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This paper presents the measurement study of locality-aware P2P solutions over real-world Internet autonomous systems (AS) topology. By using the accesses of nodes of PlanetLab testbed, we create a detailed AS-level map including the end-to-end path of all nodes, as well as the relationship of all involved ASes. Based on this map, we evaluate the performance of a set of locality-aware P2P solutions, including an optimal solution guaranteeing the minimum AS hop count, as well as modified BitTorrent system with locality-awareness built into its neighbor selection, peer choking/unchoking, and piece selection processes. Our findings suggest that locality-awareness can help existing P2P solution to significantly decrease load on Internet, and achieve shorter downloading time. By comparing the performance of different kinds of locality-aware and traditional BitTorrent systems, we also point out the necessity to tradeoff between the goals of optimizing AS-related performance and achieving fairness among peers such as intra-AS traffic and peer burden fairness.

BitTorrent is a widely popular peer-to-peer content distribution protocol. Unveiling patterns of resource demand and supply in its usage is paramount to inform operators and designers of BitTorrent and of future content distribution systems. This study examines three BitTorrent content-sharing communities regarding resource demand and supply. The resulting characterization is significantly broader and deeper than previous BitTorrent investigations: it compares multiple BitTorrent communities and investigates aspects that have not been characterized before, such as aggregate user behavior and resource contention. The main findings are three-fold: (i) resource demand - a more accurate model for the peer arrival rate over time is introduced, contributing to workload synthesis and analysis; additionally, torrent popularity distributions are found to be non-heavy-tailed, what has implications on the design of BitTorrent caching mechanisms; (ii) resource supply - a small set of users contributes most of the resources in the communities, but the set of heavy contributors changes over time and is typically not responsible for most resources used in the distribution of an individual file; these results imply some level of robustness can be expected in BitTorrent communities and directs resource allocation efforts; (iii) relation between resource demand and supply - users that provide more resources are also those that demand more from it; also, the distribution of a file usually experiences resource contention, although the communities achieve high rates of served requests.

Video-on-demand (VoD) streaming has recently become a popular service on the Internet, with several companies offering videos to a global audience. However, traditional client/server based VoD streaming systems can be very bandwidth intensive and expensive to maintain, especially for high quality video content. To improve the scalability these systems, the use of peer-to-peer (P2P) networking has been proposed, but despite the efficiency of applications such as BitTorrent for downloading of large files, it is not simple to use P2P techniques for streaming. Problems such as firewalls and freeloaders reduce the efficiency of both types of P2P systems, but for real-time services such as streaming, the result can be reduced playback quality. Other issues include the traffic load imposed on ISPs by P2P networks, which can motivate ISPs to interfere with the P2P traffic. Finally, protecting against malicious modification of content can increase overhead, response times, and startup delays. We consider these issues to be fundamental to the problem of P2P based VoD, but despite the large amount of research that has been done in this field, these issues have largely been ignored. To address this, we present an evaluation of the Streaming P2P Protocol (SPP) architecture. By studying the problem as a whole we have found a simple and comprehensive solution that addresses all the four issues listed above. To show that the system is not only scalable, but also that it can be implemented efficiently, we have used both simulations and experiments on PlanetLab for evaluation. The results show that the combination of cache nodes and use of end-user resources found in the SPP architecture can give a low load on servers and ISPs, even when firewalls are taken into consideration. Furthermore, we observed low startup delays and few playback errors during the PlanetLab experiments. The scalable and low-cost distribution of content possible with the SPP architecture should be suitable for both large-scale commercial distributors and users of community networks with limited resources.

Peer-to-peer applications are emerging into mobile devices. However, resource limitations of these devices introduce new challenges for P2P technologies. For instance, there is a need for incentive mechanisms, which address the free riding problem but do not waste devices’ battery or communication resources. A centralized and user identity based incentive mechanism enables mobile users to contribute with any device and receive P2P services with mobile devices. We explore security issues related to a centralized incentive mechanism by analyzing and classifying threats and potential security mechanisms. We propose a privacy preserving security architecture. The architecture is based on authentication, software tamper protection, and misbehavior detection mechanisms. Further, we describe a prototype implementation for mobile BitTorrent file sharing peers. We provide a discussion on potential security compromises, not jeopardizing sufficient security level, and compare our work to related research.

Most P2P systems divide a file into many pieces and fetch different pieces from many peers simultaneously. If one of the last few pieces is requested from an extremely slow peer, the overall download time may become excessive. The end-game mode was proposed to solve this problem. This method requests the last piece from all the connected peers at the same time. Unfortunately, the duplicated requests generate redundant traffic. This paper proposes a requesting method that does not increase overall download time as well as avoiding the redundant traffic. We also propose a combination of our requesting method and the end-game mode. The proposed methods are compared to the existing method with the end-game mode in simulations that use BitTorrent as a typical instance of the parallel retrieving P2P system. The results confirm that our requesting method can match the download times of the end-game mode while suppressing the redundant traffic. Our method enhances network performance by absorbing the difference in peer performance and providing steady download times without wasting traffic resources. Moreover, it is also confirmed that our combination method can distribute a file more quickly than other methods.

