaces, or you can enter each
command separately. The security appliance tries each DNS server in
order until it receives a response.
Setting the Management IP Address for a Transparent Firewall
This section describes how to configure the management IP address for transparent firewall mode, and
includes the following topics:
•
Information About the Management IP Address, page 8-7
•
Licensing Requirements for the Management IP Address for a Transparent Firewall, page 8-8
•
Guidelines and Limitations, page 8-8
•
Configuring the IPv4 Address, page 8-9
•
Configuring the IPv6 Address, page 8-9
•
Configuration Examples for the Management IP Address for a Transparent Firewall, page 8-10
•
Feature History for the Management IP Address for a Transparent Firewall, page 8-10
Information About the Management IP Address
A transparent firewall does not participate in IP routing. The only IP configuration required for the ASA
is to set the management IP address. This address is required because the ASA uses this address as the
source address for traffic originating on the ASA, such as system messages or communications with
AAA servers. You can also use this address for remote management access.
For IPv4 traffic, the management IP address is required to pass any traffic. For IPv6 traffic, you must, at
a minimum, configure the link-local addresses to pass traffic, but a global management address is
recommended for full functionality, including remote management and other management operations.
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Note
In addition to the management IP address for the device, you can configure an IP address for the
Management 0/0 or 0/1 management-only interface. This IP address can be on a separate subnet from
the main management IP address. See the “Configuring General Interface Parameters” section on
page 6-24.
Although you do not configure IPv4 or global IPv6 addresses for other interfaces, you still need to
configure the security level and interface name according to the “Configuring General Interface
Parameters” section on page 6-24.
Licensing Requirements for the Management IP Address for a Transparent
Firewall
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
Supported in single and multiple context mode. For multiple context mode, set the management IP
address within each context.
Firewall Mode Guidelines
Supported in transparent firewall mode. For routed mode, set the IP address for each interface according
to the “Configuring General Interface Parameters” section on page 6-24.
IPv6 Guidelines
•
Supports IPv6.
•
The following IPv6 address-related commands are not supported in transparent mode, because they
require router capabilities:
– ipv6 address autoconfig
– ipv6 nd suppress-ra
For a complete list of IPv6 commands that are not supported in transparent mode, see the
“IPv6-Enabled Commands” section on page 18-9.
•
No support for IPv6 anycast addresses.
•
You can configure both IPv6 and IPv4 addresses.
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Additional Guidelines and Limitations
•
In addition to the management IP address for the device, you can configure an IP address for the
Management 0/0 or 0/1 management-only interface. This IP address can be on a separate subnet
from the main management IP address. See the “Configuring General Interface Parameters” section
on page 6-24.
•
Although you do not configure IP addresses for other interfaces, you still need to configure the
security level and interface name according to the “Configuring General Interface Parameters”
section on page 6-24.
Configuring the IPv4 Address
To set the management IPv4 address, enter the following command in global configuration mode:
Command
Purpose
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). The
standby keyword and address is used for failover. See the “Configuring
Active/Standby Failover” section on page 33-7 or the “Configuring
Active/Active Failover” section on page 34-8 for more information.
Example:
hostname(config)# ip address 10.1.1.1
255.255.255.0 standby 10.1.1.2
Configuring the IPv6 Address
When you configure a global address, a link-local addresses is automatically configured on each
interface, so you do not also need to specifically configure a link-local address.
Note
If you want to only configure the link-local addresses, see the ipv6 enable or ipv6 address link-local
command in the Cisco ASA 5500 Series Command Reference.
To set the global management IPv6 address, enter the following command in global configuration mode:
Command
Purpose
ipv6 address ipv6-prefix/prefix-length
Assigns a global address. When you assign a global address, link-local
addresses are automatically created for each interface.
Example:
hostname(config)# ipv6 address
2001:0DB8::BA98:0:3210/48
Note
The eui keyword, which is available in routed mode, is not
available in transparent mode. The EUI address ties the unicast
address to the ASA interface MAC address; but because the
transparent mode IP address is not tied to an interface, an interface
MAC address cannot be used.
See the “IPv6 Addresses” section on page C-5 for more information about
IPv6 addressing.
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Configuration Examples for the Management IP Address for a Transparent
Firewall
The following example sets the IPv4 and IPv6 global management IP addresses, and configures the
inside, outside, and management interfaces:
hostname(config)# ip address 10.1.1.1 255.255.255.0 standby 10.1.1.2
hostname(config)# ipv6 address 2001:0DB8::BA98:0:3210/48
hostname(config)# interface gigabitethernet 0/0
hostname(config-if)# nameif inside
hostname(config-if)# security-level 100
hostname(config-if)# no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface gigabitethernet 0/1
nameif outside
security-level 0
no shutdown
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
hostname(config-if)#
interface management 0/0
nameif management
security-level 50
ip address 10.1.2.1 255.255.255.0
ipv6 address 2001:0DB8::BA98:0:3211/48
no shutdown
Feature History for the Management IP Address for a Transparent Firewall
Table 8-1 lists the release history for this feature.
Table 8-1
Feature History for Transparent Mode Management Address
Feature Name
Releases
Feature Information
IPv6 support
8.2(1)
IPv6 support was introduced for transparent firewall mode.
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9
Using Modular Policy Framework
This chapter describes how to use Modular Policy Framework to create security policies for multiple
features, including TCP and general connection settings, inspections, IPS, CSC, and QoS. This chapter
includes the following sections:
•
Information About Modular Policy Framework, page 9-1
•
Licensing Requirements for Modular Policy Framework, page 9-9
•
Guidelines and Limitations, page 9-9
•
Default Settings, page 9-10
•
Configuring Modular Policy Framework, page 9-12
•
Monitoring Modular Policy Framework, page 9-26
•
Configuration Examples for Modular Policy Framework, page 9-26
•
Feature History for Modular Policy Framework, page 9-30
Information About Modular Policy Framework
Modular Policy Framework provides a consistent and flexible way to configure ASA 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 9-1
•
Information About Configuring Modular Policy Framework, page 9-2
•
Information About Inspection Policy Maps, page 9-4
•
Information About Layer 3/4 Policy Maps, page 9-5
Modular Policy Framework Supported Features
Features can be applied to through traffic or to management traffic. This section includes the following
topics:
•
“Supported Features for Through Traffic” section on page 9-2
•
“Supported Features for Management Traffic” section on page 9-2
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Supported Features for Through Traffic
Table 9-1 lists the features supported by Modular Policy Framework.
Table 9-1
Modular Policy Framework Features
Feature
Application inspection (multiple types)
See:
•
Chapter 40, “Getting Started With Application Layer
Protocol Inspection.”
•
Chapter 41, “Configuring Inspection of Basic Internet
Protocols.”
•
Chapter 43, “Configuring Inspection of Database and
Directory Protocols.”
•
Chapter 44, “Configuring Inspection for Management
Application Protocols.”
•
Chapter 42, “Configuring Inspection for Voice and
Video Protocols.”
CSC
Chapter 60, “Configuring the Content Security and Control
Application on the CSC SSM.”
IPS
Chapter 59, “Configuring the IPS Module.”
NetFlow Secure Event Logging filtering Chapter 75, “Configuring NetFlow Secure Event Logging
(NSEL).”
QoS input and output policing
Chapter 55, “Configuring QoS.”
QoS standard priority queue
Chapter 55, “Configuring QoS.”
QoS traffic shaping, hierarchical priority Chapter 55, “Configuring QoS.”
queue
TCP and UDP connection limits and
timeouts, and TCP sequence number
randomization
Chapter 53, “Configuring Connection Limits and
Timeouts.”
TCP normalization
Chapter 52, “Configuring TCP Normalization.”
TCP state bypass
Chapter 51, “Configuring TCP State Bypass.”
Supported Features for Management Traffic
Modular Policy Framework supports the following features for management traffic:
•
Application inspection for RADIUS accounting traffic—See Chapter 44, “Configuring Inspection
for Management Application Protocols.”
•
Connection limits—See Chapter 53, “Configuring Connection Limits and Timeouts.”
Information About Configuring Modular Policy Framework
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.
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For example, you might want to perform actions on all traffic that passes through the ASA; 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 9-13.
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 9-17 and the “Identifying
Traffic in an Inspection Class Map” section on page 9-19.
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.”
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 9-21 and the “Creating a Regular
Expression Class Map” section on page 9-23.
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.
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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 9-24 and the “Applying Actions
to an Interface (Service Policy)” section on page 9-25.
Information About Inspection Policy Maps
See the “Configuring Application Layer Protocol Inspection” section on page 40-6 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.
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– 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.
Information About Layer 3/4 Policy Maps
This section describes how Layer 3/4 policy maps work, and includes the following topics:
•
Feature Directionality, page 9-5
•
Feature Matching Within a Policy Map, page 9-6
•
Order in Which Multiple Feature Actions are Applied, page 9-6
•
Incompatibility of Certain Feature Actions, page 9-8
•
Feature Matching for Multiple Policy Maps, page 9-8
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 enters (or
exits, depending on the feature) the interface to which you apply the policy map is affected. See
Table 9-2 for the directionality of each feature.
Table 9-2
Feature Directionality
Feature
Single Interface Direction Global Direction
Application inspection (multiple types)
Bidirectional
Ingress
CSC
Bidirectional
Ingress
IPS
Bidirectional
Ingress
NetFlow Secure Event Logging filtering
N/A
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 and UDP connection limits and timeouts, Bidirectional
and TCP sequence number randomization
Ingress
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Table 9-2
Feature Directionality
Feature
Single Interface Direction Global Direction
TCP normalization
Bidirectional
Ingress
TCP state bypass
Bidirectional
Ingress
Feature Matching Within a Policy Map
See the following information 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 ASA 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 ASA
also applies the actions for the subsequent class map, if supported. See the “Incompatibility of
Certain Feature Actions” section on page 9-8 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.
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.
Note
NetFlow Secure Event Logging filtering is order-independent.
Actions are performed in the following order:
1.
QoS input policing
2.
TCP normalization, TCP and UDP connection limits and timeouts, TCP sequence number
randomization, and TCP state bypass.
Note
When a the ASA 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)
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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 be applied along with other inspections for the same
traffic. See the “Incompatibility of Certain Feature Actions” section on page 9-8 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
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
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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 ASA 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 9-6.
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 ASA, then the ASA applies the TFTP inspection;
when TCP traffic for port 21 arrives, then the ASA applies the FTP inspection. So in this case only, you
can configure multiple inspections for the same class map. Normally, the ASA does not use the port
number to determine which inspection to apply, 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 9-1, traffic destined to port 21 is
mistakenly configured for both FTP and HTTP inspection. In Example 9-2, 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 9-1
Misconfiguration for FTP packets: HTTP Inspection Also Configured
class-map ftp
match port tcp eq 21
class-map http
match port tcp eq 21
policy-map test
class ftp
inspect ftp
class http
inspect http
Example 9-2
[it should be 80]
Misconfiguration for HTTP packets: FTP Inspection Also Configured
class-map ftp
match port tcp eq 80
class-map http
match port tcp eq 80
policy-map test
class http
inspect http
class ftp
inspect ftp
[it should be 21]
Feature Matching 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.
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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 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.
Licensing Requirements for Modular Policy Framework
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed and transparent firewall mode.
IPv6 Guidelines
Supports IPv6 for the following features:
•
Application inspection for FTP, HTTP, ICMP, SIP, SMTP and IPSec-pass-thru
•
IPS
•
NetFlow Secure Event Logging filtering
•
TCP and UDP connection limits and timeouts, TCP sequence number randomization
•
TCP normalization
•
TCP state bypass
Class Map Guidelines
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
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Default Settings
This limit also includes default class maps of all types, limiting user-configured class maps to
approximately 235. . See the “Default Class Maps” section on page 9-11.
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 up to 63 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 9-8.
Service Policy Guidelines
•
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 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.
•
You can only apply one global policy. For example, you cannot create a global policy that includes
feature set 1, and a separate global policy that includes feature set 2. All features must be included
in a single policy.
Default Settings
The following topics describe the default settings for Modular Policy Framework:
•
Default Configuration, page 9-10
•
Default Class Maps, page 9-11
•
Default Inspection Policy Maps, page 9-11
Default Configuration
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.)
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
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Default Settings
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 9-8 for more information about the
special match default-inspection-traffic command used in the default class map.
Default Class Maps
The configuration includes a default Layer 3/4 class map that the ASA 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
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 ASA, then the ASA applies the TFTP inspection;
when TCP traffic for port 21 arrives, then the ASA applies the FTP inspection. So in this case only, you
can configure multiple inspections for the same class map. Normally, the ASA does not use the port
number to determine which inspection to apply, thus giving you the flexibility to apply inspections to
non-standard ports, for example.
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 ASA 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.
Default Inspection Policy Maps
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
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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.
Configuring Modular Policy Framework
This section describes how to configure your security polcy using Modular Policy Framework, and
includes the following topics:
•
Task Flow for Configuring Hierarchical Policy Maps, page 9-12
•
Identifying Traffic (Layer 3/4 Class Map), page 9-13
•
Configuring Special Actions for Application Inspections (Inspection Policy Map), page 9-16
•
Defining Actions (Layer 3/4 Policy Map), page 9-24
•
Applying Actions to an Interface (Service Policy), page 9-25
Task Flow for Configuring 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 55, “Information About QoS,” 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 steps:
Step 1
Identify the prioritized traffic according to the “Identifying Traffic (Layer 3/4 Class Map)” section on
page 9-13.
You can create multiple class maps to be used in the hierarchical policy map.
Step 2
Create a policy map according to the “Defining Actions (Layer 3/4 Policy Map)” section on page 9-24,
and identify the sole action for each class map as priority.
Step 3
Create a separate policy map according to the “Defining Actions (Layer 3/4 Policy Map)” section on
page 9-24, and identify the shape action for the class-default class map.
Traffic shaping can only be applied the to class-default class map.
Step 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.
Step 5
Apply the shaping policy map to the interface accrding to “Applying Actions to an Interface (Service
Policy)” section on page 9-25.
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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:
•
Creating a Layer 3/4 Class Map for Through Traffic, page 9-13
•
Creating a Layer 3/4 Class Map for Management Traffic, page 9-15
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.
Detailed 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
Note
•
For features that support IPv6 (see the “Guidelines and Limitations” section on page 9-9),
then the match any and match default-inspection-traffic commands are the only
commands that match IPv6 traffic. For example, you cannot match an IPv6 access list.
Access list—The class map matches traffic specified by an extended access list. If the ASA 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 Chapter 11, “Adding an Extended Access List,”
or Chapter 12, “Adding an EtherType Access List.”.
For information about creating access lists with NAT, see the “IP Addresses Used for Access Lists
When You Use NAT” section on page 10-3.
•
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}
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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 ASA 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 ASA, then the
ASA applies the TFTP inspection; when TCP traffic for port 21 arrives, then the ASA 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 9-8 for more information about
combining actions). Normally, the ASA 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 Settings” section on page 40-4 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 and protocols to match, any ports and protocols in the access list are ignored.
Tip
We suggest that you only inspect traffic on ports on which you expect application traffic; if you
inspect all traffic, for example using match any, the ASA performance can be impacted.
Note
•
For features that support IPv6 (see the “Guidelines and Limitations” section on page 9-9),
then the match any and match default-inspection-traffic commands are the only
commands that match IPv6 traffic. For example, you cannot match an IPv6 access list.
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.
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hostname(config-cmap)# match rtp starting_port range
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.
Examples
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 ASA, 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. See the “Supported Features for Management Traffic” section on page 9-2.
Detailed Steps
Step 1
Create a class map by entering the following command:
hostname(config)# class-map type management class_map_name
hostname(config-cmap)#
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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 ASA 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 Chapter 11, “Adding an Extended Access List,”
or Chapter 12, “Adding an EtherType Access List.”
For information about creating access lists with NAT, see the “IP Addresses Used for Access Lists
When You Use NAT” section on page 10-3.
•
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:
•
Defining Actions in an Inspection Policy Map, page 9-17
•
Identifying Traffic in an Inspection Class Map, page 9-19
•
Creating a Regular Expression, page 9-21
•
Creating a Regular Expression Class Map, page 9-23
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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.
Restrictions
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 ASA
applies the actions is determined by internal ASA 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
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
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policy-map type inspect ftp ftp
class ftp3
log
class ftp2
log
class ftp1
log
Detailed Steps
Step 1
(Optional) Create an inspection class map according to the “Identifying Traffic in an Inspection Class
Map” section on page 9-19. 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)#
See the “Configuring Application Layer Protocol Inspection” section on page 40-6 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.
For information about including multiple class or match commands, see the “Restrictions”
section on page 9-17.
Note
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 9-19 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 the applicable inspection chapter. 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 the appropriate inspection chapter 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.
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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.
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
the appropriate inspection chapter.
Examples
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
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.
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.
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Restrictions
Not all applications support inspection class maps. See the CLI help for class-map type inspect for a
list of supported applications.
Detailed Steps
Step 1
(Optional) If you want to match based on a regular expression, see the “Creating a Regular Expression”
section on page 9-21 and the “Creating a Regular Expression Class Map” section on page 9-23.
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 40, “Getting Started With Application Layer
Protocol Inspection.”
The class_map_name argument is the name of the class map up to 40 characters in length.
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 the appropriate inspection chapter.
Examples
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
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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.
Guidelines
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 ASA 5500 Series Command Reference for performance impact
information when matching a regular expression to packets.
Note
As an optimization, the ASA 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 9-3 lists the metacharacters that have special meanings.
Table 9-3
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.
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Table 9-3
regex Metacharacters (continued)
Character Description
Notes
[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.
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.
Detailed 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".
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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.
Examples
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
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.
Detailed 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
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Configuring Modular Policy Framework
Examples
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.
Restrictions
The maximum number of policy maps is 64, but you can only apply one policy map per interface.
Detailed 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 9-13 to add a class map.
Step 4
Specify one or more actions for this class map. See the “Supported Features for Through Traffic” section
on page 9-2.
Note
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.
For QoS, you can configure a hierarchical policy map for the traffic shaping and priority queue
features. See the “Task Flow for Configuring Hierarchical Policy Maps” section on page 9-12
for more information.
Step 5
Repeat Step 3 and Step 4 for each class map you want to include in this policy map.
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Examples
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 ASA 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.
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Monitoring Modular Policy Framework
Restrictions
You can only apply one global policy.
Detailed Steps
•
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
Examples
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 ASA interfaces:
hostname(config)# no service-policy global_policy global
hostname(config)# service-policy new_global_policy global
Monitoring Modular Policy Framework
To monitor Modular Policy Framework, enter the following command:
Command
Purpose
show service-policy
Displays the service policy statistics.
Configuration Examples for Modular Policy Framework
This section includes several Modular Policy Framework examples, and includes the following topics:
•
Applying Inspection and QoS Policing to HTTP Traffic, page 9-27
•
Applying Inspection to HTTP Traffic Globally, page 9-27
•
Applying Inspection and Connection Limits to HTTP Traffic to Specific Servers, page 9-28
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Configuration Examples for Modular Policy Framework
•
Applying Inspection to HTTP Traffic with NAT, page 9-29
Applying Inspection and QoS Policing to HTTP Traffic
In this example (see Figure 9-1), any HTTP connection (TCP traffic on port 80) that enters or exits the
ASA 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 9-1
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 9-2), any HTTP connection (TCP traffic on port 80) that enters the ASA
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 9-2
Global HTTP Inspection
Security
appliance
port 80
A
Host A
inside
port 80 insp.
outside
Host B
143414
insp.
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Configuration Examples for Modular Policy Framework
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)# service-policy http_traffic_policy global
Applying Inspection and Connection Limits to HTTP Traffic to Specific Servers
In this example (see Figure 9-3), any HTTP connection destined for Server A (TCP traffic on port 80)
that enters the ASA 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 ASA 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 9-3
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
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hostname(config-pmap-c)# inspect http
hostname(config)# service-policy policy_serverB interface inside
hostname(config)# service-policy policy_serverA interface outside
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 9-4
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
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Feature History for Modular Policy Framework
Feature History for Modular Policy Framework
Table 9-4 lists the release history for this feature.
Table 9-4
Feature History for Feature-1
Feature Name
Releases
Feature Information
Modular Policy Framework
7.0(1)
Modular Policy Framework was introduced.
Management class map for use with RADIUS
accounting traffic
7.2(1)
The management class map was introduced for use with
RADIUS accounting traffic. The following commands were
introduced: class-map type management, and inspect
radius-accounting.
Inspection policy maps
7.2(1)
The inspection policy map was introduced. The following
command was introduced: class-map type inspect.
Regular expressions and policy maps
7.2(1)
Regular expressions and policy maps were introduced to be
used under inspection policy maps. The following
commands were introduced: class-map type regex, regex,
match regex.
Match any for inspection policy maps
8.0(2)
The match any keyword was introduced for use with
inspection policy maps: traffic can match one or more
criteria to match the class map. Formerly, only match all
was available.
Maximum connections and embryonic
connections for management traffic
8.0(2)
The set connection command is now available for a Layer
3/4 management class map, for to-the-security appliance
management traffic. Only the conn-max and
embryonic-conn-max keywords are available.
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A R T
2
Configuring Access Lists
CH A P T E R
10
Information About Access Lists
Cisco ASA 5500 Series Adaptive Security Appliances provide basic traffic filtering capabilities with
access lists, which control access in your network by preventing certain traffic from entering or exiting.
This chapter describes access lists and shows how to add them to your network configuration.
Access lists are made up of one or more access control entries (ACEs). An ACE is a single entry in an
access list that specifies a permit or deny rule (to forward or drop the packet) and is applied to a protocol,
to a source and destination IP address or network, and, optionally, to the source and destination ports.
Access lists can be configured for all routed and network protocols (IP, AppleTalk, and so on) to filter
the packets of those protocols as the packets pass through a router.
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 9, “Using Modular Policy Framework.”
This chapter includes the following sections:
•
Access List Types, page 10-1
•
Access Control Entry Order, page 10-2
•
Access Control Implicit Deny, page 10-3
•
IP Addresses Used for Access Lists When You Use NAT, page 10-3
Access List Types
The adaptive security appliance uses five types of access control lists:
•
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. For more information, see Chapter 13, “Adding a Standard Access List.”
•
Extended access lists—Use one or more access control entries (ACE) in which you can specify the
line number to insert the ACE, the source and destination addresses, and, depending upon the ACE
type, the protocol, the ports (for TCP or UDP), or the IPCMP type (for ICMP). For more
information, see Chapter 11, “Adding an Extended Access List.”
•
EtherType access lists—Use one or more ACEs that specify an EtherType. For more information,
see Chapter 12, “Adding an EtherType Access List.”
•
Webtype access lists—Used in a configuration that supports filtering for clientless SSL VPN. For
more information, see Chapter 14, “Adding a Webtype Access List.”
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Information About Access Lists
Access Control Entry Order
•
IPv6 access lists—Determine which IPv6 traffic to block and which traffic to forward at router
interfaces. For more information, see Chapter 15, “Adding an IPv6 Access List.”
Table 10-1 lists the types of access lists and some common uses for them.
Table 10-1
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 ASA 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 ASA 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 37, “Configuring Management 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 ASA.
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.
Control network access for IPV6
networks
IPv6
You can add and apply access lists to control traffic in
IPv6 networks.
EtherType
Access Control Entry Order
An access list is made up of one or more Access Control Entry (ACE). Each ACE that you enter for a
given access list name is appended to the end of the access list. 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.
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Information About Access Lists
Access Control Implicit Deny
The order of ACEs is important. When the ASA decides whether to forward or to drop a packet, the ASA
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 checked, and the packet is forwarded.
Access Control Implicit Deny
Each access list has an implicit deny statement at the end, so unless you explicitly permit traffic to pass,
it will be denied. For example, if you want to allow all users to access a network through the ASA except
for one or more particular addresses, then you need to deny those 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 that 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.
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Information About Access Lists
IP Addresses Used for Access Lists When You Use NAT
For example, if you want to apply an access list to the inbound direction of the inside interface, you
configure the ASA 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 10-1.)
Figure 10-1
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
hostname(config)# access-group INSIDE in interface inside
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IP Addresses Used for Access Lists When You Use NAT
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 10-2.)
Figure 10-2
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
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Where to Go Next
If you perform NAT on both interfaces, keep in mind the addresses that are visible to a given interface.
Figure 10-3 shows an outside server that uses static NAT so that a translated address appears on the
inside network.
Figure 10-3
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
Where to Go Next
For information about implementing access lists, see the following chapters in this guide:
•
Chapter 11, “Adding an Extended Access List”
•
Chapter 12, “Adding an EtherType Access List”
•
Chapter 13, “Adding a Standard Access List”
•
Chapter 14, “Adding a Webtype Access List”
•
Chapter 15, “Adding an IPv6 Access List”
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11
Adding an Extended Access List
This chapter describes how to configure extended access lists (also known as access control lists), and
it includes the following topics:
•
Information About Extended Access Lists, page 11-1
•
Licensing Requirements for Extended Access Lists, page 11-2
•
Guidelines and Limitations, page 11-2
•
Default Settings, page 11-4
•
Configuring Extended Access Lists, page 11-4
•
What to Do Next, page 11-7
•
Monitoring Extended Access Lists, page 11-7
•
Configuration Examples for Extended Access Lists, page 11-7
•
Feature History for Extended Access Lists, page 11-8
Information About Extended Access Lists
Access lists are used to control network access or to specify traffic for many features to act upon. An
extended access list is made up of one or more access control entries (ACE) in which you can specify
the line number to insert the ACE, the source and destination addresses, and, depending upon the ACE
type, the protocol, the ports (for TCP or UDP), or the IPCMP 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 simplify access lists with
object groups, see Chapter 16, “Configuring Object Groups.”
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.
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Adding an Extended Access List
Licensing Requirements for Extended Access Lists
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 that returning traffic is allowed through.
Table 11-1 lists common traffic types that you can allow through the transparent firewall.
Table 11-1
Transparent Firewall Special Traffic
Traffic Type
Protocol or Port
Notes
DHCP
UDP ports 67 and 68
If you enable the DHCP server, then the ASA
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
Licensing Requirements for Extended Access Lists
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 11-2
•
Firewall Mode Guidelines, page 11-2
•
Additional Guidelines and Limitations, page 11-3
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported only in routed and transparent firewall modes.
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Guidelines and Limitations
IPv6 Guidelines
IPv6 is supported.
Additional Guidelines and Limitations
The following guidelines and limitations apply to creating an extended access list:
•
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.
•
Enter the access list name in uppercase letters so that the name is easy to see in the configuration.
You might want to name the access list for the interface (for example, INSIDE), or you can name it
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.
•
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 16-7.) The ICMP inspection engine treats
ICMP sessions as stateful connections. To control ping, specify echo-reply (0) (ASA to host) or
echo (8) (host to ASA). See the “Adding an ICMP Type Object Group” section on page 16-7 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 ASA 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 enables you to keep a record of an inactive ACE in your
configuration to make reenabling easier.
•
Use the disable option to disable logging for a specified ACE.
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Default Settings
Default Settings
Table 11-2 lists the default settings for extended access list parameters.
Table 11-2
Default Extended Access List Parameters
Parameters
Default
ACE logging
ACE logging generates system log message
106023 for denied packets. A deny ACE must be
present to log denied packets.
log
When the log keyword is specified, the default
level for system log message 106100 is 6
(informational), and the default interval is 300
seconds.
Configuring Extended Access Lists
This section shows how to add and delete an access control entry and access list, and it includes the
following topics:
•
Task Flow for Configuring Extended Access Lists, page 11-4
•
Adding an Extended Access List, page 11-5
•
Adding Remarks to Access Lists, page 11-6
•
Deleting an Extended Access List Entry, page 11-6
Task Flow for Configuring Extended Access Lists
Use the following guidelines to create and implement an access list:
•
Create an access list by adding an ACE and applying an access list name. (See the “Adding an
Extended Access List” section on page 11-5.)
•
Apply the access list to an interface. (See the “Applying an Access List to an Interface” section on
page 35-4 for more information.)
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Configuring Extended Access Lists
Adding an Extended Access List
An access list is made up of one or more access control entries (ACEs) with the same access list ID. To
create an access list you start by creating an ACE and applying a list name. An access list with one entry
is still considered a list, although you can add multiple entries to the list.
To add an extended access list or an ACE, enter the following command:
Command
Purpose
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]
Adds an extended access control entry.
Example:
hostname(config)# access-list ACL_IN
extended permit ip any any
The line line_number options specify the line number at which insert the
ACE. If you do not specify a line number, the ACE is added to the end of
the access list. The line number is not saved in the configuration; it only
specifies where to insert the ACE.
The extended option adds an ACE.
The deny keyword denies a packet if the conditions are matched. Some
features do not allow deny ACEs, such as NAT. See the command
documentation for each feature that uses an access list for more
information.
The permit keyword permits a packet if the conditions are matched.
The protocol argument specifies the IP protocol name or number. For
example UDP is 17, TCP is 6, and EGP is 47.
The source_address specifies the IP address of the network or host from
which the packet is being sent. 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.
The operator port option matches the port numbers used by the source or
destination. The permitted operators are as follows:
•
lt—less than.
•
gt—greater than.
•
dq—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.
The dest_address argument specifies the IP address of the network or host
to which the packet is being sent. 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.
The icmp_type argument specifies the ICMP type if the protocol is ICMP.
The inactive keyword disables an ACE. To reenable it, enter the entire
ACE without the inactive keyword. This feature enables you to keep a
record of an inactive ACE in your configuration to make reenabling easier.
(See the access-list extended command in the Cisco Security Appliance
Command Reference for more information about command options.)
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Configuring Extended Access Lists
Adding Remarks to Access Lists
You can include remarks about entries in any access list, including extended, EtherType, IPv6, standard,
and Webtype 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:
Command
Purpose
access-list access_list_name remark text
Adds a remark after the last access-list command you entered.
Example:
hostname(config)# access-list OUT remark this is the inside admin address
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.
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.
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 the 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
Deleting an Extended Access List Entry
This section shows how to remove an ACE. If the deleted entry is the only entry in the list, then the list
and listname are deleted.
To delete an extended ACE, enter the following command:
Command
Purpose
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]
Deletes and extended access list entry.
Example:
hostname(config)# access-list ACL_IN
extended permit ip any any
Enter the no access-list command with the entire command syntax string
as it appears in the configuration.
Note
To remove the entire access list, use the clear configure access-list
command.
(See the “Adding an Extended Access List” section on page 11-5 or the
Cisco Security Appliance Command Reference for more information about
command options.)
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What to Do Next
What to Do Next
Apply the access list to an interface. See the “Applying an Access List to an Interface” section on
page 35-4 for more information.
Monitoring Extended Access Lists
To monitor extended access lists, enter one of the following commands:
Command
Purpose
show access list
Displays the access list entries by number.
show running-config access-list
Displays the current running access-list
configuration.
Configuration Examples for Extended Access Lists
The following access list allows all hosts (on the interface to which you apply the access list) to go
through the adaptive 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 selected hosts only, 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
The following access list that uses object groups restricts several hosts on the inside network from
accessing several web servers. All other traffic is allowed.
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
The following example temporarily disables an access list that permits traffic from one group of network
objects (A) to another group of network objects (B):
hostname(config)# access-list 104 permit ip host object-group A object-group B inactive
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Feature History for Extended Access Lists
To implement a time-based access list, use the time-range command to define specific times of the day
and week. Then use the access-list extended command to bind the time range to an access list. 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
Feature History for Extended Access Lists
Table 11-3 lists the release history for this feature.
Table 11-3
Feature History for Extended Access Lists
Feature Name
Releases
Feature Information
Extended access control lists
7.0
Access lists are used to control network access or to specify
traffic for many features to act upon. An extended access
control list is made up of one or more access control entries
(ACE) in which you can specify the line number to insert
the ACE, the source and destination addresses, and,
depending upon the ACE type, the protocol, the ports (for
TCP or UDP), or the IPCMP type (for ICMP).
