Virtual Private Network and Remote Access Setup

Virtual Private Network and Remote Access Setup
CHAPTER 10
Virtual Private Network
and Remote Access Setup
10.1 Introduction
A Virtual Private Network (VPN) is the extension of a private network that
encompasses links across shared or public networks like the Internet. A VPN enables
you to send data between two computers across a shared or public network in a
manner that emulates the properties of a point-to-point private link.
There are two types of VPN connections: the remote dial-in access VPN connection
and the LAN-to-LAN VPN connection. The “Remote Dial-In Access” facility allows
a remote access node, a NAT router or a single user computer, to dial into a VPN
router through the Internet to access the network resources of the remote network.
The “LAN-to-LAN Access” facility provides a solution to connect two independent
LANs for mutual sharing of network resources. For example, the head office
network can access the branch office network, and vice versa.
The VPN technology employed in the Vigor 2900 series of broadband security
routers supports Internet-industry standard to provide customers with interoperable
VPN solutions, such as Internet Protocol Security (IPSec), Layer 2 Tunneling
Protocol (L2TP), and Point-to-Point Tunneling Protocol (PPTP).
This chapter explains the capabilities of the VPN facility and the remote access on
the router. Use the following setup links on the Setup Main Menu to configure the
VPN and remote access functions.
VPN and Remote Access Setup
Advanced Setup > VPN and Remote Access Setup
The VPN and Remote Access Setup has five main functions, as shown below.
You may set up Remote Access Control, PPP, VPN IKE/IPSec, Remote Dial-in,
and LAN-to-LAN Profile on demand.
The Remote Access Control Setup allows you to enable each type of VPN service
or disable it for VPN pass-through purpose. For example, you can enable IPSec and
L2TP VPN service on your router and disable PPTP VPN service if you intend
running a PPTP server inside your LAN.
Use the PPP General Setup to configure your router’s PPP authentication method
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VPN and Remote Access Setup
as well as IP assignment range for remote dial-in user. This submenu only applies to
PPP-related VPN connections, such as PPTP, L2TP and L2TP over IPSec.
The VPN IKE / IPSec General Setup let you configure a common Pre-shared key
and security method for remote dial-in user or node (LAN-to-LAN) which uses
dynamic IP address.
Use Remote User Profile Setup(Teleworker) to create dial-in user accounts. Vigor
router supports three types of dial-in methods, PPTP, L2TP, and L2TP over IPSec.
The PPTP VPN connection is compatible with all Windows plateforms which have
built-in PPTP protocol. The L2TP and L2TP over IPSec are compatible with
Window 2000 and XP.
Use The LAN-to-LAN Profile Setup to create profiles for LAN to LAN VPNs.
The Vigor router supports four types of LAN-to-LAN VPN, IPSec Tunnel, PPTP,
L2TP, and L2TP over IPSec.
You can establish simultaneously up to 32 VPN
tunnels including remote dial-in users.
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VPN and Remote Access Setup
10.2 Remote Access Control Setup
As depicted in the following picture, click the appropriate checkbox to enable the
VPN service type that you want to provide.
If you intend to run a VPN server
inside your LAN, you should disable the appropriate protocol to allow pass-through,
as well as the appropriate NAT settings. For example, DMZ or open port.
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VPN and Remote Access Setup
10.3 PPP General Setup
PPP/MP Protocol
Dial-In PPP Authentication:
PAP Only: Select this option to force the router to authenticate dial-in
users with the PAP protocol.
PAP or CHAP: Selecting this option means the router will attempt to
authenticate dial-in users with the CHAP protocol first. If the dial-in
user does not support this protocol, it will fall back to use the PAP
protocol for authentication.
Dial-In PPP Encryption (MPPE):
Optional MPPE: This option represents that the MPPE encryption method
will be optionally employed in the router for the remote dial-in user.
If the remote dial-in user does not support the MPPE encryption
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VPN and Remote Access Setup
algorithm, the router will transmit “no MPPE encrypted packets”.
Otherwise, the MPPE encryption scheme will be used to encrypt the
data.
Require MPPE (40/128bits): Selecting this option will force the router to
encrypt packets by using the MPPE encryption algorithm.
