Fusing multi-layer metrics for detecting security attacks in 802.11 networks

Computer networks and more specifically wireless communication networks are increasingly becoming susceptible to more sophisticated and untraceable attacks. Most of the current Intrusion Detection Systems either focus on just one layer of observation or use a limited number of metrics without proper data fusion techniques. However, the true status of a network, is rarely accurately detectable by examining only one network layer or metric. Ideally, a synergistic approach would require knowledge from various layers to be fused and, collectively, an ultimate decision to be taken. To this aim, the Dempster-Shafer (D-S) approach is examined as a data fusion algorithm that combines beliefs of multiple metrics across multiple layers. This paper describes the methodology of using metrics from multiple layers of wireless communication networks for detecting wireless security breaches. The metrics are analysed and compared to historical data and each gives a belief of whether an attack takes place or not. The beliefs from different metrics are fused with the D-S technique with the ultimate goal of limiting false alarms by combining beliefs from various network layers. The results show that cross-layer techniques and data fusion perform more efficiently in a variety of situations compared to conventional methods.