The following command was introduced: access-list
extended.
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12
Adding an EtherType Access List
This chapter describes how to configure EtherType access lists and includes the following topics:
•
Information About EtherType Access Lists, page 12-1
•
Licensing Requirements for EtherType Access Lists, page 12-2
•
Guidelines and Limitations, page 12-2
•
Default Settings, page 12-3
•
Configuring EtherType Access Lists, page 12-4
•
Monitoring EtherType Access Lists, page 12-6
•
What to Do Next, page 12-6
•
Configuration Examples for EtherType Access Lists, page 12-7
•
Feature History for EtherType Access Lists, page 12-7
Information About EtherType Access Lists
An EtherType access list is made up of one or more Access List Entries (ACEs) that specify an
EtherType. This section includes the following topics:
•
Supported EtherTypes, page 12-1
•
Implicit Permit of IP and ARPs Only, page 12-2
•
Implicit and Explicit Deny ACE at the End of an Access List, page 12-2
•
Allowing MPLS, page 12-2
Supported EtherTypes
An EtherType ACE controls any EtherType identified by a 16-bit hexadecimal number. 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.
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Licensing Requirements for EtherType Access Lists
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.
Allowing MPLS
If you allow MPLS, ensure that Label Distribution Protocol and Tag Distribution Protocol TCP
connections are established through the ASA by configuring both MPLS routers connected to the ASA
to use the IP address on the ASA 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, either LDP or TDP. The
interface is the interface connected to the ASA.
hostname(config)# mpls ldp router-id interface force
Or
hostname(config)# tag-switching tdp router-id interface force
Licensing Requirements for EtherType Access Lists
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 12-3
•
Firewall Mode Guidelines, page 12-3
•
Additional Guidelines and Limitations, page 12-3
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Default Settings
Context Mode Guidelines
Available in single and multiple context modes.
Firewall Mode Guidelines
Supported in transparent firewall mode only.
Additional Guidelines and Limitations
The following guidelines and limitations apply to EtherType access lists:
•
When you enter the access-list command for a given access list name, the ACE is added to the end
of the access list.
•
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. Bridge protocol data units, which are allowed by default, are the only exception; they
are SNAP-encapsulated, and the adaptive security appliance is designed to specifically handle
BPDUs.
•
Because EtherTypes are connectionless, you need to apply the ACL to both interfaces if you want
traffic to pass in both directions.
•
If you allow MPLS, ensure that LDP and TDP TCP connections are established through the adaptive
security appliance by configuring both MPLD routers connected to the adaptive security appliance
to use the IP address on the adaptive security appliance interface as the router-ID for LDP or TDP
sessions. (LDP and TDP allow MPLS routers to negotiate the labels, or addresses, used to forward
packets.)
•
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.
•
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.
Default Settings
Table 12-1 lists the default settings for EtherType access lists parameters.
Table 12-1
Default EtherType Access Lists Parameters
Parameters
Default
bpdu
By default, BPDUs are permitted.
deny | permit
The adaptive security appliance denies all packets
on the originating interface unless you specifically
permit access.
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Configuring EtherType Access Lists
Table 12-1
Default EtherType Access Lists Parameters (continued)
Parameters
Default
deny
Access list logging generates system log message
106023 for denied packets. Deny packets must be
present to loge denied packets.
log
When the log optional keyword is specified, the
default severity level for system log message
106100 is 6 (informational).
Configuring EtherType Access Lists
This section includes the following topics:
•
Task Flow for Configuring EtherType Access Lists, page 12-4
•
Adding EtherType Access Lists, page 12-5
•
Adding Remarks to Access Lists, page 12-6
Task Flow for Configuring EtherType Access Lists
Use the following guidelines to create and implement an access list:
•
Create an access list by adding an ACE and applying an access list name, as shown in the “Adding
EtherType Access Lists” section on page 12-5.
•
Apply the access list to an interface. (See the “Applying an Access List to an Interface” section on
page 35-4 for more information.)
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Configuring EtherType Access Lists
Adding EtherType Access Lists
To configure an access list that controls traffic based upon its EtherType, enter the following command:
Command
Purpose
access-list access_list_name ethertype
{deny | permit} {ipx | bpdu | mpls-unicast
| mpls-multicast | any | hex_number}
Adds an EtherType ACE.
Example:
hostname(config)# hostname(config)#
access-list ETHER ethertype permit ipx
The access_list_name argument lists the name or number of an access list.
When you specify an access list name, the ACE is added to the end of the
access list. Enter the access_list_name in upper case letters so that 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 PIX).
The any keyword specifies access to anyone.
The bpdu keyword specifies access to bridge protocol data units, which are
permitted by default.
The deny keyword denies access if the conditions are matched. 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.
The hex_number argument indicates 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.)
The ipx keyword specifies access to IPX.
The mpls-multicast keyword specifies access to MPLS multicast.
The mpls-unicast keyword specifies access to MPLS unicast.
The permit keyword permits access if the conditions are matched.
Note
To remove an EtherType ACE, enter the no access-list command
with the entire command syntax string as it appears in the
configuration.
Example
The following sample access list allows common EtherTypes originating on the inside interface:
hostname(config)# access-list ETHER ethertype permit ipx
hostname(config)# access-list ETHER ethertype permit mpls-unicast
hostname(config)# access-group ETHER in interface inside
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What to Do Next
Adding Remarks to Access Lists
You can include remarks about entries in any access list, including extended, EtherType, IPv6, standard,
and Webtype access lists. The remarks make an access list easier to understand.
To add a remark after the last access-list command you entered, enter the following command:
Command
Purpose
access-list access_list_name remark text
Adds a remark after the last access-list command you entered.
Example:
hostname(config)# access-list OUT remark this is the inside admin address
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.
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 remarks are also removed.
Example
You can add remarks before each ACE, and the remarks appear in the access list in these locations.
Entering a dash (-) at the beginning of a remark helps to set it apart from the ACE.
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
What to Do Next
Apply the access list to an interface. (See the “Applying an Access List to an Interface” section on
page 35-4 for more information.)
Monitoring EtherType Access Lists
To monitor EtherType access lists, enter one of the following commands:
Command
Purpose
show access-list
Displays the access list entries by number.
show running-config access-list
Displays the current running access-list
configuration.
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Configuration Examples for EtherType Access Lists
Configuration Examples for EtherType Access Lists
The following example shows how to configure EtherType access lists:
The following access list allows some EtherTypes through the ASA, but it denies IPX:
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
access-list ETHER ethertype deny ipx
access-list ETHER ethertype permit 0x1234
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 it 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
Feature History for EtherType Access Lists
Table 12-2 lists the release history for this feature.
Table 12-2
Feature History for EtherType Access Lists
Feature Name
Releases
Feature Information
EtherType access lists
7.0
EtherType access lists control traffic based upon its
EtherType.
The feature and the following command were introduced:
access-list ethertype.
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Feature History for EtherType Access Lists
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13
Adding a Standard Access List
This chapter describes how to configure a standard access list and includes the following topics:
•
Information About Standard Access Lists, page 13-1
•
Licensing Requirements for Standard Access Lists, page 13-1
•
Guidelines and Limitations, page 13-1
•
Default Settings, page 13-2
•
Adding a Standard Access List, page 13-3
•
What to Do Next, page 13-4
•
Monitoring Access Lists, page 13-4
•
Configuration Examples for Standard Access Lists, page 13-5
•
Feature History for Standard Access Lists, page 13-5
Information About Standard Access Lists
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.
Licensing Requirements for Standard Access Lists
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 13-2
•
Firewall Mode Guidelines, page 13-2
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Default Settings
•
IPv6 Guidelines, page 13-2
•
Additional Guidelines and Limitations, page 13-2
Context Mode Guidelines
Supported in single context mode only.
Firewall Mode Guidelines
Supported in routed and transparent firewall modes.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
The following guidelines and limitations apply for standard access lists:
•
To add additional ACEs at the end of the access list, enter another access-list command, specifying
the same access list name.
•
When used with the access-group command, the deny keyword does not allow a packet to traverse
the adaptive security appliance. By default, the adaptive security appliance denies all packets on the
originating interface unless you specifically permit access.
•
When specifying a source, local, or destination address, use the following guidelines:
– Use a 32-bit quantity in four-part, dotted-decimal format.
– Use the keyword any as an abbreviation for an address and mask of 0.0.0.0.0.0.0.0.
– Use the host ip_address option as an abbreviation for a mask of 255.255.255.255.
•
You can disable an ACE by specifying the keyword inactive in the access-list command.
Default Settings
Table 13-1 lists the default settings for standard access list parameters.
Table 13-1
Default Standard Access List Parameters
Parameters
Default
deny
The adaptive security appliance denies all packets
on the originating interface unless you specifically
permit access.
Access list logging generates system log message
106023 for denied packets. Deny packets must be
present to log denied packets.
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Adding a Standard Access List
Adding a Standard Access List
This section includes the following topics:
•
Task Flow for Configuring Extended Access Lists, page 13-3
•
Adding a Standard Access List, page 13-3
•
Adding Remarks to Access Lists, page 13-4
Task Flow for Configuring Extended Access Lists
Use the following guidelines to create and implement an access list:
•
Create an access list by adding an ACE and applying an access list name. See in the “Adding a
Standard Access List” section on page 13-3.
•
Apply the access list to an interface. See the “Applying an Access List to an Interface” section on
page 35-4 for more information.
Adding a Standard Access List
To add an access list to identify the destination IP addresses of OSPF routes, which can be used in a route map for OSPF
redistribution, enter the following command:
Command
Purpose
hostname(config)# access-list
access_list_name standard {deny | permit}
{any | ip_address mask}
Adds a standard access list entry. To add another ACE to the end of the
access list, enter another access-list command, specifying the same access
list name.
Example:
hostname(config)# access-list OSPF
standard permit 192.168.1.0 255.255.255.0
The access_list_name argument specifies the name of number of an access
list.
The any keyword specifies access to anyone.
The deny keyword denies access if the conditions are matched.
The host ip_address syntax specifies access to a host IP address
The ip_address ip_mask argument specifies access to a specific IP address
and subnet mask.
The line line-num option specifies the line number at which to insert an
ACE.
The permit keyword permits access if the conditions are matched.
Note
To remove an ACE, enter the no access-list command with the
entire command syntax string as it appears in the configuration.
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What to Do Next
Adding Remarks to Access Lists
You can include remarks about entries in any access list, including extended, EtherType, IPv6, standard,
and Webtype 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:
Command
Purpose
access-list access_list_name remark text
Adds a remark after the last access-list command you entered.
Example:
hostname(config)# access-list OUT remark this is the inside admin address
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.
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.
Example
You can add a remark before each ACE, and the remarks appear in the access lists in these location.
Entering a dash (-) at the beginning of a remark helps to set it apart from an ACE.
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
What to Do Next
Apply the access list to an interface. See the “Applying an Access List to an Interface” section on
page 35-4 for more information.
Monitoring Access Lists
To monitor access lists, perform one of the following tasks:
Command
Purpose
show access-list
Displays the access list entries by number.
show running-config access-list
Displays the current running access-list
configuration.
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Configuration Examples for Standard Access Lists
Configuration Examples for Standard Access Lists
The following example shows how to deny IP traffic through the adaptive security appliance:
hostname(config)# access-list 77 standard deny
The following example shows how to permit IP traffic through the adaptive security appliance if
conditions are matched:
hostname(config)# access-list 77 standard permit
The following example shows how to specify a destination address:
hostname(config)# access-list 77 standard permit host 10.1.10.123
Feature History for Standard Access Lists
Table 13-2 lists the release history for this feature.
Table 13-2
Feature History for Standard Access Lists
Feature Name
Releases
Feature Information
Standard access lists
7.0
Standard access lists identify the destination IP addresses of
OSPF routes, which can be used in a route map for OSPF
redistribution.
The feature and the following command were introduced:
access-list standard.
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CH A P T E R
14T
Adding a Webtype Access List
Webtype access lists are added to a configuration that supports filtering for clientless SSL VPN. This
chapter describes how to add an access list to the configuration that supports filtering for WebVPN.
This chapter includes the following topics:
•
Licensing Requirements for Webtype Access Lists, page 14-1
•
Guidelines and Limitations, page 14-1
•
Default Settings, page 14-2
•
Adding Webtype Access Lists, page 14-2
•
What to Do Next, page 14-5
•
Monitoring Webtype Access Lists, page 14-5
•
Configuration Examples for Webtype Access Lists, page 14-5
•
Feature History for Webtype Access Lists, page 14-7
Licensing Requirements for Webtype Access Lists
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 14-1
•
Firewall Mode Guidelines, page 14-2
•
Additional Guidelines and Limitations, page 14-2
Context Mode Guidelines
Supported in single and multiple context mode.
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Default Settings
Firewall Mode Guidelines
Supported in routed and transparent firewall mode.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
The following guidelines and limitations apply to Webtype access lists:
•
The access-list Webtype command is used to configure clientless SSL VPN filtering. The URL
specified may be full or partial (no file specified), may include wildcards for the server, or may
specify a port. See the “Adding Webtype Access Lists with a URL String” section on page 14-3 for
information about using wildcard characters in the URL string.
•
Valid protocol identifiers are http, https, cifs, imap4, pop3, and smtp. The RL may also contain the
keyword any to refer to any URL. An asterisk may be used to refer to a subcomponent of a DNS
name.
Default Settings
Table 14-1 lists the default settings for Webtype access lists parameters.
Table 14-1
Default Webtype Access List Parameters
Parameters
Default
deny
The adaptive security appliance denies all packets
on the originating interface unless you specifically
permit access.
log
Access list logging generates system log message
106023 for denied packets. Deny packets must be
present to log denied packets.
Adding Webtype Access Lists
This section includes the following topics:
•
Task Flow for Configuring Webtype Access Lists, page 14-2
•
Adding Webtype Access Lists with a URL String, page 14-3
•
Adding Webtype Access Lists with an IP Address, page 14-4
•
Adding Remarks to Access Lists, page 14-5
Task Flow for Configuring Webtype Access Lists
Use the following guidelines to create and implement an access list:
•
Create an access list by adding an ACE and applying an access list name. See the “Adding Webtype
Access Lists” section on page 14-2.
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Adding Webtype Access Lists
•
Apply the access list to an interface. See the “Applying an Access List to an Interface” section on
page 35-4 for more information.
Adding Webtype Access Lists with a URL String
To add an access list to the configuration that supports filtering for clientless SSL VPN, enter the following command:
Command
Purpose
access-list access_list_name webtype {deny
| permit} url [url_string | any]
[log[[disable | default] | level] interval
secs][time_range name]]
Adds an access list to the configuration that supports filtering for
WebVPN.
Example:
hostname(config)# access-list acl_company
webtype deny url http://*.company.com
The access_list_name argument specifies the name or number of an access
list.
The any keyword specifies all URLs.
The deny keyword denies access if the conditions are matched.
The interval option specifies the time interval at which to generate system
log message 106100; valid values are from 1 to 600 seconds.
The log [[disable | default] | level] option specifies that system log
message 106100 is generated for the ACE. When the log optional keyword
is specified, the default level for system log message 106100 is 6
(informational). See the log command for more information.
The permit keyword permits access if the conditions are matched.
The time_range name option specifies a keyword for attaching the
time-range option to this access list element.
The url keyword specifies that a URL be used for filtering.
The url_string option specifies the URL to be filtered.
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.
Note
To match any http URL, you must enter http://*/* instead of the
former method of entering http://*.
To remove an access list, use the no form of this command with the
complete syntax string as it appears in the configuration.
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Adding Webtype Access Lists
Adding Webtype Access Lists with an IP Address
To add an access list to the configuration that supports filtering for clientless SSL VPN, enter the following command:
Command
Purpose
access-list access_list_name webtype {deny
| permit} tcp [host ip_address |
ip_address subnet_mask | any] [oper
port[port]] [log[[disable | default] |
level] interval secs][time_range name]]
Adds an access list to the configuration that supports filtering for
WebVPN.
Example:
hostname(config)# access-list acl_company
webtype permit tcp any
The access_list_name argument specifies the name or number of an access
list.
The any keyword specifies all IP addresses.
The deny keyword denies access if the conditions are matched.
The host ip_address option specifies a host IP address.
The interval option specifies the time interval at which to generate system
log message 106100; valid values are from 1 to 600 seconds.
The ip_address ip_mask option specifies a specific IP address and subnet
mask.
The log [[disable | default]| level] option specifies that system log message
106100 is generated for the ACE. When the log optional keyword is
specified, the default level for system log message 106100 is 6
(informational). See the log command for more information.
The permit keyword permits access if the conditions are matched.
The port option specifies the decimal number or name of a TCP or UDP
port.
The time_range name option specifies a keyword for attaching the
time-range option to this access list element.
To remove an access list, use the no form of this command with the
complete syntax string as it appears in the configuration.
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What to Do Next
Adding Remarks to Access Lists
You can include remarks about entries in any access list, including extended, EtherType, IPv6, standard,
and Webtype 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:
Command
Purpose
access-list access_list_name remark text
Adds a remark after the last access-list command you entered.
Example:
hostname(config)# access-list OUT remark this is the inside admin address
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.
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.
Example
You can add a remark before each ACE, and the remarks appear in the access list in these locations.
Entering a dash (-) at the beginning of a remark helps set it apart from an ACE.
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
What to Do Next
Apply the access list to an interface. See the “Applying an Access List to an Interface” section on
page 35-4 for more information.
Monitoring Webtype Access Lists
To monitor webtype access lists, enter the following command:
Command
Purpose
show running-config access list
Displays the access-list configuration running on
the adaptive security appliance.
Configuration Examples for Webtype Access Lists
The following example shows how to deny access to a specific company URL:
hostname(config)# access-list acl_company webtype deny url http://*.company.com
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Configuration Examples for Webtype Access Lists
The following example shows how to deny access to a specific file:
hostname(config)# access-list acl_file webtype deny url
https://www.company.com/dir/file.html
The following example shows how to deny HTTP access to any URL through port 8080:
hostname(config)# access-list acl_company webtype deny url http://my-server:8080/*
The following examples 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://*.
The following example 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*
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Feature History for Webtype Access Lists
Feature History for Webtype Access Lists
Table 14-2 lists the release history for this feature.
Table 14-2
Feature History for Webtype Access Lists
Feature Name
Releases
Feature Information
Webtype access lists
7.0
Webtype access lists are access lists that are added to a
configuration that supports filtering for clientless SSL
VPN.
The feature and the following command were introduced:
access-list webtype.
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CH A P T E R
15
Adding an IPv6 Access List
This chapter describes how to configure IPv6 access lists to control and filter traffic through the security
appliance.
This chapter includes the following sections:
•
Information About IPv6 Access Lists, page 15-1
•
Licensing Requirements for IPv6 Access Lists, page 15-1
•
Prerequisites for Adding IPv6 Access Lists, page 15-2
•
Guidelines and Limitations, page 15-2
•
Default Settings, page 15-3
•
Configuring IPv6 Access Lists, page 15-4
•
Monitoring IPv6 Access Lists, page 15-7
•
Configuration Examples for IPv6 Access Lists, page 15-7
•
Where to Go Next, page 15-7
•
Feature History for IPv6 Access Lists, page 15-7
Information About IPv6 Access Lists
The typical access list functionality in IPv6 is similar to access lists in IPv4. Access lists determine
which traffic to block and which traffic to forward at router interfaces. Access lists allow filtering based
upon source and destination addresses, inbound and outbound to specific interfaces. Each access list has
an implicit deny statement at the end. You define IPv6 access lists and set their deny and permit
conditions using the ipv6 access-list command with the deny and permit keywords in global
configuration mode.
Licensing Requirements for IPv6 Access Lists
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
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Prerequisites for Adding IPv6 Access Lists
Prerequisites for Adding IPv6 Access Lists
You should be familiar with IPv6 addressing and basic configuration. See the ipv6 commands in the
Cisco Security Appliance Command Reference for more information about configuring IPv6.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
Supported in single and multiple context modes.
Firewall Mode Guidelines
Supported in routed and transparent firewall modes.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
The following guidelines and limitations apply to IPv6 access lists:
•
The ipv6 access-list command allows you to specify whether an IPv6 address is permitted or denied
access to a port or protocol. Each command is called an ACE. One or more ACEs with the same
access list name are referred to as an access list. Apply an access list to an interface using the
access-group command.
•
The ASA denies all packets from an outside interface to an inside interface unless you specifically
permit access using an access list. All packets are allowed by default from an inside interface to an
outside interface unless you specifically deny access.
•
The ipv6 access-list command is similar to the access-list command, except that it is IPv6-specific.
For additional information about access lists, refer to the access-list extended command.
•
The ipv6 access-list icmp command is used to filter ICMPv6 messages that pass through the
ASA.To configure the ICMPv6 traffic that is allowed to originate and terminate at a specific
interface, use the ipv6 icmp command.
•
See the object-group command for information on how to configure object groups.
•
Possible operands for the operator option of the ipv6 access-list command include lt for less than,
gt for greater than, eq for equal to, neq for not equal to, and range for an inclusive range. Use the
ipv6 access-list command without an operator and port to indicate all ports by default.
•
ICMP message types are filtered by the access rule. Omitting the icmp_type argument indicates all
ICMP types. If you specify ICMP types, the value can be a valid ICMP type number (from 0 to 255)
or one of the following ICMP type literals:
– destination-unreachable
– packet-too-big
– time-exceeded
– parameter-problem
– echo-request
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Default Settings
– echo-reply
– membership-query
– membership-report
– membership-reduction
– router-renumbering
– router-solicitation
– router-advertisement
– neighbor-solicitation
– neighbor-advertisement
– neighbor-redirect
•
If the protocol argument is specified, valid values are icmp, ip, tcp, udp, or an integer in the range
of 1 to 254, representing an IP protocol number.
Default Settings
Table 15-1 lists the default settings for IPv6 access list parameters.
Table 15-1
Default IPv6 Access List Parameters
Parameters
Default
default
The default option specifies that a syslog message
106100 is generated for the ACE.
interval secs
Specifies the time interval at which to generate a
106100 syslog message; valid values are from 1 to
600 seconds. The default interval is 300 seconds.
This value is also used as the timeout value for
deleting an inactive flow.
level
The level option specifies the syslog level for
message 106100; valid values are from 0 to 7. The
default level is 6 (informational).
log
The log option specifies logging action for the
ACE. If you do not specify the log keyword or you
specify the log default keyword, then message
106023 is generated when a packet is denied by the
ACE. If you specify the log keyword alone or with
a level or interval, then message 106100 is
generated when a packet is denied by the ACE.
Packets that are denied by the implicit deny at the
end of an access list are not logged. You must
implicitly deny packets with an ACE to enable
logging.
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Configuring IPv6 Access Lists
Configuring IPv6 Access Lists
This section includes the following topics:
•
Task Flow for Configuring IPv6 Access Lists, page 15-4
•
Adding IPv6 Access Lists, page 15-5
•
Adding Remarks to Access Lists, page 15-6
Task Flow for Configuring IPv6 Access Lists
Use the following guidelines to create and implement an access list:
•
Create an access list by adding an ACE and applying an access list name, as shown in the “Adding
IPv6 Access Lists” section on page 15-5.
•
Apply the access list to an interface. (See the “Applying an Access List to an Interface” section on
page 35-4 for more information.)
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Configuring IPv6 Access Lists
Adding IPv6 Access Lists
You can add a regular IPv6 access list or add an IPv6 access list with TCP.
To add a regular IPv6 access list, enter the following command:
Command
ipv6 access-list id [line line-num] {deny |
permit} {protocol | object-group
protocol_obj_grp_id}
{source-ipv6-prefix/prefix-length | any |
host source-ipv6-address |
object-group network_obj_grp_id}
[operator {port [port] | object-group
service_obj_grp_id}]
{destination-ipv6-prefix/prefix-length |
any | host destination-ipv6-address |
object-group network_obj_grp_id}
[{operator port [port] | object-group
service_obj_grp_id}] [log [[level]
[interval secs] | disable | default]]
Example:
hostname(config)# ipv6 access-list acl_grp
permit tcp any host
3001:1::203:A0FF:FED6:162D
Purpose
Configures an IPv6 access list.
The any keyword is an abbreviation for the IPv6 prefix ::/0, indicating any
IPv6 address.
The deny keyword denies access if the conditions are matched.
The destination-ipv6-address argument identifies the IPv6 address of the
host receiving the traffic.
The destination-ipv6-prefix argument identifies the IPv6 network address
where the traffic is destined.
The disable option disables syslog messaging.
The host keyword indicates that the address refers to a specific host.
The id keyword specifies the number of an access list.
The line line-num option specifies the line number for inserting the access
rule into the list. By default, the ACE is added to the end of the access list.
The network_obj_grp_id argument specifies existing network object group
identification.
The object-group option specifies an object group.
The operator option compares the source IP address or destination IP
address ports. For a list of permitted operands, see the “Guidelines and
Limitations” section on page 15-2.
The permit keyword permits access if the conditions are matched.
The port option specifies the port that you permit or deny access. You can
specify the port either by a number in the range of 0 to 65535 or by a literal
name if the protocol is tcp or udp. For a list of permitted TCP or UDP
literal names, see the “Guidelines and Limitations” section on page 15-2.
The prefix-length argument indicates how many of the high-order,
contiguous bits of the address comprise the IPv6 prefix.
The protocol argument specifies the name or number of an IP protocol.
The protocol_obj_grp_id indicates the existing protocol object group ID.
The service_obj_grp_id option specifies the object group.
The source-ipv6-address specifies the address of the host sending traffic.
The source-ipv6-prefix specifies the IPv6 address of traffic origin.
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Configuring IPv6 Access Lists
To configure an IPv6 access list with ICMP, enter the following command:
Command
ipv6 access-list id [line line-num] {deny |
permit} icmp6
{source-ipv6-prefix/prefix-length | any |
host source-ipv6-address |
object-group network_obj_grp_id}
{destination-ipv6-prefix/prefix-length |
any | host destination-ipv6-address |
object-group network_obj_grp_id}
[icmp_type | object-group
icmp_type_obj_grp_id] [log [[level]
[interval secs] | disable | default]]
Example:
hostname(config)# ipv6 access list acl_grp
permit tcp any host
3001:1::203:AOFF:FED6:162D
Purpose
Configures an IPv6 access list with ICMP.
The icmp6 keyword specifies that the access rule applies to ICMPv6 traffic
passing through the ASA.
The icmp_type argument specifies the ICMP message type being filtered by
the access rule. The value can be a valid ICMP type number from 0 to 255.
(For a list of the permitted ICMP type literals, see the “Guidelines and
Limitations” section on page 15-2.)
The icmp_type_obj_grp_id option specifies the object group ICMP type
ID.
For details about additional ipv6 access-list command parameters, see the
preceding procedure for adding a regular IPv6 access list, or see the
ipv6 access-list command in the Cisco Security Appliance Command
Reference.
Adding Remarks to Access Lists
You can include remarks about entries in any access list, including extended, EtherType, IPv6, standard,
and Webtype 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:
Command
Purpose
access-list access_list_name remark text
Adds a remark after the last access-list command you entered.
Example:
hostname(config)# access-list OUT remark this is the inside admin address
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.
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.
Example
You can add remarks before each ACE, and the remarks appear in the access list in these locations.
Entering a dash (-) at the beginning of a remark helps set it apart from an ACE.
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
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Monitoring IPv6 Access Lists
Monitoring IPv6 Access Lists
To monitor IPv6 access lists, perform one of the following tasks:
Command
Purpose
show ipv6 access-list
Displays all IPv6 access list information.
Configuration Examples for IPv6 Access Lists
The following example shows how to configure IPv6 access lists:
The following example allows any host using TCP to access the 3001:1::203:A0FF:FED6:162D server:
hostname(config)# ipv6 access-list acl_grp permit tcp any host 3001:1::203:A0FF:FED6:162D
The following example uses eq and a port to deny access to just FTP:
hostname(config)# ipv6 access-list acl_out deny tcp any host 3001:1::203:A0FF:FED6:162D eq
ftp
hostname(config)# access-group acl_out in interface inside
The following example uses lt to permit access to all ports less than port 2025, which permits access to
the well-known ports (1 to 1024):
hostname(config)# ipv6 access-list acl_dmz1 permit tcp any host 3001:1::203:A0FF:FED6:162D
lt 1025
hostname(config)# access-group acl_dmz1 in interface dmz1
Where to Go Next
Apply the access list to an interface. (See the “Applying an Access List to an Interface” section on
page 35-4 for more information.)
Feature History for IPv6 Access Lists
Table 15-2 lists the release history for this feature.
Table 15-2
Feature History for IPv6 Access Lists
Feature Name
Releases
Feature Information
IPv6 access lists
7.0(1)
The following command was introduced: ipv6 access-list.
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Adding an IPv6 Access List
Feature History for IPv6 Access Lists
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CH A P T E R
16
Configuring Object Groups
You can configure access lists in modules, or object groups, to simplify access list creation and
maintenance. This chapter describes how to configure, organize, and display object groups, and it
includes the following sections:
•
Configuring Object Groups, page 16-1
•
Using Object Groups with Access Lists, page 16-10
•
Adding Remarks to Access Lists, page 16-13
•
Scheduling Extended Access List Activation, page 16-14
Configuring Object Groups
This section includes the following topics:
•
Information About Object Groups, page 16-2
•
Licensing Requirements for Object Groups, page 16-2
•
Guidelines and Limitations for Object Groups, page 16-3
•
Adding Object Groups, page 16-4
•
Removing Object Groups, page 16-8
•
Monitoring Object Groups, page 16-8
•
Nesting Object Groups, page 16-9
•
Feature History for Object Groups, page 16-10
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Configuring Object Groups
Configuring Object Groups
Information About Object Groups
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. For example,
consider a network object group with 100 sources, a network object group with 100 destinations, and a
port object group with 5 ports. Permitting the ports from sources to destinations could result in 50,000
ACEs (5 x 100 x 100) in the expanded access list.
Licensing Requirements for Object Groups
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
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Configuring Object Groups
Guidelines and Limitations for Object Groups
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 16-3
•
Firewall Mode Guidelines, page 16-3
•
IPv6 Guidelines, page 16-3
•
Additional Guidelines and Limitations, page 16-3
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed and transparent firewall modes.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
The following guidelines and limitations apply to object groups:
•
Object groups must have unique names. While you might want to create a network object group
named “Engineering” and a service object group named “Engineering,” you need to add an identifier
(or “tag”) to the end of at least one object group name to make it unique. For example, you can use
the names “Engineering_admins” and “Engnineering_hosts” to make the object group names unique
and to aid in identification.
•
After you add an object group you can add more objects as required by following the same procedure
again for the same group name and specifying additional objects. You do not need to reenter existing
objects: the command you already set remains in place unless you remove the object group with the
no form of the command.
•
Objects such as hosts, protocols, or services can be grouped, and then you can enter a single
command using the group name to apply every item in the group.
•
When you define a group with the object group command and then use any security appliance
command, the command applies to every item in that group. This feature can significantly reduce
your configuration size.
Note
•
You cannot remove an object group or make an object group empty if it is used in an access list.
For information about removing object groups, see the “Removing Object Groups” section on
page 16-8.
The security appliance does not support IPv6 nested object groups, so you cannot group an object
with IPv6 entities under another IPv6 object-group.
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Configuring Object Groups
Configuring Object Groups
Adding Object Groups
This section includes the following topics:
•
Adding a Protocol Object Group, page 16-4
•
Adding a Network Object Group, page 16-5
•
Adding a Service Object Group, page 16-6
•
Adding an ICMP Type Object Group, page 16-7
Adding a Protocol Object Group
To add or change a protocol object group, perform the steps in this section. 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.
