Abstract: Mobile Ad-hoc Network is a network in which multiple mobile nodes are interconnected and they communicate which other without fixed infrastructure. Such network invites multiple threats in network which affects the routing speed and decreases performance level of the network. In all these threats gray hole is silent but more vulnerable attack which attacks the network in repetition mode. There are so many techniques invented in order to detect and remove these gray hole in which all the actions need to be taken by the nodes themselves to find out malicious node. It is hard to detect gray hole node in pool if the neighbour node of gray hole node is malicious or does not work properly due to some technical reasons. So a pool manager of the pool keeps the record of routing history and detects gray hole node by iterative comparison of the data hash keys.

Keywords: Gray hole, Wireless Sensor Network, MANET.