ipfirewall

From Wikipedia, the free encyclopedia

Not to be confused with IPFW, the initialism of Indiana University-Purdue University Fort Wayne.

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. ipfirewall 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 is the built-in firewall of Mac OS X^[1] and DragonFly BSD. Like FreeBSD, ipfirewall is open source. It is used in many FreeBSD based firewall products, including m0n0wall.

There is also a version of IPFW that runs on Windows. It is called Wipfw and can be downloaded from sourceforge.net.

Mac OS X's ipfirewall tab in the Sharing Preferences Pane (ipfw is supplemented by an application firewall in Mac OS X 10.5 and can no longer be configured through System Preferences), simply titled Firewall.

ipfirewall is composed of these components:

kernel firewall filter rule processor and its integrated packet accounting facility
logging facility
"divert" rule (NAT)
advanced special purpose facilities
the dummynet traffic shaper
"fwd rule" forward facility
the bridge facility
ipstealth
per-packet kernel-wide tagging (set, unset and check 16-bit tags)
ALTQ-based QoS disciplines
rule sets for atomic management of multiple rules
a full-blown stateful engine with connection limiting
anti-spoofing rules based on routing table
lookup tables based on Radix trees
per-rule byte and packet counters
built-in NAT, Port address translation and LSNAT (load-sharing) facilities (since FreeBSD 7)
IPv6 support (with several limitations)