Detailed Steps
Step 1
Command
Purpose
object-group protocol obj_grp_id
Adds a protocol group. The obj_grp_id is a text string up to 64
characters in length and can be any combination of letters, digits,
and the following characters:
Example:
hostname(config)# object-group protocol
tcp_udp_icmp
•
underscore “_”
•
dash “-”
•
period “.”
The prompt changes to protocol configuration mode.
Step 2
description text
Example:
hostname(config-protocol)# description New
Group
Step 3
protocol-object protocol
Example:
hostname(config-protocol)# protocol-object
tcp
(Optional) Adds a description. The description can be up to 200
characters.
Defines the protocols in the group. Enter the command for each
protocol. The protocol is the numeric identifier of the specified 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 that you can specify, see the “Protocols and
Applications” section on page C-11.
Example
To create a protocol group for TCP, UDP, and ICMP, enter the following commands:
hostname
hostname
hostname
hostname
(config)# object-group protocol tcp_udp_icmp
(config-protocol)# protocol-object tcp
(config-protocol)# protocol-object udp
(config-protocol)# protocol-object icmp
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Configuring Object Groups
Adding a Network Object Group
A network object group supports IPv4 and IPv6 addresses, depending upon the type of access list. For
more information about IPv6 access lists, see Chapter 15, “Adding an IPv6 Access List.”
To add or change a network object group, perform the steps in this section. 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.
Detailed Steps
Step 1
Command
Purpose
object-group network grp_id
Adds a network group.
Example:
hostname(config)# object-group network
admins
The grp_id is a text string up to 64 characters in
length and can be any combination of letters, digits,
and the following characters:
•
underscore “_”
•
dash “-”
•
period “.”
The prompt changes to protocol configuration mode.
Step 2
(Optional) Adds a description. The description can
be up to 200 characters.
description text
Example:
hostname(config-network)# Administrator
Addresses
Step 3
network-object network {host ip_address |
ip_address mask}
Defines the networks in the group. Enter the
command for each network or address.
Example:
hostname(config-network)# network-object
host 10.1.1.4
Example
To create a network group that includes the IP addresses of three administrators, enter the following
commands:
hostname
hostname
hostname
hostname
hostname
(config)# object-group network admins
(config-protocol)# description Administrator Addresses
(config-protocol)# network-object host 10.1.1.4
(config-protocol)# network-object host 10.1.1.78
(config-protocol)# network-object host 10.1.1.34
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Configuring Object Groups
Configuring Object Groups
Adding a Service Object Group
To add or change a service object group, perform the steps in this section. 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.
Detailed Steps
Step 1
Command
Purpose
object-group service grp_id {tcp | udp |
tcp-udp}
Adds a service group. The grp_id is a text string up
to 64 characters in length and can be any
combination of letters, digits, and the following
characters:
Example:
hostname(config)# object-group service
services1 tcp-udp
•
underscore “_”
•
dash “-”
•
period “.”
Specify the protocol for the services (ports) you
want to add with either the tcp, udp, or tcp-udp
keywords. Enter the tcp-udp keyword if your
service uses both TCP and UDP with the same port
number, for example, DNS (port53).
The prompt changes to service configuration mode.
Step 2
description text
Example:
hostname(config-service)# description DNS
Group
Step 3
port-object {eq port | range begin_port
end_port}
Example:
hostname(config-service)# port-object eq
domain
(Optional) Adds a description. The description can
be up to 200 characters.
Defines the ports in the group. Enter the command
for each port or range of ports. For a list of permitted
keywords and well-known port assignments, see the
“Protocols and Applications” section on page C-11.
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
hostname
hostname
hostname
hostname
(config)# object-group service services2 udp
(config-service)# description RADIUS Group
(config-service)# port-object eq radius
(config-service)# port-object eq radius-acct
hostname (config)# object-group service services3 tcp
hostname (config-service)# description LDAP Group
hostname (config-service)# port-object eq ldap
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Configuring Object Groups
Configuring Object Groups
Adding an ICMP Type Object Group
To add or change an ICMP type object group, perform the steps in this section. 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.
Detailed Steps
Step 1
Command
Purpose
object-group icmp-type grp_id
Adds an ICMP type object group. The grp_id is a text string up to
64 characters in length and can be any combination of letters,
digits, and the following characters:
Example:
hostname(config)# object-group icmp-type
ping
•
underscore “_”
•
dash “-”
•
period “.”
The prompt changes to ICMP type configuration mode.
Step 2
description text
Example:
hostname(config-icmp-type)# description
Ping Group
Step 3
icmp-object icmp-type
Example:
hostname(config-icmp-type)# icmp-object
echo-reply
(Optional) Adds a description. The description can be up to 200
characters.
Defines the ICMP types in the group. Enter the command for each
type. For a list of ICMP types, see the“ICMP Types” section on
page C-15.
Example
Create an ICMP type group that includes echo-reply and echo (for controlling ping) by entering the
following commands.
hostname
hostname
hostname
hostname
(config)# object-group icmp-type ping
(config-service)# description Ping Group
(config-service)# icmp-object echo
(config-service)# icmp-object echo-reply
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Configuring Object Groups
Removing Object Groups
You can remove a specific object group or remove all object groups of a specified type; however, you
cannot remove an object group or make an object group empty if it is used in an access list.
Detailed Step
Step 1
Do one of the following:
no object-group grp_id
Example:
hostname(config)# no object-group
Engineering_host
clear object-group [protocol | network |
services | icmp-type]
Example:
hostname(config)# clear-object group
network
Removes the specified object group. The grp_id is a text string up
to 64 characters in length and can be any combination of letters,
digits, and the following characters:
•
underscore “_”
•
dash “-”
•
period “.”
Removes all object groups of the specified type.
Note
If you do not enter a type, all object groups are removed.
Monitoring Object Groups
To monitor object groups, enter the following commands:
Command
Purpose
show access-list
Displays the access list entries that are expanded
out into individual entries without their object
groupings.
show running-config object-group
Displays all current object groups.
show running-config object-group grp_id
Displays the current object groups by their group
ID.
show running-config object-group grp_type
Displays the current object groups by their group
type.
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Configuring Object Groups
Nesting Object Groups
You can nest object groups heirarchically so that one object group can contain other object groups of the
same type. However, the security appliance does not support IPv6 nested object groups, so you cannot
group an object with IPv6 entities under another IPv6 object-group.
To nest an object group within another object group of the same type, first create the group that you want
to nest (see the “Adding Object Groups” section on page 16-4) and then perform the steps in this section.
Detailed Steps
Step 1
Command
Purpose
object-group group {{protocol | network |
icmp-type} grp_id |service grp_id {tcp |
udp | tcp-udp}}
Adds or edits the specified object group type under which you
want to nest another object group.
Example:
hostname(config)# object-group network
Engineering_group
Step 2
group-object group_id
Example:
hostname(config-network)# network-object
host 10.1.1.5
hostname(config-network)# network-object
host 10.1.1.7
hostname(config-network)# network-object
host 10.1.1.9
The service_grp_id is a text string up to 64 characters in length
and can be any combination of letters, digits, and the following
characters:
•
underscore “_”
•
dash “-”
•
period “.”
Adds the specified group under the object group you specified in
Step 1. The nested group must be of the same type. You can mix
and match nexted group objects and regular objects within an
object group.
Examples
Create network object groups for privileged users from various departments by entering the following
commands:
hostname
hostname
hostname
hostname
(config)# object-group network eng
(config-network)# network-object host 10.1.1.5
(config-network)# network-object host 10.1.1.9
(config-network)# network-object host 10.1.1.89
hostname (config)# 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)# 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
hostname
hostname
hostname
(config)# object-group network
(config-network)# group-object
(config-network)# group-object
(config-network)# group-object
admin
eng
hr
finance
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Configuring Object Groups
Using Object Groups with Access Lists
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
Feature History for Object Groups
Table 16-1 lists the release history for this feature.
Table 16-1
Feature History for Object Groups
Feature Name
Releases
Feature Information
Object groups
7.0
Object groups simplify access list creation and
maintenance.
The following commands were introduced or modified:
object-group protocol, object-group network,
object-group service, object-group icmp_type.
Using Object Groups with Access Lists
This section contains the following topics:
•
Information About Using Object Groups with Access Lists, page 16-10
•
Licensing Requirements for Using Object Groups with Access Lists, page 16-10
•
Guidelines and Limitations for Using Object Groups with Access Lists, page 16-11
•
Configuring Object Groups with Access Lists, page 16-11
•
Monitoring the Use of Object Groups with Access Lists, page 16-12
•
Configuration Examples for Using Object Groups with Access Lists, page 16-12
•
Feature History for Using Object Groups with Access Lists, page 16-13
Information About Using Object Groups with Access Lists
You can use object groups in an access list, replace the normal protocol (protocol), network
(source_address mask, and so on) service (operator port), or ICMP type (icmp_type) parameter with the
object-group grp_id parameter.
Licensing Requirements for Using Object Groups with Access Lists
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
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Using Object Groups with Access Lists
Guidelines and Limitations for Using Object Groups with Access Lists
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 16-11
•
Firewall Mode Guidelines, page 16-11
•
IPv6 Guidelines, page 16-3
•
Additional Guidelines and Limitations, page 16-11
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed and transparent firewall modes.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
The following guidelines and limitations apply to using object groups with access lists:
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.
Configuring Object Groups with Access Lists
To use object groups for all available parameters in the access-list {tcp | udp} command, enter the
following command:
Command
Purpose
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]
Configures object groups with access lists.
For a detailed list of command options, see the access list estended
command in the Cisco Adaptive Security Appliance Command Reference.
For a complete configuration example about using object groups with
access lists, see the “Configuration Examples for Scheduling Access List
Activation” section on page 16-16.
hostname(config)# access-list 104 permit
tcp object-group A object-group B inactive
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Configuring Object Groups
Using Object Groups with Access Lists
Monitoring the Use of Object Groups with Access Lists
To monitor the use of object groups with accesslists, enter the following commands:
Command
Purpose
show access-list
Displays the access list entries that are expanded
out into individual entries without their object
groupings.
show object-group [protocol | network |
service | icmp-type | id grp_id]
Displays a list of the currently configured object
groups. If you enter the command without any
parameters, the system displays all configured
object groups.
show running-config object-group
Displays all current object groups.
show running-config object-group grp_id
Displays the current object groups by their group
ID.
show running-config object-group grp_type
Displays the current object groups by their group
type.
Example
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
Configuration Examples for Using Object Groups with Access Lists
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)#
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
access-list ACL_IN extended deny tcp host 10.1.1.4 host 209.165.201.29
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
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Adding Remarks to Access Lists
hostname(config)# access-list ACL_IN extended deny tcp host 10.1.1.89 host 209.165.201.78
eq www
hostname(config)# access-list ACL_IN extended permit ip any any
hostname(config)# 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
Feature History for Using Object Groups with Access Lists
Table 16-2 lists the release history for this feature.
Table 16-2
Feature History for Using Object Groups with Access Lists
Feature Name
Releases
Feature Information
Object groups
7.0
Object groups simplify access list creation and
maintenance.
The following commands were introduced or modified:
object-group protocol, object-group network,
object-group service, object-group icmp_type.
Adding Remarks to Access Lists
You can include remarks about entries in any access list, including extended, EtherType, IPv6, standard,
and Webtype 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:
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Scheduling Extended Access List Activation
Command
Purpose
access-list access_list_name remark text
Adds a remark after the last access-list command you entered.
Example:
hostname(config)# access-list OUT remark this is the inside admin address
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.
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.
Example
You can add a remark before each ACE, and the remarks appear in the access list in these location.
Entering a dash (-) at the beginning of a remark helps to set it apart from the ACE.
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
This section includes the following topics:
•
Information About Scheduling Access List Activation, page 16-14
•
Licensing Requirements for Scheduling Access List Activation, page 16-14
•
Guidelines and Limitations for Scheduling Access List Activation, page 16-15
•
Configuring and Applying Time Ranges, page 16-15
•
Configuration Examples for Scheduling Access List Activation, page 16-16
•
Feature History for Scheduling Access Lis t Activation, page 16-17
Information About Scheduling Access List Activation
You can schedule each ACE in an access list to be activated at specific times of the day and week by
applying a time range to the ACE.
Licensing Requirements for Scheduling Access List Activation
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
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Configuring Object Groups
Scheduling Extended Access List Activation
Guidelines and Limitations for Scheduling Access List Activation
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 16-15
•
Firewall Mode Guidelines, page 16-15
•
IPv6 Guidelines, page 16-11
•
Additional Guidelines and Limitations, page 16-15
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed and transparent firewall modes.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
The following guidelines and limitations apply to using object groups with access lists:
•
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 they are not further evaluated after the absolute end time is
reached.
Configuring and Applying Time Ranges
You can add a time range to implement a time-based access list. To identify the time range, perform the
steps in this section.
Detailed Steps
Step 1
Command
Purpose
time-range name
Identifies the time-range name.
Example:
hostname(config)# time range Sales
Step 2
Do one of the following:
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Command
Purpose
periodic days-of-the-week time to
[days-of-the-week] time
Specifies a recurring time range.
You can specify the following values for days-of-the-week:
Example:
hostname(config-time-range)# periodic
monday 7:59 to friday 17:01
•
monday, tuesday, wednesday, thursday, friday, saturday,
or 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.
Step 3
absolute start time date [end time date]
Specifies an absolute time range.
Example:
hostname(config-time-range)# absolute
start 7:59 2 january 2009
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.
access-list access_list_name [extended]
{deny | permit}...[time-range name]
Example:
hostname(config)# access list Marketing
extended deny tcp host 209.165.200.225
host 209.165 201.1 time-range
Pacific_Coast
The date is in the format day month year; for example, 1 january
2006.
Applies the time range to an ACE.
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.
See Chapter 11, “Adding an Extended Access List,” for complete
access-list command syntax.
Example
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
Configuration Examples for Scheduling Access List Activation
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
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Scheduling Extended Access List Activation
Feature History for Scheduling Access Lis t Activation
Table 16-3 lists the release history for this feature.
Table 16-3
Feature History for Scheduling Access List Activation
Feature Name
Releases
Feature Information
Scheduling access list activation
7.0
You can schedule each ACE in an access list to be activated
at specific times of the day and week.
The following commands were introduced or modified:
object-group protocol, object-group network,
object-group service, object-group icmp_type.
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17
Configuring Logging for Access Lists
This chapter describes how to configure access list logging for extended access lists and Webytpe access
lists, and it describes how to manage deny flows.
This section includes the following topics:
•
Configuring Logging for Access Lists, page 17-1
•
Managing Deny Flows, page 17-5
Configuring Logging for Access Lists
This section includes the following topics
•
Information About Logging Access List Activity, page 17-1
•
Licensing Requirements for Access List Logging, page 17-2
•
Guidelines and Limitations, page 17-3
•
Default Settings, page 17-3
•
Configuring Access List Logging, page 17-3
•
Monitoring Access Lists, page 17-4
•
Configuration Examples for Access List Logging, page 17-4
•
Feature History for Access List Logging, page 17-5
Information About Logging Access List Activity
By default, when traffic is denied by an extended ACE or a Webtype ACE, the ASA 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 ASA 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 enables you to limit the number of system messages produced. Alternatively, you can
disable all logging.
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Configuring Logging for Access Lists
Configuring Logging for Access Lists
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 shown in the following example:
hostname(config)# access-list TEST deny ip any any log
The log options at the end of the extended access-list command enable 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 uses the following form:
%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 ASA creates a flow entry
to track the number of packets received within a specific interval. The ASA 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 ASA resets the hit count to 0. If no packets match the ACE during an
interval, the ASA 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 17-5 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 ASA 5500 Series System Log Messages for detailed information about this system message.
Licensing Requirements for Access List Logging
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
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Configuring Logging for Access Lists
Configuring Logging for Access Lists
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 17-3
•
Firewall Mode Guidelines, page 17-3
•
IPv6 Guidelines, page 17-3
•
Additional Guidelines and Limitations, page 17-3
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported only in routed and transparent firewall modes.
IPv6 Guidelines
Supports IPv6.
Additional Guidelines and Limitations
ACE logging generates system log message 106023 for denied packets. A deny ACE must be present to
log denied packets.
Default Settings
Table 17-1 lists the default settings for extended access list parameters.
Table 17-1
Default Extended Access List Parameters
Parameters
Default
log
When the log keyword is specified, the default
level for system log message 106100 is 6
(informational), and the default interval is 300
seconds.
Configuring Access List Logging
This sections describes how to configure access list logging.
Note
For complete access list command syntax, see the “Configuring Extended Access Lists” section on
page 11-4 and the “Adding Webtype Access Lists” section on page 14-2.
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Configuring Logging for Access Lists
Configuring Logging for Access Lists
To configure logging for an ACE, enter the following command:
Command
Purpose
access-list access_list_name [extended]
{deny | permit}...[log [[level] [interval
secs] | disable | default]]
Configures logging for an ACE.
Example:
hostname(config)# access-list outside-acl
permit ip host 1.1.1.1 any log 7 interval
600
The access-list access_list_name syntax specifies the access list for which
you want to configure logging.
The extended option adds an ACE.
The deny keyword denies a packet if the conditions are matched. Some
features do not allow deny ACEs, such as NAT. (See the command
documentation for each feature that uses an access list for more
information.)
The permit keyword permits a packet if the conditions are matched.
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.
(See the access-list command in the Cisco Security Appliance Command
Reference for more information about command options.)
Monitoring Access Lists
To monitor access lists, enter one of the following commands:
Command
Purpose
show access list
Displays the access list entries by number.
show running-config access-list
Displays the current running access-list
configuration.
Configuration Examples for Access List Logging
This section includes sample configurations for logging access lists.
You might 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
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Managing Deny Flows
When the first ACE of outside-acl permits a packet, the ASA 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.
If one or more connections by the same host are 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 displays 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 the third ACE denies a packet, the ASA 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)
If 20 additional attempts occur within a 5 minute interval (the default), the following message appears
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)
Feature History for Access List Logging
Table 17-2 lists the release history for this feature.
Table 17-2
Feature History for Access List Logging
Feature Name
Releases
Feature Information
Access list logging
7.0
You can enable logging using system message 106100,
which provides statistics for each ACE and lets you limit the
number of system messages produced.
The following command was introduced: access-list.
Managing Deny Flows
This section includes the following topics:
•
Information About Managing Deny Flows, page 17-6
•
Licensing Requirements for Managing Deny Flows, page 17-6
•
Guidelines and Limitations, page 17-6
•
Managing Deny Flows, page 17-7
•
Monitoring Deny Flows, page 17-8
•
Feature History for Managing Deny Flows, page 17-8
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Configuring Logging for Access Lists
Managing Deny Flows
Information About Managing Deny Flows
When you enable logging for message 106100, if a packet matches an ACE, the ASA creates a flow entry
to track the number of packets received within a specific interval. The ASA 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 ASA places a limit on the number of
concurrent deny flows; the limit is placed on deny flows only (not on permit flows) because they can
indicate an attack. When the limit is reached, the ASA does not create a new deny flow for logging until
the existing flows expire.
For example, if someone initiates a DoS attack, the ASA 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 ASA issues system message 106100:
%ASA|PIX-1-106101: The number of ACL log deny-flows has reached limit (number).
The access-list alert-interval command sets the time interval for generating the system log message
106001. The system log message 106001 alerts you that the adaptive security appliance has reached a
deny flow maximum. When the deny flow maximum is reached, another system log message 106001 is
generated if at least six seconds have passed since the last 106001 message was generated.
Licensing Requirements for Managing Deny Flows
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 17-3
•
Firewall Mode Guidelines, page 17-3
•
IPv6 Guidelines, page 17-3
•
Additional Guidelines and Limitations, page 17-3
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported only in routed and transparent firewall modes.
IPv6 Guidelines
Supports IPv6.
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Managing Deny Flows
Additional Guidelines and Limitations
The ASA places a limit on the number of concurrent deny flows only—not permit flows.
Default Settings
Table 17-1 lists the default settings for managing deny flows.
Table 17-3
Default Parameters for Managing Deny Flows
Parameters
Default
numbers
The numbers argument specifies the maximum
number of deny flows. The default is 4096.
secs
The secs argument specifies the time, in seconds,
between system messages. The default is 300.
Managing Deny Flows
To configure the maximum number of deny flows and to set the interval between deny flow alert
messages (106100), enter the following command:
Command
Purpose
access-list deny-flow-max number
Sets the maximum number of deny flows.
Example:
hostname(config)# access-list
deny-flow-max 3000
The numbers argument specifies the maximum number, which can be
between 1 and 4096. The default is 4096.
To set the amount of time between system messages (number 106101), which identifies that the
maximum number of deny flows was reached, enter the following command:
Command
Purpose
access-list alert-interval secs
Sets the time, in seconds, between system messages.
Example:
hostname(config)# access-list
alert-interval 200
The secs argument specifies the time interval between each deny flow
maximum message. Valid values are from 1 to 3600 seconds. The default
is 300 seconds.
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Configuring Logging for Access Lists
Managing Deny Flows
Monitoring Deny Flows
To monitor access lists, enter one of the following commands:
Command
Purpose
show access-list
Displays access list entries by number.
show running-config access-list
Displays the current running access-list
configuration.
Feature History for Managing Deny Flows
Table 17-2 lists the release history for this feature.
Table 17-4
Feature History for Managing Deny Flows
Feature Name
Releases
Feature Information
Managing Deny Flows
7.0
You can configure the maximum number of deny flows and
set the interval between deny flow alert messages.
The following commands were introduced: access-list
deny-flow and access-list alert-interval.
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A R T
3
Configuring IP Routing
CH A P T E R
18
Information About Routing
This chapter describes underlying concepts of how routing behaves on the ASA, and the routing
protocols that are supported. Subsequent chapters address each specific routing protocol in more detail.
This chapter includes the following sections:
•
Information About Routing, page 18-1
•
How Routing Behaves Within the Adaptive Security Appliance, page 18-3
•
Supported Internet Protocols for Routing, page 18-4
•
Information About the Routing Table, page 18-5
•
Information About IPv6 Support, page 18-8
Information About Routing
Routing is the act of moving information across an internetwork from a source to a destination. Along
the way, at least one intermediate node typically is encountered. Routing involves two basic activities:
determining optimal routing paths and transporting information groups (typically called packets)
through an internetwork. In the context of the routing process, the latter of these is referred to as packet
switching. Although packet switching is relatively straightforward, path determination can be very
complex.
Switching
Switching algorithms is relatively simple; it is the same for most routing protocols. In most cases, a host
determines that it must send a packet to another host. Having acquired a router's address by some means,
the source host sends a packet addressed specifically to a router’s physical (Media Access Control
[MAC]-layer) address, this time with the protocol (network layer) address of the destination host.
As it examines the packet's destination protocol address, the router determines that it either knows or
does not know how to forward the packet to the next hop. If the router does not know how to forward the
packet, it typically drops the packet. If the router knows how to forward the packet, however, it changes
the destination physical address to that of the next hop and transmits the packet.
The next hop may be the ultimate destination host. If not, the next hop is usually another router, which
executes the same switching decision process. As the packet moves through the internetwork, its
physical address changes, but its protocol address remains constant.
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Information About Routing
Information About Routing
Path Determination
Routing protocols use metrics to evaluate what path will be the best for a packet to travel. A metric is a
standard of measurement, such as path bandwidth, that is used by routing algorithms to determine the
optimal path to a destination. To aid the process of path determination, routing algorithms initialize and
maintain routing tables, which contain route information. Route information varies depending on the
routing algorithm used.
Routing algorithms fill routing tables with a variety of information. Destination/next hop associations
tell a router that a particular destination can be reached optimally by sending the packet to a particular
router representing the "next hop" on the way to the final destination. When a router receives an
incoming packet, it checks the destination address and attempts to associate this address with a next hop.
Routing tables also can contain other information, such as data about the desirability of a path. Routers
compare metrics to determine optimal routes, and these metrics differ depending on the design of the
routing algorithm used.
Routers communicate with one another and maintain their routing tables through the transmission of a
variety of messages. The routing update message is one such message that generally consists of all or a
portion of a routing table. By analyzing routing updates from all other routers, a router can build a
detailed picture of network topology. A link-state advertisement, another example of a message sent
between routers, informs other routers of the state of the sender's links. Link information also can be
used to build a complete picture of network topology to enable routers to determine optimal routes to
network destinations.
Note
Asymetric routing is not supported on the ASA.
Supported RouteTypes
There are several types of route types that a router can use, Listed below are the route types that the ASA
uses.
•
Static Versus Dynamic, page 18-2
•
Single-Path Versus Multipath, page 18-3
•
Flat Versus Hierarchical, page 18-3
•
Link-State Versus Distance Vector, page 18-3
Static Versus Dynamic
Static routing algorithms are hardly algorithms at all, but are table mappings established by the network
administrator before the beginning of routing. These mappings do not change unless the network
administrator alters them. Algorithms that use static routes are simple to design and work well in
environments where network traffic is relatively predictable and where network design is relatively
simple.
Because static routing systems cannot react to network changes, they generally are considered unsuitable
for today's large, constantly changing networks. Most of the dominant routing algorithms today are
dynamic routing algorithms, which adjust to changing network circumstances by analyzing incoming
routing update messages. If the message indicates that a network change has occurred, the routing
software recalculates routes and sends out new routing update messages. These messages permeate the
network, stimulating routers to rerun their algorithms and change their routing tables accordingly.
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How Routing Behaves Within the Adaptive Security Appliance
Dynamic routing algorithms can be supplemented with static routes where appropriate. A router of last
resort (a router to which all unroutable packets are sent), for example, can be designated to act as a
repository for all unroutable packets, ensuring that all messages are at least handled in some way.
Single-Path Versus Multipath
Some sophisticated routing protocols support multiple paths to the same destination. Unlike single-path
algorithms, these multipath algorithms permit traffic multiplexing over multiple lines. The advantages
of multipath algorithms are obvious: They can provide substantially better throughput and reliability.
This is generally called load sharing.
Flat Versus Hierarchical
Some routing algorithms operate in a flat space, while others use routing hierarchies. In a flat routing
system, the routers are peers of all others. In a hierarchical routing system, some routers form what
amounts to a routing backbone. Packets from nonbackbone routers travel to the backbone routers, where
they are sent through the backbone until they reach the general area of the destination. At this point, they
travel from the last backbone router through one or more nonbackbone routers to the final destination.
Routing systems often designate logical groups of nodes, called domains, autonomous systems, or areas.
In hierarchical systems, some routers in a domain can communicate with routers in other domains, while
others can communicate only with routers within their domain. In very large networks, additional
hierarchical levels may exist, with routers at the highest hierarchical level forming the routing backbone.
The primary advantage of hierarchical routing is that it mimics the organization of most companies and
therefore supports their traffic patterns well. Most network communication occurs within small company
groups (domains). Because intradomain routers need to know only about other routers within their
domain, their routing algorithms can be simplified, and, depending on the routing algorithm being used,
routing update traffic can be reduced accordingly.
Link-State Versus Distance Vector
Link-state algorithms (also known as shortest path first algorithms) flood routing information to all
nodes in the internetwork. Each router, however, sends only the portion of the routing table that describes
the state of its own links. In link-state algorithms, each router builds a picture of the entire network in
its routing tables. Distance vector algorithms (also known as Bellman-Ford algorithms) call for each
router to send all or some portion of its routing table, but only to its neighbors. In essence, link-state
algorithms send small updates everywhere, while distance vector algorithms send larger updates only to
neighboring routers. Distance vector algorithms know only about their neighbors. Typically, this type of
algorithmn is used in conjunction with OSPF routing protocols.
How Routing Behaves Within the Adaptive Security Appliance
The ASA uses both routing table and XLATE tables for routing decisions. To handle destination IP
translated traffic, that is, untranslated traffic, the 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.
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Supported Internet Protocols for Routing
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 ASA 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.
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 ASA 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 ASA 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 ASA itself, but some routing process
is flapping around it, sending source translated packets that belong to the same flow through the ASA
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 ASA and around
it. That is, ensure that destination translated packets that belong to the same flow are always forwarded
the same way through the ASA.
Supported Internet Protocols for Routing
The ASA supports several internet protocols for routing. Each protocol is briefly desribed in this section.
•
Enhanced Interior Gateway Routing Protocol (EIGRP)
Enhanced IGRP provides compatibility and seamless interoperation with IGRP routers. An
automatic-redistribution mechanism allows IGRP routes to be imported into Enhanced IGRP, and
vice versa, so it is possible to add Enhanced IGRP gradually into an existing IGRP network.
For more infomation on configuring EIGRP, see the chapter ‘Configuring EIGRP’.
•
Open Shortest Path First (OSPF)
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Open Shortest Path First (OSPF) is a routing protocol developed for Internet Protocol (IP) networks
by the interior gateway protocol (IGP) working group of the Internet Engineering Task Force
(IETF). OSPF uses a link-state algorithm in order 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
For more infomation on configuring OSPF, see the chapter ‘Configuring OSPF’.
•
Routing Information Protocol
The Routing Information Protocol (RIP) is a distance-vector protocol that uses hop count as its
metric. RIP is widely used for routing traffic in the global Internet and is an interior gateway
protocol (IGP), which means that it performs routing within a single autonomous system.
For more infomation on configuring RIP, see the chapter ‘Configuring RIP’.
Information About the Routing Table
This section contains the following topics:
•
Displaying the Routing Table, page 18-5
•
How the Routing Table is Populated, page 18-5
•
How Forwarding Decisions are Made, page 18-7
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 ASA, 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 ASA 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 ASA can run multiple
routing protocols in addition to having static and connected routed in the routing table, it is possible that
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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:
– 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 ASA 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 ASA 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 ASA 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 18-1 shows the default
administrative distance values for the routing protocols supported by the ASA.
Table 18-1
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
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Table 18-1
Default Administrative Distance for Supported Routing Protocols
EIGRP external route
170
Unknown
255
The smaller the administrative distance value, the more preference is given to the protocol. For example,
if the ASA 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 ASA
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.
In the above example, if the source of the OSPF-derived route was lost (for example, due to a power
shutdown), the ASA 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 ASA 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 ASA 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
ASA. 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.
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•
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 ASA 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
....
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
Because static routing systems cannot react to network changes, they generally are considered unsuitable
for today's large, constantly changing networks. Most of the dominant routing algorithms today are
dynamic routing algorithms, which adjust to changing network circumstances by analyzing incoming
routing update messages. If the message indicates that a network change has occurred, the routing
software recalculates routes and sends out new routing update messages. These messages permeate the
network, stimulating routers to rerun their algorithms and change their routing tables accordingly.
Dynamic routing algorithms can be supplemented with static routes where appropriate. A router of last
resort (a router to which all unroutable packets are sent), for example, can be designated to act as a
repository for all unroutable packets, ensuring that all messages are at least handled in some way.
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 ASA 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.
For more information on static routs and how to configure them , see “Configuring Static and Default
Routes”.
Information About IPv6 Support
Many, but not all, features on the ASA supports IPv6 traffic. This section describes the commands and
features that support IPv6, and includes the following topics:
•
Features that Support IPv6, page 18-8
•
IPv6-Enabled Commands, page 18-9
•
Entering IPv6 Addresses in Commands, page 18-10
Features that Support IPv6
The following features support IPv6.
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Note
For features that use the Modular Policy Framework, be sure to use the match any command to match
IPv6 traffic; other match commands do not support IPv6.
