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Peer counting and sampling in overlay networks based on random walks
, 2007
"... In this article, we address the problem of counting the number of peers in a peer-to-peer system. This functionality has proven useful in the design of several peer-to-peer applications. However, it is delicate to achieve when nodes are organised in an overlay network, and each node has only a limi ..."
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Cited by 11 (1 self)
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In this article, we address the problem of counting the number of peers in a peer-to-peer system. This functionality has proven useful in the design of several peer-to-peer applications. However, it is delicate to achieve when nodes are organised in an overlay network, and each node has only a limited, local knowledge of the whole system. In this paper, we propose a generic technique, called the Sample&Collide method, to solve this problem. It relies on a sampling sub-routine which returns randomly chosen peers. Such a sampling sub-routine is of independent interest. It can be used for instance for neighbour selection by new nodes joining the system. We use a continuous time random walk to obtain such samples. The core of the method consists in gathering random samples until a target number of redundant samples are obtained. This method is inspired by the “birthday paradox” technique of Bawa et al. (Estimating aggregates on a peer-to-peer network, Technical Report, Department of Computer Science, Stanford University), upon which it improves by achieving a target variance with fewer samples. We analyse the complexity and accuracy of the proposed method. We illustrate in particular how expansion properties of the overlay affect its performance. We use simulations to
Wormshield: Fast Worm Signature Generation with Distributed Fingerprint Aggregation
- IEEE Transaction on Dependable and Secure Computing (TDSC), submitted December 2005 and revised
, 2006
"... Fast and accurate generation of worm signatures is essential to contain zero-day worms at the Internet scale. Recent work has shown that signature generation can be automated by analyzing the repetition of worm substrings (i.e., fingerprints) and their address dispersion. However, at the early stage ..."
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Cited by 7 (3 self)
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Fast and accurate generation of worm signatures is essential to contain zero-day worms at the Internet scale. Recent work has shown that signature generation can be automated by analyzing the repetition of worm substrings (i.e., fingerprints) and their address dispersion. However, at the early stage of a worm outbreak, individual edge networks are often short of enough worm exploits for generating accurate signatures. This paper presents both theoretical modeling and experimental results on a collaborative worm signature generation system (WormShield) that employs distributed fingerprint filtering and aggregation at multiple edge networks. By analyzing real-life Internet traces, we discover that fingerprints in background traffic exhibit a Zipf-like distribution. Due to this property, distributed fingerprint filtering at each monitor re-duces the amount of aggregation traffic significantly. WormShield monitors utilize a new distributed aggregation tree (DAT) to compute global fingerprint statistics in a scalable and load-balanced fash-ion. We simulated a spectrum of scanning worms including CodeRed and Slammer using realistic Internet configurations of about 100, 000 edge networks. On average, 256 collaborative monitors can generate the signature of CodeRedI-v2 about 135 times faster than using the same number of isolated monitors. In addition to speed gains, we observed less than 100 false signatures out of
A hierarchical architecture for a distributed management of p2p networks and services
- in DSOM, ser. Lecture Notes in Computer Science
, 2005
"... Abstract. We propose a management architecture for the P2P model which respects its distributed nature while building a hierarchical structure. This architecture enables the distribution of management functions, avoids an excessive centralization of the manager role and fits the dynamic of the P2P ..."
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Cited by 3 (1 self)
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Abstract. We propose a management architecture for the P2P model which respects its distributed nature while building a hierarchical structure. This architecture enables the distribution of management functions, avoids an excessive centralization of the manager role and fits the dynamic of the P2P model well. The architecture is evaluated through an implementation in the Pastry framework.
Noname manuscript No. (will be inserted by the editor) Distributed Caching over Heterogeneous Mobile Networks
"... Abstract Sharing content over a mobile network through opportunistic contacts has recently received considerable attention. In proposed scenarios, users store content they download in a local cache and share it with other users they meet, e.g., via Bluetooth or WiFi. The storage capacity of mobile d ..."
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Abstract Sharing content over a mobile network through opportunistic contacts has recently received considerable attention. In proposed scenarios, users store content they download in a local cache and share it with other users they meet, e.g., via Bluetooth or WiFi. The storage capacity of mobile devices is typically limited; therefore, identifying which content a user should store in her cache is a fundamental problem in the operation of any such content distribution system. In this work, we propose Psephos, a novel mechanism for determining the caching policy of each mobile user. Psephos is fully distributed: users compute their own policies individually, in the absence of a central authority. Moreover, it is designed for a heterogeneous environment, in which demand for content, access to resources, and mobility characteristics may vary across different users. Most importantly, the caching policies computed by our mechanism are optimal: we show that Psephos maximizes the system’s social welfare. To the best of our knowledge, our work is the first to address caching with heterogeneity in a fully distributed manner. Keywords distributed caching · heterogeneity · mobile networks · content distribution
General Terms
"... In this article we address the problem of counting the number of peers in a peer-to-peer system, and more generally of aggregating statistics of individual peers over the whole system. This functionality is useful in many applications, but hard to achieve when each node has only a limited, local kno ..."
Abstract
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In this article we address the problem of counting the number of peers in a peer-to-peer system, and more generally of aggregating statistics of individual peers over the whole system. This functionality is useful in many applications, but hard to achieve when each node has only a limited, local knowledge of the whole system. We propose two generic techniques to solve this problem. The Random Tour method is based on the return time of a continuous time random walk to the node originating the query. The Sample and Collide method is based on counting the number of random samples gathered until a target number of redundant samples are obtained. It is inspired by the “birthday paradox ” technique of [6], upon which it improves by achieving a target variance with fewer samples. The latter method relies on a sampling sub-routine which returns randomly chosen peers. Such a sampling algorithm is of independent interest. It can be used, for instance, for neighbour selection by new nodes joining the system. We use a continuous time random walk to obtain such samples. We analyse the complexity and accuracy of the two methods. We illustrate in particular how expansion properties of the overlay affect their performance.
