Patent ID: 7373426
Filing Date: 2008-05-13
Classification: H04L,Y10S

Abstract:
1. A method for communication control in a network system containing a first name server for managing first correspondence information that registers a host name corresponding to an IP address by using the IP address as a key, with respect to communication nodes belonging to a network of a prescribed range, a second name server for managing second correspondence information that registers an IP address corresponding to a host name by using the host name as a key, with respect to the communication nodes belonging to the network of the prescribed range, a communication node belonging to the network of the prescribed range, and a correspondent node belonging to external of the network of the prescribed range which becomes a correspondent of the communication node, the method comprising: transmitting a connection request from the communication node to the correspondent node; receiving the connection request from the communication node at the correspondent node, and transmitting a reverse look-up request to which a host name corresponding to a specific IP address of the communication node should be returned, from the correspondent node to the first name server; receiving the reverse look-up request to which a host name corresponding to the specific IP address should be returned, from the correspondent node at the first name server; searching through the first correspondence information by using the specific IP address contained in the reverse look-up request as a key, at the first name server; generating a pseudo host name including information indicating that the generated name is a pseudo host name in one-to-one correspondence with the specific IP address according to the specific IP address, when a host name corresponding to the specific IP address contained in the reverse look-up request is not obtained as a result of search, at the first name server; returning the pseudo host name to the correspondent node from the first name server; receiving the pseudo host name from the first name server at the correspondent node, and transmitting a normal look-up request to which an IP address corresponding to the pseudo host name should be returned, from the correspondent node to the second name server; receiving the normal look-up request to which an IP address corresponding to the pseudo host name should be returned, from the correspondent node at the second name server; searching through the second correspondence information by using the pseudo host name contained in the normal look-up request as a key, at the second name server; generating a pseudo IP address in one-to-one correspondent with the pseudo host name according to the pseudo host name, when an IP address corresponding to the pseudo host name contained in the normal look-up request is not obtained as a result of search, at the second name server; returning the pseudo IP address to the correspondent node from the second name server; and receiving the pseudo IP address from the second name server, comparing the pseudo IP address received from the second name server and the specific IP address of the communication node, and permitting the connection request of the communication node when the pseudo IP address received from the second name server and the specific IP address of the communication node coincide, or refusing the connection request of the communication node when the pseudo IP address received from the second name server and the specific IP address of the communication node do not coincide, at the correspondent node.