•
The following application inspections support IPv6 traffic:
– FTP
– HTTP
– ICMP
– SIP
– SMTP
– IPSec-pass-thru
•
IPS
•
NetFlow Secure Event Logging filtering
•
Connection limits, timeouts, and TCP randomization
•
TCP Normalization
•
TCP state bypass
•
Access group, using an IPv6 access list
•
Static Routes
•
VPN (all types)
IPv6-Enabled Commands
The following ASA 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
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The following commands were modified to work for IPv6:
•
debug
•
fragment
•
ip verify
•
mtu
•
icmp (entered as ipv6 icmp)
IPv6 Command Guidelines in Transparent Firewall Mode
The ipv6 address and ipv6 enable commands are available in global configuration mode instead of
interface configuration mode. The ipv6 address command does not support the eui keyword. (The ipv6
address link-local command is still available in interface configuration mode.
The following IPv6 commands are not supported in transparent firewall mode, because they require
router capabilities:
•
ipv6 address autoconfig
•
ipv6 nd prefix
•
ipv6 nd ra-interval
•
ipv6 nd ra-lifetime
•
ipv6 nd suppress-ra
The following VPN command is not supported, because transparent mode does not support VPN:
•
ipv6 local pool
Entering IPv6 Addresses in Commands
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 ASA 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 .
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Configuring Static and Default Routes
This chapter describes how to configure static and default routes on the ASA, and includes the following
sections:
•
Information About Static and Default Routes, page 19-1
•
Licensing Requirements for Static and Default Routes, page 19-2
•
Guidelines and Limitations, page 19-2
•
Configuring Static and Default Routes, page 19-2
•
Monitoring a Static or Default Route, page 19-5
•
Configuration Examples for Static or Default Routes, page 19-7
•
Feature History for Static and Default Routes, page 19-7
Information About Static and Default Routes
To route traffic to a non-connected host or network, you must define a static route to the host or network
or, at a minimum, a default route for any networks to which the ASA is not directly connected; for
example, when there is a router between a network and the ASA.
Without a static or default route defined, traffic to non-connected hosts or networks generates the
following error message:
%ASA-6-110001: No route to dest_address from source_address
Multiple context mode does not support dynamic routing,
You might want to use static routes in single context mode in the following cases:
•
Your networks use a different router discovery protocol from EIGRP, 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 ASA.
In transparent firewall mode, for traffic that originates on the ASA and is destined for a non-directly
connected network, you need to configure either a default route or static routes so the ASA knows out
of which interface to send traffic. Traffic that originates on the ASA might include communications to a
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Licensing Requirements for Static and Default Routes
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. Additionally, the ASA supports up
to three equal cost routes on the same interface for load balancing.
Licensing Requirements for Static and Default Routes
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed and transparent firewall mode.
IPv6 Guidelines
Supports IPv6.
Configuring Static and Default Routes
This section explains how to configure a static, and a static default route and includes the following
topics:
•
Configuring a Static Route, page 19-2
•
Configuring a Default Static Route, page 19-3
•
Configuring IPv6 Default and Static Routes, page 19-4
Configuring a Static Route
Static routing algorithms are basically table mappings established by the network administrator before
the beginning of routing. These mappings do not change unless the network administrator alters them.
Algorithms that use static routes are simple to design and work well in environments where network
traffic is relatively predictable and where network design is relatively simple. Because of this fact, static
routing systems cannot react to network changes.
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,
and are reinstated when the interface comes back up.
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Configuring Static and Default Routes
Note
If you create a static route with an administrative distance greater than the administrative distance of the
routing protocol running on the ASA, 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.
To configure a static route, enter the following command:
Detailed Steps
Command
Purpose
route if_name dest_ip mask gateway_ip
[distance]
This enables you to add a static route.
Example:
hostname(config)# route outside 10.10.10.0
255.255.255.0 192.168.1.1 [1]
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 ASA 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.
Configuring a Default Static Route
A default route identifies the gateway IP address to which the ASA 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.
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 following
message:
“ERROR: Cannot add route entry, possible conflict with existing routes.”
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Configuring Static and Default 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 ASA 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.
Limitations on Configuring a Default Static Route
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 Unicast RPF 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 a tunneled default route, enter the following command:
Detailed Steps
Command
Purpose
route if_name 0.0.0.0 0.0.0.0 gateway_ip
[distance | tunneled]
This enables you to add a static route.
Example:
hostname(config)# route outside 0 0
192.168.2.4 tunneled
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 ASA 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.
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
Configuring IPv6 Default and Static Routes
The ASA 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.
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Monitoring a Static or Default Route
To configure an IPv6 default route and static routes, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
ipv6 route if_name ::/0 next_hop_ipv6_addr
This step adds a default IPv6 route.
Example:
hostname(config)#ipv6 route inside
7fff::0/32 3FFE:1100:0:CC00::1
This example routes packets for network 7fff::0/32 to a
networking device on the inside interface at
3FFE:1100:0:CC00::1
The address ::/0 is the IPv6 equivalent of “any.”
Step 2
ipv6 route if_name destination
next_hop_ipv6_addr [admin_distance]
Example:
hostname(config)# ipv6 route inside
7fff::0/32 3FFE:1100:0:CC00::1 [110]
Note
This step adds an IPv6 static route to the IPv6 routing table.
This example routes packets for network 7fff::0/32 to a
networking device on the inside interface at
3FFE:1100:0:CC00::1 , and with an administrative distance of
110.
The ipv6 route command works like the route command used to define IPv4 static routes.
Monitoring a Static or Default Route
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 ASA 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 ASA 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 ASA 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:
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Monitoring a Static or Default Route
Detailed Steps
Step 1
Command
Purpose
sla monitor sla_id
Configure the tracked object monitoring parameters by defining
the monitoring process.
Example:
hostname(config)# sla monitor sla_id
If you are configuring a new monitoring process, you enter SLA
monitor configuration mode.
If you are changing the monitoring parameters for an unscheduled
monitoring process that already has a type defined, you
automatically enter SLA protocol configuration mode.
Step 2
type echo protocol ipIcmpEcho target_ip
interface if_name
Example:
hostname(config-sla-monitor)# type echo
protocol ipIcmpEcho target_ip interface
if_name
Specify the monitoring protocol.
If you are changing the monitoring parameters for an unscheduled
monitoring process that already has a type defined, you
automatically enter SLA protocol configuration mode and cannot
change this setting.
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.
Step 3
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]
Example:
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]
Step 4
Step 5
Schedule the monitoring process.
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.
track track_id rtr sla_id reachability
Associate a tracked static route with the SLA monitoring process.
Example:
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.
Do one of the following to define the static route to be installed in the routing table while the tracked object is
reachable.
These options allow you to track a static route, or default route obtained through DHCP or PPPOE.
route if_name dest_ip mask gateway_ip
[admin_distance] track track_id
Example:
hostname(config)# route if_name dest_ip
mask gateway_ip [admin_distance] track
track_id
This option tracks a static route.
You cannot use the tunneled option with the route command with
static route tracking.
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Configuration Examples for Static or Default Routes
Command
Purpose
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
This option tracks a default route obtained through DHCP,
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
Remember that you must use the setroute argument with the ip
address dhcp command to obtain the default route using DHCP.
This option tracks a default route obtained through PPPoE.
You must use the setroute argument with the ip address pppoe
command to obtain the default route using PPPoE.
Configuration Examples for Static or Default Routes
Step 1
Create a static route:
hostname(config)# route inside 10.1.1.0 255.255.255.0 10.1.2.45 1
In this step, a static route is created that sends all traffic destined for 10.1.1.0/24 to the router (10.1.2.45)
connected to the inside interface.
Step 2
Define three equal cost static routes that directs traffic to three different gateways on the outside
interface, and adds a default route for tunneled traffic. The ASA distributes the traffic among the
specified gateways.
hostname(config)#
hostname(config)#
hostname(config)#
hostname(config)#
route
route
route
route
outside
outside
outside
outside
10.10.10.0 255.255.255.0 192.168.2.1
10.10.10.0 255.255.255.0 192.168.2.2
10.10.10.0 255.255.255.0 192.168.2.3
0 0 192.168.2.4 tunneled
Unencrypted traffic received by the ASA 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 ASA for which there is no static or learned route is passed to the gateway with the IP address
192.168.2.4.
Feature History for Static and Default Routes
Table 19-1 lists the release history for this feature.
Table 19-1
Feature History for Static and Default Routes
Feature Name
Releases
Feature Information
route command
7.0
The route command is used to enter a static or default route
for the specified interface.
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Configuring Static and Default Routes
Feature History for Static and Default Routes
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Defining Route Maps
This chapter includes the following sections:
•
Overview, page 20-1
•
Licensing Requirements for Route Maps, page 20-3
•
Guidelines and Limitations, page 20-3
•
Defining a Route Map, page 20-4
•
Customizing a Route Map, page 20-4
•
Configuration Example for Route Maps, page 20-6
•
Related Documents, page 20-6
•
Feature History for Route Maps, page 20-6
Overview
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.
Route maps have many features in common with widely known access control lists (ACLs). These are
some of the traits common to both mechanisms:
•
They are an ordered sequence of individual statements, each has a permit or deny result. Evaluation
of ACL or route-maps consists of a list scan, in a predetermined order, and an evaluation of the
criteria of each statement that matches. A list scan is aborted once the first statement match is found
and an action associated with the statement match is performed.
•
They are generic mechanisms—criteria matches and match interpretation are dictated by the way
they are applied. The same route map applied to different tasks might be interpreted differently.
These are some of the differences between route-maps and ACLs:
•
Rout -maps frequently use ACLs as matching criteria.
•
The main result from the evaluation of an access list is a yes or no answer—an ACL either permits
or denies input data. Applied to redistribution, an ACL determines if a particular route can (route
matches ACLs permit statement) or can not (matches deny statement) be redistributed. Typical
route-maps not only permit (some) redistributed routes but also modify information associated with
the route, when it is redistributed into another protocol.
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Defining Route Maps
Overview
•
Route-maps are more flexible than ACLs and can verify routes based on criteria which ACLs can
not verify. For example, a route map can verify if the type of route is internal.
•
Each ACL ends with an implicit deny statement, by design convention; there is no similar
convention for route-maps. If the end of a route map is reached during matching attempts, the result
depends on the specific application of the route map. Fortunately, route-maps that are applied to
redistribution behave the same way as ACLs: if the route does not match any clause in a route map
then the route redistribution is denied, as if the route map contained deny statement at the end.
The dynamic protocol redistribute command allows you to apply a route map. Route-maps are preferred
if you intend to either modify route information during redistribution or if you need more powerful
matching capability than an ACL can provide. If you simply need to selectively permit some routes based
on their prefix or mask, Cisco recommends that you use route map to map to an ACL (or equivalent
prefix list) directly in the redistribute command. If you use a route map to selectively permit some
routes based on their prefix or mask, you typically use more configuration commands to achieve the
same goal.
Permit and Deny Clauses
Route-maps can have permit and deny clauses. In route map ospf-to-eigrp, there is one deny clause
(with sequence number 10) and two permit clauses. The deny clause rejects route matches from
redistribution. Therefore, these rules apply:
•
If you use an ACL in a route map permit clause, routes that are permitted by the ACL are
redistributed.
•
If you use an ACL in a route map deny clause, routes that are permitted by the ACL are not
redistributed.
•
If you use an ACL in a route map permit or deny clause, and the ACL denies a route, then the route
map clause match is not found and the next route map clause is evaluated.
Match and Set Commands
Each route map clause has two types of commands:
•
match—Selects routes to which this clause should be applied.
•
set—Modifies information which will be redistributed into the target protocol.
For each route that is being redistributed, the router first evaluates the match command of a clause in the
route map. If the match criteria succeeds, then the route is redistributed or rejected as dictated by the
permit or deny clause, and some of its attributes might be modified by set commands. If the match
criteria fails, then this clause is not applicable to the route, and the software proceeds to evaluate the
route against the next clause in the route map. Scan of the route map continues until a clause is found
whose match command(s) match the route or until the end of the route map is reached.
A match or set command in each clause can be missed or repeated several times, if one of these
conditions exist:
•
If several match commands are present in a clause, all must succeed for a given route in order for
that route to match the clause (in other words, the logical AND algorithm is applied for multiple
match commands).
•
If a match command refers to several objects in one command, either of them should match (the
logical OR algorithm is applied). For example, in the match ip address 101 121 command, a route
is permitted if it is permitted by access list 101 or access list 121.
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Defining Route Maps
Licensing Requirements for Route Maps
Note
•
If a match command is not present, all routes match the clause. In the previous example, all routes
that reach clause 30 match; therefore, the end of the route map is never reached.
•
If a set command is not present in a route map permit clause then the route is redistributed without
modification of its current attributes.
Do not configure a set command in a deny route map clause because the deny clause prohibits route
redistribution—there is no information to modify.
A route map clause without a match or set command performs an action. An empty permit clause allows
a redistribution of the remaining routes without modification. An empty deny clause does not allows a
redistribution of other routes (this is the default action if a route map is completely scanned but no
explicit match is found).
Licensing Requirements for Route Maps
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
Context Mode Guidelines
Supported in single context mode.
Firewall Mode Guidelines
Supported only in routed firewall mode. Transparent mode is not supported.
IPv6 Guidelines
Does not support IPv6.
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Defining Route Maps
Defining a Route Map
Defining a Route Map
To define a route map, enter the following command:
Detailed Steps
Command
Purpose
route-map name {permit | deny}
[sequence_number]
Create the route map entry.
Example:
hostname(config)# route-map name {permit}
[12]
Route map entries are read in order. You can identify the order using the
sequence_number option, or the ASA uses the order in which you add the
entries.
Customizing a Route Map
This section describes how to customize the route map, and includes the following topics:
•
Defining a Route to Match a Specific Destination Address, page 20-4
•
Configuring the Metric Values for a Route Action, page 20-5
Defining a Route to Match a Specific Destination Address
To define a route to match a specified desitnation address, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
route-map name {permit | deny}
[sequence_number]
Create the route map entry.
Example:
hostname(config)# route-map name {permit}
[12]
Step 2
Route map entries are read in order. You can identify the order
using the sequence_number option, or the ASA uses the order in
which you add the entries.
Enter one of the following match commands to match routes to a specified destination address:
match ip address acl_id [acl_id] [...]
Example:
hostname(config-route-map)# match ip
address acl_id [acl_id] [...]
This allows you to match any routes that have a destination
network that matches a standard ACL.
If you specify more than one ACL, then the route can match any
of the ACLs.
match metric metric_value
This allows you to match any routes that have a specified metric.
Example:
hostname(config-route-map)# match metric
200
The metric_value can be from 0 to 4294967295.
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Customizing a Route Map
Command
Purpose
match ip next-hop acl_id [acl_id] [...]
This allows you to match any routes that have a next hop router
address that matches a standard ACL.
Example:
hostname(config-route-map)# match ip
next-hop acl_id [acl_id] [...]
match interface if_name
Example:
hostname(config-route-map)# match
interface if_name
If you specify more than one ACL, then the route can match any
of the ACLs.
This allows you to match any routes with the specified next hop
interface.
If you specify more than one interface, then the route can match
either interface.
match ip route-source acl_id [acl_id]
[...]
This allows you to match any routes that have been advertised by
routers that match a standard ACL.
Example:
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.
match route-type {internal | external
[type-1 | type-2]}
This allows you to match the route type.
Example:
hostname(config-route-map)# match
route-type internal type-1
Configuring the Metric Values for a Route Action
If a route matches the match commands, then the following set commands determine the action to
perform on the route before redistributing it.
To configure a route action, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
route-map name {permit | deny}
[sequence_number]
Create the route map entry.
Example:
hostname(config)# route-map name {permit}
[12]
Step 2
Route map entries are read in order. You can identify the order
using the sequence_number option, or the ASA uses the order in
which you add the entries.
Enter one or more of the following set commands to set a metric for the route map:
set metric metric_value
This allows you to set the metric.
Example:
hostname(config-route-map)# set metric 200
The metric_value can be a value between 0 and 294967295.
set metric-type {type-1 | type-2}
This allows you to set the metric type.
Example:
hostname(config-route-map)# set
metric-type type-2
The metric-type can be type-1 or type-2.
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Defining Route Maps
Configuration Example for Route Maps
Configuration Example for Route Maps
The following example shows how to redistribute routes with a hop count equal to 1 into OSPF. The ASA
redistributes these routes as external LSAs with a metric of 5 and a 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
The following example shows how to redistribute the 10.1.1.0 static route into eigrp process 1 with the
configured metric value:
hostname(config)# route outside 10.1.1.0 255.255.255.0 192.168.1.1
hostname(config-route-map)# access-list mymap2 line 1 permit 10.1.1.0 255.255.255.0
hostname(config-route-map)# route-map mymap2 permit 10
hostname(config-route-map)# match ip address mymap2
hostname(config-route-map)# router eigrp 1
hostname(config)# redistribute static metric 250 250 1 1 1 route-map mymap2
Related Documents
For additional information related to routing, see the following:
Related Topic
Document Title
Routing Overview
Information About Routing
How to configure OSPF
Configuring OSPF
How to configure EIGRP
Configuring EIGRP
How to configure RIP
Configuring RIP
How to configure a static or default route
Configuring Static and Default Routes
How to configure multicast routing
Configuring Multicast Routing
Feature History for Route Maps
Table 20-1 lists the release history for this feature.
Table 20-1
Feature History for Route Maps
Feature Name
Releases
Feature Information
Route mapping
7.0(1)
The route-map command allows you to define a route map
entry.
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Configuring OSPF
This chapter describes how to configure the ASA to route data, perform authentication, and redistribute
routing information, using the Open Shortest Path First (OSPF) routing protocol.
This chapter includes the following sections:
•
Overview, page 21-1
•
Licensing Requirements for OSPF, page 21-2
•
Guidelines and Limitations, page 21-3
•
Enabling OSPF, page 21-3
•
Customizing OSPF, page 21-4
•
Monitoring OSPF, page 21-15
•
Configuration Example for OSPF, page 21-16
•
Feature History for OSPF, page 21-17
•
Additional References, page 21-17
Overview
OSPF is an interior gateway routing protocol that uses link states rather than distance vectors for path
selection. OSPF propagates link-state advertisements rather than routing table updates. Because only
LSAs are exchanged instead of the entire routing tables, OSPF networks converge more quickly than RIP
networks.
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 ASA 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.
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Licensing Requirements for OSPF
The ASA 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 ASA 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 ASA as a designated router or a designated backup router. The ASA also
can be set up as an ABR.
•
Support for stub areas and not-so-stubby-areas.
Area boundary router type-3 LSA filtering.
OSPF supports MD5 and clear text neighbor authentication. Authentication should be used with all
routing protocols when possible because route redistribution between OSPF and other protocols (like
RIP) can potentially be used by attackers to subvert routing information.
If NAT is used, if OSPF is operating on public and private areas, and if address filtering is required, then
you need to run two OSPF processes—one process for the public areas and one for the private areas.
A router that has interfaces in multiple areas is called an Area Border Router (ABR). A router that acts
as a gateway to redistribute traffic between routers using OSPF and routers using other routing protocols
is called an Autonomous System Boundary Router (ASBR).
An ABR uses LSAs to send information about available routes to other OSPF routers. Using ABR type
3 LSA filtering, you can have separate private and public areas with the ASA acting as an ABR. Type 3
LSAs (inter-area routes) can be filtered from one area to other. This lets you use NAT and OSPF together
without advertising private networks.
Note
Only type 3 LSAs can be filtered. If you configure the ASA as an ASBR in a private network, it will send
type 5 LSAs describing private networks, which will get flooded to the entire AS including public areas.
If NAT is employed but OSPF is only running in public areas, then routes to public networks can be
redistributed inside the private network, either as default or type 5 AS External LSAs. However, you
need to configure static routes for the private networks protected by the ASA. Also, you should not mix
public and private networks on the same ASA interface.
You can have two OSPF routing processes, one RIP routing process, and one EIGRP routing process
running on the ASA at the same time.
Licensing Requirements for OSPF
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Guidelines and Limitations
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
Context Mode Guidelines
Supported in single context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
IPv6 Guidelines
Does not support IPv6.
Configuring OSPF
This section explains how to enable and restart the OSPF process on your system. After enabling see the
section, to learn how to customize the OSPF process on your system.
•
Enabling OSPF, page 21-3
•
Restarting the OSPF Process, page 21-4
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 detailed steps:
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Customizing OSPF
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for this OSPF process.
Example:
hostname(config)# router ospf 2
Step 2
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.
network ip_address mask area area_id
Example:
hostname(config)# router ospf 2
hostname(config-router)# network 10.0.0.0
255.0.0.0 area 0
This step defines the IP addresses on which OSPF runs and to
define the area ID for that interface.
Restarting the OSPF Process
This step allows you to remove the entire OSPF configuration you have enabled. Once this is cleared,
you must reconfigure OSPF again using the router ospf command, perform the following step:
Command
Purpose
clear ospf pid {process | redistribution |
counters [neighbor [neighbor-interface]
[neighbor-id]]}
This remove entire OSPF configuration you have enabled. Once this is
cleared, you must reconfigure OSPF again using the router ospf command.
Example:
hostname(config)# clear ospf
Customizing OSPF
This section explains how to customize the OSPF process and includes the following topics:
•
Redistributing Routes Into OSPF, page 21-5
•
Generating a Default Route, page 21-6
•
Configuring OSPF Interface Parameters, page 21-8
•
Configuring Route Summarization Between OSPF Areas, page 21-8
•
Configuring OSPF Interface Parameters, page 21-8
•
Configuring OSPF Area Parameters, page 21-11
•
Configuring OSPF NSSA, page 21-12
•
Configuring Route Calculation Timers, page 21-13
•
Defining Static OSPF Neighbors, page 21-13
•
Logging Neighbors Going Up or Down, page 21-14
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Customizing OSPF
Redistributing Routes Into OSPF
The ASA can control the redistribution of routes between OSPF routing processes. The ASA matches
and changes routes according to settings in the redistribute command or by using a route map.
If you want to redistribute a route by defining which of the routes from the specified routing protocol are
allowed to be redistributed into the target routing process, you must firstgenerate a default map and then
define a route map.
Note
(Optional) Create a route-map to further define which routes from the specified routing protocol are
redistributed in to the OSPF routing process. See Chapter 20, “Defining Route Maps.” Also, see the
“Generating a Default Route” section on page 21-6 for another use for route maps.
To redistribute static, connected, RIP, or OSPF routes into an OSPF process, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for tfor the OSPF process you want to
redistribute.
Example:
hostname(config)# router ospf 2
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
Do one of the following to redistribute the selected route type into the OSPF routing process:
redistribute connected
[[metric metric-value]
[metric-type {type-1 | type-2}]
[tag tag_value] [subnets] [route-map
map_name]
This step redistributes connected routes into the OSPF routing
process
Example:
hostname(config)# redistribute connected
redistribute static [metric metric-value]
[metric-type {type-1 | type-2}]
[tag tag_value] [subnets] [route-map
map_name
This step redistribute static routes into the OSPF routing process.
Example:
hostname(config)# redistribute static
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Customizing OSPF
Command
Purpose
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]
This step allows you to redistribute routes from an OSPF routing
process into another OSPF routing process.
Example:
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)# router ospf 2
hostname(config-router)# redistribute ospf
1 route-map 1-to-2
redistribute rip [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 subnet
option does 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.
This example shows route redistribution from OSPF process 1
into OSPF process 2 by matching routes with a metric equal to 1.
The ASA redistributes these routes as external LSAs with a metric
of 5, metric type of Type 1.
This step allows you to redistribute routes from a RIP routing
process into the OSPF routing process.
Example:
hostname(config)# redistribute rip 25
redistribute eigrp as-num
[metric metric-value]
[metric-type {type-1 | type-2}]
[tag tag_value] [subnets] [route-map
map_name]
This step allows you to redistribute routes from an EIGRP routing
process into the OSPF routing process.
Example:
hostname(config)# redistribute eigrp 2
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:
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Customizing OSPF
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for this OSPF process.
Example:
hostname(config)# router ospf 2
Step 2
default-information originate [always]
[metric metric-value] [metric-type {1 |
2}] [route-map map-name]
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.
This step forces the autonomous system boundary router to
generate a default route.
Example:
hostname(config-router)#
default-information originate always
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 ASA 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:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for this OSPF process.
Example:
hostname(config)# router ospf 1
Step 2
summary-address ip_address mask
[not-advertise] [tag tag]
Example:
hostname(config)# router ospf 1
hostname(config-router)# summary-address
10.1.0.0 255.255.0.0
Note
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.
This step sets the summary address.
In this 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
OSPF does not support summary-address 0.0.0.0 0.0.0.0.
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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:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for this OSPF process.
Example:
hostname(config)# router ospf 1
Step 2
area area-id range ip-address mask
[advertise | not-advertise]
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.
This step sets the address range.
In this example, the address range is set between OSPF areas.
Example:
hostname(config)# router ospf 1
hostname(config-router)# area 17 range
12.1.0.0 255.255.0.0
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.
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Configuring OSPF
Customizing OSPF
To configure OSPF interface parameters, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for tfor the OSPF process you want to
redistribute.
Example:
hostname(config)# router ospf 2
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
network ip_address mask area area_id
Example:
hostname(config)# router ospf 2
hostname(config-router)# network 10.0.0.0
255.0.0.0 area 0
Step 3
hostname(config)# interface interface_name
This step defines the IP addresses on which OSPF runs and to
define the area ID for that interface.
This allows you to enter interface configuration mode.
Example:
hostname(config)# interface my_interface
Step 4
Do one of the following to configure optional OSPF interface parameters:
ospf authentication [message-digest | null]
This specifies the authentication type for an interface.
Example:
hostname(config-interface)# ospf
authentication message-digest
ospf authentication-key key
Example:
hostname(config-interface)# ospf
authentication-key cisco
ospf cost cost
Example:
hostname(config-interface)# ospf cost 20
ospf dead-interval seconds
Example:
hostname(config-interface)# ospf
dead-interval 40
This allows you to assign a password to be used by neighboring
OSPF routers on a network segment that is using the OSPF simple
password authentication.
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 ASA 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.
This allows you to explicitly specify the cost of sending a packet
on an OSPF interface. The cost is an integer from 1 to 65535.
In this example, the cost is set to 20.
This allows you 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. The value must be the same for all
nodes on the network.
In this example, the dead-interval is set to 40.
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Customizing OSPF
Command
Purpose
ospf hello-interval seconds
This allows you to specify the length of time between the hello
packets that the ASA sends on an OSPF interface. The value must
be the same for all nodes on the network.
Example:
hostname(config-interface)# ospf
hello-interval 10
In this example, the hello-interval is set to 10.
ospf message-digest-key key_id md5 key
This enables OSPF MD5 authentication.
The following values can be set:
Example:
hostname(config-interface)# ospf
message-digest-key 1 md5 cisco
•
key_id—An identifier in the range from 1 to 255.
•
key—Alphanumeric password of up to 16 bytes.
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.
ospf priority number_value
This allows you to set the priority to help determine the OSPF
designated router for a network.
Example:
hostname(config-interface)# ospf priority
20
The number_value is between 0 to 255.
ospf retransmit-interval seconds
In this example, the priority number value is set to 20.
This allows you to specify the number of seconds between LSA
retransmissions for adjacencies belonging to an OSPF interface.
The value for 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 value
is 5 seconds.
Example:
hostname(config-interface)# ospf
retransmit-interval seconds
In this example, the retransmit-interval value is set to 15.
ospf transmit-delay seconds
Sets the estimated number of seconds required to send a link-state
update packet on an OSPF interface. The seconds value is from 1
to 65535 seconds. The default value is 1 second.
Example:
hostname(config-interface)# ospf
transmit-delay 5
In this example, the transmit-delay is 5 seconds.
ospf network point-to-point non-broadcast
Specifies the interface as a point-to-point, non-broadcast
network.
Example:
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 21-13, for more information.
Additionally, you can only define one OSPF neighbor on that
interface.
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Customizing OSPF
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:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for tfor the OSPF process you want to
redistribute.
Example:
hostname(config)# router ospf 2
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
Do one of the following to configure optional OSPF area parameters:
area area-id authentication
This step enables authentication for an OSPF area.
Example:
hostname(config-router)# area 0
authentication
area area-id authentication message-digest
This step enables MD5 authentication for an OSPF area.
Example:
hostname(config-router)# area 0
authentication message-digest
area area-id stub [no-summary]
This defines an area to be a stub area.
Example:
hostname(config-router)# area 17 stub
area area-id default-cost cost
This step assigns a specific cost to the default summary route used
for the stub area.
Example:
hostname(config-router)# area 17
default-cost 20
The cost is an integer from 1 to 65535. The default value is 1.
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Customizing OSPF
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.
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.
To specify area parameters for your network as needed to configure OSPF NSSA, perform the following
steps:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for tfor the OSPF process you want to
redistribute.
Example:
hostname(config)# router ospf 2
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
Do one of the following to configure optional OSPF NSSA parameters:
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Customizing OSPF
Command
Purpose
area area-id nssa [no-redistribution]
[default-information-originate]
This step defines an NSSA area.
Example:
hostname(config-router)# area 0 nssa
summary-address ip_address mask
[not-advertise] [tag tag]
Example:
hostname(config)# router ospf 1
hostname(config-router)# summary-address
10.1.0.0 255.255.0.0
Note
This step sets the summary address and 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.
In this 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
OSPF does not support summary-address 0.0.0.0 0.0.0.0.
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.
Before you begin, you must create a static route to the OSPF neighbor. See the chapter, ‘Configuring
Static and Default Routes’ for more information about creating static routes.
To define a static OSPF neighbor, perform the following tasks:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for this OSPF process.
Example:
hostname(config)# router ospf 2
Step 2
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.
neighbor addr [interface if_name]
This step defines the OSPF neighborhood.
Example:
hostname(config-router)# neighbor
255.255.0.0 [interface my_interface]
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.
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.
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Customizing OSPF
To configure route calculation timers, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for this OSPF process.
Example:
hostname(config)# router ospf 2
Step 2
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.
timers spf spf-delay spf-holdtime
This step configure the route calculation times.
Example:
hostname(config-router)# timers spf 10 120
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.
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.
To log neighbors going up or down, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
router ospf process_id
This creates an OSPF routing process, and the user enters router
configuration mode for this OSPF process.
Example:
hostname(config)# router ospf 2
Step 2
log-adj-changes [detail]
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.
This step configures logging for neighbors going up or down.
Example:
hostname(config-router)# log-adj-changes
[detail]
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Monitoring OSPF
Note
Logging must be enabled for the the neighbor up/down messages to be sent.
Monitoring OSPF
You can display specific statistics such as the contents of IP routing tables, caches, and databases. You
can also 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 monitor or display various OSPF routing statistics, perform one of the following tasks:
Command
Purpose
show ospf [process-id [area-id]]
Displays general information about OSPF routing
processes.
show ospf border-routers
Displays the internal OSPF routing table entries
to the ABR and ASBR.
show ospf [process-id [area-id]] database
Displays lists of information related to the OSPF
database for a specific router.
show ospf flood-list if-name
Displays a list of LSAs waiting to be flooded over
an interface (to observe OSPF 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
show ospf interface [if_name]
Displays OSPF-related interface information.
show ospf neighbor [interface-name]
[neighbor-id] [detail]
Displays OSPF neighbor information on a
per-interface basis.
show ospf request-list neighbor if_name
Displays a list of all LSAs requested by a router.
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Configuration Example for OSPF
Command
Purpose
show ospf retransmission-list neighbor
if_name
Displays a list of all LSAs waiting to be resent.
show ospf [process-id] summary-address
Displays a list of all summary address
redistribution information configured under an
OSPF process.
show ospf [process-id] virtual-links
Displays OSPF-related virtual links information.
