A few works deal with the forwarding attacks in Self Organized Network, as most of research care for securing the routing process to minimize the effects of an attacker on the network stability. However, data packet forwarding behavior is a very important aspect that should be taken into account to achieve a high-quality performance in application and network stability. We propose in this paper an effective mechanism to detect forwarding-attacks in self organized networks, and we will deploy our mechanism to secure PARTY routing protocol. Within our approach, nodes are enabled to localize malicious node that start to drop or to duplicate packets. Our approach is scalable and can be implemented independently of routing protocol.