Security is an essential requirement in mobile ad hoc networks to provide protected communication between mobile nodes. Due to unique characteristics of MANETS, it creates a number of consequential challenges to its security design. To overcome the challenges, there is a need to build a multifence security solution that achieves both broad protection and desirable network performance. MANETs are vulnerable to various attacks, blackhole, is one of the possible attacks. Black hole is a type of routing attack where a malicious node advertise itself as having the shortest path to all nodes in the environment by sending fake route reply. By doing this, the malicious node can deprive the traffic from the source node. It can be used as a denial-of-service attack where it can drop the packets later. In this paper, we proposed a DPRAODV (Detection, Prevention and Reactive AODV) to prevent security threats of blackhole by notifying other nodes in the network of the incident. The simulation results in ns2 (ver-2.33) demonstrate that our protocol not only prevents blackhole attack but consequently improves the overall performance of (normal) AODV in presence of black hole attack.

When the nodes in a mobile ad hoc network move, existing links often no longer exist and/or new links are created. Any communication protocol designed for such multi-hop ad hoc networks must be able to tolerate such change in network topology that can occur anywhere in the network. Another characteristics of such networks is that bandwidth is a comparatively precious resource and needs to be conserved. Our purpose in the present paper is to explore the possibilities of applying the relatively new paradigm of self-stabilization in distributed fault tolerant algorithm design to tackle the problem of topology change in mobile networks. Self-stabilizing distributed algorithms converge to a global legitimate state in presence of any number of intermittent faults and still use only local knowledge for actions at each node. Our objective is to view the topology change as a change in the node adjacency information at one or more nodes and utilize the tools of self-stabilization to converge to ...

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