In UMTS (universal mobile telecommunications system) networks upgraded with HSPA (high speed packet access) technology, the high access bandwidth and advanced mobile devices make it applicable to share large files among mobile users by peer-to-peer applications. To receive files quickly is essential for mobile users in file sharing applications, mainly because they are subject to unstable signal strength and battery failures. While many researches present peer-to-peer file sharing architectures in mobile environments, few works focus on decreasing the time spent in disseminating files among users. In this paper, we present an efficient peer-to-peer file sharing design for HSPA networks called AFAM — Adaptive efficient File shAring for uMts networks. AFAM can decrease the dissemination time by efficiently utilizing the upload-bandwidth of mobile nodes. It uses an adaptive rearrangement of a node's concurrent uploads, which causes the count of the node's concurrent uploads to lower while ensuring that the node's upload-bandwidth can be efficiently utilized. AFAM also uses URF — Upload Rarest First policy for the block selection and receiver selection, which achieves real rarest-first for the spread of blocks and effectively avoids the “last-block” problem in file sharing applications. Our simulations show that, AFAM achieves much less dissemination time than other protocols including BulletPrime and a direct implementation of BitTorrent for mobile environments.

This article focuses on identifying file-sharing peer-to-peer (P2P) (such as BitTorrent (BT)) traffic at the borders of a stub network. By analyzing protocols and traffic of applications, it is found that file-sharing P2P traffic of a single user differs greatly from traditional and other P2P (such as QQ) applications' traffic in the distribution of involved remote hosts and remote ports. Therefore, a method based on discreteness of remote hosts (RHD) and discreteness of remote ports (RPD) is proposed to identify BT-like traffic. This method only relies on flow information of each user host in a stub network, and no packet payload needs to be monitored. At intervals, instant RHD for concurrent transmission control protocol and user datagram protocol flows for each host are calculated respectively through grouping flows by the stub network that the remote host of each flow belongs to. On given conditions, instant RPD are calculated through grouping flows by the remote port to amend instant RHD. Whether a host has been using a BT-like application or not can be deduced from instant RHD or average RHD for a period of time. The proposed method based on traffic characteristics is more suitable for identifying protean file-sharing P2P traffic than content-based methods. Experimental results show that this method is effective with high accuracy.

With the popularity of BitTorrent-like P2P applications, improving its performance has been an active research area. Super-seeding, a special upload policy for the initial seeder, improves the efficiency in producing multiple seeds and reduces the uploading bytes of content initiators, thus being highly expected as a promising solution for improving downloading performance while decreasing uploading cost. However, the overall impacts of super seeding upon BitTorrent performance remain a question and have not been analyzed so far in literature. In this paper, we present an analytical and experimental study over the performance of super-seeding scheme. We attempt to answer the following questions: whether and how much super-seeding saves uploading cost, whether the overall downloading time is decreased by super-seeding, and in which circumstances super-seeding performs worse. Based on the seeding process, our analytical study gives formulas on the new piece distribution time, average downloading time and minimum distribution time for heterogeneous P2P file distribution system with super-seeding. Robust evidence supporting the use (or not) of super-seeding is given based on our worldwide Internet experiments over wide distribution of 250 PlanetLab nodes. With a well-designed experimental scenario, we study the overall download time and upload cost of super seeding scheme under varying seed bandwidth and peer behavior. Results show that super-seeding can save an upload ratio of 20% and does help speeding up swarms in certain modes. Tentative conclusions about the effectiveness of super-seeding and its optimal working circumstances are given with inside mechanism analyzed and negative factor identified. Our work not only provides reference for the potential adoption of super-seeding in BitTorrent and other P2P applications, but also much insights for the tussle of enhancing of Quality of Experience (QoE) and saving cost for a large-scale BitTorrent-like P2P commercial application.

With an enhanced client computer performance and network bandwidth, content distribution services are receiving much attention. However client/server model and peer-to-peer model require vast cost for content distributions. These costs pose an impediment to broaden commercialization of content distribution services via the Internet. Content distribution cost consists of investment for server and network infrastructure which client/server model and peer-to-peer model require respectively. Thus, We focus on network infrastructure, especially in peer-to-peer content distribution networks which drastically increase traffic volume. The main feature of our proposal is utilization of inexpensive inter-ISP connections. This paper presents methods to constitute peer-to-peer content distribution networks that realizes lower cost content distribution and a reduction in the amount of inter-ISP traffic and its costs by considering the priority in usage of ISP interconnections in its distribution. Our proposal extends BitTorrent, which has been widely deployed by several content providers to reduce the load in congested servers and the distribution costs. Our performance evaluations show that our proposal achieves a reduction in network infrastructure costs and improved performance such as distribution time.

In this paper, we consider a peer-to-peer (P2P) network, where multimedia streams are broadcast by matched peers based on their resource reciprocation profiles. We propose a new framework where each peer creates a coalition of matched peers with which it can exchange resources in order to improve its utility. The utility is determined based on explicit consideration of the peer's multimedia attributes and the quality derived by the peers' reciprocation behavior. We adopt the proportional bargaining solution to negotiate the upload bandwidth among the matched peers. Proportional bargaining allows to determine each peer's optimal (in a Pareto optimal sense) upload rates in a coalition in terms of its utility impact. The impact of an incoming peer on the coalition value, which represents the collective utility achieved by the peers in a coalition, is assessed by explicitly investigating the coalition value improvement. Finally, our results show that the proposed coalition-based resource reciprocation can improve the resource allocation/scheduling algorithms deployed in existing P2P systems such as BitTorrent and CoolStreaming. We also discuss how the proposed resource reciprocation approach can be implemented in other multimedia broadcasting applications.