In
addition, the remote dial-in user will use 40-bit to perform encryption
prior to using 128-bit for encryption.
In other words, if 40-bit
MPPE encryption method is not available, then 128-bit encryption
scheme will be applied to encrypt the data.
Maximum MPPE: This option indicates that the router will use the MPPE
encryption scheme with maximum bits (128 bits) to encrypt the data.
Mutual Authentication (PAP): The Mutual Authentication function is
mainly used to communicate with other routers or clients which need
bidirectional authentication in order to provide stronger security.
example, Cisco routers.
For
That is, enable it only if the connecting router
requires mutual authentication. By default, the option is set to No.
Notice that if you enable the Mutual Authentication function, you should
further specify the Username and Password for communication purpose.
Username: Specify the username for the purpose of the Mutual Authentication.
Password: Specify the password for the purpose of the Mutual Authentication.
IP Address Assignment for Dial-In Users
Start IP Address: Enter a start IP address for the dial-in PPP connection. You
should choose an IP address from the local private network. For example,
if the local private network is 192.168.1.0/255.255.255.0, you could
choose 192.168.1.200 to be the Start IP Address.
10.4 VPN IPSec / IKE General Setup
Set up a common Pre-shared key and security method for remote dial-in user or
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VPN and Remote Access Setup
nonspecified node (LAN to LAN) which do not have fixed IP address. This setup
only applies to IPSec-related VPN connections.
For example, L2TP over IPSec
and IPSec tunnel.
IKE
Authentication
Method:
Currently
only
support
Pre-Shared
Key
authentication.
Pre-Shared Key: Specify a key for IKE authentication.
Re-type Pre-Shared-Key: Confirm the pre-shared-key.
IPSec Security Method: Select allowed IPSec security methods.
Medium (AH): Data will be authenticated, but not be encrypted.
By default,
this option is active.
High (ESP): Data will be encrypted and authenticated.
DES, 3DES, and AES encryption methods.
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Herein, we support
By default, these methods
VPN and Remote Access Setup
are available to support.
10.5 Creating an Access Account for a Remote Dial-in User
After completing the general setup, you must create an access account for each
remote dial-in user. The router provides 32 access accounts for dial-in users. Besides,
you can extend the user accounts to the RADIUS server through the built-in
RADIUS client function.
The following figure shows the Remote User Profile
Setup for up to 32 access accounts.
(Set to Factory Default): Click here to clear all dial-in user accounts.
User: Display the username for the specific dial-in user.
of the LAN-to-LAN
profile. The symbol ??? represents that the profile is empty.
Status: Display the access state of the specific dial-in user. The symbol V and X
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VPN and Remote Access Setup
represent the specific dial-in user to be active and inactive, respectively.
Index: Click the index number to open an individual setup page for a dial-in user
account, as shown below.
User Account and Authentication
Enable this account: Check this item to activate the individual dial-in user
account.
Idle Timeout:
If the dial-in user is idle over the limitation of the timer, the
router will drop this connection.
By default, the Idle Timeout is set to
300 seconds.
Allowed Dial-In Type : Select the allowed dial-in type.
Herein, the Vigor 2900
series of broadband security routers provides three types: PPTP, IPSec Tunnel,
and L2TP with IPSec Policy.
For the L2TP with IPSec Policy, you have
other three choices (None, Nice to Have, and Must) to set up the dial-in VPN
type.
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VPN and Remote Access Setup
PPTP: Allow the remote dial-in user to make a PPTP VPN connection through
the Internet.
IPSec Tunnel: Allow the remote dial-in user to trigger a IPSec VPN
connection through Internet.
L2TP: Allow the remote dial-in user to make a L2TP VPN connection through
the Internet. Specify the IPSec policy to be “None”, “Nice to Have”, or
“Must”.
None: Do not apply the IPSec policy.
Accordingly, the VPN connection
employed the L2TP without IPSec Policy can be viewed as one pure
L2TP connection.
Nice to Have: Apply the IPSec policy first, if it is available.
Otherwise,
the dial-in VPN connection becomes one pure L2TP connection.
Must: Specify the IPSec policy to be definitely applied on the L2TP
connection.
