Defence against packet injection in ad hoc networks

Wireless ad hoc networks have very limited network resources and are thus susceptible to attacks that focus on resource exhaustion, such as the injection of junk packets. These attacks cause serious denial-of-service via wireless channel contention and network congestion. Although ad hoc network security has been extensively studied, most previous work focuses on secure routing, but cannot prevent attackers from injecting a large number of junk data packets into a route that has been established. We propose an on-demand hop-by-hop source authentication protocol, namely Source authentication forwarding (SAF), to defend against this type of packet injection attacks. The protocol can either immediately filter out injected junk packets with very high probability or expose the true identity of an injector. Unlike other forwarding defences, this protocol is designed to fit in the unreliable environment of ad hoc networks and incurs lightweight overhead in communication and computation.