Linux IP Firewalling Chains, normally called ipchains, is
free software
Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...
to control the
packet filter
In computing, a firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. A firewall typically establishes a barrier between a trusted network and an untrusted ne ...
or
firewall
Firewall may refer to:
* Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts
* Firewall (construction), a barrier inside a building, designed to limit the spre ...
capabilities in the 2.2 series of
Linux kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
s. It superseded
ipfirewall
ipfirewall or ipfw is a FreeBSD IP, stateful firewall, 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 memb ...
(managed by ipfwadm command), but was replaced by
iptables
iptables is a user-space utility program that allows a system administrator to configure the IP packet filter rules of the Linux kernel firewall, implemented as different Netfilter modules. The filters are organized in different tables, which ...
in the 2.4 series. Unlike iptables, ipchains is
stateless.
It is a rewrite of Linux's previous
IPv4
Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. IPv4 was the first version de ...
firewall
Firewall may refer to:
* Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts
* Firewall (construction), a barrier inside a building, designed to limit the spre ...
,
ipfirewall
ipfirewall or ipfw is a FreeBSD IP, stateful firewall, 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 memb ...
. This newer ipchains was required to manage the
packet filter
In computing, a firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. A firewall typically establishes a barrier between a trusted network and an untrusted ne ...
in
Linux kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
s starting with version 2.1.102 (which was a 2.2 development release). Patches are also available to add ipchains to 2.0 and earlier 2.1 series kernels. Improvements include larger maxima for packet
counting
Counting is the process of determining the number of elements of a finite set of objects, i.e., determining the size of a set. The traditional way of counting consists of continually increasing a (mental or spoken) counter by a unit for every ele ...
, filtering for
fragmented packets and a wider range of
protocols
Protocol may refer to:
Sociology and politics
* Protocol (politics), a formal agreement between nation states
* Protocol (diplomacy), the etiquette of diplomacy and affairs of state
* Etiquette, a code of personal behavior
Science and technology
...
, and the ability to match packets based on the inverse of a rule.
The ipchains suite also included some shell scripts for easier maintenance and to emulate the behavior of the old ipfwadm command.
The ipchains software was superseded by the
iptables
iptables is a user-space utility program that allows a system administrator to configure the IP packet filter rules of the Linux kernel firewall, implemented as different Netfilter modules. The filters are organized in different tables, which ...
system in
Linux kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
2.4 and above.
References
External links
* IPChains HOWTO
on TLDPan
{{Linux kernel
Discontinued software
Firewall software
Free network-related software
Free security software
Free software programmed in C
Linux kernel features
Linux security software