SECURING DSR PROTOCOL DEFENDING AGAINST SYBIL ATTACK IN MANET

Mobile ad hoc networks (MANETs) are infrastructure-free networks in which nodes are free to move in any direction. These networks use specific routing protocols that can create a path between nodes that are not within transmission range of each other. Because MANETs are easy to configure, they are mostly used in areas where infrastructure is not available, such as military and rescue operations, etc. Due to the open approach, MANETs are always vulnerable to external and internal attacks such as Denial of Service (DoS), Flooding, Worms hole, Black hole, Gray hole Sinkholes etc. There is no central point of administration. In this project, we focus on the Sybil attack. An SYBIL attack is an individual type of association layer attack in a specially selected mobile network. In this attack, a fake hub is introduced that has a direct path to reach the target. So it collects the entire packet from the source and drops it. Nowadays, it is very difficult to secure the network against such attacks. The Dynamic Source Routing (DSR) algorithm uses caching concepts to store all newly created routing paths in mobile ad hoc networks. Route caching aggressively uses DSR. With source routing, it is possible to cache each overhead path without causing loops. Forwarding nodes cache the source path from a packet and forward it for future use. The destination also meets all the requirements. Thus, the source learns many alternative paths to the destination, which are stored in the cache. Here, we propose a novel approach to prevent Sybil attacks in DSR based on route caching. In this approach, once a Sybil node is detected in the MANET during path construction, we pass the Sybil node id to the DSR path function. In this function, routes are ready to be added to the route cache; however, adding each route to the route cache is decided by parsing those routes for the presence of a Sybil node id. This process uses only the normal time of the caching process. In this project, we propose a cache-based Sybil attack prevention algorithm for DSR routing protocols in MANET. Simulations in NS-2 show that our proposed mechanism greatly reduces the packet drop rate with a very low false positive rate.