Comparison of Two Intrusion Detection Schemes for Sparsely Connected Ad Hoc Networks

Several approaches have been proposed for intrusion detection in mobile ad hoc networks. Most of the approaches assume that there are sufficient neighbors to help monitor the transmissions and receptions of data packets by other nodes to detect abnormality. However, in a sparsely connected ad hoc network, nodes usually have very small number of neighbors. Using a traditional intrusion detection and mitigation scheme designed for well-connected ad hoc networks, the delivery ratio in a sparsely connected ad hoc network (50 nodes over 2000times2000 m ²) can only improve from 76.5% to 79.9% with selective dropping attacks. Thus, we propose a ferry-based intrusion detection and mitigation (FBIDM) scheme for sparsely connected ad hoc networks. Our simulation results indicate that our new ferry-based scheme is more effective than the traditional mitigation schemes that are used for well-connected mobile ad hoc networks. Our FBIDM scheme reduces the impact of the data dropping attacks performed by malicious nodes in a sparsely connected ad hoc network. Without any mitigation scheme, the delivery ratio is 76.5% with selective dropping attacks. With FBIDM, the system achieves a delivery ratio that ranges from 87% (with a single ferry) to 93% (with four ferries) with selective dropping attacks. Without the mitigation scheme, the delivery ratio with black hole attacks drops to 65.9%. With FBIDM, the achieved delivery ratio ranges from 82.9% (with a single ferry) to 91.9% (with four ferries) with black hole attacks