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Group membership: a novel approach and the first single-round algorithm

Author:
Published in:
23rd ACM SIGACT-SIGOPS Symp. on Principles of Distributed Computing, PODC, 25-28 July 2004, pp. 347–356.

Summary

We establish a new worst-case upper bound on the Membership problem: We present a simple algorithm that is able to always achieve Agreement on Views within a single message latency after the final network events leading to stability of the group become known to the membership servers. In contrast, all of the existing membership algorithms may require two or more rounds of message exchanges. Our algorithm demonstrates that the Membership problem can be solved simpler and more efficiently than previously believed. By itself, the algorithm may produce disagreement (that is, inconsistent, transient views) prior to the "final" view. Even though this is allowed by the problem specification, such views may create overhead at the application level, and are therefore undesirable. We propose a new approach for designing group membership services in which our algorithm for reaching Agreement on Views is combined with a filter-like mechanism for reducing disagreements. This approach can use the mechanisms of existing algorithms, yielding the same multi-round performance as theirs. However, the power of this approach is in being able to use other mechanisms. These can be tailored to the specifics of the deployment environments and to the desired combinations of the speed of agreement vs. the amount of preceding disagreement. We describe one mechanism that keeps the combined performance to within a single-round, and sketch another two.
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Summary

We establish a new worst-case upper bound on the Membership problem: We present a simple algorithm that is able to always achieve Agreement on Views within a single message latency after the final network events leading to stability of the group become known to the membership servers. In contrast, all...

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System adaptation as a trust response in tactical ad hoc networks

Published in:
IEEE MILCOM 2003, 13-16 October 2003, pp. 209-214.

Summary

While mobile ad hoc networks offer significant improvements for tactical communications, these networks are vulnerable to node capture and other forms of cyberattack. In this paper we evaluated via simulation of the impact of a passive attacker, a denial of service (DoS) attack, and a data swallowing attack. We compared two different adaptive network responses to these attacks against a baseline of no response for 10 and 20 node networks. Each response reflects a level of trust assigned to the captured node. Our simulation used a responsive variant of the ad hoc on-demand distance vector (AODV) routing algorithm and focused on the response performance. We assumed that the attacks had been detected and reported. We compared performance tradeoffs of attack, response, and network size by focusing on metrics such as "goodput", i.e., percentage of messages that reach the intended destination untainted by the captured node. We showed, for example, that under general conditions a DoS attack response should minimize attacker impact while a response to a data swallowing attack should minimize risk to the system and trust of the compromised node with most of the response benefit. We show that the best network response depends on the mission goals, network configuration, density, network performance, attacker skill, and degree of compromise.
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Summary

While mobile ad hoc networks offer significant improvements for tactical communications, these networks are vulnerable to node capture and other forms of cyberattack. In this paper we evaluated via simulation of the impact of a passive attacker, a denial of service (DoS) attack, and a data swallowing attack. We compared...

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Information Survivability for Mobile Wireless Systems

Published in:
Lincoln Laboratory Journal, Vol. 12, No. 1, pp. 65-80.

Summary

Mobile wireless networks are more vulnerable to cyber attack and more difficult to defend than conventional wired networks. In discussing security and survivability issues in mobile wireless networks, we focus here on group communication, as applied to multimedia conferencing. The need to conserve resources in wireless networks encourages the use of multicast protocols for group communication, which introduces additional security concerns. We point out the need for rate-adaptation techniques to simultaneously support multiple receivers that each experience different network conditions. The security properties associated with a number of approaches to rate adaptation are compared. We also identify several security issues for reliable group communication, providing examples of denial-of-service attacks and describing appropriate security measures to guard against such attacks. We examine the costs of these security measures in terms of network efficiency and computational overhead. Finally, we introduce a survivability approach called dynamically deployed protocols, in which the effects of an information attack are mitigated by dynamically switching to a new protocol to evade the attack. We suggest that this dynamic protocol deployment can be achieved effectively by transmission of in-line mobile code.
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Summary

Mobile wireless networks are more vulnerable to cyber attack and more difficult to defend than conventional wired networks. In discussing security and survivability issues in mobile wireless networks, we focus here on group communication, as applied to multimedia conferencing. The need to conserve resources in wireless networks encourages the use...

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Security implications of adaptive multimedia distribution

Published in:
Proc. IEEE Int. Conf. on Communications, Multimedia and Wireless, Vol. 3, 6-10 June 1999, pp. 1563-1567.

Summary

We discuss the security implications of different techniques used in adaptive audio and video distribution. Several sources of variability in the network make it necessary for applications to adapt. Ideally, each receiver should receive media quality commensurate with the capacity of the path leading to it from each sender. Several different techniques have been proposed to provide such adaptation. We discuss the implications of each technique for confidentiality, authentication, integrity, and anonymity. By coincidence, the techniques with better performance also have better security properties.
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Summary

We discuss the security implications of different techniques used in adaptive audio and video distribution. Several sources of variability in the network make it necessary for applications to adapt. Ideally, each receiver should receive media quality commensurate with the capacity of the path leading to it from each sender. Several...

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Vulnerabilities of reliable multicast protocols

Published in:
IEEE MILCOM '98, Vol. 3, 21 October 1998, pp. 934-938.

Summary

We examine vulnerabilities of several reliable multicast protocols. The various mechanisms employed by these protocols to provide reliability can present vulnerabilities. We show how some of these vulnerabilities can be exploited in denial-of-service attacks, and discuss potential mechanisms for withstanding such attacks.
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Summary

We examine vulnerabilities of several reliable multicast protocols. The various mechanisms employed by these protocols to provide reliability can present vulnerabilities. We show how some of these vulnerabilities can be exploited in denial-of-service attacks, and discuss potential mechanisms for withstanding such attacks.

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