International Journal of Current Trends in Engineering & Technology ISSN: 2395-3152 Volume: II, Issue: II (MAR-APR, 2016) 184 An Intrusion Detection System for detecting malicious nodes in MANET using Trust Aware EAACK Vivek D. Badgujar 1 , Kailash Patidar 2 , Jitendra Rai 3 SSSIST Sehore, RGPV, Bhopal, India badgujarvivek83@hotmail.com Abstract —Due to limitations of wired network, the transformation has been seen from wired network to wireless network in last few years. Wireless network is a technology that allows users to access easily information and services from regardless of geographical position. Due to mobility & scalability features wireless networks uses in many areas as an applications. Different types of wireless network is available, among all the types of wireless networks (Mobile Adhoc Network) MANET is very important applications. MANET is infrastructure less, IP based network of mobile and wireless machine nodes connected with radio range. In working, the node of a MANET gives decentralized administration mechanism. In MANET working node act as a host and router at within the communication range nodes communicate directly. Otherwise they pass the messages to his neighbor nodes. Due to self- configuring nature MANET becomes very popular in military applications and recovery applications. But due to open medium nodes becomes malicious easily by malicious attackers. For this, Intrusion-Detection System (IDS) is made for protection from malicious attackers. In Intrusion Detection System the performance of the network will be increased by detecting the malicious nodes in the network. Many IDSs is available in the market but have drawbacks available. To overcome the drawbacks new very efficient IDSs is designed known as Enhanced Adaptive Acknowledgement (EAACK). Compared to other IDS, EAACK gives higher malicious- behavior- detection rates in certain conditions without affecting the overall network performances. The proposed system uses DSR routing protocol by EAACK for providing better performance for large size MANET. The proposed EAACK scheme find out the exact malicious nodes using simulation, thus reducing the false detection rate EAACK is enhanced by using the concept of trust value. Keywords: DSR, EAACK, IDS, MANET, Monitor node. I. INTRODUCTION Mobile Ad - hoc Network (MANET) gives unique characteristics in a highly challenging network environment such as decentralization, dynamic topology and neighbor based routing. The communication done in MANET is a group of wireless mobile nodes via bidirectional wireless links without any fixed infrastructure [1]. Mobile nodes are acts as a wireless transmitter and a receiver. They are communicating directly with each other or forward message through other nodes [2]. The key advantages of wireless networks are that its ability to send data between different parties and still maintain their mobility. Mobile communication is depending upon the range of transmitters. This means that two nodes are communicated with each other when the distance between the two nodes is in the communication range of their own. MANET is divided into two types of networks, namely, single - hop and multi hop [3]. In a single - hop network, all nodes within the same radio range communicate directly with each other. On the other hand, in a multi hop network, nodes rely on other intermediate nodes to transmit if the destination node is not in their radio range. MANET is infrastructure less network, thus all nodes are free to move remotely. MANET infeasible in critical mission applications like military conflict or emergency recovery due to creating a self - configuring and self - maintaining network without the help of a centralized infrastructure, [3].The MANET topology may change uncertainly and speedily due to high mobility of the independent mobile nodes. Also due to the limitations of most MANET routing protocols, nodes in MANETs assume that other nodes always cooperate with each other to relay data. This assumption leaves the attackers with the opportunities to achieve significant impact on the network with just one or two compromised nodes. In such case, it is required to develop an intrusion - detection system (IDS) especially for MANETs [4]. An intrusion detection system (IDS) inspects all inbound and outbound network activity and identifies suspicious patterns that may indicate a network or system attack from someone attempting to break into or compromise a system. An intrusion detection system does not include preventing the intrusion from occurring; it can only be detected and