Patent ID: 7051369

Claim:
A system for monitoring a network which performs communications based on IP (Internet Protocol), for a cracker attack, comprising: attack detecting means disposed at a gateway of the network, for successively acquiring IP packets passing through the gateway, storing the acquired IP packets accumulatively, and monitoring the stored IP packets while said gateway remains open to detect a cracker attack against the network; and processing means for effecting a predetermined process depending on the detected type of cracker attack when the attack detecting means detects the cracker attack, wherein said processing means comprises means for preventing an IP packet having a source IP address and/or a destination IP address associated with the attack detected by the attack detecting means from entering the network in the predetermined process, for a predetermined time after the attack detecting means detects the attack, and when said predetermined time has elapsed after said detecting means detects said attack, reopening said gateway for allowing an IP packet having a source IP address and/or a destination IP address associated with said attack to enter said network.