We propose two unstructured file sharing games, unilateral and bilateral unstructured file sharing games, to study the interaction among self-interested players (users) of unstructured P2P file sharing applications. In a unilateral unstructured file sharing game, players compete for network resources (link bandwidth) by opening multiple connections to each other on multiple paths so as to maximize their individual benefits. A player always allows other players to connect to itself. Multiple concurrent connections are allowed on any path between a pair of players. Per-connection throughput is determined by the transport protocol implemented by users' computers. In a bilateral unstructured file sharing game, users adopt a Tit-for-Tat strategy, under which an active connection between two players is set up only when they both find it beneficial. Two players can set up at most one connection between themselves and bottlenecks occur only at upstream access links in a star network. For both games, we prove the existence of an equilibrium, quantify the efficiency losses of equilibria, and demonstrate the dynamic stability of equilibria in best-response or better-response dynamic game playing processes.

Current infrastructures for Volunteer Computing follow a centralized architecture for data distribution, creating a potential bottleneck when tasks require large input files or the central server has limited bandwidth. In this paper we propose two new data models for Berkeley Open Infrastructure for Network Computing (BOINC): an approach based on the popular BitTorrent protocol; and a Content Delivery Network approach. While the latter remains on a theoretical level, we developed a prototype that adds BitTorrent functionality for task distribution and conducted medium-scale tests of the environment. Our preliminary results indicate that the BitTorrent client had a negligible influence on the BOINC client's computation time. The BOINC server showed an unexpectedly low bandwidth output when seeding the file, as well as spikes on CPU usage. This paper discusses the tests that were performed, how they were evaluated, as well as some improvements that could be made in future research on both approaches.

Peer-to-peer (P2P) systems, which provide a variety of popular services, such as file sharing, video streaming and voice-over-IP, contribute a significant portion of today's Internet traffic. By building overlay networks that are oblivious to the underlying Internet topology and routing, these systems have become one of the greatest traffic-engineering challenges for Internet Service Providers (ISPs) and the source of costly data traffic flows. In an attempt to reduce these operational costs, ISPs have tried to shape, block or otherwise limit P2P traffic, much to the chagrin of their subscribers, who consistently finds ways to eschew these controls or simply switch providers. In this paper, we present the design, deployment and evaluation of an approach to reducing this costly cross-ISP traffic without sacrificing system performance. Our approach recycles network views gathered at low cost from content distribution networks to drive biased neighbor selection without any path monitoring or probing. Using results collected from a deployment in BitTorrent with over 120,000 users in nearly 3,000 networks, we show that our lightweight approach significantly reduces cross-ISP traffic and, over 33% of the time, it selects peers along paths that are within a single autonomous system (AS). Further, we find that our system locates peers along paths that have two orders of magnitude lower latency and 30% lower loss rates than those picked at random, and that these high-quality paths can lead to significant improvements in transfer rates. In challenged settings where peers are overloaded in terms of available bandwidth, our approach provides 31% average download-rate improvement; in environments with large available bandwidth, it increases download rates by 207% on average (and improves median rates by 883%

Service and resource discovery has become an integral part of modern networked systems. In this survey we give an overview of the existing solutions for service and resource discovery for a wide variety of network types. We cover techniques used in existing systems, as well as recent developments from the research front. We also provide taxonomy for discovery systems and architectures, and review the various algorithms and search methods applicable for such systems. Peer-to-peer overlays are discussed in detail and solutions for non-IP-based networks are also included in the review. We also specifically comment on issues related to wireless networks, and give an overview of the various issues and complications that should be considered in future work in this domain.

In this paper we report new results of our continuous effort on analyzing the impact of incentive mechanisms on user behavior in BitTorrent. In this second measurement and analysis study we find that free riders’ population has significantly increased comparing to our previous measurement study. We relate this increase to the advance in end-users’ connection speeds and to users’ increased knowledge in BitTorrent. We also categorize free riders based on the behavior they exhibit in multiple-torrent system into three types: cheaters, strategic and lucky peers. Furthermore, refuting the findings of other studies, we show that peers who exploit the system in BitTorrent are both high bandwidth capacity peers and low bandwidth capacity peers. Moreover, we argue that the Tit-for-Tat mechanism does not discriminate peers based on their bandwidth capacities and that it reacts successfully against inter-class bandwidth capacity strategic peers. Finally, we propose a memory-backoff approach to the optimistic unchoke policy that reduces the volume of free riding in BitTorrent.

BitTorrent (bt), a Peer-to-Peer (p2p) distribution system, is a major bandwidth consumer in the current Internet. This paper reports on a measurement study of bt traffic intended to identify potential traffic invariants. To this end, we employ high-accuracy packet capture hardware together with specialized parsing software. Important characteristics regarding bt sessions and messages as well as general system characteristics are reported. The results indicate that characteristics such as session inter-arrival times are corroborated to be exponentially distributed, while other characteristics are shown to differ from previously reported results. These differences are attributed to changes in the core bt algorithms. Further, it is observed that long- and heavy-tailed distributions can be used to model several characteristics. The log-normal, Pareto and mixtures of these distributions are used to model session sizes and durations, while the Weibull distribution has been observed to model message inter-arrival and inter-departure times for bandwidth-limited clients.

