I recently upgraded my system and installed the OpenSource package Smoothwall (
http://www.smoothwall.org) behind which sits my OpenACS server and multiple sites. I have to recommend this package, its a complete Linux system stripped down for gateway/firewall duty with web amin. It supports port redirection (nice for website), SSH, IPsec VPN, Snort Intrusion detection etc. The other very nice feature is that is will run on an older machine (486 or above) and the install complete sets up the system to allow untrusted, trusted and dmz zones. This is a really convenient and secure addition to an OpenACS site in my humble opinion so far.. definately worth checking out.
cheers, Jamie