Configuration Example for OSPF
The following example shows how to enable and configure OSPF with various optional processes:
Step 1
Enable OSPF.
hostname(config)# router ospf 2
hostname(config-router)# network 10.0.0.0 255.0.0.0 area 0
Step 2
Redistribute routes from one OSPF process to another OSPF process (optional):
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)# router ospf 2
hostname(config-router)# redistribute ospf 1 route-map 1-to-2
Step 3
Configure OSPF interface parameters (optional):
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
Step 4
Configure OSPF area parameters (optional):
hostname(config)# router
hostname(config-router)#
hostname(config-router)#
hostname(config-router)#
hostname(config-router)#
Step 5
ospf
area
area
area
area
2
0 authentication
0 authentication message-digest
17 stub
17 default-cost 20
Configure the route calculation timers and show the log neighbor up/down messages (optional):
hostname(config-router)# timers spf 10 120
hostname(config-router)# log-adj-changes [detail]
Step 6
Restart the OSPF process .
hostname(config)# clear ospf pid {process | redistribution | counters
[neighbor [neighbor-interface] [neighbor-id]]}
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Feature History for OSPF
Step 7
Show the results of your OSPF configuration (optional):
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
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
Feature History for OSPF
Table 21-1 lists the release history for this feature.
Table 21-1
Feature History for OSPF
Feature Name
Releases
Feature Information
router ospf
7.0
route data, perform authentication, redistribute and monitor
routing information, using the Open Shortest Path First
(OSPF) routing protocol.
Additional References
For additional information related to routing, see the following:
•
Related Documents, page 21-18
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Additional References
Related Documents
Related Topic
Document Title
Routing Overview
Information About Routing
How to configure EIGRP
Configuring EIGRP
How to configure RIP
Configuring RIP
How to configure a static or default route
Configuring Static and Default Routes
How to configure a route map
Defining Route Maps
How to configure multicast routing
Configuring Multicast Routing
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22
Configuring RIP
This chapter describes how to configure the ASA to route data, perform authentication, and redistribute
routing information, using the Routing Information Protocol (RIP) routing protocol.
This chapter includes the following sections:
•
Overview, page 22-1
•
Licensing Requirements for RIP, page 22-2
•
Guidelines and Limitations, page 22-2
•
Configuring RIP, page 22-3
•
Customizing RIP, page 22-3
•
Monitoring RIP, page 22-8
•
Configuration Example for RIP, page 22-9
•
Feature History for RIP, page 22-10
•
Additional References, page 22-10
Overview
The Routing Information Protocol, or RIP, as it is more commonly called, is one of the most enduring
of all routing protocols. RIP has four basic components: routing update process, RIP routing metrics,
routing stability, and routing timers. 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 ASA supports RIP Version 1 and RIP Version 2.
Routing Update Process
RIP sends routing-update messages at regular intervals and when the network topology changes. When
a router receives a routing update that includes changes to an entry, it updates its routing table to reflect
the new route. The metric value for the path is increased by 1, and the sender is indicated as the next hop.
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Licensing Requirements for RIP
RIP routers maintain only the best route (the route with the lowest metric value) to a destination. After
updating its routing table, the router immediately begins transmitting routing updates to inform other
network routers of the change. These updates are sent independently of the regularly scheduled updates
that RIP routers send.
RIP Routing Metric
RIP uses a single routing metric (hop count) to measure the distance between the source and a destination
network. Each hop in a path from source to destination is assigned a hop count value, which is typically
1. When a router receives a routing update that contains a new or changed destination network entry, the
router adds 1 to the metric value indicated in the update and enters the network in the routing table. The
IP address of the sender is used as the next hop.
RIP Stability Features
RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops
allowed in a path from the source to a destination. The maximum number of hops in a path is 15. If a
router receives a routing update that contains a new or changed entry, and if increasing the metric value
by 1 causes the metric to be infinity (that is, 16), the network destination is considered unreachable. The
downside of this stability feature is that it limits the maximum diameter of a RIP network to less than 16
hops.
RIP includes a number of other stability features that are common to many routing protocols. These
features are designed to provide stability despite potentially rapid changes in network topology. For
example, RIP implements the split horizon and holddown mechanisms to prevent incorrect routing
information from being propagated.
RIP Timers
RIP uses numerous timers to regulate its performance. These include a routing-update timer, a
route-timeout timer, and a route-flush timer. The routing-update timer clocks the interval between
periodic routing updates. Generally, it is set to 30 seconds, with a small random amount of time added
whenever the timer is reset. This is done to help prevent congestion, which could result from all routers
simultaneously attempting to update their neighbors. Each routing table entry has a route-timeout timer
associated with it. When the route-timeout timer expires, the route is marked invalid but is retained in
the table until the route-flush timer expires.
Licensing Requirements for RIP
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
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Configuring RIP
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed and transparent firewall mode.
IPv6 Guidelines
Does not support IPv6.
Configuring RIP
This section explains how to enable and restart the RIP process on your system.
•
Enabling RIP, page 22-3
After enabling see the section Customizing RIP, page 22-3, to learn how to customize the RIP process
on your system.
Enabling RIP
You can only enable one RIP routing process on the ASA. 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 ASA sends RIP Version 1 updates and accepts RIP Version 1 and Version 2 updates.
To enable the RIP routing process, perform the following step:
Detailed Steps
Command
Purpose
router rip
This starts the RIP routing process and places you in router configuration
mode.
Example:
hostname(config)# router rip
Use the no router rip command to remove entire RIP configuration you have enabled. Once this is
cleared, you must reconfigure RIP again using the router rip command.
Customizing RIP
This section describes how to configure RIP, and includes the following topics:
•
Generating a Default Route, page 22-4
•
Configuring Interfaces for RIP, page 22-4
•
Disabling Route Summarization, page 22-5
•
Filtering Networks in RIP, page 22-5
•
Redistributing Routes into the RIP Routing Process, page 22-6
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Customizing RIP
•
Configuring RIP Send/Receive Version on an Interface, page 22-7
•
Enabling RIP Authentication, page 22-8
Generating a Default Route
To generate a default route in RIP, use the following steps:
Detailed Steps
Step 1
Command
Purpose
router rip
This starts the RIP routing process and places you in router
configuration mode.
Example:
hostname(config)# router rip
Step 2
default-information originate
This step generates a default route into RIP.
Example:
hostname(config-router):#
default-information originate
Configuring Interfaces for RIP
If you have an interface that you do not want to participate in RIP routing, but that is attached to a
network that you want advertised, you can configure a network command that covers the network to
which the interface is attached, and use the passive-interface command to prevent that interface from
sending RIP advertisements. Additionally, you can specify the version of RIP that is used by the ASA
for updates.
Detailed Steps
Step 1
Command
Purpose
router rip
This starts the RIP routing process and places you in router
configuration mode.
Example:
hostname(config)# router rip
Step 2
network network_address
Example:
hostname(config)# router rip
hostname(config-router)# network 10.0.0.0
Step 3
This step specifies the interfaces that will participate in the RIP
routing process.
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.
Do one of the following to customize an interface to participate in RIP routing:
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Customizing RIP
Command
Purpose
version [1 | 2]
Specifies the version of RIP used by the ASA.
Example:
hostname(config-router):# version [1]
You can override this setting on a per-interface basis
passive-interface [default | if_name]
This step specifies an interface to operate in passive mode.
Example:
hostname(config-router):#
passive-interface [default]
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 that you
want to set to passive mode.
Disabling Route Summarization
RIP Version 1 always uses automatic route summarization. You cannot disable this feature for RIP
Version 1. RIP Version 2 uses automatic route summarization by default. The RIP 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 RIP, the RIP 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 RIP, 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 RIP routing process:
Detailed Steps
Step 1
Command
Purpose
router rip
This starts the RIP routing process and places you in router
configuration mode.
Example:
hostname(config)# router rip
Step 2
no auto-summarize
This step disables automatic route summarization.
Example:
hostname(config-router):# no
auto-summarize
Filtering Networks in RIP
To filter the networks received in updates, perform the following steps:
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Customizing RIP
Note
Before you begin, you must 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. For
more information on creating standard access lists, see the chapter, “Identifying Traffic with Access
Lists”.
Detailed Steps
Step 1
Command
Purpose
router rip
This starts the RIP routing process and places you in router
configuration mode.
Example:
hostname(config)# router rip
Step 2
distribute-list acl in [interface if_name]
distribute-list acl out [connected | eigrp
| interface if_name | ospf | rip | static]
Example:
hostname(config-router)# distribute-list
acl2 in [interface interface1]
This step filters the networks sent in updates.
You can specify an interface to apply the filter to only those
updates received or sent by that interface. 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.
hostname(config-router): distribute-list
acl3 out [connected]
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:
Note
Before you begin this procedure, you must create a route-map to further define which routes from the
specified routing protocol are redistributed in to the RIP routing process. See Chapter 20, “Defining
Route Maps,” for more information about creating a route map.
Detailed Steps
Command
Step 1
Purpose
Do one of the following to redistribute the selected route type into the RIP routing process. You must specify the
RIP metric values in the redistribute command if you do not have a default-metric command in the RIP router
configuration.
redistribute connected [ metric
<metric-value> | transparent ] [route-map
<route-map-name>]
Use this step to redistribute connected routes into the RIP routing
process.
Example:
hostname(config-router): # redistribute
connected [ metric <metric-value> |
transparent ] [route-map <route-map-name>]
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Customizing RIP
Command
Purpose
redistribute static [metric {metric_value
| transparent}] [route-map map_name]
Use this step to redistribute static routes into the EIGRP routing
process.
Example:
hostname(config-router):# redistribute
static [metric {metric_value |
transparent}] [route-map map_name]
redistribute ospf pid [match {internal |
external [1 | 2] | nssa-external [1 | 2]}]
[metric {metric_value | transparent}]
[route-map map_name]
Use this step to redistribute routes from an OSPF routing process
into the RIP routing process.
Example:
hostname(config-router):# redistribute
ospf pid [match {internal | external [1 |
2] | nssa-external [1 | 2]}] [metric
{metric_value | transparent}] [route-map
map_name]
redistribute eigrp as-num [metric
{metric_value | transparent}] [route-map
map_name]
Use this step to redistribute routes from an EIGRP routing process
into the RIP routing process.
Example:
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 ASA uses to send and receive RIP updates on a
per-interface basis.
To configure the RIP send and receive version, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
interface phy_if
This step enters interface configuration mode for the interface you
are configuring.
Example:
hostname(config)# interface phy_if
Step 2
Do one of the following to to send or receive RIP updates on a per-interface basis.
rip send version {[1] [2]}
Example:
hostname(config-if)# rip send version 1
rip receive version {[1] [2]}
Example:
hostname(config-if)# rip receive version 2
This step specifies the version of RIP to use when sending RIP
updates out of the interface.
In this example, version 1 is selected.
This step specifies the version of RIP advertisements permitted to
be received by an interface.
In this example, version 2 is selected.
RIP updates received on the interface that do not match the
allowed version are dropped.
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Monitoring RIP
Enabling RIP Authentication
Note
The ASA supports RIP message authentication for RIP Version 2 messages.
RIP route authentication provides MD5 authentication of routing updates from the RIP routing protocol.
The MD5 keyed digest in each RIP packet prevents the introduction of unauthorized or false routing
messages from unapproved sources.
RIP route authentication is configured on a per-interface basis. All RIP neighbors on interfaces
configured for RIP message authentication must be configured with the same authentication mode and
key for adjacencies to be established.
Note
Before you can enable RIP route authentication, you must enable RIP.
To enable RIP authentication on an interface, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
router rip
This creates an RIP routing process, and the user enters router
configuration mode for this RIP process.
Example:
hostname(config)# router rip
Step 2
interface phy_if
Example:
hostname(config)# interface phy_if
Step 3
rip authentication mode {text | md5}
Example:
hostname(config-if)# rip authentication
mode md5
Step 4
The as-num argument is the autonomous system number of the
RIP routing process.
Enter interface configuration mode for the interface on which you
are configuring RIP message authentication.
This step sets the authentication mode. By default, text
authentication is used. We recommend MD5 authentication.
rip authentication key key key-id key-id
Configure the authentication key used by the MD5 algorithm.
Example:
hostname(config-if)# rip authentication
key cisco key-id 200
The key argument can contain up to 16 characters.
The key-id argument is a number from 0 to 255.
Monitoring RIP
You can use the following commands to monitor or debug the RIP routing process.
We recommend that you only use the debug commands to troubleshoot specific problems or during
troubleshooting sessions with Cisco TAC.
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Configuration Example for RIP
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. For examples and descriptions of the command output, see the Cisco Security
Appliance Command Reference.
To monitor or debug various RIP routing statistics, perform one of the following tasks:
Command
Purpose
Monitoring RIP Routing
show rip database
Display the contents of the RIP routing database.
show running-config router rip
Displays the RIP commands.
Debug RIP
debug rip events
Displays RIP processing events.
debug rip database
Displays RIP database events.
Configuration Example for RIP
The following example shows how to enable and configure RIP with various optional processes:
Step 1
Enable RIP:
hostname(config)# router rip 2
Step 2
Configure a default route into RIP:
hostname(config-router): default-information originate
Step 3
Specify the version of RIP to use:
hostname(config-router): version [1]
Step 4
Specify the interfaces that will participate in the RIP routing process:
hostname(config-router)# network 225.25.25.225
Step 5
Specify an interface to operate in passive mode:
hostname(config-router)# passive-interface [default]
Step 6
Redistribute a connected route into the RIP routing process
hostname(config-router): redistribute connected [metric bandwidth delay reliability
loading mtu] [route-map map_name]
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Feature History for RIP
Feature History for RIP
Table 22-1 lists the release history for this feature.
Table 22-1
Feature History for RIP
Feature Name
Releases
Feature Information
router rip
7.0
This feature allows you to route data, perform
authentication, redistribute and monitor routing
information, using the Routing Information Protocol (RIP)
routing protocol.
Additional References
For additional information related to routing, see the following:
•
Related Documents, page 22-10
Related Documents
Related Topic
Document Title
Routing Overview
Information About Routing
How to configure EIGRP
Configuring EIGRP
How to configure RIP
Configuring RIP
How to configure a static or default route
Configuring Static and Default Routes
How to configure a route map
Defining Route Maps
How to configure multicast routing
Configuring Multicast Routing
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Configuring EIGRP
This chapter describes how to configure the ASA to route data, perform authentication, and redistribute
routing information, using the Enhanced Interior Gateway Routing Protocol (EIGRP) routing protocol.
This chapter includes the following sections:
•
Overview, page 23-1
•
Licensing Requirements for EIGRP, page 23-2
•
Guidelines and Limitations, page 23-2
•
Enabling EIGRP, page 23-3
•
Customizing EIGRP, page 23-4
•
Monitoring EIGRP, page 23-13
•
Configuration Example for EIGRP, page 23-14
•
Feature History for EIGRP, page 23-15
•
Additional References, page 23-15
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. Key
capabilities that distinguish EIGRP from other routing protocols include fast convergence, support for
variable-length subnet mask, support for partial updates, and support for multiple network layer
protocols.
A router running EIGRP stores all the neighbor routing tables so that it can quickly adapt to alternate
routes. If no appropriate route exists, EIGRP queries its neighbors to discover an alternate route. These
queries propagate until an alternate route is found. Its support for variable-length subnet masks permits
routes to be automatically summarized on a network number boundary. In addition, EIGRP can be
configured to summarize on any bit boundary at any interface. EIGRP does not make periodic updates.
Instead, it sends partial updates only when the metric for a route changes. Propagation of partial updates
is automatically bounded so that only those routers that need the information are updated. As a result of
these two capabilities, EIGRP consumes significantly less bandwidth than IGRP.
Neighbor discovery is the process that the ASA 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 ASA 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 ASA.
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Licensing Requirements for EIGRP
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 ASA can expect to
receive a hello packet from that neighbor. If the ASA does not receive a hello packet from that neighbor
within the hold time advertised by that neighbor, the ASA considers that neighbor to be unavailable.
The EIGRP protocol uses four key algorithm technologies, four key technologies, including neighbor
discover/recovery, Reliable Transport Protocol (RTP), and the fourth one, DUAL being important 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 ASA waits for three
minutes to receive a response from its neighbors. If the ASA 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.
Licensing Requirements for EIGRP
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
Supported in single context mode.
Firewall Mode Guidelines
Supported only in routed firewall mode. Transparent mode is not supported.
IPv6 Guidelines
Does not support IPv6.
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Configuring EIGRP
Configuring EIGRP
This section explains how to enable and restart the EIGRP process on your system. After enabling see
the section, to learn how to customize the EIGRP process on your system.
•
Enabling EIGRP, page 23-3
•
Enabling EIGRP Stub Routing, page 23-3
•
Restarting the EIGRP Process, page 23-4
Enabling EIGRP
You can only enable one EIGRP routing process on the ASA. To enable EIGRP, perform the following
detailed steps.
Detailed Steps
Step 1
Command
Purpose
router eigrp as-num
This creates an EIGRP routing process, and the user enters router
configuration mode for this EIGRP process.
Example:
hostname(config)# router eigrp 2
Step 2
network ip-addr [mask]
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
The as-num argument is the autonomous system number of the
EIGRP routing process.
This step configure the interfaces and networks that participate in
EIGRP routing. You can configure one or more network
statements with this command.
Directly-connected and static networks that fall within the defined
network are advertised by the ASA. 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, see the section Configuring Interfaces in EIGRP.
Enabling EIGRP Stub Routing
You can enable, and configure the ASA as an EIGRP stub router. Stub routing decreases memory and
processing requirements on the ASA. As a stub router, the ASA 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
ASA responds to all queries for summaries, connected routes, redistributed static routes, external routes,
and internal routes with the message “inaccessible.” When the ASA 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
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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 the ASA as an EIGRP stub routing process, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
router eigrp as-num
This creates an EIGRP routing process, and the user enters router
configuration mode for this EIGRP process.
Example:
hostname(config)# router eigrp 2
Step 2
network ip-addr [mask]
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
The as-num argument is the autonomous system number of the
EIGRP routing process.
This step configure the interfaces and networks that participate in
EIGRP routing. You can configure one or more network
statements with this command.
Directly-connected and static networks that fall within the defined
network are advertised by the ASA. 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, see the section Configuring Interfaces for EIGRP.
Step 3
eigrp stub {receive-only | [connected]
[redistributed] [static] [summary]}
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
hostname(config-router)# eigrp stub
{receive-only | [connected]
[redistributed] [static] [summary]}
This step configure the stub routing process. 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.
Restarting the EIGRP Process
To restart an EIGRP process, clear redistribution, or counters, enter the following command:
hostname(config)# clear eigrp pid {<1-65535> | neighbors | topology | events)}
Customizing EIGRP
This section describes how to customize the EIGRP routing, and includes the following topics:
•
Configuring Interfaces for EIGRP, page 23-5
•
Configuring the Summary Aggregate Addresses on Interfaces, page 23-6
•
Changing the Interface Delay Value, page 23-6
•
Enabling EIGRP Authentication on an Interface, page 23-7
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•
Defining an EIGRP Neighbor, page 23-8
•
Redistributing Routes Into EIGRP, page 23-9
•
Filtering Networks in EIGRP, page 23-10
•
Customizing the EIGRP Hello Interval and Hold Time, page 23-11
•
Disabling Automatic Route Summarization, page 23-12
•
Disabling EIGRP Split Horizon, page 23-13
Configuring Interfaces for EIGRP
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, you can 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.
Detailed Steps
Step 1
Command
Purpose
router eigrp as-num
This creates an EIGRP routing process, and the user enters router
configuration mode for this EIGRP process.
Example:
hostname(config)# router eigrp 2
Step 2
hostname(config-router)# network ip-addr
[mask]
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
The as-num argument is the autonomous system number of the
EIGRP routing process.
This step configure the interfaces and networks that participate in
EIGRP routing. You can configure one or more network
statements with this command.
Directly-connected and static networks that fall within the
defined network are advertised by the ASA. 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, see the section Configuring Interfaces for EIGRP.
Step 3
Do one of the following to customize an interface to participate in EIGRP routing:
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Command
Purpose
passive-interface {default | if-name}
This step prevents an interface from sending or receiving EIGRP
routing message.
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
hostname(config-router)# passive-interface
{default}
no default-information {in | out | WORD}
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
hostname(config-router)# no
default-information {in | out | WORD}
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.
This allows you to control the sending or receiving of candidate
default route information.
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.
Configuring the Summary Aggregate Addresses on Interfaces
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 ASA 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:
Detailed Steps
Step 1
Command
Purpose
interface phy_if
Enter interface configuration mode for the interface on which you
are changing the delay value used by EIGRP.
Example:
hostname(config)# interface phy_if
Step 2
summary-address eigrp as-num address mask
[distance]
Example:
hostname(config-if)# summary-address eigrp
2 address mask [20]
This step creates the summary address.
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.
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:
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Detailed Steps
Step 1
Command
Purpose
interface phy_if
Enter interface configuration mode for the interface on which you
are changing the delay value used by EIGRP.
Example:
hostname(config)# interface phy_if
Step 2
The value entered is in tens of microseconds. So, to set the delay
for 2000 microseconds, you would enter a value of 200.
delay value
Example:
hostname(config-if)# delay 200
To view the delay value assigned to an interface, use the show
interface command.
Enabling EIGRP Authentication on an Interface
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.
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.
Note
Before you can enable EIGRP route authentication, you must enable EIGRP.
To enable EIGRP authentication on an interface, perform the following steps:
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Detailed Steps
Step 1
router eigrp as-num
Example:
hostname(config)# router eigrp 2
This creates an EIGRP routing process, and the user
enters router configuration mode for this EIGRP
process.
The as-num argument is the autonomous system
number of the EIGRP routing process.
Step 2
network ip-addr [mask]
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
This step configure the interfaces and networks that
participate in EIGRP routing. You can configure one
or more network statements with this command.
Directly-connected and static networks that fall
within the defined network are advertised by the
ASA. 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, see the section
Configuring Interfaces in EIGRP.
Step 3
Step 4
Example:
hostname(config)# interface phy_if
Enter interface configuration mode for the interface
on which you are configuring EIGRP message
authentication.
authentication mode eigrp as-num md5
Enable MD5 authentication of EIGRP packets.
Example:
hostname(config)# authentication mode
eigrp 2 md5
The as-num argument is the autonomous system
number of the EIGRP routing process configured on
the ASA. If EIGRP is not enabled or if you enter the
wrong number, the ASA returns the following error
message:
interface phy_if
% Asystem(100) specified does not exist
Step 5
authentication key eigrp as-num key key-id
key-id
Example:
hostname(config)# authentication key eigrp
2 cisco key-id 200
Configure the key used by the MD5 algorithm.
The as-num argument is the autonomous system
number of the EIGRP routing process configured on
the ASA. If EIGRP is not enabled or if you enter the
wrong number, the ASA 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:
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Customizing EIGRP
Detailed Steps
Step 1
Command
Purpose
router eigrp as-num
This creates an EIGRP routing process, and the user enters router
configuration mode for this EIGRP process.
Example:
hostname(config)# router eigrp 2
Step 2
The as-num argument is the autonomous system number of the
EIGRP routing process.
neighbor ip-addr interface if_name
This step defines the static neighbor.
Example:
hostname(config)# router eigrp 2
hostname(config-router)# neighbor 10.0.0.0
interface interface1
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.
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.
Note
For RIP only: Before you begin this procedure, you must create a route-map to further define which
routes from the specified routing protocol are redistributed in to the RIP routing process. See Chapter 20,
“Defining Route Maps,” for more information about creating a route map.
To redistribute routes into the EIGRP routing process, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
router eigrp as-num
This creates an EIGRP routing process, and the user enters router
configuration mode for this EIGRP process.
Example:
hostname(config)# router eigrp 2
Step 2
Step 3
The as-num argument is the autonomous system number of the
EIGRP routing process.
default-metric bandwidth delay reliability
loading mtu
(Optional) Specify the default metrics that should be applied to
routes redistributed into the EIGRP routing process.
Example:
hostname(config)# router eigrp 2
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.
Do one of the following to redistribute the selected route type into the EIGRP routing process. 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.
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Customizing EIGRP
Command
Purpose
redistribute connected [metric bandwidth
delay reliability loading mtu] [route-map
map_name]
To redistribute connected routes into the EIGRP routing process.
Example:
hostname(config-router): redistribute
connected [metric bandwidth delay
reliability loading mtu] [route-map
map_name]
redistribute static [metric bandwidth
delay reliability loading mtu] [route-map
map_name]
To redistribute static routes into the EIGRP routing process.
Example:
hostname(config-router): redistribute
static [metric bandwidth delay reliability
loading mtu] [route-map map_name]
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 an OSPF routing process into the
EIGRP routing process.
Example:
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]
redistribute rip [ metric bandwidth delay
reliability load mtu] [route-map map_name]
To redistribute routes from a RIP routing process into the EIGRP
routing process.
Example:
(config-router): redistribute rip [metric
bandwidth delay reliability load mtu]
[route-map map_name]
Filtering Networks in EIGRP
Note
Before you begin this process, you must create a standard access list that defines the routes you want to
advertise. That is, create a standard access list that defines the routes you want to filter from sending or
receiving updates. For more information on creating standard access lists, see the chapter, “Identifying
Traffic with Access Lists”.
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Detailed Steps
Step 1
Command
Purpose
router eigrp as-num
This creates an EIGRP routing process, and the user enters router
configuration mode for this EIGRP process.
Example:
hostname(config)# router eigrp 2
Step 2
hostname(config-router)# network ip-addr
[mask]
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
The as-num argument is the autonomous system number of the
EIGRP routing process.
This step configure the interfaces and networks that participate in
EIGRP routing. You can configure one or more network
statements with this command.
Directly-connected and static networks that fall within the
defined network are advertised by the ASA. 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, see the section Configuring Interfaces for EIGRP.
Step 3
Do one of the following to filter networks sent or received in EIGRP routing updates. You can enter multiple
distribute-list commands in your EIGRP router configuration.
distribute-list acl out [connected | ospf
| rip | static | interface if_name]
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
hostname(config-router): distribute-list
acl out [connected]
distribute-list acl in [interface if_name]
Example:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0
255.0.0.0
hostname(config-router): distribute-list
acl in [interface interface1]
This allows you to filter networks sent in EIGRP routing updates.
You can specify an interface to apply the filter to only those
updates sent by that specific interface.
This allows you to filter networks received in EIGRP routing
updates.
You can specify an interface to apply the filter to only those
updates received by that interface.
Customizing the EIGRP Hello Interval and Hold Time
The ASA 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 ASA hold time. The hold time indicates to EIGRP neighbors the length
of time the neighbor should consider the ASA reachable. If the neighbor does not receive a hello packet
within the advertised hold time, then the ASA 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:
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Detailed Steps
Step 1
Command
Purpose
interface phy_if
Enter interface configuration mode for the interface on which you
are configuring hello interval or advertised hold time.
Example:
hostname(config)# interface phy_if
Step 2
hello-interval eigrp as-num seconds
This step allows you to change the hello interval.
Example:
hostname(config)# hello-interval eigrp 2
60
Step 3
hold-time eigrp as-num seconds
This step allows you to change the hold time.
Example:
hostname(config)# hold-time eigrp 2 60
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:
Detailed Steps
Step 1
Command
Purpose
router eigrp as-num
This creates an EIGRP routing process, and the user enters router
configuration mode for this EIGRP process.
Example:
hostname(config)# router eigrp 2
Step 2
no auto-summary
Example:
hostname(config-router)# no auto-summary
The as-num argument is the autonomous system number of the
EIGRP routing process.
Automatic summary addresses have an adminstrative distance of
5. You cannot configure this value.
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Monitoring EIGRP
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:
Detailed Steps
Step 1
Command
Purpose
interface phy_if
Enter interface configuration mode for the interface on which you
are changing the delay value used by EIGRP.
Example:
hostname(config)# interface phy_if
Step 2
no split-horizon eigrp as-number
This step disables the split horizon.
Example:
hostname(config-if)# no split-horizon
eigrp 2
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.
Additionally, you can disable the logging of neighbor change message and neighbor warning messages
To monitor or disable various EIGRP routing statistics, perform one of the following tasks:
Command
Purpose
Monitoring EIGRP Routing
show eigrp [as-number] events [{start end}
| type]
Displays the EIGRP event log.
show eigrp [as-number] neighbors [detail |
static] [if-name]
Displays the EIGRP neighbor table.
show eigrp [as-number] interfaces [if-name]
[detail]
Displays the interfaces participating in EIGRP
routing.
show eigrp [as-number] topology [ip-addr
[mask] | active | all-links | pending |
summary | zero-successors]
Displays the EIGRP topology table.
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Configuration Example for EIGRP
Command
Purpose
show eigrp [as-number] traffic
Displays EIGRP traffic statistics.
router-id
Displays the router-id for this EIGRP process.
Disabling EIGRP Logging Messages
Note
no eigrp log-neighbor-changes
Disables the logging of neighbor change
messages. Enter this command in router
configuration mode for the EIGRP routing
process.
no eigrp log-neighbor-warnings
Disables the logging of neighbor warning
messages.
By default neighbor change, and neighbor warning messages are logged.
Configuration Example for EIGRP
The following example shows how to enable and configure EIGRP with various optional processes:
Step 1
Enable EIGRP:
hostname(config)# router eigrp 2
hostname(config-router)# network 10.0.0.0 255.0.0.0
Step 2
Configure an interface from sending or receiving EIGRP routing message:
hostname(config-router)# passive-interface {default}
Step 3
Define an EIGRP neighbor:
hostname(config-router)# neighbor 10.0.0.0 interface interface1
Step 4
Configure the interfaces and networks that participate in EIGRP routing:
hostname(config-router)# network 10.0.0.0 255.0.0.0
Step 5
Change the interface delay value is used in EIGRP distance calculations:
hostname(config-router)# exit
hostname(config)# interface phy_if
hostname(config-if)# delay 200
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Feature History for EIGRP
Feature History for EIGRP
Table 23-1 lists the release history for this feature.
Table 23-1
Feature History for EIGRP
Feature Name
Releases
Feature Information
router eigrp
7.0
This feature allows you to route data, perform
authentication, redistribute and monitor routing
information, using the Enhanced Interior Gateway Routing
Protocol (EIGRP) routing protocol.
Additional References
For additional information related to routing, see the following:
•
Related Documents, page 23-15
Related Documents
Related Topic
Document Title
Routing Overview
Information About Routing
How to configure OSPF
Configuring OSPF
How to configure RIP
Configuring RIP
How to configure a static or default route
Configuring Static and Default Routes
How to configure a route map
Defining Route Maps
How to configure multicast routing
Configuring Multicast Routing
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Additional References
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24
Configuring Multicast Routing
This chapter describes how to configure the ASA to use the multicast routing protocol and includes the
following sections:
•
Information About Multicast Routing, page 24-17
•
Licensing Requirements for Multicast Routing, page 24-18
•
Guidelines and Limitations, page 24-18
•
Enabling Multicast Routing, page 24-19
•
Customizing Multicast Routing, page 24-20
•
Configuration Example for Multicast Routing, page 24-30
•
Configuration Example for Multicast Routing, page 24-30
•
Additional References, page 24-31
Information About Multicast Routing
Multicast routing is a bandwidth-conserving technology that reduces traffic by simultaneously
delivering a single stream of information to thousands of corporate recipients and homes. Applications
that take advantage of multicast routing include videoconferencing, corporate communications, distance
learning, and distribution of software, stock quotes, and news.
Multicast routing protocols delivers source traffic to multiple receivers without adding any additional
burden on the source or the receivers while using the least network bandwidth of any competing
technology. Multicast packets are replicated in the network by Cisco routers enabled with Protocol
Independent Multicast (PIM) and other supporting multicast protocols resulting in the most efficient
delivery of data to multiple receivers possible.
The ASA supports both stub multicast routing and PIM multicast routing. However, you cannot
configure both concurrently on a single ASA.
Note
The UDP and non-UDP transports are both supported for multicast routing. However, the non-UDP
transport has no FastPath optimization.