BitTorrent employs a static quota-based peer selection strategy to fixedly allocate upload quotas for the Tit-For-Tat (TFT) choke algorithm and Optimistic Unchoke (OU) algorithm. This static quota allocation scheme would incur a paradox of supply and demand between upload peers and request peers. The paradox of supply and demand means that many request peers stay in the starvation state while many upload quotas stay in the idleness state. We propose a dynamic quota-based peer selection strategy, where request peers are classified by the principle of investment return and each upload peer adaptively allocates upload quotas for the TFT and OU algorithms according to dynamically changed numbers of different request peers. Simulation experiments show that our dynamic quota allocation scheme can eliminate the paradox of supply and demand, increase the resource utility ratio of upload peers, and decrease the file download time, at the cost of uploading more a few file blocks for each upload peer.

BitTorrent has emerged as a very popular peer-to-peer file sharing system, which uses an embedded set of incentive mechanisms to encourage contribution and prevent free-riding. However, BitTorrent's ability to prevent free-riding needs further study. In this paper, we present a fluid model with two different classes of peers to capture the effect of free-riding on BitTorrent-like systems. With the model, we find that BitTorrent's incentive mechanism is successful in preventing free-riding in a system without seeds but may not succeed in producing a disincentive for free-riding in a system with a high number of seeds. The reason for this is that BitTorrent does not employ any effective mechanisms for seeds to effectively guard against free-riding. Therefore, we propose a seed bandwidth allocation strategy for the BitTorrent system to reduce the effect of seeds on free-riding. Finally, simulation results are given that validate what we have found in our analysis and demonstrate the effectiveness of the proposed strategy.

This paper develops analytic models that characterize the behavior of on-demand stored media content delivery using BitTorrent-like protocols. The models capture the effects of different piece selection policies, including Rarest-First and two variants of In-Order. Our models provide insight into transient and steady-state system behavior, and help explain the sluggishness of the system with strict In-Order streaming. We use the models to compare different retrieval policies across a wide range of system parameters, including peer arrival rate, upload/download bandwidth, and seed residence time. We also provide quantitative results on the startup delays and retrieval times for streaming media delivery. Our results provide insights into the optimal design of peer-to-peer networks for on-demand media streaming.

The net neutrality debate began a few years ago, prematurely, with overheated rhetoric about potential disasters for the Internet but little in the way of real threats requiring immediate government action. Beginning around May 2007, one of the largest ISPs in the US, Comcast, began a program of discriminatory blocking of certain Internet communications protocols. The blocking has focused on BitTorrent and Gnutella peer-to-peer protocols but also included, for a time, Lotus Notes enterprise collaboration software traffic. Comcast hasn't disputed the blocking, and a variety of independent, although perhaps not entirely unbiased, investigations have verified it. So, for the first time in the Internet's modern history, we have selective discrimination against a particular type of traffic that's widely used and presumptively legal.

Many people associate peer-to-peer technology with file-sharing applications such as BitTorrent, Gnutella, Kazaa, and Napster and with concerns about the unauthorized, free distribution of video, audio, and other copyrighted content. These concerns have led the entertainment industry to crack down on P2P systems. For example, the US Recording Industry Association of America (RIAA) has taken numerous file sharers to court to recover copyright-infringement damages. P2P was adopted first by folks looking to share unauthorized content and is still widely used for that purpose. In addition, ISPs have complained that high volumes of large video files and other P2P traffic traveling between multiple peers have hurt their networks' performance. This has also inhibited P2P usage in some cases and cast doubts upon its future growth potential. In response, proponents have undertaken a major effort to change P2P technology, rehabilitate the approach's reputation, and encourage its use for fast, efficient content distribution and improved Internet-based communications services, including telephony.

In a large-scale BitTorrent-like peer-to-peer file sharing system, the track server could be overloaded to update the state information of constantly arriving and leaving peers. Upon the connection request from a peer, the track server responses with a random list of peers and such randomly selected peers among the whole peer-to-peer network could create a long delay of file sharing between two peers. To improve the file sharing performance, we propose a hierarchical architecture to group peers into clusters according to their proximity in the underlying overlay network in such a way that clusters are evenly distributed and that the peers within each cluster are relatively close to each other. We achieve this by constructing the CBT (Clustered BitTorrent) system with two novel algorithms: a peer joining algorithm and a super-peer selection algorithm. We develop a fluid model to compare the performance of the proposed CBT system with a original BitTorrent system. With this model, we find that the CBT system quite effectively improves the performance of the system. Finally, simulation results are given, which demonstrate that the CBT system achieves better results than a randomly organized BitTorrent network, improving the system scalability and efficiency while retaining the robustness and incentives of the original BitTorrent paradigm.

Bandwidth trading schemes give peers an incentive to provide upload bandwidth to other peers in a P2P network for fast file distribution. A popular example is the tit-for-tat strategy used in the BitTorrent protocol. Although this game theoretical scheme provides an incentive to peers to contribute resources to the network it does not prevent unfairness and the performances of peers vary considerably. Therefore, we propose two new trading schemes, which are based on pricing. One uses explicit price information whereas the other scheme uses the download rates from other peers as the price. For both distributed algorithms the stable point provides a fair resource allocation as well as a Nash equilibrium. Thus, fairness is preserved although peers behave selfishly and try to maximize their own download rates only. We compare both pricing schemes with BitTorrent in simulations of static and dynamic networks. In BitTorrent peers receive different download rates even if they provide the same upload bandwidth. Furthermore, peers with small upload capacities compared to others receive considerably more than what they contribute. The pricing algorithms outperform BitTorrent with respect to fairness. With both algorithms a peer receives a download performance proportional to its upload capacity. With explicit prices the download rates converge faster to the fair equilibrium than with implicit ones.

