In Ad hoc networks, malicious nodes can enter in radio transmission range on the routing path and disrupt network activity. Therefore, protecting from intrusion of malicious node and enhance data security is an important issue on Ad hoc networks. In this study, we provide a path hopping method based on reverse AODV (R-AODV). By reverse AODV, source node builds multipath to destination and adaptively hops available paths for data communications. Hopping paths can protect data from the intrusion of malicious nodes. We propose an analytic method to expect intrusion rate and a path hopping routing mechanism to implement simulation models using NS-2.