  Intrusion detection in wireless ad hoc networks is a challenging task because
these networks change their topologies dynamically, lack concentration points
where aggregated traffic can be analyzed, utilize infrastructure protocols that
are susceptible to manipulation, and rely on noisy, intermittent wireless
communications. Security remains a major challenge for these networks due their
features of open medium, dynamically changing topologies, reliance on
co-operative algorithms, absence of centralized monitoring points, and lack of
clear lines of defense. In this paper, we present a cooperative, distributed
intrusion detection architecture based on clustering of the nodes that
addresses the security vulnerabilities of the network and facilitates accurate
detection of attacks. The architecture is organized as a dynamic hierarchy in
which the intrusion data is acquired by the nodes and is incrementally
aggregated, reduced in volume and analyzed as it flows upwards to the
cluster-head. The cluster-heads of adjacent clusters communicate with each
other in case of cooperative intrusion detection. For intrusion related message
communication, mobile agents are used for their efficiency in lightweight
computation and suitability in cooperative intrusion detection. Simulation
results show effectiveness and efficiency of the proposed architecture.
