SmoothWall's Corporate Guardian 3 is one of the best value firewalls on the market. Just provide your own base PC, and the installation will take care of everything else.
However, you mighty struggle with new hardware, as the installation would not recognize our SATA hard disk. Instead, we used a standard parallel ATA disk, which was formatted and partitioned automatically before the hardened version of Linux was installed.
You also only need one dedicated network card, as the software supports direct internet connections via an ISDN or ADSL modem. You also have the option to install a third network device if you want a DMZ.
Once installed configuration can be performed directly on the firewall or remotely via a secure HTTP connection to the firewall's web browser, which was our preferred method. The default policy blocks all incoming connections, but allows all outgoing, so you'll have to do some work to get it up to the level of the company policy. As Corporate Server 3 has a full stateful inspection engine, it is simple to create new rules blocking or allowing specific services.
The software also comes with the Open Source Snort intrusion detection engine, which is useful, once properly configured, for detecting and preventing threats. New Snort rules can be downloaded and applied in realtime, although you will need a high-specification PC to run these features to their optimum level.
Corporate Server also has some additional security features, including blocking SYN floods.
Beyond the basic firewall, the software does not offer much in its own right. However, it is the cheapest gateway firewall on test and there are expansion modules available, including SmoothTunnel 3.1, for VPNs; SmoothGuardian, for web content filtering; and SmoothRule, for controlling non-HTTP internet access, such as games and chat.
The excellent base package gives you an incredibly cheap and powerful stateful inspection firewall, while the add-ons mean you can grow the system to suit any need without paying through the nose.