Abstract: A repeater device receives from a first repeater device, which is adjacent to the repeater device on a network, a signature for controlling passage of a packet through the repeater device and determines whether to send the received signature to a second repeater device, which is adjacent to the repeater device on the network, based on contents of the received signature, and sends the received signature to the second repeater device when determining that the received signature is to be sent to the second repeater device.

Abstract: A repeater selecting unit selects at least one repeater that becomes a notification destination of route information for routing a malicious packet through a defense device, from among a plurality of repeaters adjacent to the defense device, based on the information on the attack. A route-information notifying unit notifies the route information for routing the malicious packet through the defense device to the selected repeater. A packet control unit controls a passage of the malicious packet routed to the defense device from the repeater to which the route information has been notified.