Patent ID: 8560676
Filing Date: 2013-10-15
Classification: A63F,H04L

Abstract:
1. A communication system comprising: a first terminal device which is connected to a computer communication network through a first router device; a second terminal device which is connected to the computer communication network through a second router device; and a server device which is connected to the computer communication network, the first terminal device and the second terminal device communicating with each other as respective communication counterparties through the first router device, the computer communication network, and the second router device, wherein (a) the first terminal device and the second terminal device each includes a counterparty communication unit which communicates with the communication counterparty through the router device to which the local terminal device is connected; a router-identifier acquiring unit which acquires a communication identifier of the router device to which the communication counterparty is connected when a communication from the counterparty communication unit to the local communication counterparty succeeds; a router communication unit which communicates with the router device having the acquired communication identifier when a communication from the counterparty communication unit to the communication counterparty succeeds but then failed; and a status transmitting unit which transmits, at a predetermined timing, connection status information specifying whether communication from the counterparty communication unit to the communication counterparty is successful and whether communication from the router communication unit to the router device to which the communication counterparty is connected is successful to the server device, and (b) the server device includes: a status receiving unit which receives the connection status information transmitted from the first terminal device and the connection status information transmitted from the second terminal device; and a fraudulence determining unit which determines, based on the connection status information received from the first terminal device and the connection status information received from the second terminal device, (1) that a user of the first terminal device has taken a fraudulent action when it is specified that all of the following has occurred: (a) a communication from the first terminal device to the second terminal device is successful, and (b) a communication from the second terminal device to the first terminal device has failed, and (c) a communication from the second terminal device to the first router device is successful, the fraudulent action taken by the user of the first terminal being changing a firewall/gateway setting of the first router, and (2) that a user of the second terminal device has taken a fraudulent action when it is specified that all of the following has occurred: (a) a communication from the second terminal device to the first terminal device is successful, and (b) a communication from the first terminal device to the second terminal device has failed, and (c) a communication from the first terminal device to the second router device is successful, the fraudulent action taken by the user of the second terminal being changing a firewall/gateway setting of the second router.