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Licensing Requirements for Multicast Routing
Stub Multicast Routing
Stub multicast routing provides dynamic host registration and facilitates multicast routing. When
configured for stub multicast routing, the ASA acts as an IGMP proxy agent. Instead of fully
participating in multicast routing, the ASA forwards IGMP messages to an upstream multicast router,
which sets up delivery of the multicast data. When configured for stub multicast routing, the ASA cannot
be configured for PIM.
The ASA 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.
PIM Multicast Routing
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.
Note
If the ASA is the PIM RP, use the untranslated outside address of the ASA as the RP address.
Multicast Group Concept
Multicast is based on the concept of a group. An arbitrary group of receivers expresses an interest in
receiving a particular data stream. This group does not have any physical or geographical
boundaries—the hosts can be located anywhere on the Internet. Hosts that are interested in receiving data
flowing to a particular group must join the group using IGMP. Hosts must be a member of the group to
receive the data stream.
Multicast Addresses
Multicast addresses specify an arbitrary group of IP hosts that have joined the group and want to receive
traffic sent to this group.
Licensing Requirements for Multicast Routing
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
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Enabling Multicast Routing
Context Mode Guidelines
Supported in single context mode. In multiple context mode, shared interfaces are not supported.
Firewall Mode Guidelines
Supported only in routed firewall mode. Transparent mode is not supported.
IPv6 Guidelines
Does not support IPv6.
Enabling Multicast Routing
Enabling multicast routing lets the ASA forward multicast packets. Enabling multicast routing
automatically enables PIM and IGMP on all interfaces.
To enable multicast routing, perform the following step:
Detailed Steps
Command
Purpose
multicast-routing
This step enables multicast routing.
Example:
hostname(config)# multicast-routing
The number of entries in the multicast routing tables are limited by the
amount of RAM on the system.
Table 24-1 lists the maximum number of entries for specific multicast tables based on the amount of
RAM on the ASA. Once these limits are reached, any new entries are discarded.
Table 24-1
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
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Customizing Multicast Routing
Customizing Multicast Routing
This section describes how to customize multicast routing and includes the following topics:
•
Configuring Stub Multicast Routing, page 24-20
•
Configuring a Static Multicast Route, page 24-20
•
Configuring IGMP Features, page 24-21
•
Configuring PIM Features, page 24-25
Configuring Stub Multicast Routing
Note
Stub Multicast Routing and PIM are not supported concurrently.
A ASA 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 ASA 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, perform the following step from the interface attached to
the stub area:
Detailed Steps
Command
Purpose
igmp forward interface if_name
This step configures stub multicast routing.
Example:
hostname(config-if)# igmp forward
interface interface1
Configuring a Static Multicast Route
When using PIM, the ASA 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.
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To configure a static multicast route or a static multicast route for a stub area, perform the following
steps:
Detailed Steps
Command
Step 1
Purpose
Do one of the following to configure a static multicast route or a static multicast route for a stub area.
mroute src_ip src_mask {input_if_name |
rpf_neighbor} [distance]
This step configures a static multicast route.
Example:
hostname(config)# mroute src_ip src_mask
{input_if_name | rpf_neighbor} [distance]
mroute src_ip src_mask input_if_name
[dense output_if_name] [distance]
Example:
hostname(config)# mroute src_ip src_mask
input_if_name [dense output_if_name]
[distance]
This step configures a static multicast route for a stub area.
The dense output_if_name keyword and argument pair is only
supported for stub multicast routing.
Configuring IGMP Features
IP hosts use Internet Group Management Protocol, or IGMP, to report their group memberships to
directly connected multicast routers.
IGMP is used to dynamically register individual hosts in a multicast group on a particular LAN. Hosts
identify group memberships by sending IGMP messages to their local multicast router. Under IGMP,
routers listen to IGMP messages and periodically send out queries to discover which groups are active
or inactive on a particular subnet.
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 ASA, 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 24-22
•
Configuring IGMP Group Membership, page 24-22
•
Configuring a Statically Joined IGMP Group, page 24-22
•
Controlling Access to Multicast Groups, page 24-23
•
Limiting the Number of IGMP States on an Interface, page 24-23
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Customizing Multicast Routing
•
Modifying the Query Messages to Multicast Groups, page 24-24
•
Changing the IGMP Version, page 24-25
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 ASA from sending host query
messages on that interface.
To disable IGMP on an interface, perform the following steps:
Detailed Steps
Command
Purpose
no igmp
This step disables IGMP on an interface.
Example:
hostname(config-if)# no igmp
To reenable IGMP on an interface, do the following:
Note
hostname(config-if)# igmp
Only the no igmp command appears in the interface configuration.
Configuring IGMP Group Membership
You can configure the ASA to be a member of a multicast group. Configuring the ASA 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 ASA join a multicast group, perform the following steps:
Detailed Steps
Command
Purpose
igmp join-group group-address
This step configures the ASA to be a member of a multicast group.
Example:
hostname(config-if)# igmp join-group
mcast-group
The group-address is the IP address of the group.
Configuring a Statically Joined IGMP 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 IGMP Group Membership, page 24-22).
This causes the ASA to accept and to forward the multicast packets.
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•
Using the igmp static-group command. The ASA does not accept the multicast packets but rather
forwards them to the specified interface.
To configure a statically joined multicast group on an interface,perform the following steps:
Detailed Steps
Command
Purpose
igmp static-group
This step configures the ASA statistically join a multicast group on an
interface.
Example:
hostname(config-if)# igmp static-group
group-address
The group-address is the IP address of the group.
Controlling Access to Multicast Groups
To control the multicast groups that hosts on the ASA interface can join, perform the following steps:
Detailed Steps
Command
Step 1
Purpose
Do one of the following to to create a standard or extended access list.
access-list name standard [permit | deny]
ip_addr mask
Example:
hostname(config)# access-list acl1
standard permit 192.52.662.25
access-list name extended [permit | deny]
protocol src_ip_addr src_mask dst_ip_addr
dst_mask
This step creates a standard 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.
The ip_addr mask argument is the IP address of the multicast
group being permitted or denied.
This step creates an extended access list.
The dst_ip_addr argument is the IP address of the multicast group
being permitted or denied.
Example:
hostname(config)# access-list acl2
extended permit protocol src_ip_addr
src_mask dst_ip_addr dst_mask
Step 2
igmp access-group acl
Apply the access list to an interface.
Example:
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.
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Customizing Multicast Routing
To limit the number of IGMP states on an interface, perform the following steps:
Detailed Steps
Command
Purpose
igmp limit number
This limit the number of IGMP states on an interface.
Example:
hostname(config-if)# igmp limit 50
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 Messages to Multicast Groups
Note
The igmp query-timeout and igmp query-interval commands require IGMP Version 2.
The ASA 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 ASA. If the
ASA 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.
When changing the query response time, by default, the maximum query response time advertised in
IGMP queries is 10 seconds. If the ASA does not receive a response to a host query within this amount
of time, it deletes the group.
To change the query interval, query response time, and query timeout value, perform the following steps:
Detailed Steps
Step 1
Command
Purpose
igmp query-interval seconds
To set the query interval time in seconds.
Example:
hostname(config-if)# igmp query-interval
30
Valid values range from 0 to 500, with 125 being the default
value.
If the ASA does not hear a query message on an interface for the
specified timeout value (by default, 255 seconds), then the ASA
becomes the designated router and starts sending the query
messages.
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Step 2
Step 3
Command
Purpose
igmp query-timeout seconds
To change this timeout value of the query.
Example:
hostname(config-if)# igmp query-timeout 30
Valid values range from 0 to 500, with 225 being the default
value.
igmp query-max-response-time seconds
Example:
To change the maximum query response time.
hostname(config-if)# igmp
query-max-response-time 30
Changing the IGMP Version
By default, the ASA 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 ASA 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 ASA running IGMP Version 2 works correctly when IGMP Version 1
hosts are present.
To control which version of IGMP is running on an interface, perform the following steps:
Detailed Steps
Command
Purpose
igmp version {1 | 2}
This step controls which version of IGMP you want to run on the interface.
Example:
hostname(config-if)# igmp version 2
Configuring PIM Features
Routers use PIM to maintain forwarding tables for forwarding multicast diagrams. When you enable
multicast routing on the ASA, 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:
•
Enabling and Disabling PIM on an Interface, page 24-26
•
Configuring a Static Rendezvous Point Address, page 24-26
•
Configuring the Designated Router Priority, page 24-27
•
Filtering PIM Register Messages, page 24-28
•
Configuring PIM Message Intervals, page 24-28
•
Configuring a Multicast Boundary, page 24-28
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Customizing Multicast Routing
•
Filtering PIM Neighbors, page 24-29
•
Supporting Mixed Bidirectional/Sparse-Mode PIM Networks, page 24-29
Enabling and Disabling PIM on an Interface
You can disable PIM on specific interfaces. To disable PIM on an interface, use the following steps
Detailed Steps
Step 1
Command
Purpose
pim
This step enables or reenables PIM on a specific interface.
Example:
hostname(config-if)# pim
Step 2
This step disables PIM on a specific interface.
no pim
Example:
hostname(config-if)# no pim
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 ASA 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 ASA 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).
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To configure the address of the PIM PR, use the following step:
Detailed Steps
Command
Purpose
pim rp-address ip_address [acl] [bidir]
This step enables or reenables PIM on a specific interface.
Example:
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 ASA 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 ASA has a DR priority of 1. You can change this value by performing this step:
Detailed Steps
Command
Purpose
pim dr-priority num
This step changes the designated router priority.
Example:
hostname(config-if)# pim dr-priority 500
The num argument can be any number from 1 to 4294967294.
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Filtering PIM Register Messages
You can configure the ASA to filter PIM register messages. To filter PIM register messages, perform the
following step:
Detailed Steps
Command
Purpose
pim accept-register {list acl | route-map
map-name}
This step configure the ASA to filter PIM register messages.
Example:
hostname(config)# pim accept-register
{list acl | route-map map-name}
Configuring PIM Message Intervals
Router query messages are used to select the PIM DR. The PIM DR is responsible for sending router
query messages. By default, router query messages are sent every 30 seconds. Additionally, every 60
seconds, the ASA sends PIM join/prune messages. To change these intervals, perform the following
steps:
Detailed Steps
Step 1
Step 2
Command
Purpose
pim hello-interval seconds
This step sends router query messages.
Example:
hostname(config-if)# pim hello-interval 60
Valid values for the seconds argument range from 1 to 3600
seconds.
pim join-prune-interval seconds
This step changes the amount of time (in seconds) that the ASA
sends PIM join/prune messages.
Example:
hostname(config-if)# pim
join-prune-interval 60
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.
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.
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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.
To configure a multicast boundary, perform the following step:
Detailed Steps
Command
Purpose
multicast boundary acl [filter-autorp]
This step configures a multicast boundary.
Example:
hostname(config-if)# multicast boundary
acl [filter-autorp]
Filtering PIM Neighbors
You can define the routers that can become PIM neighbors . 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:
Detailed Steps
Step 1
Step 2
Command
Purpose
access-list pim_nbr deny router-IP_addr
PIM neighbor
This step uses the access-list command to define a standard access
list defines the routers you want to participate in PIM.
Example:
hostname(config)# access-list pim_nbr deny
10.1.1.1 255.255.255.255
In this 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:
pim neighbor-filter pim_nbr
Use the pim neighbor-filter command on an interface to filter the
neighbor routers.
Example:
hostname(config)# interface
GigabitEthernet0/3
hostname(config-if)# pim neighbor-filter
pim_nbr
In this example, the 10.1.1.1 router is prevented from becoming a
PIM neighbor on interface GigabitEthernet0/3.
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.
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Configuration Example for Multicast Routing
Bidirectional PIM 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 bidirectional PIM 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:
Detailed Steps
Step 1
Command
Purpose
access-list pim_bidir deny any
This step uses the access-list command to define a standard access
list defines the routers you want to participate in in the DF
election and denies all others.
Example:
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
In this 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.
pim bidir-neighbor-filter pim_bidir
Enable bidirectional PIM on an interface.
Example:
hostname(config)# interface
GigabitEthernet0/3
hostname(config-if)# pim
bidir-neighbor-filter pim_bidir
This example applies the access list created previous step to the
interface GigabitEthernet0/3.
Configuration Example for Multicast Routing
The following example shows how to enable and configure muticastrouting with various optional
processes:
Step 1
Enable multicast routing.
hostname(config)# multicast-routing
Step 2
Configure a static multicast route.
hostname(config)# mroute src_ip src_mask {input_if_name | rpf_neighbor} [distance]
hostname(config)# exit
Step 3
Configure the configure the ASA to be a member of a multicast group:
hostname(config) # interface
hostname(config-if)# igmp join-group group-address
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Additional References
Additional References
For additional information related to routing, see the following:
•
Related Documents, page 24-31
•
RFCs, page 24-31
Related Documents
Related Topic
Document Title
Routing Overview
Information About Routing
How to configure OSPF
Configuring OSPF
How to configure EIGRP
Configuring EIGRP
How to configure RIP
Configuring RIP
How to configure a static or default route
Configuring Static and Default Routes
How to configure a route map
Defining Route Maps
RFCs
The following is list of 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
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25
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 readability of
a neighbor, and keep track of neighboring routers.
This chapter describes how to enable and configure IPv6 neighbor discovery on the security appliance,
and it includes the following topics:
•
Configuring Neighbor Solicitation Messages, page 25-1
•
Configuring Router Advertisement Messages, page 25-7
•
Configuring a Static IPv6 Neighbor, page 25-22
Configuring Neighbor Solicitation Messages
This section includes the following configuration task topics:
•
Configuring Neighbor Solicitation Message Interval, page 25-1
•
Configuring the Neighbor Reachable Time, page 25-5
Configuring Neighbor Solicitation Message Interval
•
Information About Neighbor Solicitation Messages, page 25-2
•
Licensing Requirements for Neighbor Solicitation Messages, page 25-3
•
Guidelines and Limitations for the Neighbor Solicitation Message Interval, page 25-3
•
Default Settings for the Neighbor Solicitation Message Interval, page 25-3
•
Configuring the Neighbor Solicitation Message Interval, page 25-3
•
Monitoring Neighbor Solicitation Message Intervals, page 25-4
•
Feature History for Neighbor Solicitation Message Interval, page 25-4
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Configuring Neighbor Solicitation Messages
Information About 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 25-1 shows the neighbor solicitation and response process.
Figure 25-1
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.
This section shows how you can configure the neighbor solicitation message interval and neighbor
reachable time on a per-interface basis.
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Configuring Neighbor Solicitation Messages
Licensing Requirements for Neighbor Solicitation Messages
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for the Neighbor Solicitation Message Interval
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 25-23
•
Firewall Mode Guidelines, page 25-23
•
Additional Guidelines and Limitations, page 25-23
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
Additional Guidelines and Limitations
The interval value is included in all IPv6 router advertisements sent out this interface.
Default Settings for the Neighbor Solicitation Message Interval
Table 25-13 lists the default settings for neighbor solicitation message parameters.
Table 25-1
Default Neighbor Solicitation Messages Parameters
Parameters
Default
value (transmission interval)
1000 seconds between neighbor solicitation
transmissions
Configuring the Neighbor Solicitation Message Interval
To configure the interval between IPv6 neighbor solicitation retransmissions on an interface, enter the
following command:
Command
Purpose
ipv6 nd ns-interval value
Sets the interval between IPv6 neighbor solicitation retransmissions on an
interface.
Example:
hostname (config-if)# ipv6 nd ns-interval
9000
Valid values for the value argument range from 1000 to 3600000
milliseconds.
This information is also sent in router advertisement messages.
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Configuring Neighbor Solicitation Messages
Example
The following example configures an IPv6 neighbor solicitation transmission interval of 9000
milliseconds for Gigabitethernet 0/0:
hostname (config)# interface gigabitethernet 0/0
hostname (config-if)# ipv6 nd ns-interval 9000
Monitoring Neighbor Solicitation Message Intervals
To monitor IPv6 neighbor solicitation message intervals, perform one of the following tasks:
Command
Purpose
show ipv6 interface
Displays the usability status of interfaces
configured for IPv6. Including the interface name,
such as “outside,” displays the settings for the
specified interface. Excluding the name from the
command displays the settings for all interfaces
that have IPv6 enabled on them. Output for the
command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
•
The multicast groups to which the interface
belongs.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
•
The actual time when the command is set to 0.
•
The neighbor discovery reachable time that is
being used.
Feature History for Neighbor Solicitation Message Interval
Table 25-14 lists the release history for this feature.
Table 25-2
Feature History for Neighbor Solicitation Message Interval
Feature Name
Releases
Feature Information
Neighbor solicitation message interval
7.0(1)
The feature was introduced.
The following command was introduced: ipv6 nd
ns-interval.
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Configuring Neighbor Solicitation Messages
Configuring the Neighbor Reachable Time
This section includes the following topics:
•
Information About Neighbor Reachable Time, page 25-5
•
Licensing Requirements for Neighbor Reachable Time, page 25-5
•
Guidelines and Limitations for Neighbor Reachable Time, page 25-5
•
Default Settings for Neighbor Reachable Time, page 25-6
•
Configuring Neighbor Reachable Time, page 25-6
•
Monitoring Neighbor Reachable Time, page 25-7
•
Feature History for Neighbor Reachable Time, page 25-7
Information About 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.
Licensing Requirements for Neighbor Reachable Time
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for Neighbor Reachable Time
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 25-5
•
Firewall Mode Guidelines, page 25-5
•
Additional Guidelines and Limitations, page 25-6
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
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Configuring Neighbor Solicitation Messages
Additional Guidelines and Limitations
•
The interval value is included in all IPv6 router advertisements sent out this interface.
•
The configured 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.
Default Settings for Neighbor Reachable Time
Table 25-3 lists the default settings for neighbor reachable time parameters.
Table 25-3
Default Neighbor Reachable Time Parameters
Parameters
Default
value (time mode is reachable)
The default is 0.
Configuring Neighbor Reachable Time
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:
Command
Purpose
ipv6 nd reachable-time value
Sets the amount of time that a remote IPv6 node is reachable.
Example:
hostname (config-if)# ipv6 nd
reachable-time 1700000
Valid values for the value argument range from 0 to 3600000 milliseconds.
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.
Example
The following example configures an IPv6 reachable time of 1700000 milliseconds for the selected
interface, Gigabitethernet 0/0:
hostname (config)# interface gigabitethernet 0/0
hostname (config-if)# ipv6 nd reachable-time 1700000
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Configuring Router Advertisement Messages
Monitoring Neighbor Reachable Time
To monitor IPv6 neighbor reachable time, perform one of the following tasks:
Command
Purpose
show ipv6 interface
Displays the usability status of interfaces
configured for IPv6. Including the interface name,
such as “outside,” displays the settings for the
specified interface. Excluding the name from the
command displays the settings for all interfaces
that have IPv6 enabled on them. Output for the
command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
•
The multicast groups to which the interface
belongs.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
•
The actual time when the command is set to 0.
•
The neighbor discovery reachable time that is
being used.
Feature History for Neighbor Reachable Time
Table 25-4 lists the release history for this feature.
Table 25-4
Feature History for Neighbor Reachable Time
Feature Name
Releases
Feature Information
Neighbor solicitation message interval
7.0
The feature was introduced.
The following command was introduced: ipv6 nd
ns-interval.
Configuring Router Advertisement Messages
A security appliance can participate in router advertisements so that neighboring devices can
dynamically learn a default router address.
This section includes the following topics:
•
Information About Router Advertisement Messages, page 25-8
•
Configuring the Router Advertisement Transmission Interval, page 25-9
•
Configuring the Router Lifetime Value, page 25-12
•
Configuring the IPv6 Prefix, page 25-15
•
Suppressing Router Advertisement Messages, page 25-21
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Configuring Router Advertisement Messages
Information About Router Advertisement Messages
A security appliance can participate in router advertisements so that neighboring devices can
dynamically learn a default router address. Router advertisement messages (ICMPv6 Type 134) are
periodically sent out each IPv6 configured interface of the ASA. 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 25-2
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.
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 ASA
to be the default router.
•
The IPv6 network prefixes in use on the link.
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
•
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 25-9
•
Configuring the Router Lifetime Value, page 25-12
•
Configuring the IPv6 Prefix, page 25-15
•
Suppressing Router Advertisement Messages, page 25-19
Configuring the Router Advertisement Transmission Interval
This section shows how to configure the interval between IPv6 router advertisement transmissions on an
interface.
This section includes the following topics:
•
Licensing Requirements for Router Advertisement Transmission Interval, page 25-9
•
Guidelines and Limitations for Router Advertisement Transmission Interval, page 25-9
•
Default Settings for Router Advertisement Transmission Interval, page 25-10
•
Configuring Router Advertisement Transmission Interval, page 25-10
•
Monitoring Router Advertisement Transmission Interval, page 25-11
•
Feature History for Router Advertisement Transmission Interval, page 25-11
Licensing Requirements for Router Advertisement Transmission Interval
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for Router Advertisement Transmission Interval
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 25-9
•
Firewall Mode Guidelines, page 25-9
•
Additional Guidelines and Limitations, page 25-10
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Additional Guidelines and Limitations
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 specified value.
Default Settings for Router Advertisement Transmission Interval
Table 25-5 lists the default settings for neighbor reachable time parameters.
Table 25-5
Default Router Advertisement Transmission Interval Parameters
Parameters
Default
value (interval between transmissions)
The default is 200 seconds.
Configuring Router Advertisement Transmission Interval
To configure the interval between IPv6 router advertisement transmissions on an interface, enter the
following command:
Command
Purpose
ipv6 nd ra-interval [msec] value
Sets the interval between IPv6 router advertisement transmissions.
Example:
hostname (config-if)# ipv6 nd ra-interval
201
The optional msec keyword indicates that the value provided is in
milliseconds. If this keyword is not present, the value provided is in
seconds.
Valid values for the value argument range from 3 to 1800 seconds or from
500 to 1800000 milliseconds if the msec keyword is provided.
Example
The following example configures an IPv6 router advertisement interval of 201 seconds for the selected
interface, Gigabitethernet 0/0:
hostname (config)# interface gigabitethernet 0/0
hostname (config-if)# ipv6 nd ra-interval 201
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Monitoring Router Advertisement Transmission Interval
To monitor IPv6 neighbor reachable time, perform one of the following tasks:
Command
Purpose
show ipv6 interface
Displays the usability status of interfaces
configured for IPv6. Including the interface name,
such as “outside,” displays the settings for the
specified interface. Excluding the name from the
command displays the settings for all interfaces
that have IPv6 enabled on them. Output for the
command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
•
The multicast groups to which the interface
belongs.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
•
The actual time when the command is set to 0.
•
The neighbor discovery reachable time that is
being used.
Feature History for Router Advertisement Transmission Interval
Table 25-6 lists the release history for this feature.
Table 25-6
Feature History for Router Advertisement Transmission Interval
Feature Name
Releases
Feature Information
Router advertisement transmission interval
7.0(1)
The feature was introduced.
The following command was introduced: ipv6 nd
ra-interval.
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Chapter 25
Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Configuring the Router Lifetime Value
This section shows how to configure the interval between IPv6 router advertisement transmissions on an
interface.
This section includes the following topics:
•
Licensing Requirements for Router Advertisement Transmission Interval, page 25-9
•
Guidelines and Limitations for Router Advertisement Transmission Interval, page 25-9
•
Default Settings for Router Advertisement Transmission Interval, page 25-10
•
Configuring Router Advertisement Transmission Interval, page 25-10
•
Monitoring Router Advertisement Transmission Interval, page 25-11
•
Feature History for Router Advertisement Transmission Interval, page 25-11
Licensing Requirements for Router Advertisement Transmission Interval
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for Router Advertisement Transmission Interval
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 25-12
•
Firewall Mode Guidelines, page 25-12
•
Additional Guidelines and Limitations, page 25-13
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Additional Guidelines and Limitations
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 specified value.
Default Settings for Router Advertisement Transmission Interval
Table 25-7 lists the default settings for neighbor reachable time parameters.
Table 25-7
Default Router Advertisement Transmission Interval Parameters
Parameters
Default
value (interval between transmissions)
The default is 200 seconds.
Configuring Router Advertisement Transmission Interval
To configure the interval between IPv6 router advertisement transmissions on an interface, enter the
following command:
Command
Purpose
ipv6 nd ra-interval [msec] value
Sets the interval between IPv6 router advertisement transmissions.
Example:
hostname (config-if)# ipv6 nd ra-interval
201
The optional msec keyword indicates that the value provided is in
milliseconds. If this keyword is not present, the value provided is in
seconds.
Valid values for the value argument range from 3 to 1800 seconds or from
500 to 1800000 milliseconds if the msec keyword is provided.
Example
The following example configures an IPv6 router advertisement interval of 201 seconds for the selected
interface, Gigabitethernet 0/0:
hostname (config)# interface gigabitethernet 0/0
hostname (config-if)# ipv6 nd ra-interval 201
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Monitoring Router Advertisement Transmission Interval
To monitor IPv6 neighbor reachable time, perform one of the following tasks:
Command
Purpose
show ipv6 interface
Displays the usability status of interfaces
configured for IPv6. Including the interface name,
such as “outside,” displays the settings for the
specified interface. Excluding the name from the
command displays the settings for all interfaces
that have IPv6 enabled on them. Output for the
command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
•
The multicast groups to which the interface
belongs.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
•
The actual time when the command is set to 0.
•
The neighbor discovery reachable time that is
being used.
Where to Go Next
Configure the “router lifetime” value in IPv6 router advertisements on an interface with the ipv6 nd
ra-lifetime command.
Feature History for Router Advertisement Transmission Interval
Table 25-8 lists the release history for this feature.
Table 25-8
Feature History for Router Advertisement Transmission Interval
Feature Name
Releases
Feature Information
Router advertisement transmission interval
7.0(1)
The feature was introduced.
The following command was introduced: ipv6 nd
ra-interval.
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
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. The prefix advertisement can be used by neighboring
devices to autoconfigure their interface addresses. You can configure which IPv6 prefixes ar e included
in IPv6 router advertisements.
This section shows how to configure IPv6 prefixes and includes the following topics:
•
Licensing Requirements for IPv6 Prefixes, page 25-15
•
Guidelines and Limitations for IPv6 Prefixes, page 25-15
•
Default Settings for IPv6 Prefixes, page 25-16
•
Configuring IPv6 Prefixes, page 25-17
•
Monitoring IPv6 Prefixes, page 25-18
•
Feature History for IPv6 Prefixes, page 25-19
Licensing Requirements for IPv6 Prefixes
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for IPv6 Prefixes
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 25-15
•
Firewall Mode Guidelines, page 25-15
•
Additional Guidelines and Limitations, page 25-16
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Additional Guidelines and Limitations
The ipv6 nd prefix command allows control over the individual parameters per prefix, including
whether or not the prefix should be advertised.
By default, prefixes configured as addresses on an interface using the ipv6 address command are
advertised in router advertisements. If you configure prefixes for advertisement using the ipv6 nd prefix
command, then only these prefixes are advertised.
The default keyword can be used to set default parameters for all prefixes.
A date can be set to specify the expiration of a prefix. The valid and preferred lifetimes are counted down
in real time. When the expiration date is reached, the prefix will no longer be advertised.
When onlink is “on” (by default), the specified prefix is assigned to the link. Nodes sending traffic to
such addresses that contain the specified prefix consider the destination to be locally reachable on the
link.
When autoconfig is “on” (by default), it indicates to hosts on the local link that the specified prefix can
be used for IPv6 autoconfiguration.
For stateless autoconfiguration to work properly, the advertised prefix length in router advertisement
messages must always be 64 bits.
Default Settings for IPv6 Prefixes
Table 25-9 lists the default settings for neighbor reachable time parameters.
Table 25-9
Default for IPv6 Prefixes Parameters
Parameters
Default
prefix lifetime
The default lifetime is 2592000 seconds (30 days)
and a preferred lifetime of 604800 seconds (7
days).
on-link flag
The flag is on by default, which means that the
prefix is used on the advertising interface.
autoconfig flag
The flag is on by default, which means that the
prefix is used for autoconfiguration.
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Configuring IPv6 Prefixes
To configure the which IPv6 prefixes are included in IPv6 router advertisements, enter the following
command:
Command
Purpose
ipv6 nd prefix ipv6-prefix/prefix-length |
default [[valid-lifetime
preferred-lifetime] | [at valid-date
preferred-date] | infinite | no-advertise
| off-link | no-autoconfig]
Configures which IPv6 prefixes are included in IPv6 router advertisements.
Example:
hostname (config-if)# ipv6 nd prefix
2001:200:200::/35 1000 900
The at valid-date preferred-date syntax indicates the date and time at
which the lifetime and preference expire. The prefix is valid until this
specified date and time are reached. Dates are expressed in the form
date-valid-expire month-valid-expire hh:mm-valid-expire
date-prefer-expire month-prefer-expire hh:mm-prefer-expire.
The default keyword indicates that default values are used.
The optional infinite keyword specifies that the valid lifetime does not
expire.
The ipv6-prefix argument specifies the IPv6 network number to include in
router advertisements. This argument must be in the form documented in
RFC 2373 where the address is specified in hexadecimal using 16-bit
values between colons.
The optional no-advertise keyword indicates to hosts on the local link that
the specified prefix is not to be used for IPv6 autoconfiguration.
The optional no-autoconfig keyword indicates to hosts on the local link
that the specified prefix cannot be used for IPv6 autoconfiguration.
The optional off-link keyword indicates that the specified prefix is not used
for on-link determination.
The preferred-lifetime argument specifies the amount of time (in seconds)
that the specified IPv6 prefix is advertised as being preferred. Valid values
range from 0 to 4294967295 seconds. The maximum value represents
infinity, which can also be specified with infinite. The default is 604800 (7
days).
The prefix-length argument specifies the length of the IPv6 prefix. This
value indicates how many of the high-order, contiguous bits of the address
comprise the network portion of the prefix. The slash (/) must precede the
prefix length.
The valid-lifetime argument specifies the amount of time that the specified
IPv6 prefix is advertised as being valid. Valid values range from 0 to
4294967295 seconds. The maximum value represents infinity, which can
also be specified with infinite. The default is 2592000 (30 days).
Example
The following example includes the IPv6 prefix 2001:200::/35, with a valid lifetime of 1000 seconds and
a preferred lifetime of 900 seconds, in router advertisements sent out on the specified interface, which
is Gigabitethernet 0/0:
hostname (config)# interface gigabitethernet 0/0
hostname (config-if)# ipv6 nd prefix 2001:200:200::/35 1000 900
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Monitoring IPv6 Prefixes
To monitor IPv6 neighbor reachable time, perform one of the following tasks:
Command
Purpose
show ipv6 interface
Displays the usability status of interfaces
configured for IPv6. Including the interface name,
such as “outside,” displays the settings for the
specified interface. Excluding the name from the
command displays the settings for all interfaces
that have IPv6 enabled on them. Output for the
command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
•
The multicast groups to which the interface
belongs.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
•
The actual time when the command is set to 0.
•
The neighbor discovery reachable time that is
being used.
Additional References
For additional information related to implementing IPv6 router advertisement messages, see the
following sections:
•
Related Documents for IPv6 Prefixes, page 25-19
•
RFCs for IPv6 Prefixes, page 25-19
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Related Documents for IPv6 Prefixes
Related Topic
Document Title
ipv6 commands
Cisco Security Appliance Command Reference
RFCs for IPv6 Prefixes
RFC
Title
RFC 2373 includes complete documentation to show RFC 2373—IP Version 6 Addressing Architecture
how IPv6 network address numbers must be shown in
router advertisements. The command argument
ipv6-prefix indicates this network number, where the
address must be specified in hexadecimal using 16-bit
values between colons.
