Patent ID: 8000280

Claim:
A network communication apparatus which is connected to a network and which performs communication with a second network communication apparatus through one or more routers equipped with an address conversion function (hereinafter, referred to as a “NAT router”), said network communication apparatus comprising one or more processors including: a direct search unit configured to transmit a direct search request to the second network communication apparatus; a route information obtaining unit configured to obtain first route information from an address management apparatus connected to the network, the first route information including a LAN side address and a WAN side address of each NAT router that is passed on a way leading from the second network communication apparatus to the address management apparatus; a route deriving unit configured to derive a route leading from said network communication apparatus to the second network communication apparatus by comparing the first route information and second route information, the second route information including a LAN side address and a WAN side address of each NAT router that is passed on a way leading from said network communication apparatus to the address management apparatus; and a communication control unit configured to perform communication with the second network communication apparatus, wherein said communication control unit performs communication directly with the second network communication apparatus through a local network using an address of the second network communication apparatus obtained by said direct search unit when it is detected by the direct search request that the second network communication apparatus and said network communication apparatus belong to the local network, and wherein said communication control unit performs communication with the second network communication apparatus based on the route derived by the route deriving unit when it is not detected by the direct search request that the second network communication apparatus and said network communication apparatus belong to the local network.