[ale] NAT Help needed!

[Philip Polstra]

Our router went down yesterday at the high school so we decided to set
up a FC3 machine to be the new router.  I can't get it to forward
packets from other machines in the network despite following the
instructions to set up the router with NAT exactly.  I have the
ability to connect to the internet and the local network on the router
machine, but nothing gets forwarded.

I'm using iptables.  Any ideas?