Feature History for IPv6 Prefixes
Table 25-10 lists the release history for this feature.
Table 25-10
Feature History for Router Advertisement Transmission Interval
Feature Name
Releases
Feature Information
Router advertisement transmission interval
7.0(1)
The feature was introduced.
The following command was introduced: ipv6 nd prefix.
Suppressing Router Advertisement Messages
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).
This section shows how to suppress IPv6 router advertisement transmissions on an interface, and it
includes the following topics:
•
Licensing Requirements for Suppressing Router Advertisement Messages, page 25-20
•
Guidelines and Limitations for Suppressing Router Advertisement Messages, page 25-20
•
Default Settings for Suppressing Router Advertisement Messages, page 25-20
•
Suppressing Router Advertisement Messages, page 25-21
•
Monitoring Router Advertisement Messages, page 25-21
•
Feature History for Suppressing Router Advertisement Messages, page 25-22
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Licensing Requirements for Suppressing Router Advertisement Messages
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for Suppressing Router Advertisement Messages
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 25-20
•
Firewall Mode Guidelines, page 25-20
•
Additional Guidelines and Limitations, page 25-20
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
Additional Guidelines and Limitations
The “router lifetime” value is included in all IPv6 router advertisements sent out the interface. The value
indicates the usefulness of the security appliance as a default router on this interface.
Setting the value to a non-zero value indicates that the security appliance should be considered a default
router on this interface. The no-zero value for the “router lifetime” value should not be less than the
router advertisement interval.
Default Settings for Suppressing Router Advertisement Messages
Table 25-11 lists the default settings for neighbor reachable time parameters.
Table 25-11
Default for Suppressing Router Advertisement Parameters
Parameters
Default
router lifetime
The default lifetime is 1800 seconds. Setting the
value to 0 indicates that the security appliance
should not be considered a default router on this
interface.
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Configuring IPv6 Neighbor Discovery
Configuring Router Advertisement Messages
Suppressing Router Advertisement Messages
To configure the “router lifetime” value in IPv6 router advertisements on an interface, enter the
following command. Entering this command causes the security appliance to appear as a regular IPv6
neighbor on the link and not as an IPv6 router.
Command
Purpose
ipv6 nd ra-lifetime seconds
Configures the “router lifetime” value.
Example:
hostname (config-if)# ipv6 nd prefix
2001:200:200::/35 1000 900
The seconds argument specifies the validity of the security appliance as a
default router on this interface. Valid values range from 0 to 9000 seconds.
The default is 1800 seconds. 0 indicates that the security appliance should
not be considered a default router on the specified interface.
Example
The following example configures an IPv6 router advertisement lifetime of 1801 seconds for the
specified interface, which is Gigabitethernet 0/0:
hostname (config)# interface gigabitethernet 0/0
hostname (config-if)# ipv6 nd ra-lifetime 1801
Monitoring Router Advertisement Messages
To monitor IPv6 neighbor reachable time, perform one of the following tasks:
Command
Purpose
show ipv6 interface
Displays the usability status of interfaces
configured for IPv6. Including the interface name,
such as “outside,” displays the settings for the
specified interface. Excluding the name from the
command displays the settings for all interfaces
that have IPv6 enabled on them. Output for the
command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
•
The multicast groups to which the interface
belongs.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
•
The actual time when the command is set to 0.
•
The neighbor discovery reachable time that is
being used.
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Configuring IPv6 Neighbor Discovery
Configuring a Static IPv6 Neighbor
Feature History for Suppressing Router Advertisement Messages
Table 25-12 lists the release history for this feature.
Table 25-12
Feature History for Suppressing Router Advertisement Messages
Feature Name
Releases
Feature Information
Suppressing router advertisement messages
7.0(1)
The feature was introduced.
The following command was introduced: ipv6 nd
ra-lifetime.
Configuring a Static IPv6 Neighbor
This section includes the following topics:
•
Information About a Static IPv6 Neighbor, page 25-22
•
Licensing Requirements for Static IPv6 Neighbor, page 25-22
•
Guidelines and Limitations, page 25-22
•
Default Settings, page 25-23
•
Configuring a Static IPv6 Neighbor, page 25-24
•
Monitoring Neighbor Solicitation Messages, page 25-24
•
Feature History for Configuring a Static IPv6 Neighbor, page 25-25
Information About 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
Licensing Requirements for Static IPv6 Neighbor
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 25-23
•
Firewall Mode Guidelines, page 25-23
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Configuring IPv6 Neighbor Discovery
Configuring a Static IPv6 Neighbor
•
Additional Guidelines and Limitations, page 25-23
Context Mode Guidelines
Supported in single and multiple context mode.
Firewall Mode Guidelines
Supported in routed firewall mode only. Transparent mode is not supported.
Additional Guidelines and Limitations
The following guidelines and limitations apply for configuring a static IPv6 neighbor:
•
The ipv6 neighbor command is similar to the arp command. 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. These entries are stored in
the configuration when the copy command is used to store the configuration.
•
Use the show ipv6 neighbor command to view static entries in the IPv6 neighbor discovery cache.
•
The clear ipv6 neighbor command deletes all entries in the IPv6 neighbor discovery cache except
static entries. The no ipv6 neighbor command deletes a specified static entry from the neighbor
discovery cache; the command does not remove dynamic entries—entries learned from the IPv6
neighbor discovery process—from the cache. Disabling IPv6 on an interface by using the no ipv6
enable command deletes all IPv6 neighbor discovery cache entries configured for that interface
except static entries (the state of the entry changes to INCMP [Incomplete]).
•
Static entries in the IPv6 neighbor discovery cache are not modified by the neighbor discovery
process.
•
The clear ipv6 neighbor command does not remove static entries from the IPv6 neighbor discovery
cache; it only clears the dynamic entries.
Default Settings
Table 25-13 lists the default settings for static IPv6 neighbor parameters.
Table 25-13
Default Static IPv6 Neighbor Parameters
Parameters
Default
Static IPv6 neighbor
Static entries are not configured in the IPv6
neighbor discovery cache.
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Configuring IPv6 Neighbor Discovery
Configuring a Static IPv6 Neighbor
Configuring a Static IPv6 Neighbor
To configure a static entry in the IPv6 neighbor discovery cache, enter the following command:
Command
Purpose
ipv6 neighbor ipv6_address if_name
mac_address
Configures a static entry in the IPv6 neighbor discovery cache.
Example:
hostname)config-if)# ipv6 neighbor
3001:1::45A inside 002.7D1A.9472
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.
Example
The following example adds a static entry for an inside host with an IPv6 address of 3001:1::45A and a
MAC address of 002.7D1a.9472 to the neighbor discovery cache:
hostname)config-if)# ipv6 neighbor 3001:1::45A inside 002.7D1A.9472
Monitoring Neighbor Solicitation Messages
To monitor IPv6 neighbor discovery, perform the following task:
Command
Purpose
show ipv6 interface
Displays the usability status of interfaces
configured for IPv6. Including the interface name,
such as “outside,” displays the settings for the
specified interface. Excluding the name from the
command displays the settings for all interfaces
that have IPv6 enabled on them. Output for the
command shows the following:
•
The name and status of the interface.
•
The link-local and global unicast addresses.
•
The multicast groups to which the interface
belongs.
•
ICMP redirect and error message settings.
•
Neighbor discovery settings.
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Configuring IPv6 Neighbor Discovery
Configuring a Static IPv6 Neighbor
Feature History for Configuring a Static IPv6 Neighbor
Table 25-14 lists the release history for this feature.
Table 25-14
Feature History for Configuring a Static IPv6 Neighbor
Feature Name
Releases
Feature Information
Static IPv6 Neighbor
7.0(1)
The feature was introduced.
The following command was introduced: ipv6 neighbor.
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Configuring IPv6 Neighbor Discovery
Configuring a Static IPv6 Neighbor
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A R T
4
Configuring Network Address Translation
CH A P T E R
26
Information About NAT
This chapter provides an overview of how Network Address Translation (NAT) works on the ASA and
includes the following sections:
•
Introduction to NAT, page 26-1
•
NAT Types, page 26-2
•
NAT in Routed Mode, page 26-2
•
NAT in Transparent Mode, page 26-3
•
Policy NAT, page 26-5
•
NAT and Same Security Level Interfaces, page 26-8
•
Order of NAT Commands Used to Match Real Addresses, page 26-8
•
Mapped Address Guidelines, page 26-8
•
DNS and NAT, page 26-9
•
Where to Go Next, page 26-11
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 ASA 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 interface (outside) match
a NAT rule, or processing for the packet stops. See the “Security Levels” section on page 6-5 for more
information about security levels. See Chapter 27, “Configuring NAT Control,” 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:
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NAT Types
•
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 40-1 on page 40-4 for information about protocols that do not support NAT.
NAT Types
You can implement address translation as dynamic NAT, Port Address Translation (PAT), 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. The following translation types are available:
•
Dynamic NAT—Dynamic NAT translates a group of real addresses to a pool of mapped addresses
that are routable on the destination network. For details about dynamic NAT, see the Chapter 29,
“Configuring Dynamic NAT and PAT.”
•
PAT—PAT translates multiple real address to a single mapped IP address. For details about PAT, see
the Chapter 29, “Configuring Dynamic NAT and PAT.”
•
Static NAT—Static NAT creates a fixed translation of real addresses to mapped addresses. With
dynamic NAT and PAT, each host uses a different address or port for each subsequent translation.
For details about static NAT, see the Chapter 28, “Configuring Static NAT.”
•
Static PAT—Static PAT is the same as static NAT, except that it enables you to specify the protocol
and port for the real and mapped addresses. For details about static PAT, see the Chapter 30,
“Configuring Static PAT.”
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. For details about bypassing NAT, see Chapter 31, “Bypassing NAT.”
NAT in Routed Mode
Figure 26-1 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.
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NAT in Transparent Mode
Figure 26-1
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
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 ASA is useful between two VRFs so tha 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 ASA).
•
When you have VoIP or DNS traffic with NAT and inspection enabled, to successfully translate the
IP address inside VoIP and DNS packets, the ASA needs to perform a route lookup. Unless the host
is on a directly-connected network, then you need to add a static route on the ASA for the real host
address that is embedded in the packet.
•
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.
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NAT in Transparent Mode
Figure 26-2 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.
Figure 26-2
NAT Example: Transparent Mode
www.example.com
Internet
Static route on router:
209.165.201.0/27 to 10.1.1.1
Source Addr Translation
10.1.1.75
209.165.201.15
Static route on ASA:
192.168.1.0/24 to 10.1.1.3
10.1.1.2
Management IP
10.1.1.1
ASA
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
1.
When the inside host at 10.1.1.75 sends a packet to a web server, the real source address of the
packet, 10.1.1.75, is changed to a mapped address, 209.165.201.15.
2.
When the server responds, it sends the response to the mapped address, 209.165.201.15, and the
ASA receives the packet because the upstream router includes this mapped network in a static route
directed through the ASA.
3.
The ASA then undoes the translation of the mapped address, 209.165.201.15, back to the real
address, 10.1.1.1.75. Because the real address is directly-connected, the ASA sends it directly to the
host.
4.
For host 192.168.1.2, the same process occurs, except that the ASA 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.
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
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Policy NAT
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, not the destination address . For
example, with policy NAT you can translate the real address to mapped address A when it accesses server
A, but also translate the real address to mapped address B when it accesses server B.
Note
Policy NAT does not support time-based access lists.
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 it differs from policy NAT in that the ports are not considered. See the
“Bypassing NAT When NAT Control is Enabled” section on page 27-3 for other differences. You can
accomplish the same result as NAT exemption using static identity NAT, which does support policy NAT.
Figure 26-3 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.
Figure 26-3
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
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Policy NAT
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
Figure 26-4 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 26-4
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), you can
initiate traffic to and from the real host. However, the destination address in the access list is only used
for traffic initiated by the real host. For traffic to the real host from the destination network, the source
address is not checked, and the first matching NAT rule for the real host address is used. So if you
configure static policy NAT such as the following:
hostname(config)# access-list NET1 permit ip 10.1.2.0 255.255.255.224 209.165.201.0
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Policy NAT
255.255.255.224
hostname(config)# static (inside,outside) 209.165.202.128 access-list NET1
Then when hosts on the 10.1.2.0/27 network access 209.165.201.0/24, they are translated to
corresponding addresses on the 209.165.202.128/27 network. But any host on the outside can access the
mapped addresses 209.165.202.128/27, and not just hosts on the 209.165.201.0/24 network.
For the same reason (the source address is not checked for traffic to the real host), you cannot use policy
static NAT to translate different real addresses to the same mapped address. For example, Figure 26-5
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, because the destination address in the access list is not checked
for traffic to the real host, then the first ACE that matches the real host is 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.
Figure 26-5
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
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 40-2 for information about NAT support for other
protocols.
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NAT and Same Security Level Interfaces
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 Chapter 27, “Configuring NAT Control,” for more information. Also,
when you specify a group of IP addresses 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 Same Security Level Communication” section on page 6-30 to enable same security
communication.
Note
The ASA 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 40-2 for supported inspection engines.
Order of NAT Commands Used to Match Real Addresses
The ASA 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 ASA.
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
ASA), the ASA uses proxy ARP to answer any requests for mapped addresses, and thus it intercepts
traffic destined for a real address. This solution simplifies routing because the ASA 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.
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DNS and NAT
If you need more addresses than are available on the mapped interface network, you can identify
addresses on a different subnet. The ASA uses proxy ARP to answer any requests for mapped
addresses, and thus it 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 ASA.
DNS and NAT
You might need to configure the ASA 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 ASA 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 26-6.) 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.
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DNS and NAT
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 ASA 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 26-6
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
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.
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Where to Go Next
Figure 26-7 shows a web server and DNS server on the outside. The ASA 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 26-7
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
Where to Go Next
•
Chapter 27, “Configuring NAT Control”
•
Chapter 29, “Configuring Dynamic NAT and PAT”
•
Chapter 28, “Configuring Static NAT”
•
Chapter 30, “Configuring Static PAT”
•
Chapter 31, “Bypassing NAT”
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Where to Go Next
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27
Configuring NAT Control
This chapter describes NAT control, and it includes the following sections:
•
Information About NAT Control, page 27-1
•
Licensing Requirements, page 27-3
•
Prerequisites for NAT Control, page 27-4
•
Guidelines and Limitations, page 27-4
•
Default Settings, page 27-4
•
Configuring NAT Control, page 27-5
•
Monitoring NAT Control, page 27-5
•
Configuration Examples for NAT Control, page 27-5
•
Feature History for NAT Control, page 27-6
Information About NAT Control
This section describes NAT control, and it includes the following topics:
•
NAT Control and Inside Interfaces, page 27-1
•
NAT Control and Same Security Interfaces, page 27-2
•
NAT Control and Outside Dynamic NAT, page 27-2
•
NAT Control and Static NAT, page 27-3
•
Bypassing NAT When NAT Control is Enabled, page 27-3
NAT Control and Inside Interfaces
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 27-1.
Note
NAT control is used for NAT configurations defined with earlier versions of the ASA. The best practice
is to use access rules for access control instead of relying on the absence of a NAT rule to prevent traffic
through the ASA.
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Information About NAT Control
Figure 27-1
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
NAT Control and Same Security Interfaces
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 27-2.
Figure 27-2
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
NAT Control and Outside Dynamic NAT
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 27-3.)
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
Inside
10.1.1.50
209.165.200.240 No NAT
Outside
Inside
132213
Figure 27-3
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Licensing Requirements
NAT Control and Static NAT
NAT control does not affect static NAT and does not cause the restrictions seen with dynamic NAT.
Bypassing NAT When NAT Control is Enabled
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.
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 40-2 for
information about inspection engines that do not support NAT.
You can configure traffic to bypass NAT using one of the following three methods. All methods achieve
compatibility with inspection engines. However, each method offers slightly different capabilities.
•
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 you use identity NAT when accessing interface B.
Regular dynamic NAT, on the other hand, enables you to 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 enables you to 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
enables you to use policy NAT, which identifies the real and destination addresses when determining
the real addresses to translate. (See the “Policy NAT” section on page 26-5 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 enable you to 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.
Licensing Requirements
Model
License Requirement
All models
Base License.
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Configuring NAT Control
Prerequisites for NAT Control
Prerequisites for NAT Control
NAT control has the following prerequisites:
•
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.
•
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 with NAT control enabled, then all
traffic from the interface to a same security interface or an outside interface must match a NAT rule.
•
Similarly, if you enable outside dynamic NAT or PAT with NAT control, then all outside traffic must
match a NAT rule when it accesses an inside interface.
•
Static NAT with NAT control does not cause these restrictions.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
•
Supported in single and multiple context modes.
•
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 5-3 for more information about the
relationship between the classifier and NAT.
Firewall Mode Guidelines
Supported in routed and transparent modes.
Additional Guidelines and Limitations
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 (nat 0 access-list) or identity NAT (nat 0 or static) rule on those
addresses.
Default Settings
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 Chapter 29, “Configuring Dynamic NAT and PAT,” for
more information about how dynamic NAT is applied.
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Configuring NAT Control
Configuring NAT Control
Configuring NAT Control
To enable NAT control, enter the following command:
Command
Purpose
nat-control
Enables NAT control.
Example:
hostname(config)# nat-control
To disable NAT control, enter the no form of the command.
Monitoring NAT Control
To monitor NAT control, perform one of the following tasks:
Command
Purpose
show running-config nat-control
Shows the NAT configuration requirement.
Configuration Examples for NAT Control
When NAT control is disabled with the no-nat control command, and a NAT and a global command pair
are configured for an interface, the real IP addresses cannot go out on other interfaces unless you define
those destinations with the nat 0 access-list command.
For example, the following NAT is the that one you want performed when going to the outside network:
nat (inside) 1 0.0.0.0 0.0.0.0
global (outside) 1 209.165.201.2
The above configuration catches everything on the inside network, so if you do not want to translate
inside addresses when they go to the DMZ, then you need to match that traffic for NAT exemption, as
shown in the following example:
access-list EXEMPT extended permit ip any 192.168.1.0 255.255.255.0
access-list EXEMPT remark This matches any traffic going to DMZ1
access-list EXEMPT extended permit ip any 10.1.1.0 255.255.255.0
access-list EXEMPT remark This matches any traffic going to DMZ1
nat (inside) 0 access-list EXEMPT
Alternately, you can perform NAT translation on all interfaces:
nat (inside) 1 0.0.0.0 0.0.0.0
global (outside) 1 209.165.201.2
global (dmz1) 1 192.168.1.230
global (dmz2) 1 10.1.1.230
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Configuring NAT Control
Feature History for NAT Control
Feature History for NAT Control
Table 27-1 lists the release history for this feature.
Table 27-1
Feature History for NAT Control
Feature Name
Releases
Feature Information
Ability to enable and disable NAT control
7.0(1)
The ability to enable and disable NAT control was
introduced.
The following command was introduced: nat-control.
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28
Configuring Static NAT
This chapter describes how to configure a static network translation and includes the following topics:
•
Information About Static NAT, page 28-1
•
Licensing Requirements for Static NAT, page 28-2
•
Guidelines and Limitations, page 28-2
•
Default Settings, page 28-3
•
Configuring Static NAT, page 28-4
•
Monitoring Static NAT, page 28-9
•
Configuration Examples for Static NAT, page 28-9
•
Additional References, page 28-11
•
Feature History for Static NAT, page 28-11
Information About 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.
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Configuring Static NAT
Licensing Requirements for Static NAT
Figure 28-1 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 28-1
Static NAT
10.1.1.1
209.165.201.1
10.1.1.2
209.165.201.2
Inside Outside
130035
Security
Appliance
Licensing Requirements for Static NAT
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 28-2
•
Firewall Mode Guidelines, page 28-2
•
Additional Guidelines and Limitations, page 28-2
Context Mode Guidelines
•
Supported in single and multiple context mode.
Firewall Mode Guidelines
•
Supported in routed and transparent firewall mode.
Additional Guidelines and Limitations
The following features are not supported for static NAT:
•
You cannot use the same real or mapped address in multiple static commands between the same two
interfaces unless you use static PAT. (For more information, see Chapter 30, “Configuring Static
PAT.”)
•
Do not use a mapped address in the static command that is also defined in a global command for
the same mapped interface.
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Configuring Static NAT
Default Settings
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 26-9 for more information.)
•
•
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.
Default Settings
Table 28-1 lists the command options and defaults for static NAT.
Table 28-1
Command Options and Defaults for Policy NAT
Command
Purpose
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; for more information,
see Chapter 53, “Configuring Connection Limits and Timeouts.”
For tcp_max_conns, emb_limit, and udp_max_conns, the default value is 0
(unlimited), which is the maximum available.
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Configuring Static NAT
Table 28-2
Command Options and Defaults for Regular NAT
nat_id
An integer between 1 and 2147483647. The NAT ID must
match a global command NAT ID. See the “Information
About Implementing Dynamic NAT and PAT” section on
page 29-5 for more information about how NAT IDs are used.
0 is reserved for identity NAT. See the “Configuring Identity
NAT” section on page 31-1 for more information about
identity NAT.
See Table 28-1, “Command Options and Defaults for Policy
NAT,” for information about other command options.
Configuring Static NAT
This section describes how to configure a static translation and includes the following topics:
•
Configuring Policy Static NAT, page 28-5
•
Configuring Regular Static NAT, page 28-8
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Configuring Static NAT
Configuring Static NAT
Configuring Policy Static NAT
When you configure “policy NAT,” you identify the real addresses and destination/source addresses
using an extended access list. To configure policy static NAT, enter the following command:
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Configuring Static NAT
Configuring Static NAT
Command
Purpose
static (real_interface,mapped_interface)
{mapped_ip | interface} access-list
acl_name [dns] [norandomseq] [[tcp]
tcp_max_conns [emb_limit]] [udp
udp_max_conns]
Configures a persistent one-to-one address translation rule by mapping a
real IP address to a mapped IP address.
Example:
hostname(config)# static (inside,outside)
209.165.202.129 access-list NET1
Identify the real addresses and destination/source addresses using an
extended access list. Create the extended access list using the access-list
extended command. The first address in the access list is the real address;
the second address is either the source or destination address, depending on
where the traffic originates. (For more information, see Chapter 11,
“Adding an Extended Access List.”). 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.
The real_ifc argument specifies the name of the interface connected to the
real IP address network.
The mapped_ifc argument specifies the name of the interface connected to
the mapped IP address network.
The mapped_ip argument specifies the address to which the real address is
translated.
The interface keyword uses the interface IP address as the mapped
address. Use this keyword if you want to use the interface address, but the
address is dynamically assigned using DHCP.
The dns option rewrites the A record, or address record, in DNS replies that
match this static. For DNS replies traversing from a mapped interface to
any other interface, the A record is rewritten from the mapped value to the
real value. Inversely, for DNS replies traversing from any interface to a
mapped interface, the A record is rewritten from the real value to the
mapped value.
The norandomseq disables TCP ISN randomization protection.
The tcp tcp_max_cons option specifies the maximum number of
simultaneous TCP connections allowed to the local-host. (See the
local-host command). (Idle connections are closed after the idle timeout
specified by the timeout conn command.)
The emb_limit is the maximum number of embryonic connections per host.
Note
An embryonic limit applied using static NAT is applied to all
connections to or from the real IP address, and not just connections
between the specified interfaces. To apply limits to specific flows,
see the “Configuring Connection Limits and Timeouts” section on
page 53-3.
The udp tcp_max_cons option specifies the maximum number of
simultaneous UDP connections allowed to the local-host. (See the
local-host command.) (Idle connections are closed after the idle timeout
specified by the timeout conn command.)
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.
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Configuring Static NAT
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 as follows:
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
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 26-5 for more information.
If you specify a network for translation (for example, 10.1.1.0 255.255.255.0), then the ASA 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 Chapter 29, “Configuring Dynamic NAT and PAT,” for information about the other options.
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Configuring Static NAT
Configuring Regular Static NAT
To configure regular static NAT, enter the following command:
Command
Purpose
static (real_interface,mapped_interface)
{mapped_ip | interface} real_ip [netmask
mask][dns] [norandomseq] [[tcp]
tcp_max_conns [emb_limit]] [udp
udp_max_conns]
Configures a persistent one-to-one address translation rule by mapping a
real IP address to a mapped IP address.
Example:
hostname(config)# static (inside,outside)
209.165.201.12 10.1.1.3 netmask
255.255.255.255
The mapped_ifc argument specifies the name of the interface connected to
the mapped IP address network.
The real_ifc argument specifies the name of the interface connected to the
real IP address network.
The mapped_ip argument specifies the address to which the real address is
translated.
The interface keyword uses the interface IP address as the mapped
address. Use this keyword if you want to use the interface address, but the
address is dynamically assigned using DHCP.
The real_ip specifies the real address that you want to translate.
The netmask mask specifies the subnet mask for the real and mapped
addresses. For single hosts, use 255.255.255.255. If you do not enter a
mask, then the default mask for the IP address class is used, with one
exception. If a host-bit is non-zero after masking, a host mask of
255.255.255.255 is used. If you use the access-list keyword instead of the
real_ip, then the subnet mask used in the access list is also used for the
mapped_ip.
The dns option rewrites the A record, or address record, in DNS replies that
match this static. For DNS replies traversing from a mapped interface to
any other interface, the A record is rewritten from the mapped value to the
real value. Inversely, for DNS replies traversing from any interface to a
mapped interface, the A record is rewritten from the real value to the
mapped value.
The norandomseq disables TCP ISN randomization protection.
The tcp tcp_max_cons option specifies the maximum number of
simultaneous TCP connections allowed to the local-host. (See the
local-host command). (Idle connections are closed after the idle timeout
specified by the timeout conn command.)
The emb_limit is the maximum number of embryonic connections per host.
Note
An embryonic limit applied using static NAT is applied to all
connections to or from the real IP address, and not just connections
between the specified interfaces. To apply limits to specific flows,
see the “Configuring Connection Limits and Timeouts” section on
page 53-3.
The udp tcp_max_cons option specifies the maximum number of
simultaneous UDP connections allowed to the local-host. (See the
local-host command.) (Idle connections are closed after the idle timeout
specified by the timeout conn command.)
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Configuring Static NAT
Monitoring Static NAT
Monitoring Static NAT
To monitor static NAT, perform one of the following tasks:
Command
Purpose
show running-config static
Displays all static commands in the configuration
Configuration Examples for Static NAT
This section contains configuration examples for static NAT and contains these sections:
•
Typical Static NAT Examples, page 28-9
•
Example of Overlapping Networks, page 28-10
Typical Static NAT Examples
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 26-3 on page 26-5, “Policy NAT
with Different Destination Addresses,” 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
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Configuration Examples for Static NAT
Example of Overlapping Networks
In Figure 28-2, the ASA connects two private networks with overlapping address ranges.
Figure 28-2
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
dmz
192.168.100.0/24
10.1.1.1
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 ASA, 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.
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
ASA:
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
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Additional References
The ASA already has a connected route for the inside network. These static routes allow the ASA 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 ASA receives this packet, the ASA translates the source address from 192.168.100.2 to
10.1.3.2.
3.
Then the ASA translates the destination address from 10.1.2.2 to 192.168.100.2, and the packet is
forwarded.
Additional References
For additional information related to implementing Static NAT, see the following sections:
•
Related Documents, page 28-11
Related Documents
Related Topic
Document Title
static command
Cisco Security Appliance Command Reference
Feature History for Static NAT
Table 28-3 lists the release history for this feature.
Table 28-3
Feature History for Static NAT
Feature Name
Releases
Feature Information
Regular static NAT and policy static NAT
7.0
Static NAT creates a fixed translation of real addresses to
mapped addresses.
The static command was introduced.
Regular static NAT and policy static NAT
7.3.1
NAT began support in transparent firewall mode.
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29
Configuring Dynamic NAT and PAT
This section describes dynamic network address translation. 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.
This chapter includes the following topics:
•
Information About Dynamic NAT and PAT, page 29-1
•
Licensing Requirements for Dynamic NAT and PAT, page 29-10
•
Guidelines and Limitations, page 29-11
•
Default Settings, page 29-11
•
Configuring Dynamic NAT or Dynamic PAT, page 29-13
•
Monitoring Dynamic NAT and PAT, page 29-18
•
Configuration Examples for Dynamic NAT and PAT, page 29-18
•
Feature History for Dynamic NAT and PAT, page 29-19
Information About Dynamic NAT and PAT
This section includes the following topics:
•
Information About Dynamic NAT, page 29-1
•
Information About PAT, page 29-4
•
Information About Implementing Dynamic NAT and PAT, page 29-5
Information About 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 ASA 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 ASA 5500
Series 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
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Information About Dynamic NAT and PAT
the ASA rejects any attempt to connect to a real host address directly. See Chapter 28, “Configuring
Static NAT,” or Chapter 30, “Configuring Static PAT,” for information about 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 ASA. 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 ASA
5500 Series Command Reference.
Figure 29-1 shows a remote host attempting to connect to the real address. The connection is denied
because the ASA only allows returning connections to the mapped address.
Figure 29-1
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 29-2 shows a remote host attempting to initiate a connection to a mapped address. This address
is not currently in the translation table; therefore, the ASA drops the packet.
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Information About Dynamic NAT and PAT
Figure 29-2
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
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 40-2 for more information about
NAT and PAT support.
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Information About Dynamic NAT and PAT
Information About 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 ASA does not create a translation at all unless the translated
host is the initiator. See Chapter 28, “Configuring Static NAT,” or Chapter 30, “Configuring Static PAT,”
for information about reliable access to hosts.
PAT lets you use a single mapped address, thus conserving routable addresses. You can even use the ASA
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 40-2 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.
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Information About Dynamic NAT and PAT
Information About Implementing Dynamic NAT and PAT
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 29-3.)
Figure 29-3
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
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Information About 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 29-4.)
Figure 29-4
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
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Information About 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 29-5.)
Figure 29-5
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 29-6.) If
you use policy NAT, you can specify the same real addresses for multiple nat commands, as long as the
destination addresses and ports are unique in each access list.
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Information About Dynamic NAT and PAT
Figure 29-6
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 ASA uses the
dynamic NAT global commands first, in the order they are in the configuration, and then it 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 you should 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 29-7.)
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Information About Dynamic NAT and PAT
Figure 29-7
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 29-8.) 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.
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Licensing Requirements for Dynamic NAT and PAT
Figure 29-8
Outside NAT and Inside NAT Combined
Translation
10.1.1.15
209.165.201.4
Outside
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.
Licensing Requirements for Dynamic NAT and PAT
The following table shows the licensing requirements for these features:
Model
License Requirement
All models
Base License.
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Guidelines and Limitations
Guidelines and Limitations
This section includes the guidelines and limitations for this feature.
Context Mode Guidelines
•
Supported in single and multiple context mode.
Firewall Mode Guidelines
•
Supported only in routed and transparent firewall mode.
Additional Guidelines and Limitations
The following features are not supported for dynamic NAT and PAT:
•
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.
Note
If you remove a dynamic NAT or PAT rule, and then add a new rule with mapped addresses
that overlap the addresses in the removed rule, then the new rule will not be used until all
connections associated with the removed rule time out or are cleared using the clear xlate
command. This safeguard ensures that the same address is not assigned to multiple hosts.
•
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.
•
All types of NAT support policy NAT except for NAT exemption. NAT exemption uses an access list
to identify the real addresses, but it differs from policy NAT in that the ports are not considered. You
can accomplish the same result as NAT exemption using static identity NAT, which does support
policy NAT.
•
When using dynamic PAT, 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 (both real and mapped) is
unpredictable, a connection to the host is unlikely. However, in this case you can rely on the security
of the access list.
•
If the mapped pool has fewer addresses than the real group, you might 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.
