I have read doc to do it but when i apply this doc i have a "your kernel seems to not support ipchains" messages when i try to do this. After this i have a 192.168.0.1 ip on eth1 but my pc´s on the internal lan can´t have internet access througth the eth0 (internet conexion).
Simple case of RTFM. The "IP-Masquerade-HOWTO.gz" found in /usr/doc/howto/ lists what kernal options are needed.
Ross