  Adhoc wireless network with their changing topology and distributed nature
are more prone to intruders. The network monitoring functionality should be in
operation as long as the network exists with nil constraints. The efficiency of
an Intrusion detection system in the case of an adhoc network is not only
determined by its dynamicity in monitoring but also in its flexibility in
utilizing the available power in each of its nodes. In this paper we propose a
hybrid intrusion detection system, based on a power level metric for potential
adhoc hosts, which is used to determine the duration for which a particular
node can support a network monitoring node. Power aware hybrid intrusion
detection system focuses on the available power level in each of the nodes and
determines the network monitors. Power awareness in the network results in
maintaining power for network monitoring, with monitors changing often, since
it is an iterative power optimal solution to identify nodes for distributed
agent based intrusion detection. The advantage that this approach entails is
the inherent flexibility it provides, by means of considering only fewer nodes
for reestablishing network monitors. The detection of intrusions in the network
is done with the help of Cellular Automat CA. The CAs classify a packet routed
through the network either as normal or an intrusion. The use of CAs enable in
the identification of already occurred intrusions as well as new intrusions.
