pfSense is an open source firewall/router distribution based on FreeBSD. pfSense is meant to be installed on a personal computer and is noted for its reliability and offering features often only found in expensive commercial firewalls. It can be configured and upgraded through a web-based interface, and requires no knowledge of the underlying FreeBSD system to manage. pfSense is commonly deployed as a Perimeter Firewall, router, wireless access point, DHCP server, DNS server, and as a VPN endpoint.
The name was derived from the fact that it helps make the OpenBSD packet-filtering tool pf make more sense to non-technical users.
PFSense Download : http://mirror.myip.be/pub/pfsense/downloads/
Full Installation Guide : http://www.impromptu-it.com/?p=179