Notice that when you choose either the PPTP or the L2TP with IPSec Policy for
the dial-in VPN type, you should specify the Username and Password.
Other
functions including IKE Pre-Shared Key, IPSec Security Method, Remote Client
IP or Peer ID and optional Local ID are reserved for the option of the IPSec
Tunnel and will be disabled for the PPTP or the L2TP with IPSec Policy option.
One exception for the L2TP with IPSec Policy option is that policy sets to Nice to
Have or Must.
In this exception, you should move on the setting of IKE
Pre-Shared Key, IPSec Security Method, Remote Client IP or Peer ID, and
optional Local ID.
Hence, if you enable the PPTP or L2TP without IPSec Policy option for the remote
dial-in VPN type, you should move on the following setting
Username: Specify a username for the specific dial-in user.
Password: Specify a password for the specific dial-in user.
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VPN and Remote Access Setup
Once you enable the IPSec Tunnel or L2TP with IPSec Plolicy with selection
of Nice to Have or Must for the remote dial-in setting, you should move on the
following setting.
Specify Remote Node:
For extra security, you should enable the option to
allow the remote client to connect only from a specific IP address.
Remote Client IP or Peer ID: Specify the IP address of the remote client or
the peer ID in the field.
Afterward, you should fill a Pre-Shared Key for
this specific node.
IKE Pre-shared Key: Click it and a window will be automatically poped up
for you, as depicted below. Please fill a Pre-shared Key and confirm it
for this specific node.
IPSec Security Method: Specify the IPSec security method, either
authentication or encryption algorithm, to determine the security level.
You can only select one.
Medium(AH): Specify the IPSec protocol for the Authentication Header
protocol.
The data will be authenticated, but not be encrypted.
High (ESP): Specify the IPSec protocol for the Encapsulating Security
Payload protocol.
The data will be encrypted.
algorithms are DES, 3DES, and AES.
algorithms are available.
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Supported
By default, these three
VPN and Remote Access Setup
Local ID: Specify a local ID to be used for Dial-in setting in the LAN-to-LAN
Profile setup. This item is optional.
Notice that if you do not activate the “Specify Remote Node” and leave the field of
“Remote Client IP or Peer ID” to be empty, the settings of IKE Pre-Shared Key, IPSec
Security Method, Remote Client IP or Peer ID, and optional Local ID will be disabled
and, therefore, no IPSec-related VPN conneciton can be triggered successfully.
10.6 Creating a LAN-to-LAN Profile
In this section, we will explain how to set up the LAN-to-LAN Profile in more
detail. The path to configure it in the Web configurator is Advanced Setup > VPN
and Remote Access Setup > LAN-to-LAN Profile Setup.
The web page is
shown below. Herein, you can create up to 32 LAN-to-LAN profiles.
(Set to Factory Default): Click here will clear all the LAN-to-LAN profiles.
Index: Click a number to open a detailed setting page for each profile.
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VPN and Remote Access Setup
Name: Indicate the name of the LAN-to-LAN profile. The symbol ??? represents
that the profile is empty.
Status: Indicate the status of individual profiles. The symbol V and X represent
the profile to be active and inactive, respectively.
Each LAN-to-LAN profile includes 4 subgroups: Common Settings, Dial-Out
Settings, Dial-In Settings, and TCP/IP Network Settings.
In the following, we
explain each subgroup in detail.
10.6.1 Common Settings
Profile Name: Specify a name for the remote network.
Enable this profile: Check here to activate this profile.
Call Direction: Specify the call direction for this profile. Both means it can be used
for outgoing and incoming access. Dial-Out means it can only be used for
outgoing access. Dial-In allows only incoming access.
Always on: Click it to always activate this profile.
The field of Idle Timeout will
be grayed to disallow any input.
Idle Timeout: By default, set to 300 seconds. If the profiles connection is idle over
the limitation of the timer, the router will drop the connection.
Enable PING to keep alive: Click this item to enable the transmission of PING
packets to an IP address defined in the field of “PING to the IP”.
PING to the IP: Specify the IP address of the remote host that located at the
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VPN and Remote Access Setup
other-end of the VPN tunnel.
Notice that this function is useful to determine the state of a specific VPN
connection.
