Blackhole and grayhole attacks in MANET

MANET is gaining more popularity due to two main characteristics, dynamic topology and no requirement of centralized administration. But due to these two properties, MANET is highly prone to various security attacks. One of the most important categories of attack is the Denial of Service (DoS) and the most important attacks under this category are the Blackhole and Grayhole Attacks. Lot of research work has been done to develop various techniques to mitigate the Blackhole and Grayhole attacks. This paper shows how the performance of the network is degraded due to these two attacks. This paper also provides the description of the various techniques that are used to detect and prevent these types of attacks.