Default Settings
Table 29-1 lists the command options and default settings for policy NAT and regular NAT. Table 29-2
lists an additional command option for regular NAT.
See the nat command in the Cisco Security Appliance Command Reference for a complete description
of command options.
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Default Settings
Table 29-1
Configuring Command Options and Defaults for Policy NAT and Regular NAT
Command
Purpose
access-list acl_name
Identifies the real addresses and destination addresses using an extended
access list. Create the extended access list using the access-list extended
command. (See Chapter 11, “Adding an Extended Access List.”) 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 “Information About Implementing Dynamic
NAT and PAT” section on page 29-5 for more information about how NAT
IDs are used. 0 is reserved for NAT exemption. (See the “Configuring
Static Identity NAT” section on page 31-5 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 26-9 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; for more information,
see Chapter 53, “Configuring Connection Limits and Timeouts.”
The default value for tcp_max_conns, emb_limit, and udp_max_conns is 0
(unlimited), which is the maximum available.
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Configuring Dynamic NAT or Dynamic PAT
Table 29-2
Command Options and Defaults for Regular NAT
nat_id
An integer between 1 and 2147483647. The NAT ID must
match a global command NAT ID. See the “Information
About Implementing Dynamic NAT and PAT” section on
page 29-5 for more information about how NAT IDs are used.
0 is reserved for identity NAT. See the “Configuring Identity
NAT” section on page 31-1 for more information about
identity NAT.
Configuring Dynamic NAT or Dynamic PAT
This section describes how to configure dynamic NAT or dynamic PAT, and it includes the following
topics:
•
Task Flow for Configuring Dynamic NAT and PAT, page 29-13
•
Configuring Policy Dynamic NAT, page 29-15
•
Configuring Regular Dynamic NAT, page 29-17
Task Flow for Configuring Dynamic NAT and PAT
Use the following guidelines to configure either Dynamic NAT or PAT:
Note
•
First configure a nat command, identifying the real addresses on a given interface that you want to
translate.
•
Then 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.
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 29-9 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 29-9
Dynamic NAT
10.1.1.1
209.165.201.1
10.1.1.2
209.165.201.2
Inside Outside
130032
Security
Appliance
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Configuring Dynamic NAT or Dynamic PAT
Figure 29-10 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.
Dynamic PAT
Security
Appliance
10.1.1.1:1025
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
Figure 29-10
For more information about dynamic NAT, see the “Information About Dynamic NAT” section on
page 29-1. For more information about PAT, see the “Information About PAT” section on page 29-4.
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Configuring Dynamic NAT or Dynamic PAT
Configuring Policy Dynamic NAT
To configure dynamic NAT and PAT and identify the real addresses on one interface that are translated
to mapped addressed on another interface, perform the following steps:
Step 1
Command
Purpose
nat (real_interface) nat_id access-list
acl_name [dns] [outside][[tcp]
tcp_max_conns [emb_limit]] [udp
udp_max_conns][norandomseq]
Configures dynamic policy NAT or PAT, identifying the real
addresses on a given interface that you want to translate to one of
a pool of mapped addresses.
Example:
hostname(config)# nat (inside) 1
access-list NET1 tcp 0 2000 udp 10000
The real_interface specifies the name of the interface connected
to the real IP address network.
The 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. 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 policy NAT, the nat_id argument is an integer between 1 and
65535.
The access-list keyword identifies the real addresses and
destination/source addresses using an extended access list.
The acl_name argument identifies the name of the access list.
The dns option rewrites the A record, or address record, in DNS
replies that match this static. For DNS replies traversing from a
mapped interface to any other interface, the A record is rewritten
from the mapped value to the real value. Inversely, for DNS
replies traversing from any interface to a mapped interface, the A
record is rewritten from the real value to the mapped value.
Enter the outside optional keyword if this interface is on a lower
security level than the interface you identify by the matching
global statement. This feature is called outside NAT or
bidirectional NAT.
The tcp option specifies the protocol at TCP.
The tcp_max_cons argument specifies the maximum number of
simultaneous TCP connections allowed to the local-host (see the
local-host command). The default is 0, which means unlimited
connections. (Idle connections are closed after the idle timeout
specified by the timeout conn command.)
The emb_limit option specifies the maximum number of
embryonic connections per host. The default is 0, which means
unlimited embryonic connections.
The udp udp_max_conns options specify the maximum number
of simultaneous UDP connections allowed to the local host. The
default is 0, which means unlimited connections.
The norandomseq option disables TCP ISN randomization
protection.
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Configuring Dynamic NAT or Dynamic PAT
Step 2
Command
Purpose
global (mapped_interface) nat_id
{mapped_ip[-mapped_ip] | interface}
Identifies the mapped address(es) to which you want to translate
the real addresses when they exit a particular interface. (In the
case of PAT, this is one address.)
Example:
hostname(config)# global (outside) 1
209.165.202.129
The mapped_interface option specifies the name of the interface
connected to the mapped IP address network.
The nat_id argument must match a global command NAT ID. See
the “Information About Implementing Dynamic NAT and PAT”
section on page 29-5 for more information about using NAT IDs.
The mapped_ip mapped_ip specify the mapped address(es) to
which you want to translate the real addresses when they exit the
mapped interface. If you specify a single address, then you
configure PAT. If you specify a range of addresses, then you
configure dynamic NAT. If the external network is connected to
the Internet, each global IP address must be registered with the
Network Information Center (NIC).
The interface keyword uses the interface IP address as the
mapped address. Use this keyword if you want to use the interface
address, but the address is dynamically assigned using DHCP.
See Table 29-1, “Command Options and Defaults for Policy NAT
and Regular NAT,” for information about other command options.
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Configuring Dynamic NAT or Dynamic PAT
Configuring Regular Dynamic NAT
To configure regular dynamic NAT and identify the real addresses on one interface that are translated to
mapped addressed on another interface, perform the following steps:
Step 1
Command
Purpose
nat (real_interface) nat_id real_ip [mask
[dns] [outside]] [[tcp] tcp_max_conns
[emb_limit]] [udp udp_max_conns]]
[norandomseq]
Configures dynamic NAT or PAT, identifying the real addresses
on a given interface that you want to translate to one of a pool of
mapped addresses.
Example:
hostname(config)# nat (inside) 1 10.1.2.0
255.255.255.0
The 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. 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 regular
NAT, the nat_id argument is an integer between 1 and
2147483647.
The real_ip argument specifies the real address that you want to
translate. You can use 0.0.0.0 (or the abbreviation 0) to specify all
addresses.
The mask argument specifies the subnet mask for the real
addresses. If you do not enter a mask, then the default mask for
the IP address class is used.
The dns keyword rewrites the A record, or address record, in DNS
replies that match this command. For DNS replies traversing from
a mapped interface to any other interface, the A record is rewritten
from the mapped value to the real value. Inversely, for DNS
replies traversing from any interface to a mapped interface, the A
record is rewritten from the real value to the mapped value.
Enter the outside option if this interface is on a lower security
level than the interface you identify by the matching global
statement. This feature is called outside NAT or bidirectional
NAT.
The tcp tcp_max_cons argument specifies the maximum number
of simultaneous TCP connections allowed to the local-host. (See
the local-host command.) The default is 0, which means
unlimited connections. (Idle connections are closed after the idle
timeout specified by the timeout conn command.)
The udp udp_max_conns specify the maximum number of
simultaneous UDP connections allowed to the local-host. (See the
local-host command.) The default is 0, which means unlimited
connections. (Idle connections are closed after the idle timeout
specified by the timeout conn command.)
The norandomseq keyword disables TCP ISN randomization
protection. Not supported for NAT exemption (nat 0 access-list).
Although you can enter this argument at the CLI, it is not saved to
the configuration.
(For additional information about command options, see the
Cisco Security Appliance Command Reference.)
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Monitoring Dynamic NAT and PAT
Step 2
Command
Purpose
global (mapped_interface) nat_id
{mapped_ip[-mapped_ip] | interface}
Identifies the mapped address(es) to which you want to translate
the real addresses when they exit a particular interface.
Example:
hostname(config)# global (outside) 1
209.165.201.3-209.165.201.10
The mapped_interface option specifies the name of the interface
connected to the mapped IP address network.
The nat_id must match a global command NAT ID. For more
information about how NAT IDs are used, see the “Information
About Implementing Dynamic NAT and PAT” section on
page 29-5.
The mapped_ip mapped_ip specify the mapped address(es) to
which you want to translate the real addresses when they exit the
mapped interface. If you specify a single address, then you
configure PAT. If you specify a range of addresses, then you
configure dynamic NAT. If the external network is connected to
the Internet, each global IP address must be registered with the
Network Information Center (NIC).
The interface keyword uses the interface IP address as the
mapped address. Use this keyword if you want to use the interface
address, but the address is dynamically assigned using DHCP.
See Table 29-1, “Command Options and Defaults for Policy NAT
and Regular NAT,” for information about other command options,
and see and Table 29-2 for additional information specific to
regular NAT only.
Monitoring Dynamic NAT and PAT
To monitor dynamic NAT and PAT, perform the following task:
Command
Purpose
show running-config nat
Displays a pool of global IP addresses that are
associated with the network.
Configuration Examples for Dynamic NAT and PAT
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:
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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 26-3 on page 26-5 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 26-4 on page 26-6 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
Feature History for Dynamic NAT and PAT
Table 29-3 lists the release history for this feature.
Table 29-3
Feature History for Dynamic NAT and PAT
Feature Name
Releases
Feature Information
NAT in transparent firewall mode
8.0(2)
NAT is now supported in transparent firewall mode.
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30
Configuring Static PAT
Static PAT translations allow a specific UDP or TCP port on a global address to be translated to a specific
port on a local address. That is, both the address and the port numbers are translated. This chapter
describes how to configure static PAT and includes the following topics:
•
Information About Static PAT, page 30-1
•
Licensing Requirements for Static PAT, page 30-3
•
Prerequisites for Static PAT, page 30-3
•
Guidelines and Limitations, page 30-4
•
Default Settings, page 30-4
•
Configuring Static PAT, page 30-5
•
Monitoring Static PAT, page 30-9
•
Configuration Examples for Static PAT, page 30-9
•
Feature History for Static PAT, page 30-11
Information About Static PAT
Static PAT is the same as static NAT, except that it enables you to specify the protocol (TCP or UDP)
and port for the real and mapped addresses. Static PAT enables you to identify the same mapped address
across many different static statements, provided that the port is different for each statement. You cannot
use the same mapped address for multiple static NAT statements.
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Information About Static PAT
Figure 30-1 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 are statically assigned by the
static command.
Figure 30-1
Typical Static PAT Scenario
Security
Appliance
209.165.201.1:23
10.1.1.2:8080
209.165.201.2:80
130044
10.1.1.1:23
Inside Outside
For applications that require application inspection for secondary channels (for example, FTP and VoIP),
the ASA automatically translates the secondary ports.
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 30-2.)
Figure 30-2
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
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Licensing Requirements for Static PAT
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.
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.
Licensing Requirements for Static PAT
Model
License Requirement
All models
Base License.
Prerequisites for Static PAT
Static PAT has the following prerequisites:
An extended access list must be configured. Create the extended access list using the access-list extended
command. (See the Chapter 11, “Adding an Extended Access List,” for more information.)
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 Chapter 11, “Adding an Extended
Access List.”). The first address in the access list is the real address; the second address is either the
source or destination 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
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 26-5 for more information.
If you specify a network for translation (for example, 10.1.1.0 255.255.255.0), then the ASA 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 Chapter 29, “Configuring Dynamic NAT and PAT,” for information about the
other options.
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Guidelines and Limitations
Guidelines and Limitations
This section includes the guidelines and limitations for this feature:
•
Context Mode Guidelines, page 30-4
•
Firewall Mode Guidelines, page 30-4
•
Additional Guidelines and Limitations, page 30-4
Context Mode Guidelines
•
Supported in single and multiple context mode.
Firewall Mode Guidelines
•
Supported only in routed and transparent firewall mode.
Additional Guidelines and Limitations
The following guidelines and limitations apply to the static PAT feature:
•
Static translations can be defined for a single host or for all addresses contained in an IP subnet.
•
Do not use a mapped address in the static command that is also defined in a global command for
the same mapped interface.
•
If you remove a static command, existing connections that use the translation are not affected. To
removed 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.
•
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.
Default Settings
Table 30-1 lists the default settings for static PAT parameters.
Table 30-1
Default static PAT Parameters
Parameters
Default
emb_limit
The default value is 0 (unlimited), which is the
maximum available.
tcp_max_cons
The default value is 0 (unlimited), which is the
maximum available.
udp_max_cons
The default value is 0 (unlimited), which is the
maximum available.
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Configuring Static PAT
Configuring Static PAT
This section describes how to configure a static port translation and includes the following topics:
•
Configuring Policy Static PAT, page 30-5
•
Configuring Regular Static PAT, page 30-7
Configuring Policy Static PAT
Policy static PAT enables you to reference a route map to identify specific conditions or policies that
trigger a static translation.
To configure policy static PAT, enter the following command:
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Configuring Static PAT
Command
Purpose
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]
Configures a route map to identify policies that trigger a static translation.
Example:
hostname(config)# static (inside,outside)
tcp 10.1.2.14 telnet access-list TELNET
The real real_interfaceargument specifies the name of the interface
connected to the real IP address network, and the mapped_interface
argument specifies the name of the interface connected to the mapped IP
address network.
Either tcp or udp specifies the protocol.
The mapped_ip argument specifies the address to which the real address is
translated (the interface connected to the mapped IP address network).
The interface keyword uses the interface IP address as the mapped
address. Use this keyword if you want to use the interface address, but the
address is dynamically assigned using DHCP. You must use the interface
keyword instead of specifying the actual IP address when you want to
include the IP address of an interface in a static PAT entry.
The mapped_port argument specifies the mapped TCP or UDP port. You
can specify the ports by either a literal name or a number in the range of 0
to 65535. You can view valid port numbers online at the following website:
http://www.iana.org/assignments/port-numbers
The access-list keyword and acl_id argument 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
Chapter 11, “Adding an Extended Access List,” for more information.)
This access list should include only permit ACEs. Make sure that the
source address in the access list matches the real_ip in this command.
The optional dns keyword rewrites the A record, or address record, in DNS
replies that match this static command. For DNS replies traversing from a
mapped interface to any other interface, the A record is rewritten from the
mapped value to the real value. Inversely, for DNS replies traversing from
any interface to a mapped interface, the A record is rewritten from the real
value to the mapped value. DNS inspection must be enabled to support this
functionality.
The optional norandomseq keyword disables TCP ISN randomization
protection
The optional tcp tcp_max_conns keyword specifies the maximum number
of simultaneous TCP connections allowed to the local host. The optional
emb_limit argument specifies the maximum number of embryonic
connections per host.
Note
An embryonic limit applied using static NAT is applied to all
connections to or from the real IP address, and not just connections
between the specified interfaces. To apply limits to specific flows,
see the “Configuring Connection Limits and Timeouts” section on
page 53-3.
The optional udp udp_max_conns keyword and argument specify the
maximum number of simultaneous UDP connections allowed to the local
host. (For additional information about command options, see the Cisco
Security Appliance Command Reference.)
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Configuring Static PAT
Configuring Regular Static PAT
Static PAT translations allow a specific UDP or TCP port on a global address to be translated to a specific
port on a local address.
To configure regular static PAT, enter the following command:
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Configuring Static PAT
Command
Purpose
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]
Configures static PAT.
Example:
hostname(config)# static (inside,outside)
tcp 10.1.2.14 telnet 10.1.1.15 telnet
netmask 255.255.255.255
Either tcp or udp specifies the protocol.
The real real_interfaceargument specifies the name of the interface
connected to the real IP address network, and the mapped_interface
argument specifies the name of the interface connected to the mapped IP
address network.
The mapped_ip argument specifies the address to which the real address is
translated (the interface connected to the mapped IP address network).
The interface keyword uses the interface IP address as the mapped
address. Use this keyword if you want to use the interface address, but the
address is dynamically assigned using DHCP. You must use the interface
keyword instead of specifying the actual IP address when you want to
include the IP address of an interface in a static PAT entry.
The mapped_port and real_port arguments specify the mapped and real
TCP or UDP ports. You can specify the ports by either a literal name or a
number in the range of 0 to 65535. You can view valid port numbers online
at the following website: http://www.iana.org/assignments/port-numbers
The netmask mask option specifies the subnet mask for the real and
mapped addresses. For single hosts, use 255.255.255.255. If you do not
enter a mask, then the default mask for the IP address class is used, with
one exception. If a host-bit is non-zero after masking, a host mask of
255.255.255.255 is used. If you use the access-list keyword instead of the
real_ip, then the subnet mask used in the access list is also used for the
mapped_ip.
The dns option rewrites the A record, or address record, in DNS replies that
match this static command. For DNS replies traversing from a mapped
interface to any other interface, the A record is rewritten from the mapped
value to the real value. Inversely, for DNS replies traversing from any
interface to a mapped interface, the A record is rewritten from the real
value to the mapped value. DNS inspection must be enabled to support this
functionality.
The norandomseq option disables TCP ISN randomization protection
The tcp tcp_max_conns options specify the maximum number of
simultaneous TCP connections allowed to the local host. The emb_limit
option specifies the maximum number of embryonic connections per host.
Note
An embryonic limit applied using static NAT is applied to all
connections to or from the real IP address, and not just connections
between the specified interfaces. To apply limits to specific flows,
see the “Configuring Connection Limits and Timeouts” section on
page 53-3.
The udp udp_max_conns options specify the maximum number of
simultaneous UDP connections allowed to the local host. (For additional
information about command options, see the Cisco Security Appliance
Command Reference.)
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Configuring Static PAT
Monitoring Static PAT
Monitoring Static PAT
To monitor static PAT, enter the following command:
Command
Purpose
show running-config static
Displays all static commands in the configuration.
Configuration Examples for Static PAT
This section includes configuration examples for policy static PAT and regular static PAT, and it contains
these topics:
•
Examples of Policy Static PAT, page 30-9
•
Examples of Regular Static PAT, page 30-9
•
Example of Redirecting Ports, page 30-10
Examples of Policy Static PAT
For Telnet traffic initiated from hosts on the 10.1.3.0 network to the ASA 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 ASA 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
Examples of Regular Static PAT
To redirect Telnet traffic from the ASA 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
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Configuration Examples for Static PAT
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
Example of Redirecting Ports
Figure 30-3 shows an example of a network configuration in which the port redirection feature might be
useful.
Figure 30-3
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 ASA 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.
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Feature History for Static PAT
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 ASA 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
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
Feature History for Static PAT
Table 30-2 lists the release history for this feature.
Table 30-2
Feature History for Static PAT
Feature Name
Releases
Feature Information
Static PAT
7.0
Static PAT translations allow a specific UDP or TCP port on
a global address to be translated to a specific port on a local
address.
This feature was introduced.
NAT and static PAT
7.3.(1)
NAT are supported in transparent firewall mode.
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31
Bypassing NAT
If you enable NAT control, then inside hosts must match a NAT rule when accessing outside hosts. You
might want to bypass NAT when you enable NAT control so that local IP addresses appear untranslated.
You also might want to bypass NAT if you are using an application that does not support NAT. See the
“When to Use Application Protocol Inspection” section on page 40-2 for information about inspection
engines that do not support NAT.
You can bypass NAT using identity NAT, static identity NAT, or NAT exemption.
This chapter describes how to bypass NAT, and it includes the following topics:
•
Configuring Identity NAT, page 31-1
•
Configuring Static Identity NAT, page 31-5
•
Configuring NAT Exemption, page 31-11
Configuring Identity NAT
This section includes the following topics:
•
Information About Identity NAT, page 31-2
•
Licensing Requirements for Identity NAT, page 31-2
•
Guidelines and Limitations for Identity NAT, page 31-2
•
Default Settings for Identity NAT, page 31-3
•
Configuring Identity NAT, page 31-4
•
Monitoring Identity NAT, page 31-5
•
Feature History for Identity NAT, page 31-5
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Configuring Identity NAT
Information About 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.
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. For
example, you cannot choose to perform normal translation on real addresses when you access interface
A and then use identity NAT when accessing interface B. Because you use identity NAT for all
connections through all interfaces, make sure that the real addresses for which you use identity NAT are
routable on all networks that are available according to your access list.
Note
If you need to specify a particular interface on which to translate the addresses, use regular dynamic
NAT.
Figure 31-1 shows a typical identity NAT scenario.
Figure 31-1
Identity NAT
209.165.201.1
209.165.201.1
209.165.201.2
209.165.201.2
Inside Outside
130033
Security
Appliance
Licensing Requirements for Identity NAT
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for Identity NAT
This section includes the guidelines and limitations for this feature:
Context Mode Guidelines
•
Supported in single and multiple context mode.
Firewall Mode Guidelines
•
Supported in routed and transparent firewall modes.
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Configuring Identity NAT
Additional Guidelines and Limitations
The following guidelines and limitations apply to identity NAT:
•
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.
•
The real addresses for which you use identity NAT must be 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.
Default Settings for Identity NAT
Table 31-1 lists the default settings for identity NAT parameters.
Table 31-1
Default Identity NAT Parameters
Parameters
Default
emb_limit
The default is 0, which means unlimited
embryonic connections
tcp tcp_max_conns
The default is 0, which means unlimited
connections.
udp udp_max_conns
The default is 0, which means unlimited
connections.
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Configuring Identity NAT
Configuring Identity NAT
To configure identity NAT, enter the following command:
Command
Purpose
nat (real_interface) nat_id real_ip [mask
[dns] [outside] [norandomseq] [[tcp]
tcp_max_conns [emb_limit]] [udp
udp_max_conns]
Configures identity NAT for the inside 10.1.1.0/24 network.
Example:
hostname(config)# nat (inside) 0 10.1.1.0
255.255.255.0
The real_interface argument specifies the name of the interface connected
to the real IP address network.
The nat_id argument specifies an integer for the NAT ID. For identity NAT,
use the NAT ID of 0. This ID is referenced by the global command to
associate a global pool with the real_ip.
The real_ip argument specifies the real address that you want to translate.
You can use 0.0.0.0 (or the abbreviation 0) to specify all addresses.
The optional mask argument specifies the subnet mask for the real
addresses. If you do not enter a mask, then the default mask for the IP
address class is used.
The optional dns keyword rewrites the A record, or address record, in DNS
replies that match this command. For DNS replies traversing from a
mapped interface to any other interface, the A record is rewritten from the
mapped value to the real value. Inversely, for DNS replies traversing from
any interface to a mapped interface, the A record is rewritten from the real
value to the mapped value.
You must enter outside if this interface is on a lower security level than the
interface you identify by the matching global statement.
The optional norandomseq keyword disables TCP ISN randomization
protection.
The optional tcp tcp_max_conns keyword and argument specify the
maximum number of simultaneous TCP connections allowed to the local
host. The default is 0, which means unlimited connections.
The optional emb_limit argument specifies the maximum number of
embryonic connections per host. The default is 0, which means unlimited
embryonic connections.
The optional udp udp_max_conns keyword and argument specify the
maximum number of simultaneous UDP connections allowed to the local
host. The default is 0, which means unlimited connections.
(For additional information about command options, see the nat command
in the Cisco Security Appliance Command Reference.)
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Bypassing NAT
Configuring Static Identity NAT
Monitoring Identity NAT
To monitor NAT bypass, enter the following command:
Command
Purpose
show running-config nat
Displays a pool of global IP addresses that are
associated with the network.
Feature History for Identity NAT
Table 31-2 lists the release history for this feature.
Table 31-2
Feature History for Identity NAT
Feature Name
Releases
Feature Information
Identity NAT
7.0
Identity NAT translates the real IP address to the same IP
address. You use identity NAT for connections through all
interfaces.
The following command was introduced: nat.
NAT
8.0(2)
NAT began support in transparent firewall mode.
Configuring Static Identity NAT
This section includes the following topics:
•
Information About Static Identity NAT, page 31-5
•
Licensing Requirements for Static Identity NAT, page 31-6
•
Guidelines and Limitations for Static Identity NAT, page 31-6
•
Default Settings for Static Identity NAT, page 31-7
•
Configuring Static Identity NAT, page 31-7
•
Monitoring Static Identity NAT, page 31-10
•
Feature History for Static Identity NAT, page 31-10
Information About Static Identity NAT
Static identity NAT translates the real IP address to the same IP address. Static identity NAT enables you
to 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 enables you to use policy NAT, which identifies the real and destination addresses
when determining the real addresses to translate. (See the “Policy NAT” section on page 26-5 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 you can use a normal translation
when accessing the outside server B. The translation is always active, and both “translated” and remote
hosts can originate connections.
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Configuring Static Identity NAT
Figure 31-2 shows a typical static identity NAT scenario.
Figure 31-2
Static Identity NAT
209.165.201.1
209.165.201.1
209.165.201.2
209.165.201.2
Inside Outside
130036
Security
Appliance
Licensing Requirements for Static Identity NAT
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
Guidelines and Limitations for Static Identity NAT
This section includes the guidelines and limitations for this feature:
Context Mode Guidelines
•
Supported in single and multiple context mode.
Firewall Mode Guidelines
•
Supported in routed and transparent firewall modes.
Additional Guidelines and Limitations
The following guidelines and limitations apply to static identity NAT:
•
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.
•
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.
•
Policy static identity NAT does not consider the inactive or time-range keywords; all ACEs are
considered to be active for policy NAT configurations. (See the“Policy NAT” section on page 26-5
for more information.)
•
For static policy 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.
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Default Settings for Static Identity NAT
Table 31-3 lists the default settings for static identity NAT parameters.
Table 31-3
Default Static Identity NAT Parameters
Parameters
Default
emb_limit
The default is 0, which means unlimited
embryonic connections.
tcp tcp_max_conns
The default is 0, which means unlimited
embryonic connections.
udp udp_max_conns
The default is 0, which means unlimited
embryonic connections.
Configuring Static Identity NAT
This section describes how to configure policy static identity NAT and regular static identity NAT, and
it includes the following topics:
•
Configuring Policy Static Identity NAT, page 31-8
•
Configuring Regular Static Identity NAT, page 31-9
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Configuring Static Identity NAT
Configuring Policy Static Identity NAT
To configure policy static identity NAT, enter the following command:
Command
Purpose
static (real_interface,mapped_interface)
real_ip access-list acl_id [dns]
[norandomseq] [[tcp] tcp_max_conns
[emb_limit]] [udp udp_max_conns]
Configures policy static NAT.
Example:
hostname(config)# static (inside,outside)
209.165.202.129 access-list NET1
The real_interface,mapped_interface arguments specify the name of the
interface connected to the real IP address network and the name of the
interface connected to the mapped IP address network.
The real_ip argument specifies the real address that you want to translate.
The access-list keyword and acl_id argument 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
Chapter 11, “Adding an Extended Access List.”) This access list should
include only permit ACEs. Make sure that the source address in the access
list matches the real_ip in this command.
The optional dns keyword rewrites the A record, or address record, in DNS
replies that match this static command. For DNS replies traversing from a
mapped interface to any other interface, the A record is rewritten from the
mapped value to the real value. Inversely, for DNS replies traversing from
any interface to a mapped interface, the A record is rewritten from the real
value to the mapped value. DNS inspection must be enabled to support this
functionality.
The optional norandomseq keyword disables TCP ISN randomization
protection.
The optional tcp tcp_max_conns keyword and argument specify the
maximum number of simultaneous TCP connections allowed to the local
host. The default is 0, which means unlimited connections.
The optional emb_limit argument specifies the maximum number of
embryonic connections per host. The default is 0, which means unlimited
embryonic connections.
The optional udp udp_max_conns keyword and argument specify the
maximum number of simultaneous UDP connections allowed to the local
host. The default is 0, which means unlimited connections.
(For additional information about command options, see the static
command in the Cisco Security Appliance Command Reference.)
Example of Policy Static Identity NAT
The following policy static identity 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) 209.165.202.129 access-list NET1
static (inside,outside) 209.165.202.130 access-list NET2
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Configuring Regular Static Identity NAT
To configure regular static identity NAT, enter the following command:
Command
Purpose
static (real_interface,mapped_interface)
real_ip real_ip [netmask mask] [dns]
[norandomseq] [[tcp] tcp_max_conns
[emb_limit]] [udp udp_max_conns]
Configures static identity NAT.
Example:
hostname(config)# static (inside,outside)
10.1.1.3 10.1.1.3 netmask 255.255.255.255
The real_interface,mapped_interface arguments specify the name of the
interface connected to the real IP address network and the name of the
interface connected to the mapped IP address network.
The real_ip argument specifies the real address that you want to translate.
Specify the same IP address for both real_ip arguments.
The netmask mask options specify the subnet mask for the real and
mapped addresses.
The dns option rewrites the A record, or address record, in DNS replies that
match this static. For DNS replies traversing from a mapped interface to
any other interface, the A record is rewritten from the mapped value to the
real value. Inversely, for DNS replies traversing from any interface to a
mapped interface, the A record is rewritten from the real value to the
mapped value.
Note
Note DNS inspection must be enabled to support this functionality.
The norandomseq option disables TCP ISN randomization protection.
Each TCP connection has two ISNs: one generated by the client and one
generated by the server. The security appliance randomizes the ISN of the
TCP SYN passing in both the inbound and outbound directions.
For static PAT, the tcp option specifies the protocol as TCP.
The tcp_max_cons argument specifies the maximum number of
simultaneous TCP connections allowed to the local-host. (See the
local-host command.) The default is 0, which means unlimited
connections.
The optional emb_limit argument specifies the maximum number of
embryonic connections per host. The default is 0, which means unlimited
embryonic connections.
The udp udp_max_conns option specifies the maximum number of
simultaneous UDP connections allowed to the local-host. (See the
local-host command.) The default is 0, which means unlimited
connections.
The example shown uses static identity NAT for an inside IP address
(10.1.1.3) when accessed by the outside.
Examples of Regular Static Identity NAT
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
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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
Monitoring Static Identity NAT
To monitor static identity NAT, enter the following command:
Command
Purpose
show running-config static
Displays all static commands in the configuration.
Feature History for Static Identity NAT
Table 31-4 lists the release history for this feature.
Table 31-4
Feature History for Static Identity NAT
Feature Name
Releases
Feature Information
Static identity NAT
7.0
Static identity NAT translates the real IP address to the same
IP address.
The following command was introduced: static.
NAT
8.0(2)
NAT began support in transparent firewall mode.
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Configuring NAT Exemption
Configuring NAT Exemption
This section includes the following topics:
•
Information About NAT Exemption, page 31-11
•
Licensing Requirements for NAT Exemption, page 31-11
•
Guidelines and Limitations for NAT Exemption, page 31-12
•
Default Settings for NAT Exemption, page 31-12
•
Configuring NAT Exemption, page 31-13
•
Monitoring NAT Exemption, page 31-13
•
Configuration Examples for NAT Exemption, page 31-13
•
Feature History for NAT Exemption, page 31-14
Information About NAT Exemption
NAT exemption exempts addresses from translation and 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 enable
you to 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 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 31-3 shows a typical NAT exemption scenario.
Figure 31-3
NAT Exemption
Security
Appliance
209.165.201.1
209.165.201.2
209.165.201.2
130036
209.165.201.1
Inside Outside
Licensing Requirements for NAT Exemption
The following table shows the licensing requirements for this feature:
Model
License Requirement
All models
Base License.
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Configuring NAT Exemption
Guidelines and Limitations for NAT Exemption
This section includes the guidelines and limitations for this feature:
Context Mode Guidelines
•
Supported in single and multiple context mode.
Firewall Mode Guidelines
•
Supported in routed and transparent firewall modes.
Additional Guidelines and Limitations
The following guidelines and limitations apply to NAT exemption:
•
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.
•
NAT exemption does not support connection settings, such as maximum TCP connections.
•
By default, the nat 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 ident