On my Linux server (Ubuntu), how can I configure traffic originating from one of my network interfaces (my VPN device - ppp0) to route through its own gateway address?
- I can't set it up as a default route on the server because it is expensive to route all traffic through it
- There isn't a specific subnet linked to the VPN - it could be traffic to any public IP or port (the VPN behaves as a proxy)
The end goal is to be able to configure a single local application to bind to the VPN IP and communicate only over the VPN, but no other server traffic should be routed through it. I've set it up like this, but I seem to need some sort of additional routing rules to get it working.