A Robust Reputation Framework for Mitigating Dropping Attacks in MANETs

In Mobile Ad hoc Networks (MANETs), nodes have to rely on their neighbors and several other intermediate nodes in order to communicate with non-neighbor nodes. Early routing and communication protocols for MANETs have been developed optimistically, where cooperative behavior of all the participating nodes is presumed. However, it may not be always the case and in the absence of a fixed trust or security infrastructure; some nodes may decide to exhibit a non-cooperative behavior for a variety of incentives. For example a selfish node may choose to deliberately drop a certain percentage of packets passing through it to preserve its battery resource. In this paper, we present a reputation framework that is based on first-hand evidences obtained via direct observations at the MAC layer as well as second-hand evidences that are obtained via recommendations from other nodes. To counter with the intrinsic uncertainty associated with the collected evidences from other nodes, Dempster’s rule for combination is applied. Dempster’s rule for combination gives a numerical procedure for fusing together multiple pieces of evidence from unreliable observers. We present simulation results on DSR protocol which demonstrate the robustness and effectiveness of the proposed framework even in the presence of malicious nodes that propagate erroneous recommendations.