Network Address Translation

A method of allowing computers to access the Internet without assigning real Internet addresses. The connections must originate from the internal machines to reach Internet addresses. The NAT router puts these on the Internet using the router's IP address. When data is returned, it forwards the data to the requesting internal machine. Part of this process includes mapping the internal IP/Port combinations that correspond to external port usage. This allows the router to know where data needs to be sent when it returns. Special port mappings can be made to specific internal IP addresses to support connections originating from the Internet.