All you need is SNF, Mandrake's Single Network Firewall. Y ou can get it here (http://www.linux-mandrake.com/en/ftp.php3#security) it is an outstanding solution for any network. Not only doesit provide outside routing services, but it is also very stable and extremely easy to configure (all you need is a web browser or an SSH client). It also includes many additional features DHCP LOGING PROXY(which allows you to block banner adds if need be) advandced firewall tools, and a ton more it is really worth trying out it will be up and running in no time.