NAT with iptables
Set up IP FORWARDing and Masquerading
iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE iptables --append FORWARD --in-interface eth1 -j ACCEPT
Enables packet forwarding by kernel
echo 1 > /proc/sys/net/ipv4/ip_forward
Apply the configuration
service iptables restart