Intrusion Detection System for AODV Protocol in MANET Ms. S.R. Shirke M.Tech.-II, Shivaji University, Kolhapur, India, Prof. (Dr.) V. R. Ghorpade Principal, D.Y.Patil, COE&T, Kolhapur, India, Abstract Mobile ad hoc network (MANET) is collection of wireless mobile nodes where the participating nodes communicate with each other without any pre-established infrastructures such as a centralized access point. They provide the connectivity by forwarding packets over themselves. To support this connectivity, nodes use some routing protocols such as Ad-hoc On-Demand Distance Vector (AODV). AODV protocol is vulnerable to different attacks such as black hole attack and gray hole attack. Therefore, Security is an important for this protocol to provide secure communication between mobile nodes. Encryption and Authentication are the existing intrusion prevention methods. These prevention techniques are used to prevent network from attacker, but it cannot defend against compromised nodes. To obtain an acceptable level of security, prevention method should be coupled with an intrusion detection mechanism as second line of defense. In this paper, intrusion detection system is proposed to detect malicious nodes inside the network. Black hole attack and gray hole attack have been implemented. Network simulator 2(NS2) is used to conduct simulations and consider scenario for detecting attacks. Keywords: MANET, AODV, Blackhole attack, Intrusion Detection System,NS2, Security. 1. Introduction Mobile Ad-Hoc Networks are autonomous and decentralized wireless systems. Nodes are the systems or devices i.e. mobile phone, laptop, personal digital assistance that are participating in the network. Nodes are mobile and they have limited resources. Each node acts as a host and a router at the same time. MANET is very useful in other applications such as emergency rescues and disaster recovery situations, where cellular infrastructures are non-existent. Ad-hoc networks have certain characteristics like high degree of mobility, absence of centralized administration, limited resources etc. MANET nodes perform the routing functions themselves. Due to the limited wireless transmission range, the routing generally consists of multiple hops. Therefore, the nodes depend on one another to forward packets to the destinations. Routing in such networks is particularly challenging because typical routing protocols do not operate efficiently in the presence of frequent movements. 2. Routing Protocols An ad hoc routing protocol decides the way to route the packets between computing devices. Based on route discovery time, MANET routing protocols fall into three general categories. 2.1. Proactive (table-driven) routing protocols. This type of protocols maintains fresh list of destinations and their routes by periodically distributing routing tables throughout the network. Example of proactive routing protocol is Destination Sequenced Distance Vector (DSDV). 2.2. Reactive (on-demand) routing protocols. This type of protocols creates routes only when they are required by the source node. It finds a route on demand by broadcasting Route request packets. Examples of reactive routing protocols are the 335 International Journal of Engineering Research & Technology (IJERT) Vol. 2 Issue 5, May - 2013 ISSN: 2278-0181 www.ijert.org