Patent ID: 7835341

Claim:
A packet communication apparatus connected through a network to a user terminal and an authentication server, comprising: an interface control unit for transmitting and receiving a packet between the user terminal and the authentication server; an authentication control unit for determining a type of a packet transmitted from the user terminal and, when the type of the packet transmitted from the user terminal is an authentication request, for transmitting the packet to the authentication server; the authentication control unit for determining a type of a packet transmitted from the authentication server and, when the type of the packet transmitted from the authentication server is a result of authentication, for determining whether a type in an attribute of a Remote Authentication Dial In User Service (RADIUS) message of the packet includes connection limit information regarding a communication range for the user terminal; a storage storing therein connection limit information for the user terminal; a connection limit control unit which, if the authentication control unit determines that a type in an attribute of the Remote Authentication Dial In User Service (RADIUS) message of the packet from the authentication server includes connection limit information regarding a communication range for the user terminal as a result of the authentication by the authentication control unit, updates the connection limit information for the user terminal with the connection limit information regarding the communication range; a transfer control unit for determining a first interface to transmit therethrough the packet with address information included in the packet received from the user terminal; and the connection limit control unit for determining, when the first interface is determined to be not within the communication range based on the connection limit information, a second interface within the communication range, instead of the first interface, to transmit therethrough the packet with address information included in the packet received from the user terminal on the basis of the connection limit information stored in the storage; wherein the second interface control unit transmits the packet received from the user terminal through the second interface.