Network attack defense system relay device, relay method, as well as the relay program

摘要

After receiving the signature from the adjacent relay apparatus, the relay apparatus 10 determines the number of packets per unit time satisfy the signature whether the received exceeds a predetermined threshold. When it is determined that the number of packets per unit time has exceeded a predetermined threshold, the relay device 10 determines whether or not exceeded the predetermined value the number of times it is exceeded in succession the threshold of the predetermined . Result of such determination, if it is determined that the number of times it is exceeded in succession a predetermined threshold value has exceeded a predetermined value, the relay device 10, other except the adjacent relay apparatus a signature received from an adjacent relay apparatus I is transmitted to the adjacent relay device.