NAT

NAT (network address translation) is also called masquerading under Linux and friends.

Here's what you should enter on your server.

 $ sudo sysctl -w net.ipv4.ip_forward=1
 $ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

This assumes, that:

• your server has eth0 as its WAN interface
• your client is connected to any interface on the server
• your client has its IP address network matching the server's eth1 configuration, plus a working DNS configuration