ipfirewall

ipfirewall or ipfw is a FreeBSD IP, stateful firewall,[1] packet filter and traffic accounting facility.

Its ruleset logic is similar to many other packet filters except IPFilter.

ipfw is authored and maintained by FreeBSD volunteer staff members.

ipfw was the built-in firewall of Mac OS X[2][3] until Mac OS X 10.7 Lion in 2011 when it was replaced with the OpenBSD project's PF.

[4] A modern port of ipfw and the dummynet traffic shaper is available for Linux (including a prebuilt package for OpenWrt) and Microsoft Windows.

FreeBSD "/etc/rc.firewall" shell script for configuring ipfw
Mac OS X 's ipfirewall tab in the Sharing Preferences Pane