A Survey Paper On Detection Of Gray-Hole Attack in MANET Nirali Modi 1 , Vinit Kumar Gupta 2 , Indr jeet Rajput 3 1 Hasmukh Goswami College of Engineering, Ahmedabad, India modinirali7@gmail.com 2 Hasmukh Goswami College of Engineering, Ahmedabad, India guptasvnit@gmail.com 3 Hasmukh Goswami College of Engineering, Ahmedabad, India Indr.rajput@gmail.com Abstract-MANET is a wireless ad hoc network, decentralized network and autonomous system. Mobile ad hoc network is created by mobile nodes. To forward the packet, each node in MANET acts as router. That is free to moving in and out in the network. There are some constraints like limited resources, self – configuration ability, power consumption ratio and security. Among them security is the most challenging job in MANET to maintain the networks performance. There are different types of attacks detected in MANET. Denial–Of-Service (DOS) attacks are detected on network layer which are namely as gray hole attack, black hole attack and worm hole attack. We have surveyed research papers based on detection of gray hole attack in MANET. This survey paper analyze the gray hole attack detection technique on AODV routing protocol. Keywords—MANET, gray hole, AODV, RREQ, RREP I. I NTRODUCTION Most important concern for network is security in mobile ad hoc network. It is highly adaptable and deployable network. It is a self- configuring infrastructure less network of mobile devices connected by wireless. Radio communication is used by mobile nodes. Basically there are two types of attacks. Active attack: Active attack can be external or internal. They can disturb the network’s task by alarming the false message or modifying information. Internal attacks are attacker within the network and external network are outside the network by carried out nodes that do not belongs to the network e.g. modification, jamming and message reply. Passive attack: Passive attacks are difficult to detect and does not disturb the network’s performance or operation e.g. traffic analysis, traffic monitoring. Gray hole attack detects on the network layer. It can be act as slow poison. It is the variation of black hole attack. In gray hole attack malicious node either drop packets selectively or Refuse to forward packets and drop them (e.g. dropping 50% of packet or dropping with some probability or forward all TCP packets while dropping all UDP packets). Malicious node some Fig 1: Security Attacks for different layers. [3] Time acts as normal node after dropping packets. Due to these constraints it is difficult to maintain network’s performance good. [2,3] and very hard to find out this kind of attack. It has two phases. In First phase the malicious node advertises AODV routing protocol as a fresh and valid route to reach the destination node. In second phase node drop the packet with Nirali Modi et al , International Journal of Computer Science & Communication Networks,Vol 4(1),09-12 9 ISSN:2249-5789