BARKATULLAH UNIVERSITY BHOPAL
Mobile ad hoc network is an assembly of mobile nodes that haphazardly forms the temporary network and it is an infrastureless network. Due to its self-motivated or mobility in nature the nodes are more vulnerable to security threats which stimulate the performance of the network. In this paper, a review on a various types of coordinated attack is deliberated such as blackhole / grayhole attack which are most serious threats in mobile ad hoc network. In cooperative blackhole attack more than one node collude to each other hence this attack is more challenging to identify. This paper presents a review of different security mechanism to eliminate the blackhole / grayhole attack from the network.