| 摘要 |
<p>A communication apparatus (10) transmits to a server (001) three address information check requests 1 to 3 whose destination port numbers are set to be [SP1] and whose source port numbers are set to be respective [LP1] to [LP3] different from each other. The communication apparatus (10) also transmits a P2P communication preparation packet whose source port number is set to be one of [LP1] to [LP3], to a destination different from the server (001), between the address information check requests 1 and 3. The communication apparatus (10) determines the NAT characteristic of a router (101) based on port numbers [GP11], [GP12] and [GP14] of the router (101) notified of by address information check responses 1 to 3.</p> |