In an era where communication technologies can move digital media at close to the speed of light, this paper explores the rupture between this technical potential and the actual model by which international television screening dates are determined in Australia. As the delays between overseas and Australian airdates can be as long two years, and average over six months, the rapid rise in both official and fan-produced online material and interaction relating to television series has given rise to a massive but largely unfulfilled demand for simultaneous access to episodes across the globe. Using the case study of the critically acclaimed fan favourite Battlestar Galactica, this paper outlines some of the strategies by which producers build global fan loyalty — from official websites, blogs, commentary podcasts and online deleted scenes to exclusive webisodes and official participation in fan forums. The paper argues that these trends, combined with the time delay between release dates, are the largest factors contributing to the unlawful downloading of television via peer-to-peer file-sharing platforms such as BitTorrent. In attempting to maintain distribution models that began as geographic necessities, but have become exclusively political and economic decisions in an era of digital communication technologies, this paper argues that media corporations are perpetuating a ‘tyranny of digital distance’ and alienating their own audiences.

In both academia and industry, peer-to-peer (P2P) applications have attracted great attentions. P2P applications such as Napster, Gnutella, FastTrack, BitTorrent, Skype and PPLive, have witnessed tremendous success among the end users. Unlike a client-server based system, peers bring with them serving capacity. Therefore, as the demand of a P2P system grows, the capacity of the network grows, too. This enables a P2P application to be cheap to build and superb in scalability. In this paper, we survey the state of the art of the research and the development of P2P content delivery application. Using examples of the deployed P2P applications and research prototypes, we survey the best practices in P2P overlay building and P2P scheduling. We hope that the information may help the readers to build a reliable, robust P2P content delivery application.

This study traces the evolution of commons-based peer production by a measurement-based analysis of case studies and discusses the impact of peer production on net neutrality and copyright law. The measurements include websites such as suprnova.org, youtube.com, and facebook.com, and the Peer-to-Peer (P2P) systems Kazaa, Bittorrent, and Tribler. The measurements show the two sides of peer production, the pirate side with free availability of Hollywood movies on these P2P systems and the Samaritan side exhibited by the quick joining of 400,000+ people in a community to organize protests against events in Burma. The telecommunications and content industry are disrupted by this way of peer production. As a consequence, revenues of both industries are likely to suffer in the coming years. On the other hand, innovative P2P systems could win the battle on merit over classical distribution technologies. As a result, a continuation is expected of both legal actions against P2P and possible blocking actions of P2P traffic, violating net neutrality. It is argued that this hinders innovation and causes a large discrepancy between legal and user perspectives. A reform of copyright laws is clearly needed, otherwise they will be unenforceable around 2010.

Datacentric applications are still a challenging issue for large-scale distributed computing systems. The emergence of new protocols and software for collaborative content distribution over the Internet offers a new opportunity for efficient and fast delivery of a high volume of data. This paper presents an evaluation of the BitTorrent protocol for computational desktop grids. We first present a prototype of a generic subsystem dedicated to data management and designed to serve as a building block for any desktop grid system. Based on this prototype we conduct experiments to evaluate the potential of BitTorrent compared to a classical approach based on FTP data server. The preliminary results obtained with a 65-node cluster measure the basic characteristics of BitTorrent in terms of latency and bandwidth and evaluate the scalability of BitTorrent for the delivery of large input files. Moreover, we show that BitTorrent has a considerable latency overhead compared to FTP but clearly outperforms FTP when distributing large files or files to a high number of nodes. Tests on a synthetic application show that BitTorrent significantly increases the communication/computation ratio of the applications eligible to run on a desktop grid system.

The ongoing problem of digital file sharing technology evolving at a speed far greater than the law can keep up with is demonstrable with litigation upheld against the producers of peer-to-peer networks such as Grokster1 towards the ends of their natural useful lives. As file sharers and, with them, copyright infringers, move onto more efficient networks such as BitTorrent, the story is repeated but with the new problem of the client software being open source. This has led to avenues alternative to litigating against makers of peer-to-peer network clients being explored. Perspectives on what constitutes "to affect prejudicially the owner of the copyright" as laid out in the CDPA 1988 are considered in light of the Hong Kong case of HKSAR v. Chan Nai-Ming. It is argued that the highly strict and surprisingly low level at which the test for prejudicial effect is set is counter-intuitive to the goals of curbing the problems piracy poses. It is concluded that the ongoing battle between file sharers and their opponents has led to the loss of sight of the true goal of regulation: the protection of copyright holders from suffering de facto harm that is at least above a relatively negligible standard.

In this paper we present a peer-to-peer dialup architecture for accelerated "Internet access" in the developing world. Our proposed architecture provides a mechanism for multiplexing the scarce and expensive international Internet bandwidth over higher bandwidth p2p dialup connections within a developing country. Our system combines a number of architectural components, such as incentive-driven p2p data transfer, intelligent connection interleaving and content-prefetching. This paper presents a detailed design, implementation and evaluation of our dialup p2p data transfer architecture inspired by Bittorrent.

