Iptables

summary
iptables is the interface to the packet filtering capabilities of the Linux kernel, netfilter


 * http://netfilter.org/


 * http://netfilter.org/projects/iptables/index.html

manpage
iptables

further links

 * Iptables Tutorial 1.2.2 by Oskar Andreasson


 * iptables generator von Harry's Linux-Seite,


 * IPv6 iptables firewall (Linux Reviews)