The
Sentry Firewall CD is a Linux-based Firewall/Server/IDS that you can start from a CD-Rom. Its system is designed to be immediately configurable for a variety of different operating environments via a configuration file located on a floppy disk, a local hard drive, and/or a network via HTTP(S), FTP, SFTP, or SCP.
The default kernel is a current 2.4.x series kernel with various Netfilter patches applied. An OpenWall-patched current 2.2.x kernel is also available on the CD.
Cool expert-firewall that is not only cheap (i.e. 0 bucks) but also easy to install!