Port address translation

Port Address Translation (PAT) is a feature of a network address translation device that translates Transmission Control Protocol or User Datagram Protocol connections made to a host and port (computing) on an outside network to a host and port on an inside network.

PAT allows one single IP address to be used for many internal hosts. With PAT one outside IP address can account for over 64000 inside hosts.

In a typical firewall (networking) configuration, the outside network is the Internet and the inside network is the local area network.

In a typical Demilitarized zone (computing) configuration, the outside network is the Internet and the inside network is the DMZ.