Ipchains

IPChains is an older packet filtering software. It was developed in 1999 by Rusty Russell based on ipfwadm and is included with the 2.2.x (or later ) Linux kernel. IPChains similar to the Cisco Access Control Lists, it controls which packets into the system and can come out. Although it is primarily used as a firewall, it can also be used to cure a Linux operating system additionally.