IPFilter (commonly referred to as ipf) is an open source software package that provides firewall services and network address translation (NAT) for many UNIX-like operating systems. The author and software maintainer is Darren Reed.

IPFilter is delivered with FreeBSD, NetBSD and Solaris 10. It used to be a part of OpenBSD, but it was removed in May 2001 due to problems with the license of IP Filter, after negotiations between Theo de Raadt and Reed broke down. At first glance, the license looks a lot like BSD Licenses, but does not allow redistribution of modified versions.

IPFilter can be installed as a runtime-loadable kernel module or directly incorporated into the operating system kernel, depending on the specifics of each kernel and user preferences. The software's documentation recommends the module approach, if possible.

Operating systems that are known to support IPFilter include the following:

• AIX 5.3 ML05
• BSD/OS-1.1 - 4
• FreeBSD 2.0.0 - 7.0
• IRIX 6.2, 6.5
• HP-UX 11.00
• Linux kernel 2.4 - 2.6
• NetBSD 1.0 - 3.0
• OpenBSD 2.0 - 3.8
• OpenSolaris
• QNX 6 port
• Solaris 2.3 - 10
• SunOS 4.1.3 - 4.1.4
• Tru64 5.1a

See also

• iptables
• ipfw
• PF (firewall)

External links

• IPFilter Homepage
• The IPFilter FAQ by Phil Dibowitz
• IPFilter How-To
• Current IPFilter license
• FreeBSD handbook - The IPFILTER (IPF) Firewall

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