I tried several Floppy Firewalls earlier and one I really liked was FloppyFW. I was running on a 486dx2/66 with 16mb of ram and two old 3C509B-TPO NICs.

I tried with 4 "normal" users behind it and it worked perfectly but I have not tried to host any LAN party behind it though .

It's a quite nice solution since it's run in the momory only so no need for a hdd and I also "killed" the fan in the powersupply and with that setup it was a ultra quiet firewall/router (quite simple, but it worked).

Brief Description
floppyfw is a static router with the firewall-capabilities in Linux.

Although it is called a firewall it does not have all the functionality we are expecting from a firewall of today. It is basically a Screening router or Packet filtering firewall. (Although many firewalls sold today are just this.)

I am using this to put my home network behind a box running this and an ADSL modem on the other side. It can of course be used with cable modems and everything else giving you an ethernet port to connect to. It is also used as a basic firewall at some sites that do not need proxying proxies.

The 1.9 series has stateful packet filtering.