MANET plays a major role in next generation wireless networking technology. Information exchange in a mobile network without any infrastructure support, such networks are called Adhoc networks. This plays a major platform and used in important applications. A Mobile Adhoc Network is a mobile multihop wireless network, which is capable of autonomous operation. Because of the open medium and wide distribution of nodes make MANET harm to malicious attackers. It is crucial to develop efficient intrusion detection mechanisms to protect MANET from attacks. We present a various types of attacks in the network layer and Intrusion Detection mechanisms are used for protecting multihop MANET. To overcome the attacks, enhancing security method called Hybrid Cryptography and a comparison of various types of attacks with different IDs mechanisms is made. We classify, a single type of attack can be achieved by point detection algorithm (PDA) and range of attacks can be achieved by intrusion detection systems (IDs). Our survey is based on various types of attacks on multihop MANET and investigation of problems caused through malicious nodes by various types of Active and Passive group.  

Keywords: Hybrid Cryptography, Multihop, Intrusion Detection Systems (IDs), network layer attacks, mobile adhoc networks (MANETs), Active attacks, Passive attacks, ABID, KBID, SBID, PDAs