Ad hoc networks have some nodes that are linked together freely without any radio frequency. Their fast establishment has made them to function very remarkably in different domains including military and emergency, natural disasters, universities and cities. Mobile nodes, and wireless communications, dynamic transformation of network structure, lack of centralized management to study behaviors and functions, lack of specific defense lines, and limited power of the used nodes create adequate domain for various attacks against the network. This paper is on AODV routing security. Gray Hole attack is analyzed in AODV routing protocol and some solutions are given to identify and confront them.