Problems with aTrust and WSL 20

Newbie574394 Lv1Posted Jul-10-2025 03:25

Hello everyone,

I'm currently facing an issue with aTrust and WSL (Windows Subsystem for Linux).

When using aTrust on native Windows, everything works as expected — the connection is established, traffic flows through the aTrust interface, and the applications receive proper responses. I can clearly see the traffic being routed through the aTrust tunnel and returning with no issues.

However, when I try to perform the same operation using WSL, the behavior changes. I can see the traffic leaving WSL, getting routed through the aTrust tunnel, and even returning via the same interface, but for some reason, it never reaches back into the WSL environment. It just gets lost in the process and never makes it back to the application (even thought the DNS resolution Works).

Has anyone experienced this behavior before or found a workaround to make aTrust fully functional within WSL?

Any help would be greatly appreciated.

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mantasha Lv2Posted Jul-21-2025 17:21
  
A common routing issue with WSL2 with VPN clients is that the return traffic from the aTrust VPN on the Windows host isn't instantly routed back to WSL's virtual network interface.  The typical technique is to manually synchronize the network configurations.  Write a script that determines the IP address of the aTrust virtual network adapter and then executes a command in WSL to set it as the default route in order to achieve this.  For example, use <aTrust_Interface_IP> dev eth0 to sudo ip route add 0.0.0.0/0.  Additionally, to ensure that WSL makes use of the VPN's DNS server, you need to modify /etc/resolv.conf.  Additionally, in order to specifically allow traffic forwarding from the VPN, you may need to construct a Windows Defender Firewall rule with high security.
Ayra Posted Jul-18-2025 05:03
  
Hi

The return traffic from the aTrust VPN on the Windows host isn't immediately routed back to WSL's virtual network interface, which is a common routing problem with WSL2 and VPN clients.  Manually synchronizing the network configurations is the standard solution.  To accomplish this, write a script that finds the aTrust virtual network adapter's IP address and then runs a command in WSL to make it the default route. For instance, sudo ip route add 0.0.0.0/0 via <aTrust_Interface_IP> dev eth0.  Additionally, you must change /etc/resolv.conf to make sure WSL utilizes the VPN's DNS server. Additionally, you might need to create a Windows Defender Firewall rule with high security to specifically permit traffic forwarding from the VPN.in order to stop the host from discarding the return packets, to your WSL virtual switch.
Zonger Lv5Posted Jul-18-2025 03:33
  
Hi,

This is a common routing issue with WSL2 and VPN clients, where the return traffic from the aTrust VPN on the Windows host isn't automatically routed back to WSL's virtual network interface. The typical solution is to manually synchronize the network configurations. You can achieve this by creating a script that identifies the IP address of the aTrust virtual network adapter and then executes a command within WSL to set it as the default route; for example: sudo ip route add 0.0.0.0/0 via <aTrust_Interface_IP> dev eth0. You will also need to ensure WSL uses the VPN's DNS server by modifying /etc/resolv.conf and may need to add a Windows Defender Firewall rule with advanced security to explicitly allow traffic forwarding from the VPN to your WSL virtual switch to prevent the host from dropping the return packets.

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