Tun0 Interface Not Present in ifconfig After OpenVPN Configuration

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It seems like you’ve already taken some important steps, such as ensuring the tun kernel module is loaded and the OpenVPN client service is active. However, the absence of the tun0 interface in ifconfig suggests that there might be an issue with the OpenVPN configuration or the service startup.

Here are a few steps you can take to troubleshoot and resolve the issue:

  1. Check OpenVPN Logs:

    • The OpenVPN logs can provide detailed information about what might be going wrong. You can check the logs using:
      sudo journalctl -u openvpn@client
    • Look for any error messages or warnings that might indicate why the tun0 interface is not being created.

  2. Verify Configuration Files:

    • Ensure that the client.conf file is correctly configured. Pay special attention to the following lines:
      dev tun
ca /etc/openvpn/ca.crt
cert /etc/openvpn/client.crt
key /etc/openvpn/client.key
remote <server_ip> <port>
    • Make sure the paths to the certificate and key files are correct and that the remote line points to the correct server IP and port.

  3. Check Network Configuration:

    • Ensure that IP forwarding is enabled on your system. You can check this by running:
      sudo sysctl net.ipv4.ip_forward
    • If it is not enabled, you can enable it by adding the following line to /etc/sysctl.conf:
      net.ipv4.ip_forward = 1
    • Then reload the sysctl configuration:
      sudo sysctl -p

  4. Restart OpenVPN Service:

    • Sometimes, simply restarting the OpenVPN service can resolve the issue:
      sudo systemctl restart openvpn@client

  5. Check for Conflicting Network Interfaces:

    • Ensure that there are no other network interfaces that might be conflicting with tun0.

  6. Manual Interface Creation:

    • As a last resort, you can try to manually create the tun0 interface to see if it helps:
      sudo ip tuntap add dev tun0 mode tun
sudo ip link set tun0 up

If none of these steps resolve the issue, please provide more details from the OpenVPN logs, and any error messages you encounter. This will help in diagnosing the problem further.

Please, also check if these links can help you solve your problem:

Can't open PID file /run/openvpn/client.pid (yet?) after start: Operation not permitted in VPN client configuration in imx6ull.