Mitigating malicious control packet floods in ad hoc networks

We investigate the impact of hacker attacks by malicious nodes on the overall network performance. These malicious nodes mimic normal nodes in all aspects, except that they do route discoveries much more frequently than other nodes. We show, using simulations, that the basic route discovery mechanism used in many ad hoc network protocols can be exploited by as few as one malicious or compromised node to bring down throughput dramatically. We propose an adaptive statistical packet dropping mechanism to mitigate such situations and reduce the loss of throughput. The proposed mechanism works even when the identity of the malicious node is unknown and does not use any additional network bandwidth. It is simple to implement and maintains or improves network throughput when there are no malicious nodes, but the network is congested with excess traffic.