The network security is the issue which rose due to self configuring and decentralized nature of the network. The adhoc networks are of three type’s mobile adhoc networks, wireless sensor networks and vehicular adhoc networks. The malicious nodes may join the network due to which various type of active and passive attacks are possible in the network. The passive type of attack is the type of attack in which malicious nodes do not affect the network performance. The active type of attacks is the attacks in which malicious nodes reduce networks performance in terms of various parameters.
The black hole, wormhole, sinkhole, Sybil etc are the various type of active attacks which reduce network. In the recent times, various techniques have been proposed which detect malicious nodes from the network. To improve security of the network, techniques of the data encryption, intrusion detection systems are proposed in the recent times. The area of research in the network security is secure channel establishment algorithms which are diffie-helman, RSA etc which increase security of the network.