A Linux kernel packet control tool, iptables along with netfilters and the NAT subsystem form the framework of the Linux 2.4 x and Linux 2.6 x systems. Targeted towards system administrators, iptables is a user space program run from the command prompt and is used to configure the Linux 2.4.x and Linux 2.6.x packet filtering ruleset that uses IPV4 and IPV6 protocols for data transmission. Each rule in an iptables consists of a number of classifiers called iptables matches and one action that is connected with the classifiers called the iptables target.   read more »