Starting from version 10.7 (Lion), Mac OS X includes 2 firewalls: PF & Application Firewall. Both are disabled by default. Mac OS X 10.6 (and earlier) came with IPFW, a port of FreeBSD's stateful firewall[1]. IPFW was deprecated in OS X 10.7, and was completely removed in OS X 10.10; it was replaced with PF. PF (Packet Filter) is OpenBSD's system for filtering TCP/IP traffic and doing Network Addr