route

Setting up a routing

In this example is I have connected to a VPN and certain servers are meant to be accessed via the VPN.

The IP I have been given by the VPN is 192.168.2.22

route add 123.123.123.123 mask 255.255.255.255 192.168.2.22
    

Any network connection to 123.123.123.123 will go via the VPN.

route add 192.168.1.0 mask 255.255.255.0 192.168.2.22
    

Any network connection to 192.168.1.* will go via the VPN.