Abstract: A mobile ad hoc network (MANETs) is infrastructure-less network where nodes communicate with each other without any centralized administration. MANETs are prone to various kinds of security attacks due to its nature as mobile and open media. Blackhole and Grayhole are one of them. The impact of both attacks is most drastic. In both attacks, attacker attracts traffic by claiming that it has shortest route to the required destination and then simply drops the packets. As a result, efficient techniques to detect and prevent blackhole and grayhole attack are needed. In this paper, a review on different existing techniques for detection and prevention of blackhole and grayhole attack are presented.

Keywords: MANET; OLSR; AODV; ZRP; Black hole attack; Grey hole attack.