Available Online at www.ijcsmc.com International Journal of Computer Science and Mobile Computing A Monthly Journal of Computer Science and Information Technology ISSN 2320–088X IJCSMC, Vol. 2, Issue. 4, April 2013, pg.384 – 390 RESEARCH ARTICLE © 2013, IJCSMC All Rights Reserved 384 Enhanced Anomaly Detection IDS-Based Scheme for Dynamic MANET on-Demand (DYMO) Routing Protocol for MANETS Anand Nayyar 1 1 Assistant Professor, Department of Computer Applications & IT, KCL Institute of Management and Technology, Jalandhar, Punjab, India 1 anand_nayyar@yahoo.co.in Abstract— Mobile Ad hoc network (MANET) is a kind of wireless network which has no infrastructure. Security is an essential requirement in mobile ad hoc network to provide protected communication between mobile nodes. Due to unique characteristic of MANETs, it creates a number of consequential challenges to its security design. In this paper, we propose a new anomaly-detection scheme for Dynamic MANET On- demand (DYMO) Routing protocol based on dynamic learning process that allows IDS system to monitor the network and updating the training data at particular time interval. In the dynamic environment, a trustable node (IDS system) in the network will do monitor process of each node in the network using dynamic training data. The dynamic learning process involves calculating the projection distances based on multidimensional statistics using weighted coefficients. For maintaining security the data packet are send in the encrypted format using RSA algorithm. Key Terms: - Anomaly Detection; DYMO Protocol; MANETS; Security; IDS; Weighted Coefficients I. INTRODUCTION In general, mobile ad hoc networks are formed dynamically by an autonomous system of mobile nodes that are connected via wireless links without using the existing network infrastructure or centralized administration. The nodes are free to move randomly and organize themselves arbitrarily; thus, the network wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet. Mobile adhoc networks are infrastructure-less networks since they do not require any fixed infrastructure, such as a base station, for their operation. In general, routes between nodes in an adhoc network may include multiple hops, and hence it is appropriate to call such networks as ‘‘multi-hop wireless adhoc networks’’. Each node will be able to communicate directly with any other node that resides within its transmission range. For communicating with nodes that reside beyond this range, the node needs to use intermediate nodes to relay the messages hop by hop. The ad hoc networks flexibility and convenience do come at a price. Adhoc wireless networks inherit the traditional problems of wireless communications and wireless networking. • The wireless medium has neither absolute, nor readily observable boundaries outside of which stations are known to be unable to receive network frames. • The channel is unprotected from outside signals; • The wireless medium is significantly less reliable than wired media. • The channel has time-varying and asymmetric propagation properties. • Hidden-terminal and exposed-terminal phenomena may occur.