Multihop Wireless Networks: Opportunistic Routing

9.4 Conclusion

In this chapter, we investigated the existing link-quality measurement mechanisms, and analyzed the security vulnerabilities in them. A common fact inherent in all the existing LQM mechanisms is that they use receiver-dependent measuring; that is, a node's knowledge about the forward PRR from itself to its neighbors is informed by its neighbors. We proposed a broadcast-based secure LQM mechanism that prevents a neighboring node from maliciously claiming a higher measurement result. Our mechanism has very low computation, storage and communication overheads and thus can be implemented in resource-constraint sensor networks as well as mesh networks. Our SLQM mechanism can be easily applied to unicast-based and cooperative LQM with slight modifications.

We demonstrated that opportunistic routing is more resilient than traditional routing in the presence of a link-quality bluffing attack. We also discussed possible attacks on the existing opportunistic routing coordination protocols and proposed countermeasures. For implicitly prioritized coordination protocols, the inherent vulnerability comes from the fact that the location of the attacker cannot be verified. For explicitly prioritized protocols, it is harder for the attacker to obtain the packet-forwarding authority because there is a predefined packet forwarding priority. We finally compare the resilience of the opportunistic routing and traditional routing under packet dropping attack. Generally, opportunistic routing ...