Patent ID: 7979575

Claim:
An attack detecting system for detecting an attack to a terminal device, which exists in a communications network external to an organization, from any of a plurality of server devices, which exist in a communications network within the organization and to which a shared virtual address is assigned by an address translating device in addition to a real address unique to each of the plurality of server devices, comprising: a packet examining unit which examines a communication packet exchanged between the communications network within the organization and the communications network external to the organization, and which detects a particular packet that satisfies a particular condition; a source communications network determining unit which determines whether the particular packet was transmitted from the communications network within the organization or from the communications network external to the organization when the packet examining unit detects the particular packet; a detection request message creating unit which creates a detection request message which includes a request to detect a source of the particular packet and a destination of which is set to the virtual address, and which transmits the created message to the address translating device, when the source communications network determining unit determines that the particular packet was transmitted from the communications network within the organization; and a destination extracting unit which extracts a real address indicated as the destination in the detection request message, upon receipt of the detection request message the destination of which is rewritten by the address translating device from the virtual address to a real address of the server device, which is the source of the particular packet.