MANET security through a distributed policy-based evaluation of node behaviour

While MANETs can provide seamless networking that is fast and easy to deploy, the lack of a stable topology, no centralized control, and the use of wireless links with limited bandwidth make MANETs highly vulnerable to attacks. The autonomy of individual nodes must be balanced with the need to ensure that nodes contribute to the network function as a whole. Trust-based systems are often proposed in this situation, but the mechanisms by which trust are built is still an active area of research. In this paper we present a policy-based trust management framework that uses the observed behaviour of neighbouring MANET nodes to identify and react to attacks. The system uses policy rules to evaluate observed behaviour of neighbouring nodes and reputation values shared by peers. The calculated trust values are then sent to neighbours. The calculation of trust based on a combination of flexible policy rules and distributed evaluation is a novel approach and a significant contribution of the paper. A simulation-based evaluation of our framework based on a wormhole attack shows that the scheme is both scalable and robust.