pf is the OpenBSD Packet Filter, a feature-rich IP-layer firewall used on FreeBSD, NetBSD, and Mac OS X, as well as in the pfSense open-source firewall appliance software.
pf is a Packet Filtering firewall originally developed by the OpenBSD project, and since adopted by FreeBSD, NetBSD and Mac OS X (10.7 Lion & up). pf is also used in the pfSense project's firewall code.
pf features include:
- Packet Filtering
- Network Address Translation (NAT)
- Port Redirection
- Packet Queueing / QoS
- Load Balancing
- "Policy Filtering" (packet tagging)
More information on the pf firewall can be found in the OpenBSD FAQ, including some examples.
