Network AddressPortTranslation (NAPT) is a Network Address
Translation (NAT) method with translation of the
port number.In the NAPT method, the NAT router is assigned a private IPv4 address on the LAN side and a public one on the WAN side. Behind the NAT router, there can be many computers with private IPv4 addresses, they just all need to have the internal router address entered. The NAT router manages the port numbers of the individual computers.