Patent ID: 7159033

Claim:
A router search system, which examines network connection apparatuses connected to a first network to search for a network connection apparatus that is connected to a second network outside said first network, comprising: a transmitter router search apparatus and a recipient router search apparatus that are respectively connected to said first and said second networks, wherein said transmitter router search apparatus includes generating means, for generating an inspection IP packet including search packet information indicating that a destination IP address and a source IP address are defined as IP addresses for a target network connection apparatus to be inspected and said recipient router search apparatus, and that said inspection IP packet is for a router search, and inspection IP packet transmission means, for transmitting said inspection IP packet to said target network connection apparatus to be inspected, wherein said recipient router search apparatus includes reception means, for receiving an IP packet addressed to the recipient, and determination means, for determining whether said IP packet received by said reception means is a response IP packet that constitutes a response to said inspection IP packet transmitted by said target network connection apparatus to be inspected, and for, based on the determination results, determining whether said target network connection apparatus is currently operating as a router.