Patent ID: 7987359

Claim:
An information communication system comprising: a plurality of information communication devices, including a processor, exchanging IP packets over IP networks, when performing a predetermined packet exchanging procedure in which the number of router hops is limited to a predetermined control value or less, each of the information communication devices is configured to monitor current Time-To-Live values and maximum Time-To-Live values designated in the headers of IP packets received over a period of time from the start of the predetermined packet exchanging procedure to immediately before the end of the predetermined packet exchanging procedure, said devices further configured to continuously increase the maximum Time-To-Live value to be equal to the current Time-To-Live value if the current Time-To-Live value is greater than the maximum Time-To-Live value such that each time the current Time-To-Live value exceeds the maximum Time-To-Live value, the devices increase the maximum Time-To-Live value to be equal to the current Time-To-Live value, and checks whether the maximum Time-To-Live value does not exceed the control value, the predetermined packet exchanging procedure including an authentication and key exchange procedure in accordance with DTCP-IP, and each of the information communication devices monitors the current Time-To-Live values and the maximum Time-to-Live values in the headers of IP packets carrying authentication-and-key-exchange commands.