Mobile ad hoc network is a wireless and non-self-organization network. And in MANET it does not have any structure in other word the authors say it does not have topology. Here there is no centralized system, each node act as router to route the packet. If the source node need to transact the data to destination to overhear the neighbor node of source and check if there is route and that particular node is legitimate user or not. So while make transaction here they may affect by rushing attack.