|Building The Network You Need With PF, The OpenBSD Packet Filter: BSDCan 2016, Ottawa, Canada, June 8th 2016|
Kernel level code (module + admin software) which determines network packets' paths
'the world consists of packets, protocols, connections and ports'
Important feature: Stopping undesirable traffic, 'firewall'
PF is a flexible tool, for taking control of your network traffic
Also see If you came from elsewhere