Novel Defense Schemes against DoS Attacks in MANETs

Abstract

The desire to be connected anytime, anywhere and anyhow has led to the development of wireless networks. From the early radio and telephone to current devices such as mobile phones and laptops, accessing the global network has become the most essential and indispensable part of every one’s lifestyle. Mobile Adhoc NETwork (MANET) is a self configurable network consisting of mobile nodes connected by wireless links. The inherent features of MANETs like- dynamic topology, limited resources and lack of centralized trusted authority makes it more vulnerable to attacks than wired networks. When MANET routing protocols were proposed, security issues were not given due consideration. Lately, researchers have highlighted the vulnerabilities and attacks that can be mounted against ad hoc protocols and solutions devised to combat them. So security is quite challenging and vital issue in MANETs. This thesis focuses on MANET’s routing vulnerability and analyzes network performance under popular DoS attacks- Flooding, Blackhole and Grayhole attack. Flooding attack cripples the smooth operation of the network by continually sending packets to consume network resources and bandwidth. In Blackhole attack, a malicious node falsely advertises shortest path to the destination node and thereafter absorbs all data packets whereas Grayhole attack is selective Blackhole attack that drops selective data packets. An attempt is made to propose a secure route from source to destination in presence of DoS attacks and effectiveness of proposed scheme is validated using NS-2. Novel defense schemes are proposed for securing AODV against these attacks that not only detect malicious nodes but also isolate multiple malicious nodes from further participating in route discovery and data forwarding process. Simulation results show significant improvement in PDF approximately 94% in presence of Blackhole and Grayhole nodes and 86% in presence of RREQ Flooding nodes with marginal rise in average end to end delay and routing load thus indicating the closeness to the AODV algorithm.