Detection and Prohibition of NAPT for Network User Authentication System "Opengate"

NAPT is one of the most important technologies for Network. Depletion of IPv4 address made conserving IPv4 address with use of NAPT more important issue. Open gate is a user authentication gateway system for network in the environment opened to public. This system has been operating for controlling the campus-wide open network in Saga University since 2001. On the other hand, nobody can identify that which node of local network has access because of sharing a single global IP address accessed from multiple local IP addresses. Therefore, if public terminals downstream of the NAPT are used incorrectly, it becomes more difficult to specify user. In this research, we have developed a method for detection and prohibition of NAPT under the Opengate.