The Seattle Firewall is an ipchains firewall that supports IP masquerading and can be used on a standalone system, on a dedicated firewall system, or on a multi-use gateway/server. It supports VPN via IPIP tunnels, IPSec, and PPTP. It is easily configurable by editing configuration files, and can be extended without modifying the base product. It also includes realtime monitoring with an audible alarm that sounds when suspect packets are detected.
