Trust Assurance Mechanism against Gray Hole Attack in Mobile Ad Hoc Networks

Hole and black hole attacks are the major routing attacks in MANET (Moblie Ad hoc NETwork). In Gray hole attack the packets are dropped selectively by the attacker node after correctly participating in the route discovery phase. In this paper a trust algorithm based on uncertain reasoning is used for the gray hole attack detection. AODV (Ad-hoc On-demand distance Vector) is used as the routing protocol. Direct and indirect observations are used for the trust evaluation of a node. These observations along with packet drop checking mechanism provide more accurate trust value. Based on this value the behavior of each node is predicted and the attacker node is detected. The removal of the attacker node is done by flooding alarm packets in the network. Thereby trust of the participating nodes in the network is assured by a less complex trust assurance mechanism