pfSense is an open sourcefirewall/router computer software distribution based on FreeBSD. It is installed on a computer to make a dedicated firewall/router for a network 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 pfSense project started in 2004 as a fork of the m0n0wall project by Chris Buechler and Scott Ullrich. From the beginning, it focused on full PC installations, as opposed to m0n0wall's focus on embedded hardware. However, pfSense is also available as an embedded image for CompactFlash-based installations. Version 1.0 of the software was released on October 4, 2006. Version 2.0 was released on September 17, 2011, with updates 2.0.1 to 2.0.3 between then and 2013, and version 2.1 was released on September 15, 2013.
Filtering by source/destination IP, protocol, OS/network fingerprinting
Per-rule configurable logging and per-rule limiters (IPs, connections, states, new connections, state types), Layer 7 protocol inspection, policy filtering (or packet marking), TCP flag state filtering, scheduling, gateway
Layer 2/bridging capable
State table "up to several hundred thousand" states (1KB RAM per state approx)
State table algorithms customizable including low latency and low-dropout
Packages available as "push button installs" (as of March 2013[update]) include but are not limited to: Asterisk, Squid (file caching), ClamWin download scanner, Apache with mod-security, FreeSWITCHG (Voice over IP), jail, LCD panel support, spamd email tarpit, nmap, stunnel, Varnish accelerator, multiple monitoring and statistics packages, file managers.
Although the main focus of pfSense is on full-PC installation, it is also available in versions for embedded use on hardware using Compact Flash rather than a hard drive. Many companies produce system boards, or complete low power computers, specifically designed to run pfSense embedded.