Normally, when the remote host wants to disconnect the VPN
connection, this host should send some necessary packets to infom the Vigor router.
Accordingly, the Vigor router will drop the designated VPN connection and clear its
associated parameters, for example, key for encryption. However, once the remote
host abnormally disconnects a VPN connection, say VPN k, the Vigor router has no
ideal about VPN k at this moment due to its abnormal behaviour. Hence, the Vigor
router will regard this VPN k to be alive, which results in no more packets to send
within the VPN k and no more chance to trigger the VPN k again.
To resolve this
dilemma, this function (Enable PING to keep alive) is designed to determine of the
status of the VPN k.
By continueously sending PING packets to the remote host,
the Vigor router can know the existence of this VPN k.
If there is no response for
PING packets, the Vigor router will consider the state of the VPN k as disconnection.
In this way, the Vigor router will clear all related parameters of the VPN k so that the
VPN k can be triggered again.
10.6.2 Dial Out Settings
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VPN and Remote Access Setup
Type of Server I am calling: Indicate the dial-out VPN type.
options are available and only one option can be activated.
PPTP, IPSec Tunnel, and L2TP with IPSec Policy.
Herein, three
These options are
For the L2TP with IPSec
Policy, you have other three choices (None, Nice to Have, and Must) to set up
the dial-out VPN type.
PPTP: Specify the dial-out VPN connection to be the PPTP connection.
IPSec Tunnel: Specify the dial-out VPN connection to be the IPSec Tunnel
connection.
L2TP with IPSec Policy: Specify the IPSec policy for the L2TP connection.
None: Do not apply IPSec.
Accordingly, the VPN connection employed
the L2TP without IPSec Policy can be viewed as one pure L2TP
connection.
Nice to Have: Apply the IPSec policy first, if it is available.
Otherwise,
the dial-out VPN connection becomes one pure L2TP connection.
Must: Specify the IPSec policy to be definitely applied on the L2TP
connection.
Notice that when you choose either the PPTP or the L2TP with IPSec Policy for
the dial-out VPN type, you should specify the Username, Password, PPP
Authentication, and VJ Compression. Other functions including IKE Pre-Shared
Key, IPSec Security Method, Server IP/Host Name for VPN, Scheduler, and
Advance Setting are reserved for the option of the IPSec Tunnel and will be
disabled for the PPTP or the L2TP with IPSec Policy option.
One exception for
the L2TP with IPSec Policy option is that policy sets to Nice to Have or Must.
In
this exception, you should move on the setting of IKE Pre-Shared Key, IPSec
Security Method, and Server IP/Host Name for VPN.
Hence, if you enable the PPTP or L2TP without IPSec Policy option for the
dial-out VPN type, you should move on the following setting.
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VPN and Remote Access Setup
Username: Specify a username for authentication by the remote router.
Password: Specify a password for authentication by the remote router.
PPP Authentication: Specify the PPP authentication method for PPTP, and
L2TP over IPSec.
Normally set to PAP/CHAP for the widest
compatibility.
VJ Compression: VJ Compression is used for TCP/IP protocol header
compression. Normally set to Yes to improve bandwidth utilization.
Once you enable the IPSec Tunnel or the L2TP with IPSec Plolicy (applying Nice
to Have or Must option) for the dial-out VPN type, you should move on the
following setting.
Server IP/Host Name for VPN: Specify the IP address of the destination VPN
server or the Host Name for dialup.
IKE Pre-shared Key: Click it and a window will be automatically poped up
for you, as depicted below.
Please fill a Pre-shared Key and confirm it
for this specific node.
IPSec Security Method: Specify the IPSec security method, either
authentication or encryption algorithm, to determine the security level.
You can only select one.
Medium(AH): Specify the IPSec protocol for the Authentication Header
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VPN and Remote Access Setup
protocol.
The data will be authenticated, but not be encrypted.
High (ESP): Specify the IPSec protocol for the Encapsulating Security
Payload protocol.
The data will be encrypted.
Supported
algorithms are listed below.
DES without Authentication: Use DES encryption algorithm and not
apply any authentication scheme.
DES with Authentication: Use DES encryption algorithm and apply MD5
or SHA-1 authentication algorithm.
