ISSN : 1796-2056
Volume : 3    Issue : 5    Date : May 2008

Prevention of Co-operative Black Hole Attack in MANET
Latha Tamilselvan and V. Sankaranarayanan
Page(s): 13-20
Full Text:
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A mobile ad hoc network (MANET) is an autonomous network that consists of mobile nodes that
communicate with each other over wireless links. In the absence of a fixed infrastructure, nodes
have to cooperate in order to provide the necessary network functionality. One of the principal routing
protocols used in Ad hoc networks is AODV (Ad hoc On demand Distance Vector) protocol. The
security of the AODV protocol is compromised by a particular type of attack called ‘Black Hole’ attack
In this attack a malicious node advertises itself as having the shortest path to the node whose
packets it wants to intercept. To reduce the probability it is proposed to wait and check the replies
from all the neighboring nodes to find a safe route. Our approach to combat the Black hole attack is
to make use of a ‘Fidelity Table’ wherein every participating node will be assigned a fidelity level that
acts as a measure of reliability of that node. In case the level of any node drops to 0, it is considered
to be a malicious node, termed as a ‘Black hole’ and is eliminated. Computer simulation using
GLOMOSIM shows that our protocol provides better security and also better performance in terms of
packet delivery than the conventional AODV in the presence of Black holes with minimal additional
delay and Overhead.

Index Terms
Ad hoc Networks, Routing Protocols, AODV, Black Hole Attack, fidelity level.