hello
1. do you have the right kernel? (2.4.X?)
2. enable ip-forwarding (this is enough to use the linuxbox as a router) command echo "1" > /proc/sys/net/ip_forward (or so... look for it there).
3. set up iptables. ther are a lot of docs around in the net. go to
www.tldp.org.
have fun
raven