Defending against wormhole attacks in mobile ad hoc networks

In ad hoc networks, malicious nodes can carry wormhole attacks to fabricate a false scenario on neighbor relations among mobile nodes. The attacks threaten the safety of ad hoc routing protocols and some security enhancements. We propose a classification of the attacks according to the format of the wormholes. It establishes a basis on which the detection capability of the approaches can be identified. The analysis shows that previous approaches focus on the prevention of wormholes between neighbors that trust each other. As a more generic approach, we present an end-to-end mechanism that can detect wormholes on a multi-hop route. Only trust between the source and the destination is assumed. The mechanism uses geographic information to detect anomalies in neighbor relations and node movements. To reduce the computation and storage overhead, we present a scheme, Cell-based Open Tunnel Avoidance(COTA), to manage the information. COTA achieves a constant space for every node on the path and the computation overhead increases linearly to the number of detection packets. We prove that the savings do not deteriorate the detection capability. The schemes to control communication overhead are studied. We show by simulations and experiments on real devices that the proposed mechanism can be combined with existent routing protocols to defend against wormhole attacks.