iptables 1.4.21-1ubuntu1 (i386 binary) in ubuntu utopic

 iptables is the userspace command line program used to configure
 the Linux packet filtering ruleset. It is targeted towards system
 administrators. Since Network Address Translation is also configured
 from the packet filter ruleset, iptables is used for this, too. The
 iptables package also includes ip6tables. ip6tables is used for
 configuring the IPv6 packet filter