A gradual solution to detect selfish nodes in mobile ad hoc networks

In this paper we deal with an emergent security problem related to mobile ad hoc network (MANET) to which we present a gradual solution. This new problem is node selfishness on packet forwarding. The resource limitation of nodes forming the ad hoc network, particulary the energy limitation, along with the multi-hop nature of this network may cause a new phenomena which does not exist in the traditional networks. To save its energy, a node may behave selfishly, thereby it uses the forwarding service of other nodes, but it does not forward packets for them . This deviation from the correct behavior represents a potential threat against the service availability , which is one of the most important security requirements. Recently, some solutions have been proposed, however, almost all these solutions rely on the watchdog technique [1] which suffers from many problems. To mitigate these problems, we propose a new technique, we call Two hops acknowledgment , whose performance is improved gradually.