Patent ID: 8295268

Claim:
A management server connectable to a IP device via a router, a global IP address being assigned to the router, the router having a port, the IP device being configured to be connectable to the port, the router being configured to assign a port number of the port to the IP device, the management server comprising: an interface configured to receive, from the IP device, via the router, the global IP address of the router and the port number assigned to the IP device; and a controller configured to: receive, via a first session, from the IP device, a first request for the management server to access the IP device; transmit, in response to the first request in the first session, a second request, via a second session, for the IP device to access the management server, using the global IP address of the router and the port number assigned to the IP device; judge whether a connection between the IP device and the management server in the second session is successful or not, based on a response to the second request; and transmit, via the first session, to the IP device, a result of the judgment in the second session as a response to the first request.