Peer-to-peer systems have seen a tremendous growth in the last few years and peer-to-peer traffic makes a major fraction of the total traffic seen in the Internet. The dominating application for peer-to-peer is file sharing. Some of the most popular peer-to-peer systems for file sharing have been Napster, FastTrack, BitTorrent, and eDonkey, each one counting a million or more users at their peak time. We got interested in kad since it is the only DHT that has been part of very popular peer-to-peer system with several million simultaneous users. As we have been studying kad over the course of the last 18 months we have been both, fascinated and frightened by the possibilities kad offers. Mounting a Sybil attack is very easy in kad and allows to compromise the privacy of kad users, to compromise the correct operation of the key lookup and to mount DDOS with very little resources. In this paper, we will relate some of our findings and point out how kad can be used and misused.

Among all peer-to-peer (P2P) systems, BitTorrent seems to be the most prevalent one. This success has drawn a great deal of research interest on the system. In particular, there have been many lines of research studying its scalability, performance, efficiency, and fairness. However, despite the large body of work, there has been no attempt mathematically to model, in a heterogeneous (and hence realistic) environment, what is perhaps the most important performance metric from an end user's point of view: the average file download delay. In this paper we propose a mathematical model that accurately predicts the average file download delay in a heterogeneous BitTorrent-like system. Our model is quite general, has been derived with minimal assumptions, and requires minimal system information. Then, we propose a flexible token-based scheme for BitTorrent-like systems that can be used to tradeoff between overall system performance and fairness to high bandwidth users, by properly setting its parameters. We extend our mathematical model to predict the average file download delays in the token- based system, and demonstrate how this model can be used to decide on the scheme's parameters that achieve a target performance/fairness. © 2007 Elsevier Ltd. All rights reserved.

File swarming (or file sharing) is one of the most important applications in P2P networks. In this paper, we propose a stochastic framework to analyze a file-swarming system under realistic setting: constraints in upload/download capacity, collaboration among peers and incentive for chunk exchange. We first extend the results in the coupon system [L. Massoulie, M. Vojnovic, Coupon replication systems, in: Proc. ACM SIGMETRICS, Banff, Alberta, Canada, 2005] by providing a tighter performance bound. Then we generalize the coupon system by considering peers with limited upload and download capacity. We illustrate the last-piece problem and show the effectiveness of using forward error-correction (FEC) code and/or multiple requests to improve the performance. Lastly, we propose a framework to analyze an incentive-based file-swarming system. The stochastic framework we propose can serve as a basis for other researchers to analyze and design more advanced features of file-swarming systems.

The technical impact of the Peer-to-Peer (P2P) paradigm on content distribution applications has been proved successful and efficient, when participants cooperation is achieved. Conversely, the business model is not clear: given a copy-protected object, its owner must be paid back for each transaction taking place from a provider to a receiver. The P2P paradigm assumes that a receiver turns into a provider, but it is questionable why she/he should provide properly the content, if the owner wants to be reimbursed. Actual systems introduce fairness, giving incentives (e.g., a differential service, like in BitTorrent) to altruistic peers, with the consequence that the owner of an object is economically damaged everyday. Hence, music and film industry sees P2P techniques as a hostile framework for distributing copy protected content for free: today's answer of the industry is investing in DRM-based solutions, that are not interoperable between different devices and players. In this paper, we present FairPeers, a P2P market framework, that joins a straightforward intellectual property protection and a fair economic model by maintaining the efficiency typical of P2P file sharing systems. The study is completed with an exhaustive security analysis, and the description of a prototype implementation that shows that the P2P paradigm is mature enough to present to the broadest community new revenue models, simply using available tools and state-of-the-art techniques.

In January 2005 a Hong Kong resident was arrested and charged with distributing three Hollywood movies over the internet using BitTorrent software. At his trial, the prosecution argued that the defendant’s actions amounted to the criminal offence of “distribution” under section 118 (1)(f) of the Copyright Ordinance. The defence countered that defendant’s actions in uploading the files to his computer did not constitute distribution and amounted to no more than “making available” copyright materials—which was covered under civil provisions in section 26 of the same Ordinance. The defendant was found guilty and became the world’s first BitTorrent user to be criminally convicted of piracy. The case has opened up strong debate in Hong Kong, with moves afoot to introduce a new raft of copyright legislation.

Some major P2P file distribution systems adopt Tit-For-Tat exchange strategy, which means "initially cooperate, then respond in kind to a previous opponent's action, i.e. cooperative or not." However, when sharing a file on such P2P systems, the random peer selection has a problem in that each peer cannot download the file enough efficiently. The peer selection method that groups peers according to their rate has been proposed to solve this problem. This method is supposed to be able to alleviate the difference in performance among peers because it lets peers with similar transmitting rate connect to each other. However, when reduction in peer performance or link one occurs, which is often observed on today's Internet, some problems will emerge, such as it takes a long time for the existing method to reconfigure groups; 2) immediate reconstruction of neighbor peers has not been taken into account when peers detect deterioration in downloading performance. Therefore, we propose a method that reconfigures the group of neighbor peers once a peer notices that the performance of connected peers decreases. The proposed method is evaluated through simulation experiments using BitTorrent as an instance of Tit-For-Tat strategy. The download time of all peers and that of the peer with performance deterioration are estimated focusing on the effect of switching a degraded peer to another immediately. As a result, we confirm that our proposal can distribute files among all peers faster than the existing method keeping incentives for users to some extent. We believe that the proposal which can adapt to the sudden network deterioration is one of the most important technologies for evolution of network software.

