Abstract: When an attack is detected, a controller samples an attack-target addressed DNS reply, received by a border router, from each of the border routers. Then, the controller adds the transmission-source IP address of the sampled DNS reply to the black list of the border router. Furthermore, upon reception of any of a target-addressed DNS reply and a target-addressed UDP subsequent fragment from the IP address that is described in the black list, the controller gives a command to the border router to discard the packet. Furthermore, the controller specifies the setting, for each of the border routers, that DNS replies to a DNS request from the target are excluded from discarding.

Abstract: When an attack is detected, a controller samples an attack-target addressed DNS reply, received by a border router, from each of the border routers. Then, the controller adds the transmission-source IP address of the sampled DNS reply to the black list of the border router. Furthermore, upon reception of any of a target-addressed DNS reply and a target-addressed UDP subsequent fragment from the IP address that is described in the black list, the controller gives a command to the border router to discard the packet. Furthermore, the controller specifies the setting, for each of the border routers, that DNS replies to a DNS request from the target are excluded from discarding.

Abstract: An unauthorized-access detection device in which when a relationship between information regarding a request transmitted from a terminal operated by a user to a service server that provides a service, which is acquired by a request acquisition unit, and information regarding a query transmitted from the service server to a DB that accumulates information regarding the service, which is acquired by a query acquisition unit, is different from a normal pattern, a detection unit detects the query as unauthorized access to the DB.