ipfirewall or
ipfw is a
FreeBSD IP 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. Its syntax enables use of sophisticated filtering capabilities and thus enables professional users to satisfy advanced requirements. It can either be used as a
loadable kernel module or incorporated into the
kernel; use as a loadable kernel module where possible is highly recommended. ipfw was the built-in firewall of
Mac OS X until Mac OS X 10.7 Lion when it was replaced with the OpenBSD project's
PF. Like FreeBSD, ipfw is
open source. It is used in many FreeBSD-based firewall products, including
m0n0wall and
FreeNAS. There is a
port of ipfw and the dummynet traffic shaper is available for
Linux,
OpenWrt and
Microsoft Windows.
wipfw is a Windows port of an old (2001) version of ipfw.