Cooperative black and gray hole attacks in mobile ad hoc networks

Abstract

In this paper, we propose a complete protocol to detect a chain of cooperating malicious nodes in an ad hoc network that disrupts transmission of data by feeding wrong routing information. Our technique is based on sending data in equal but small sized blocks instead of sending whole of data in one continuous stream. The flow of traffic is monitored independently at the neighborhoods of both source and destination. The results of monitoring are gathered by a backbone network of trusted nodes. With assumption that a neighborhood of any node in the ad hoc network has more trusted nodes than malicious nodes, our protocol can not only detect but also remove a chain of cooperating malicious nodes (gray/black hole) by ensuring an end-to-end checking between the transmission of two blocks of data. The protocol takes O(mdBN) time for detection and removal of gray/black holes chain which betters an earlier O(n2) time bound [4] for detecting a single black hole in the network. Here, m is the number of malicious nodes in the network, dBN is the diameter of a backbone network formed out of the flat ad hoc network, and n is the total number of nodes in the ad hoc network.