filtergen takes a high-level language and compiles
it into packet filtering rules for a variety of
packet filters. Iptables, ipchains, and ipfilter
backends are available.
fk is an application proxy suite designed for building IP gateways. Ultimately, the intent is to provide a free software replacement for the TIS firewall toolkit.
Developers and users wanted
I feel that FK is now at a stage where it's more than useful for most home/small office setups. However, it does need some testing beyond what I can do, and ...
A network protocol analyzer.
A mail filtering manager, supporting Sieve, procmail, maildrop and IMAP filters.