Patent ID: 7950053
Filing Date: 2011-05-24
Classification: H04L

Abstract:
1. A firewall system for controlling communications between an external network and an internal network, comprising: a call control proxy section for relaying a call control sequence for establishing communications between terminals connected to the external network or the internal network; an address correspondence information management section for managing the correspondence between new and old addresses of each terminal changed as the terminal moves or re-connects to the network; a filtering control section for setting an address and port number pair as a filtering condition of a packet permitted to pass through between the internal network and the external network based on information of the address and the port number of the terminal used for communications obtained from the call control proxy section and information of the correspondence between new and old addresses obtained from the address correspondence information management section; a packet filtering section for allowing a packet determined based on the filtering condition containing the address and port number pair to pass through; a normal access determination condition storage section for storing a normal access determination condition defined for each communication media type; and an unauthorized access detection section for detecting unauthorized access if a passing packet does not meet the normal access determination condition based on information obtained from the call control proxy section of the address, the port number, and the media type of the terminal used for communications, information of the correspondence between new and old addresses obtained from the address correspondence information management section, and the normal access determination condition obtained from the normal access determination condition storage section, wherein said information obtained from the call control proxy section of the address, the port number, and the media type are determined by the call control proxy section during the call control sequence that establishes said communications between terminals.