3DES without Authentication: Use triple DES encryption algorithm and
not apply any authentication scheme.
3DES with Authentication: Use triple DES encryption algorithm and
apply MD5 or SHA-1 authentication algorithm.
Advanced Setting: Click it and a window will be automatically poped up for
advanced setting, as shown below.
In this window, you need to decide
which mode (Main mode or Aggressive Mode) to be used for Phase 1 IKE
negotiation process, specify the authentication and encryption algorithms,
fill the lifetime for the IKE phase 1 and phase 2, enable or disable the
“Perfect Forward Secret”, and provide the Local ID for remote VPN
gateway.
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VPN and Remote Access Setup
IKE phase 1 mode: Main mode and Aggressive mode are provided in the
Vigor 2900 series of broadband security routers.
Basically, both modes
are two kinds of Phase 1 IKE negotiation process.
Most VPN servers
support Main mode and so does the Vigor 2900 series of routers.
Aggressive mode is a more recent implementation to speed up the
negotiation process, but may incur less security.
of routers also support this Aggressive mode.
The Vigor 2900 series
By default, Main mode is
active for consideration of greatest compatibility.
IKE phase 1 proposal:
As stated above, you should specify authentication
scheme, encryption algorithm, or their combinations.
Then the router
will deliver the specified algorithm to the remote VPN server and ask
whether it supports such an algorithm.
Two options are available for
selection in Aggressive mode and nine choices are provided for Main
mode.
For Main mode, you have better to choos the lastest term, i.e.
“DES_MD5_G1/DES_SHA1_G1/3DES_MD5_G1/3DES_MD5_G2”.
This is because that more selections are available, more likehood of
consistent algorithm is.
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VPN and Remote Access Setup
IKE phase 1 key lifetime:
In order to increase the security level, the router
should limit the key lifetime.
By default, the key lifetime is set to the
standard value, i.e. 28800 seconds. You are able to specify a value in
between 900 and 86400 seconds on demand.
IKE phase 2 key lifetime: By default, the phase 2 key lifetime is set to the
standard value, i.e. 3600 seconds. You also are able to specify a value in
between 600 and 86400 seconds according to your demand.
Perfect Forward Secrect:
If you enable this term, then the Phase 1 key will
be reused to reduce the computation complexity in phase 2.
new key will be generated for phase 2 key.
Otherwise, a
By default, this option is
inactive.
Local ID:
This term is mainly used in Aggressive mode and is on behalf of
the IP address to perform identity authentication with remote VPN server.
It is not necessary for Main mode.
Scheduler (1-15): Specify the index of the call schedule.
10.6.3 Dial-In Settings
Allowed Dial-In Type: Indicate the allowed dia-in connection type.
In the Vigor
2900 series of broadband security routers, we provide three options: PPTP,
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VPN and Remote Access Setup
IPSec Tunnel, and L2TP with IPSec Policy.
By default, these three options
are active.
PPTP: Check to allow the PPTP dial-in connection.
IPSec Tunnel: Click it to allow the IPSec tunnel dial-in connection.
L2TP with IPSec Policy: Specify the IPSec policy for the L2TP connection.
None: Do not apply the IPSec policy.
Nice to Have: Apply the IPSec policy first.
If it fails, the dial-in VPN
connection will be the L2TP connection without employing the IPSec
policy.
Must: Specify the IPSec policy to be definitely applied on the L2TP
connection.
Notice that, similar to the setting for dial-out users, when you choose either the
PPTP or the L2TP with IPSec Policy for dial-in setting, you should specify the
Username, Password, PPP Authentication, and VJ Compression.
Other
functions including IKE Pre-Shared Key, IPSec Security Method, and Peer VPN
Server IP or Peer ID are reserved for the option of IPSec Tunnel and will be
disabled for the PPTP or L2TP with IPSec Policy option.
One exception for the
L2TP with IPSec Policy option is that policy sets to Nice to Have or Must.
In this
exception, you should move on the setting of IKE Pre-Shared Key, IPSec Security
Method, and Peer VPN Server IP or Peer ID.
Hence, if you enable the PPTP, L2TP, or L2TP with IPSec Policy option for
dial-in setting, you should move on the setting of the following fields.
