How to configure Firewall to route all traffic from L2TP VPN client to the remote site via MPLS VPN

10/14/2021 16 People found this article helpful 494,105 Views

Description

Resolution

Resolution for SonicOS 6.5

This release includes significant user interface changes and many new features that are different from the SonicOS 6.2 and earlier firmware. The below resolution is for customers using SonicOS 6.5 firmware.

In the below scenario, outside laptop connects to Site A through L2TP VPN. Both Site A and Site B can access to Internet via WAN interface X1, while there is an MPLS VPN tunnel between these two sites. This article will describe how to route all traffic from terminal laptop to the remote Site B through MPLS VPN tunnel.

How to configure:

Go to Manage > VPN > L2TP Server

Select Enable L2TP Server and click Configure as shown below:

Kepp alive should be set for 60 Secs.

Configure the Primary and Secondary DNS Server with the ip addresses of your internal DNS Servers.

Example:

- DNS Server 1: 10.190.202.200

- DNS Server 2: 10.102.1.51

Step 1: Configure L2TP Server on the firewall of Site A.
Please refer to the KB 5378: Configuring L2TP Server on SonicOS Enhanced

Go to Manage > VPN > L2TP Server > L2TP Users

Step 2: Route all traffic of terminal laptop to Site A.

Navigate to Manage | Users | LocalUsers & Groups, Click the Edit button of L2TP VPN user (If non existant please create a user)

Add group Trusted Users (Configured for L2TP) in the Groups tab.

Add WAN RemoteAccess Networks in the VPN Access tab.

Navigate to Manage | VPN | Base Settings page
Enable WAN Group VPN | Click the Edit button of WAN GroupVPN
Select This Gateway Only for option Allow Connections to: at Client tab | Tick options Set Default Route as this Gateway and also Apply VPN Access Control List.

Step 3 : Route all traffic of terminal laptop from Site A to Site B.

Add a routing policy on the firewall of Site A. Go to Manage| Network | Routing | Routing Policies | Click button Add.
Source: L2TP IP Pool
Destination: Any
Service: Any
Gateway: To SiteB Gateway
Interface: Select interface connected to MPLS Tunnel
Metric: 1

On site A, add a NAT policy to translate L2TP IP Pool addresses to the IP address visible on Site B (you can choose IP address of the interface connecting to MPLS tunnel ).
Navigate to Manage | Rules | NAT Policies | Click button Add.

Note: when browse NAT policies you will find there is a default NAT policy for L2TP IP Pool which was generated by system when configuring WAN GroupVPN. In order to ensure the policy you just created can be hit as default, y ou are required to change the Priority of the NAT policy you just added to be prior to the default NAT Policy by clicking Priority button. In this case, the priority for the policy is configured as 3.

Step 4 : this step depends on the zone type of the interface connecting to MPLS VPN tunnel. If the type of the interface is LAN, you can ignore this step. If the interface is set as DMZ or WAN, you are required to add Access Rules (Manage | Rules | Access Rules ) on Site B for WAN/DMZ to LAN and WAN to WAN access. While, when using WAN zone, you may also need to add a NAT policy to translate the IP address of MPLS VPN to the WAN primary IP address on site B.

How to test:

On the mobile laptop, connect to the L2TP server of site A and ping any LAN subnet IP address of site B or Interet site.

You can capture the packets on Site B to check whether the traffic has been routed.

Resolution for SonicOS 6.2 and Below

The below resolution is for customers using SonicOS 6.2 and earlier firmware. For firewalls that are generation 6 and newer we suggest to upgrade to the latest general release of SonicOS 6.5 firmware.

In the below scenario, outside laptop connects to Site A through L2TP VPN. Both Site A and Site B can access to Internet via WAN interface X1, while there is an MPLS VPN tunnel between these two sites. This article will describe how to route all traffic from terminal laptop to the remote Site B through MPLS VPN tunnel.

How to configure:

Step 1: Configure L2TP Server on the firewall (TZ205) of Site A.
Please refer to the KB 5378: Configuring L2TP Server on SonicOS Enhanced

Step 2: Route all traffic of terminal laptop to Site A.

Navigate to Users | LocalUsers | Click the Edit button of L2TP VPN user | Add group Trusted Users (Configured for L2TP) in the Groups tab | Add WAN RemoteAccess Networks in the VPN Access tab.

Navigate to VPN | Settings page | Enable WAN Group VPN | Click the Edit button of WAN GroupVPN | Select This Gateway Only for option Allow Connections to: at Client tab | Tick options Set Default Route as this Gateway and also Apply VPN Access Control List.

Step 3 : Route all traffic of terminal laptop from Site A to Site B.

Add a routing policy on the firewall of Site A. Go to Network | Routing | Click button Add.

On site A, add a NAT policy to translate L2TP IP Pool addresses to the IP address visible on Site B (you can choose IP address of the interface connecting to MPLS tunnel ). Navigate to Network | NAT Policies | Click button Add.

Note: when browse NAT policies you will find there is a default NAT policy for L2TP IP Pool which was generated by system when configuring WAN GroupVPN. In order to ensure the policy you just created can be hit as default, y ou are required to change the Priority of the NAT policy you just added to be prior to the default NAT Policy by clicking Priority button. In this case, the priority for the policy is configured as 3.

Step 4 : this step depends on the zone type of the interface connecting to MPLS VPN tunnel. If the type of the interface is LAN, you can ignore this step. If the interface is set as DMZ or WAN, you are required to add Access Rules (Firewall | Access Rules ) on Site B for WAN/DMZ to LAN and WAN to WAN access. While, when using WAN zone, you may also need to add a NAT policy to translate the IP address of MPLS VPN to the WAN primary IP address on site B.

How to test:

On the mobile laptop, connect to the L2TP server of site A and ping any LAN subnet IP address of site B or Interet site.

You can capture the packets on Site B to check whether the traffic has been routed.

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How to configure Firewall to route all traffic from L2TP VPN client to the remote site via MPLS VPN

Description

Resolution

Resolution for SonicOS 6.5

Resolution for SonicOS 6.2 and Below

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