Detecting and Avoiding Wormhole Attacks in Optimized Link State Routing Protocol

A particularly severe attack on routing protocols in ad hoc networks is the so-called wormhole attack in which two or more colluding attacking nodes record packets at one location, and tunnel them to another location for a replay at that remote location. When this attack targets specifically routing control packets, the nodes that are close to the attackers are in effect shielded from finding any alternative routes to the remote location with more than one or two hops, and thus all the routes are directed to the wormhole established by the attackers. In optimized link state routing protocol (OLSR), if a wormhole attack is launched during the propagation of link state packets, the wrong link information propagates throughout the network, leading to routing disruption. In this paper, we devise an efficient method to detect and avoid wormhole attacks in the OLSR protocol. This method tries first to infer links that may potentially lead to wormhole tunnels. The proper wormhole detection was then be applied to suspicious links by means of an exchange of encrypted probing packets between the two supposed neighbors (endpoints of the wormhole). Our solution has several advantages since it does not require any time synchronization or location information and shows high detection rate under various scenarios.