SUMMARY In this paper, we present a simple mathematical model for studying the performance of the BitTorrent (http://www.bittorrent.com) file sharing system. We are especially interested in the distribution of peers in different states of the download job progress. With the model we find that the distribution of the download peers follows an asymmetric U-shaped curve under the stable state, due to BitTorrent’s unchoking strategies. In addition, we find that the seeds’ departure rate and the download peers’ abort rate will influence the peer distribution in different ways notably. We also analyze the content availability under the dying process of the BitTorrent file sharing system. We find that the system’s stability deteriorates with decreasing and unevenly distributed online peers, and BitTorrent’s built-in ‘tit-for-tat’ unchoking strategy could not help to preserve the integrity of the file among the download peers. We propose an innovative ‘tit-for-tat’ unchoking strategy which enables more peers to finish the download job and prolongs the system’s lifetime. By playing our innovative strategy, download peers could cooperate to improve the stability of the system by making a trade-off between the current downloading rate and the future service availability. Finally, experimental results are presented to validate our analytical results and support our proposals. Copyright © 2007 John Wiley & Sons, Ltd.

This paper assesses BitTorrent’s robustness against selfish peers who try to download content faster than their fair share by abusing existing protocol mechanisms. We present three exploits that can deliver potential benefits to a selfish peer and evaluate their impact on both public and private download sessions. Our results show that BitTorrent is quite robust against these exploits. Although selfish peers can sometimes attain high download throughput and compliant peers’ download rates suffer slightly in consequence, we observe no significant degradation of the overall system’s quality of service. We identify scenarios where a selfish peer could attain significant benefits at the expense of compliant peers, and discuss the protocol characteristics that render these scenarios unlikely and hence lead to the system’s robustness. Copyright c © 2007 John Wiley & Sons, Ltd.

This paper presents a performance study of BitTorrent-like P2P systems by modeling, based on extensive measurements and trace analysis. Existing studies on BitTorrent systems are single-torrent based and usually assume the process of request arrivals to a torrent is Poisson-like. However, in reality, most BitTorrent peers participate in multiple torrents and file popularity changes over time. Our study of representative BitTorrent traffic provides insights into the evolution of single-torrent systems and several new findings regarding the limitations of BitTorrent systems: (1) Due to the exponentially decreasing peer arrival rate in a torrent, the service availability of the corresponding file becomes poor quickly, and eventually it is hard to locate and download this file. (2) Client performance in the BitTorrent-like system is unstable, and fluctuates significantly with the changes of the number of online peers. (3) Existing systems could provide unfair services to peers, where a peer with a higher downloading speed tends to download more and upload less. Motivated by the analysis and modeling results, we have further proposed a graph based model to study interactions among multiple torrents. Our model quantitatively demonstrates that inter-torrent collaboration is much more effective than stimulating seeds to serve longer for addressing the service unavailability in BitTorrent systems. An architecture for inter-torrent collaboration under an exchange based instant incentive mechanism is also discussed and evaluated by simulations

Peer-to-Peer file sharing applications in the Internet, such as BitTorrent, Gnutella, etc., have been immensely popular. Prior research mainly focuses on peer and content discovery, overlay topology formation, fairness and incentive issues, etc. However, little attention has been paid to investigate the data distribution problem which is also a core component of any file sharing application. In this paper, we present the first effort in addressing this collaborative file distribution problem and formally define the scheduling problem in a simplified context. We develop several algorithms to solve the problem and study their performance. We deduce a theoretical bound on the minimum download time experienced by users and also perform simulations to evaluate our algorithms. Simulation results show that our graph-based dynamically weighted maximum-flow algorithm outperforms all other algorithms. Therefore, we believe our algorithm is a promising solution to be employed as the core scheduling module in P2P file sharing applications.

Excessive bandwidth consuming by peer-to-peer (P2P) applications is one of serious problems in residential networks such as in dorms, apartments and even Small and Medium-sized Enterprises (SMEs) networks which have a limited bandwidth. P2P file sharing and P2P streaming applications usually are the cause of this problem. To share the bandwidth fairly among users, the traffic of these applications needs to be classified and filtered out. However, traditional port-based and payload-based classification will fail when the applications use dynamic ports, port disguise and payload encryption. In this paper, we present the classification technique that based on characteristics of number of peer connection and number of traffic in both incoming and outgoing direction for 5-minute duration to classify the P2P traffic. We make use of decision tree J48 to model and classify the traffic. Experimental results over three well-known P2P applications (BitTorrent, Skype and SopCast) confirm that this technique can detect the existence of P2P traffic from the background traffic with 100% accuracy and can classify three types of P2P applications with 90% accuracy.

