Netfilter – packet filtering framework

Netfilter is a framework that provides a set of hooks inside the Linux kernel that allows kernel modules to register callback functions with the network stack. A registered callback function is then called back for every packet that traverses the respective hook within the network stack.

Software inside this framework enables packet filtering, network address [and port] translation (NA[P]T) and other packet mangling.

iptables is a generic table structure for the definition of rulesets. Each rule within an IP table consists of a number of classifiers (iptables matches) and one connected action (iptables target).

Features include:

• Stateless packet filtering (IPv4 and IPv6).
• Stateful packet filtering (IPv4 and IPv6).
• All kinds of network address and port translation, e.g. NAT/NAPT (IPv4 only).
• Flexible and extensible infrastructure.
• Multiple layers of API’s for 3rd party extensions.
• Large number of plugins/modules kept in ‘patch-o-matic’ repository.

Website: www.netfilter.org
Support: HOWTO’s
Developer: Patrick McHardy, Harald Welte, Jozsef Kadlecsik, Martin Josefsson, Yasuyuki Kozakai, Pablo Neira Ayuso and many other conributor
License: GNU General Public License v2.0

Netfilter is written in C. Learn C with our recommended free books and free tutorials.

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