The important security issue in mobile ad hoc networks is to protect the routing layer from malicious attacks. A unified security solution for such networks is applied to protect both routing and data forwarding operations in the routing layer. In this paper the proposed model does not apply the cryptographic primitives on the routing messages This model protects the network by detecting and isolating the malicious nodes. In this proposed model, every node is monitoring other nearest neighboring nodes. A novel recognition strategy is applied to decrease its overhead as time evolves. In the proposed model information cross-validation is used to protect the network in a self-organized manner. Through both analysis and simulation results, the effectiveness of proposed model in a MANET environment is demonstrated.