Username: Specify a username to authenticate the dial-in router.
Password: Specify a password to authenticate the dial-in router.
PPP Authentication: Specify the PPP authentication method for PPTP, L2TP,
and L2TP over IPSec.
Normally set to PAP/CHAP for the widest
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VPN and Remote Access Setup
compatibility.
VJ Compression: VJ Compression is used for TCP/IP protocol header
compression. Normally set to Yes to improve bandwidth utilization.
Once you enable the IPSec Tunnel or L2TP with IPSec Plolicy with selection of
Nice to Have or Must for dial-in setting, you should move on the following setting.
Specify Remote VPN Gateway:
For extra security, you should enable the
option to allow the remote client to connect only from a specific IP
address.
Peer VPN Server IP or Peer ID: Specify the IP address of the remote VPN
server or the peer ID in the field. Afterward, you should fill a Pre-Shared
Key for this specific node.
IKE Pre-shared Key: Click it and a window will be automatically poped up
for you, as depicted below.
Please fill a Pre-shared Key for this specific
node.
IPSec Security Method: Specify the IPSec security method, either
authentication or encryption algorithm, to determine the security level.
You can only select one.
Medium(AH): Specify the IPSec protocol for the Authentication Header
protocol.
The data will be authenticated, but not be encrypted.
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VPN and Remote Access Setup
High (ESP): Specify the IPSec protocol for the Encapsulating Security
Payload protocol.
The data will be encrypted.
algorithms are DES, 3DES, and AES.
Supported
By default, these three
algorithms are available.
Notice that if you do not activate the “Specify Remote VPN Gateway” and leave
the field of “Peer VPN Server IP or Peer ID” to be empty, the settings of IKE
Pre-Shared Key, and IPSec Security Method will be disabled and, therefore, no
IPSec-related VPN conneciton can be triggered successfully.
10.6.4 TCP/IP Network Settings
The following settings are required for proper LAN-to-LAN operations.
My WAN IP: In most cases, you may accept the default value of 0.0.0.0 in this field.
The router will then get a WAN IP address from the remote router during the
IPCP negotiation phase. If the WAN IP address is fixed by remote side, specify
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VPN and Remote Access Setup
the fixed IP address here.
Remote Gateway IP: In most cases, you may accept the default value of 0.0.0.0 in
this field. The router will then get a Remote Gateway IP address from the
remote router during the IPCP negotiation phase.
If the Remote Gateway IP
address is fixed, specify the fixed IP address here.
Notice that if you are not familiar with IPCP protocol, please set these two fields as
0.0.0.0.
Remote Network IP: Specify the network identification of the remote network.
For example, 192.168.1.0 is a network identification of a class-C subnet with
subnet mask of 255.255.255.0 (/24).
Remote Network Mask: Specify the subnet mask of the remote network.
More: This button let you add a static route when this connection is up. Clicking it
will pop up a window for more setting, as depicted below.
RIP Direction: The option specifies the direction of RIP (Routing Information
Protocol) packets. You can enable/disable one of direction here.
Herein, we
provide four options: TX/RX Both, TX Only, RX Only, and Disable.
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VPN and Remote Access Setup
RIP Version: Select the RIP protocol version. Specify Ver. 2 for greatest
compatibility.
For NAT operation, treat remote sub-net as:
The Vigor router supports two
local IP networks: the 1st subnet and 2nd subnet. Thus, you can set which
subnet will be used as the local network for VPN connection and exchange RIP
packets with the remote network.
Usually set to Private IP for routing
between the 1st subnet and the remote network.
10.7 An example of LAN-to-LAN VPN connection
This example is based on the network configuration shown in the following table to
describe how to set up a LAN-to-LAN profile to connect two private networks
through Internet.
As shown in the table, the private network 192.168.1.0/24 is
located at head office, the network of off-site branch office is 192.168.2.0/24.
Before configuring the LAN-to-LAN profile for each site, you should click VPN
and Remote Access Setup > VPN IKE/IPSec Setup to configure the pre-shared
key ABC123 in advance.
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VPN and Remote Access Setup
Creating a LAN-to-LAN profile at Head Office
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VPN and Remote Access Setup
Creating a LAN-to-LAN profile at Branch Office
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