NAT

Network Address Translation (NAT) is an approach that is used to remap a IP address space into another by modifying network address information in IP datagram packet headers while they are in transit. This technique was originally used for rerouting traffic in IP networks without renumbering every host. Typically home or small business networks use NAT to share a single DLS or Cable modem IP address. However, in some cases NAT is used for servers as an additional layer of protection