531 logical neighborhoods from a security standpoint

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5.3.1. Logical Neighborhoods From a security standpoint, a primary difference between wired and wireless networks is the fact that in wired networks a router is well aware of all routers to which it is physically connected. In wireless networks, there is no way for a node A to determine the list of all entities that can hear a packet sent by A . Irrespective of the nature of the routing protocol, it is thus indeed desirable for nodes forming ad hoc networks to be able to have some control over which nodes have access to its packets. Copyright © 2010. World Scientific Publishing Company. All rights reserved. May not be reproduced in any form without permission from the publisher, except fair uses permitted under U.S. or applicable copyright law. EBSCO Publishing : eBook Collection (EBSCOhost) - printed on 2/16/2016 3:46 AM via CGC-GROUP OF COLLEGES (GHARUAN) AN: 340572 ; Beyah, Raheem, Corbett, Cherita, McNair, Janise.; Security in Ad Hoc and Sensor Networks Account: ns224671
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60 M. Ramkumar The existence of light weight schemes like MLS and KSSC for estab- lishing pairwise secrets provides a low overhead strategy for every node to enforce a logical neighborhood . For example, a node A with neighbors B, C, D, E in its physical neighborhood (and perhaps other passive nodes lurking around), can induct a subset of the nodes into its logical neigh- borhood. The node A can choose a secret K A and provide the secret (by individually encrypting K A with pairwise secrets) to only the nodes it de- sires to have in its logical neighborhood. For example, A can give the secret to B, D , and E and withhold the secret from C , and other nodes (the very existence of which is unknown to A ). Subsequently, all packets sent from A will be encrypted using the secret K A . Thus nodes that have not been explicitly welcomed by A into its logical neighborhood cannot gain access to the packet. There are many valid reasons as to why a node A may choose to cut- off a specific node C (which is physically in the neighborhood of A ) from its logical neighborhood. For instance 1) A may have observed consistent misbehavior of node C , or 2) suspect a one-way link 27 between A and C or 3) suspect the presence of a semi-active 28 attacker between them. 29 Furthermore, in a scenario where two nodes A and C are in close proximity and have identical views of the network, the nodes gain nothing by adding each other to their respective logical neighborhoods (unless A and C are end points in an interaction). Most existing approaches for mitigating participation by malicious nodes involve propagating accusatory messages regarding misbehavior of nodes. Unfortunately, in most scenarios it may be infeasible for a node ob- serving misbehavior to provide incontrovertible proof of misbehavior, verifi- able by all nodes. Thus, such strategies are themselves susceptible to simple DoS attacks where a node can send false accusations to create unnecessary traffic. The ability to cut-off neighbors in the physical neighborhood from the logical neighborhood facilitates DoS-free countermeasures to reduce the ill-effects of malicious nodes. Nodes cut off by all neighbors are effectively
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