Abstract: An information processing device, method thereof and recording medium for communication regardless of the status of the terminal device. A domain name server stores the node identifier, and address for one or more mapping agents 121 corresponding to the host name of a terminal device. The domain name server receives a transmit request for the node identifier of terminal device 11 and the address of the mapping agent, sent from a terminal device, along with the host name or node identifier of terminal device 11. The domain name server 144 selects the node identifier for terminal device and address for mapping agent when the transmit request is received. The domain name server sends the node identifier for terminal device 11 and address for mapping agent to the terminal device.

Abstract: The communication method and communication apparatus according to the invention are capable of generating a packet having a header which includes at least data representing an identifier of a transmitting end point of a logical communication channel, data representing an identifier of a receiving end point of the logical communication channel, data representing an address corresponding to the identifier of the transmitting end point of the logical communication channel, data representing an address corresponding to the identifier of the receiving end point of the logical communication channel, data representing an IP address corresponding to an address of the transmitting end point of the logical communication channel, and data representing an IP address corresponding to an address of the receiving end point of the logical communication channel; and are capable of transmitting the packet thus generated.

Abstract: A communication system includes a communication apparatus for connecting a first network to a second network, wherein a packet transmitted by a transmitting station in the first network by way of the communication apparatus to a receiving station in the second network is relayed selectively by the communication apparatus to the second network. First authentication information is created, in part, according to predetermined key information and the packet is transmitted with the header information thereof including the first authentication information. First authentication information in the header information of the packet is compared with second authentication information created, in part, according to predetermined key information, by the communication apparatus in order to determine whether or not the packet is to be relayed to the second network.