International Journal of Modern Trends in Engineering and Research www.ijmter.com      DETECTION OF SYBIL ATTACK USING POSITION VERIFICATION METHOD IN MANETS Ch. Niranjan Kumar 1 , N.Satyanarayana 2 1 CSE, Sumathi Reddy Institute of Technology for women, Telangana 2 Professor, Dept. of CSE, Nagole Institute of Technology and Science, Hyderabad Abstract— Compared to wired networks, Ad hoc networks are more vulnerable to security attacks due to the lack of trusted centralized authority, lack of trust relationships between nodes. This paper focuses on Sybil attack and its detection. A malicious node can generate and control a large number of logical identities on a single device. This gives the illusion to network as these are different legitimate nodes. An algorithm is proposed using position verification to detect the Sybil attack. The algorithm is implemented in Network Simulator and the throughput, and packet delivery ratio with and without Sybil attack. Keywords- Sybil attack; AOMDV; wireless ad hoc networks; position verification and NS2. I. INTRODUCTION Wireless ad-hoc networks are composed of autonomous nodes that are self managed without any infrastructure. Ad-hoc networks have a dynamic topology such that nodes can easily join or leave the network at any time. Ad-hoc networks have a dynamic topology such that nodes can easily join or leave the network at any time. Since the nodes communicate with each other without an infrastructure, they provide the connectivity by forwarding packets over themselves. To support this connectivity, nodes use some routing protocols such as AOMDV (Ad-hoc On-Demand multipath Distance Vector), AODV, DSR (Dynamic Source Routing) and DSDV (Destination-Sequenced Distance-Vector). Besides acting as a host, each node also acts as a router to discover a path and forward packets to the correct node in the network. Compared to wired networks, Ad-hoc networks are more vulnerable to security attacks due to the lack of trusted centralized authority, lack of trust relationships between nodes, easy eavesdropping, dynamic network topology, low bandwidth, battery and memory constraints of the devices. The attacks can be of many types where protocol compliant attack called Sybil attack is one of the most difficult attacks to detect. II. ADHOC NETWORK FEATURES Ad-hoc networks are best suited for use in situations where an infrastructure is unavailable or to deploy one is not cost effective [8]. The initial development of Ad-hoc networks was primarily driven by military applications where rapid network formation and survivability are key requirements. On the other hand, distributed network architecture with all nodes having equal responsibility and using broadcast radio is ideally suited to the military requirements. To overcome the limited radio transmission ranges (i.e. Not all nodes are within the range of every other node) nodes are equipped with the ability to forward information on behalf of others i.e. multi-hop communications. Combined with packet switching technology and suitable medium access control protocols, multi-hop communication provides the basis for resilient, large-scale military ad-hoc networks. • Independence from central network administration • Self-configuring, nodes are also routers