Based On The Wormhole Attack Defense Strategy Of The Olsr Routing Protocol

Security problems in mobile Ad Hoc networks attract more attention with its populating applications. Many researches focused on developing security mechanisms for vulnerability of mobile Ad Hoc networks. How to defend and detect malicious attacks is a vital part of these researches. Much work has done in this paper over a very special wormhole attack in Ad Hoc networks. We investigated thoroughly on defend strategies against wormhole attack and developed secure OLSR routing protocol to detect this attack.The wormhole attack is a severe attack in Ad Hoc networks that is very easy to launch and particularly challenging to defend against. It launched by two cooperated malicious nodes in most instances. The malicious nodes establish communication through a secret high quality and wide band link which called"Tunnel". One attack node catches the routing packet in network and then transmits it to colluding node through"Tunnel". Colluding node retransmit the packet into the network directly. This occurrence breaches the topology foundation and attracts routing information by disturbing the transmitting direction of routing packets. Encryption and authentication mechanism has no use to defend against wormhole attack. It is need to embed corresponding mechanism in routing protocol to guarantee security.The distance of"Tunnel"between malicious nodes is much longer than transmitting range of normal node. The peculiar representation affords method for wormhole attack detection. Most secure routing protocol avoid routing packets transmitting illegally by computing delay of communication or locating node position in network as to detect wormhole attack. These protocols require precise time synchronization in network or particular hardware assist. The detect efficiency of these protocol declines sharply when nodes are dense in large Ad Hoc networks. There is need to adopt new idea to reach high-efficiency, fast, low-overhead detection and defense on wormhole attacks.Different from the existing secure reactive routing strategies, we present a simple and efficient strategy for wormhole attack detection based on proactive OLSR routing protocol. The strategy analyzes the existence of unreasonable network topology by neighbor discovering to detect wormhole attack. This paper implemented wormhole attack module and secure OLSR routing protocol module based on NS2 software. Simulation results prove that secure OLSR routing protocol can achieve over 80% of the wormhole attack detection rate when average node degree in network is greater than 4 and the max random moving speed of node is greater than 2m/s. This strategy presents good performance on judgment of wormhole attack.