Protection from intruders is very challenging and important security issue in mobile ad hoc networks. In this paper, a modified AODV algorithm has been proposed to identify and deactivate intruder nodes. The proposed algorithm based on existing AODV routing protocol. In this modified, Ad-hoc On-demand Distance Vector (AODV) algorithm does not use any cryptographic portion on the messages which will transmit. But, this proposed modified AODV routing protocol protecting the network by detecting and deactivating the intruder nodes. To prove the practical significance of the approach, this approach is implemented on NS2.