Prevention of Blackhole Attack in MANET

An ad hoc network is a collection of mobile nodes that dynamically form a temporary network. It operates without the use of existing infrastructure. One of the principal routing protocols used in ad-hoc networks is AODV (ad-hoc on demand distance vector) protocol. The security of the AODV protocol is compromised by a particular type of attack called ´black hole´ attack. In this attack a malicious node advertises itself as having the shortest path to the node whose packets it wants to intercept. To reduce the probability it is proposed to wait and check the replies from all the neighboring nodes to find a safe route. Computer simulation using glomosim shows that our protocol provides better performance than the conventional AODV in the presence of Black holes with minimal additional delay and Overhead.