Network neutrality is a policy made by the government. It emphasizes that Internet Service Providers (ISPs) should treat all users equally, regardless of users' behavior, as long as they are legal. In this sense, it aims to build a fair and healthy network. Packet Loss Rate (PLR) is an important metric to evaluate a network's condition. In this paper, we compare PLR of two different kinds of tests, which are "speedtest" and "bittorrent", to judge network neutrality of ISPs. The difference of PLR of two tests is used to evaluate the level of network neutrality violations. We propose a general framework for analysis of network neutrality. First, by transforming the well-known Mathis model, we build a model that uses public data, collected by the network neutrality bot (Neubot), to estimate the PLR of countries all over the world. Second, a composite function model, named PECF, is proposed for fitting to get the lower limit of PLR (L-PLR). When the value of PLR is L-PLR, the frequencies of PLR of two tests differ most and a network neutrality violation appears. By mathematical inference, we draw the conclusion that ISPs violate network neutrality when PLR is larger than 0.10. Third, based on this conclusion, we concentrate on the case when PLR is larger than 0.10 to study network neutrality violations. We use R-PLR (Ranged PLR) to describe PLR within a certain range. By comparing the PLR of "speedtest" with that of "bittorrent" within a certain R-PLR, we further determine the level of network neutrality violation in time and space. Network neutrality violation is more likely to happen under network peaks. The geographical distribution of PLR shows China (CN) and South Africa (ZA) suffer the most severe network neutrality violations among the eight regions studied. Finally, we present the histogram of PLR worldwide from year 2012 to 2015, which shows a relationship between network development and user demand.

The social impact of technology has become one of the most challenging research issues. One of the most famous information technology is BitTorrent, a protocol for peer to peer file sharing. This paper discusses an ethical issue related to Peer to Peer file sharing using BitTorrent protocol of copyrighted materials. We choose an academic approach by choosing an ethical analysis tool that allows pros and cons opinions amongst different points of view. We studied this issue in Saudi community by distributing the questionnaires and analyzing its results. The result reveals that a large percentage of the participants were using Torrent to download movies and music illegally and half of them do not even realize that it is considered as illegal. Hence, it is suggested that in order to reduce the illegal use of a promising technology is to raise the awareness of the issue to the society.

Publicly released software implementations of network protocols often have bugs that arise from latent specification violations. We present Ape, a technique that explores program behavior to identify potential specification violations. Ape overcomes the challenge of exploring the large space of behavior by dynamically inferring precise models of behavior, stimulating unobserved behavior likely to lead to violations, and refining the behavioral models with the new, stimulated behavior. Ape can (1) discover new specification violations, (2) verify that violations are removed, (3) identify related violations in other versions and implementations of the protocols, and (4) generate tests. Ape works on binaries and requires a lightweight description of the protocol's network messages and a violation characteristic. We use Ape to rediscover the known heartbleed bug in OpenSSL, and discover one unknown bug and two unexpected uses of three popular BitTorrent clients. Manual inspection of Ape-produced artifacts reveals four additional, previously unknown specification violations in OpenSSL and μTorrent.

Submitted by Haia Cristina Rebouças de Almeida (haia.almeida@uniceub.br) on 2016-01-18T10:14:13Z No. of bitstreams: 1 artigoInt7615cnc08-Nov2015.pdf: 579796 bytes, checksum: b8b95c39ddb0f6d2823cde382f470730 (MD5) Made available in DSpace on 2016-01-18T10:14:14Z (GMT). No. of bitstreams: 1 artigoInt7615cnc08-Nov2015.pdf: 579796 bytes, checksum: b8b95c39ddb0f6d2823cde382f470730 (MD5) The great efficiency achieved by the BitTorrent protocol for the distribution of large amounts of data inspired its adoption to provide multimedia content on-demand delivery over the Internet. As it is not designed for this purpose, some adjustments have been proposed in order to meet the related QoS requirements like low startup delay and smooth playback continuity. Accordingly, this paper introduces a BitTorrent-like proposal named as Quota-Based Peer Selection (QBPS). This proposal is mainly based on the adaptation of the original peer-selection policy of the BitTorrent protocol. Its validation is achieved by means of simulations and competitive analysis. The final results show that QBPS outperforms other recent proposals of the literature. For instance, it achieves a throughput optimization of up to 48.0% in low-provision capacity scenarios where users are very interactive.

We present a new delay-based transport protocol named FLOWER, that aims at providing a Lower-than-Best-Effort (LBE) service. The objective is to propose an alternative to the Low Extra Delay Background Transport (LEDBAT) widely deployed within the official BitTorrent client. Indeed, besides its intra-fairness problem, known as latecomer unfairness, LEDBAT can be too aggressive against TCP, making it ill suited for providing LBE services over certain networks such as constrained wireless networks. By using a fuzzy controller to modulate the sending rate, FLOWER aims to solve LEDBAT issues while fulfilling the role of a LBE protocol. Our simulation results show that FLOWER can carry LBE traffic in network scenarios where LEDBAT cannot while solving the latecomer unfairness problem. Finally, the presented algorithm is simple to implement and does not require complex computation that would prevent its deployment.

Dokumentu honek magnet lotura eta web API arloak lantzen dituen Gradu Amaierako Proiektua deskribatzen du. Teknologia horiek liburu elektronikoak partekatzeko erabili dira eta sortutako aplikazioari Liburutruk izena eman zaio. Honakoak dira Liburutruk-en ezaugarri nagusienak: • Zerbitzariak web API api publiko eta dokumentatua eskaintzen du. • APIaren bidez liburuak eta horiei lotutako baliabideak kudeatu daitezke. • Gehitutako liburuak BitTorrent bidez partekatzen ditu eta liburu horien magnet loturak sortzen ditu. • Web-nabigatzaileetan exekutatzen den bezeroa du, orri bakarreko aplikazioa dena. • Bezeroak zerbitzariaren APIa erabiltzen du. • Aplikazioa eta kodea edonork eskura ditzake.