Resolving WSL2 Internet Connectivity Issues When Using a VPN on Windows

Problem Statement

When connecting to a VPN from a Windows PC, users may experience loss of internet connectivity within their WSL2 (Windows Subsystem for Linux 2) Ubuntu distribution. This issue arises because the VPN client routes all traffic through the VPN, causing WSL2 to lose its internet connection.

Solution

To resolve this issue, we can use wsl-vpnkit, a tool that helps WSL2 work seamlessly with VPNs. Below are the steps to set up wsl-vpnkit to restore internet connectivity in WSL2 while connected to a VPN.

Steps to Set Up wsl-vpnkit

1. Download and Extract wsl-vpnkit:

   wget -cO wsl-vpnkit.tar.gz "https://github.com/sakai135/wsl-vpnkit/releases/download/v0.4.1/wsl-vpnkit.tar.gz"
   sudo mkdir -p /opt/wsl-vpnkit
   sudo tar --directory /opt/wsl-vpnkit --strip-components=1 -xf wsl-vpnkit.tar.gz
   sudo rm wsl-vpnkit.tar.gz

2. Create the wsl-interop-env.sh Script:

   sudo nano /etc/systemd/system/wsl-interop-env.sh

   Add the following content:

   #!/bin/sh
   export WSL_INTEROP=
   for socket in $(ls /run/WSL | sort -n); do
       if ss -elx | grep "$socket"; then
           export WSL_INTEROP=/run/WSL/$socket
       else
           rm $socket
       fi
   done

3. Make the Script Executable:

   sudo chmod +x /etc/systemd/system/wsl-interop-env.sh

4. Create the wsl-vpnkit.service File:

   sudo nano /etc/systemd/system/wsl-vpnkit.service

   Add the following content:

   [Unit]
   Description=wsl-vpnkit
   After=network.target
   
   [Service]
   Type=idle
   ExecStart=/bin/sh -c '. /etc/systemd/system/wsl-interop-env.sh; /opt/wsl-vpnkit/wsl-vpnkit'
   Environment=VMEXEC_PATH=/opt/wsl-vpnkit/wsl-vm
   Environment=GVPROXY_PATH=/opt/wsl-vpnkit/wsl-gvproxy.exe
   Restart=always
   KillMode=mixed
   
   [Install]
   WantedBy=multi-user.target

5. Enable and Start the Service:

   sudo systemctl enable wsl-vpnkit
   sudo systemctl start wsl-vpnkit

Conclusion

By following these steps, you can restore internet connectivity in your WSL2 environment while connected to a VPN on Windows. This solution leverages wsl-vpnkit to ensure seamless network integration between WSL2 and your VPN.