Patent ID: 7653942

Claim:
An unauthorized access prevention system, comprising: a countermeasure method determination unit determining a method of taking countermeasures to protect a destination against unauthorized access in predetermined traffic entering a communications network based on a rate at which the countermeasures were taken without suspension in the predetermined traffic, the rate indicating a probability that the predetermined traffic is unauthorized access, the rate being a value determined by calculating a number of times that the countermeasures were taken and subtracting a number of times that countermeasures were suspended to determine a number of times that countermeasures were taken without suspension, and dividing the number of times that countermeasures were taken without suspension by the number of times that countermeasures were taken, for the predetermined traffic to be processed; a storage device storing at least the number of times that countermeasures were taken and the number of times that countermeasures were taken without suspension; and a countermeasure execution control unit controlling to take the countermeasures in the determined method, wherein the countermeasure method determination unit, when an ACL (access control list) filter or a flow rate control can be selected as a result of the determination, selects the ACL filter when the rate is larger than a first predetermined threshold, and selects the flow rate control when the rate is smaller than the first predetermined threshold, the countermeasure method determination unit, when the ACL filter or a queue control can be selected as a result of the determination, selects the ACL filter when the rate is larger than a second predetermined threshold, and selects the queue control when the rate is smaller than the second predetermined threshold, the countermeasure method determination unit, when the flow rate control or queue control can be selected as a result of the determination, selects the flow rate control when the rate is larger than a third predetermined threshold, and selects the queue control when the rate is smaller than the third predetermined threshold.