Over the years we have been exposed to literally hundreds of open source and proprietory firewall distributions , and through trial and error have settled on what we feel to be the safest most stable solution available.
Endian Firewall (EFW) is a “turn-key” linux security distribution that turns every system into a full featured security appliance with Unified Threat Management (UTM) functionality. The software has been designed with “usability in mind” and is very easy to install, use and manage, without losing its flexibility.
The features include a stateful packet inspection firewall, application-level proxies for various protocols (HTTP, FTP, POP3, SMTP) with antivirus support, virus and spam-filtering for email traffic (POP and SMTP), content filtering of Web traffic and a “hassle free” VPN solution (based on OpenVPN).