Patent ID: 7512709

Claim:
An address restriction method executed by an address restriction apparatus on a network, comprising the steps of: obtaining, from a message received from a transmission source device, a tentative network address generated by the transmission source device which is connected to the network, and a local address unique to the transmission source device; a first determining step of determining whether the obtained tentative network address is a network address which is within an address range determined according to a predetermined rule and has been generated from the obtained local address unique to the transmission source device; a second determining step of determining whether the obtained tentative network address matches an address of a connection means which connects the address restriction apparatus to the network; in a case where the first determining step determines that the tentative network address is the network address which is not within the address range determined according to the predetermined rule, sending a message to the transmission source device forbidding the use of the obtained tentative network address; in a case where the first determining step determines that the tentative network address is the network address which is within the address range determined according to the predetermined rule and has been generated from the obtained local address unique to the transmission source device, permitting the transmission source device to use the tentative network address for performing communication on the network; in a case where the first determining step determines that the tentative network address is the network address which is within the address range determined according to the predetermined rule but has not been generated from the obtained local address unique to the transmission source device, sending a message to the transmission source device forbidding the use of the obtained tentative network address; and in a case where the second determining step determines that the obtained tentative network address matches the address of the connection means, sending the message to the transmission source device forbidding the use of the obtained tentative network address.