International Journal of Communications and Engineering
The authors explore the use of clock skew of a wireless local area network Access Point (AP) as its finger print to detect unauthorized AP's quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions-the inability to effectively detect Medium Access Control (MAC) address spoofing. They calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) time stamps sent out in the beacon/probe response frames. They use two different methods for this purpose; one based on linear programming and the other based on least-square fit. They supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs.