A Defense Model for Black hole and Gray hole attacks in MANET?

Mobile Ad hoc Network is one of the most promising technologies in recent years. In MANET, a wireless network is rapidly formed using mobile nodes. Due to its characteristics such as open and undefined medium, dynamic topology, limited resources, lack of centralized control and cooperative environment, providing a secure data transmission in presence of malicious nodes in the network is the major challenge of the MANET. Attacks at the Network Layer such as Black hole and Gray hole exploit one of the MANET routing protocol such as DSR protocol to involve malicious node in the routing process and drop packets. This paper proposes a Defense model for Black hole and Gray hole attacks in the MANET.