I have an OpenVPN server set up on Ubuntu 18.04. Clients connect to the VPN and all traffic is routed through the VPN. The outgoing IP is the same IP the clients connect to.
Now I've added another network interface on a private subnet. I want the clients' outgoing traffic to be routed through that interface so that the outgoing IP will be the external ip of the NAT gateway on the private subnet.
I'm a bit at a loss as I don't know how to configure the routing. If I just increase the metric of eth1 to put it above eth0 then I can no longer connect to the VPN or SSH to the server.
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default ip-172-30-0-1.e 0.0.0.0 UG 100 0 0 eth0
default ip-172-30-10-1. 0.0.0.0 UG 200 0 0 eth1
10.8.0.0 0.0.0.0 255.255.255.0 U 0 0 0 tun0
172.30.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
ip-172-30-0-1.e 0.0.0.0 255.255.255.255 UH 100 0 0 eth0
172.30.10.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
ip-172-30-10-1. 0.0.0.0 255.255.255.255 UH 200 0 0 eth1
Green arrows are what I want to achieve, red is what happens now.