906 resultados para Peer-to-Peers Networks


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The peer-to-peer content distribution network (PCDN) is a hot topic recently, and it has a huge potential for massive data intensive applications on the Internet. One of the challenges in PCDN is routing for data sources and data deliveries. In this paper, we studied a type of network model which is formed by dynamic autonomy area, structured source servers and proxy servers. Based on this network model, we proposed a number of algorithms to address the routing and data delivery issues. According to the highly dynamics of the autonomy area, we established dynamic tree structure proliferation system routing, proxy routing and resource searching algorithms. The simulations results showed that the performance of the proposed network model and the algorithms are stable.

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With more and more multimedia applications on the Internet, such as IPTV, bandwidth becomes a vital bottleneck for the booming of large scale Internet based multimedia applications. Network coding is recently proposed to take advantage to use network bandwidth efficiently. In this paper, we focus on massive multimedia data, e.g. IPTV programs, transportation in peer-to-peer networks with network coding. By through study of networking coding, we pointed out that the prerequisites of bandwidth saving of network coding are: 1) one information source with a number of concurrent receivers, or 2) information pieces cached at intermediate nodes. We further proof that network coding can not gain bandwidth saving at immediate connections to a receiver end; As a result, we propose a novel model for IPTV data transportation in unstructured peer-to-peer networks with network coding. Our preliminary simulations show that the proposed architecture works very well.

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Propagation of Peer-to-Peer (P2P) worms in the Internet is posing a serious challenge to network security research because of P2P worms' increasing complexity and sophistication. Due to the complexity of the problem, no existing work has solved the problem of modeling the propagation of P2P worms, especially when quarantine of peers is enforced. This paper presents a study on modeling the propagation of P2P worms. It also presents our applications of the proposed approach in worm propagation research.

Motivated by our aspiration to invent an easy-to-employ instrument for worm propagation research, the proposed approach models the propagation processes of P2P worms by difference equations of a logic matrix, which are essentially discrete-time deterministic propagation models of P2P worms. To the best of our knowledge, we are the first using a logic matrix in network security research in general and worm propagation modeling in particular.

Our major contributions in this paper are firstly, we propose a novel logic matrix approach to modeling the propagation of P2P worms under three different conditions; secondly, we find the impacts of two different topologies on a P2P worm's attack performance; thirdly, we find the impacts of the network-related characteristics on a P2P worm's attack performance in structured P2P networks; and fourthly, we find the impacts of the two different quarantine tactics on the propagation characteristics of P2P worms in unstructured P2P networks. The approach's ease of employment, which is demonstrated by its applications in our simulation experiments, makes it an attractive instrument to conduct worm propagation research.

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Peer-to-peer (P2P) networks are gaining increased attention from both the scientific community and the larger Internet user community. Data retrieval algorithms lie at the center of P2P networks, and this paper addresses the problem of efficiently searching for files in unstructured P2P systems. We propose an Improved Adaptive Probabilistic Search (IAPS) algorithm that is fully distributed and bandwidth efficient. IAPS uses ant-colony optimization and takes file types into consideration in order to search for file container nodes with a high probability of success. We have performed extensive simulations to study the performance of IAPS, and we compare it with the Random Walk and Adaptive Probabilistic Search algorithms. Our experimental results show that IAPS achieves high success rates, high response rates, and significant message reduction.

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Micro-payment systems are an important part of peer-to-peer (P2P) networks and address the "free-rider" problem in most existing content sharing systems. To address this issue, the authors have developed a new micro-payment system for content sharing in P2P networks called P2P-Netpay. This is an offline, debit based protocol that provides a secure, flexible, usable and reliable credit service. This article compares micro-payment with non-micro-payment credit systems for file sharing applications and finds that this approach liberates the "free-rider" problem. The authors analyse the heuristic evaluation performed by a set of evaluators and present directions for research aiming to improve the overall satisfaction and efficiency of the proposed model.

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Cloud services are becoming ever more important for everyone's life. Cloud storage? Web mails? Yes, we don't need to be working in big IT companies to be surrounded by cloud services. Another thing that's growing in importance, or at least that should be considered ever more important, is the concept of privacy. The more we rely on services of which we know close to nothing about, the more we should be worried about our privacy. In this work, I will analyze a prototype software based on a peer to peer architecture for the offering of cloud services, to see if it's possible to make it completely anonymous, meaning that not only the users using it will be anonymous, but also the Peers composing it will not know the real identity of each others. To make it possible, I will make use of anonymizing networks like Tor. I will start by studying the state of art of Cloud Computing, by looking at some real example, followed by analyzing the architecture of the prototype, trying to expose the differences between its distributed nature and the somehow centralized solutions offered by the famous vendors. After that, I will get as deep as possible into the working principle of the anonymizing networks, because they are not something that can just be 'applied' mindlessly. Some de-anonymizing techniques are very subtle so things must be studied carefully. I will then implement the required changes, and test the new anonymized prototype to see how its performances differ from those of the standard one. The prototype will be run on many machines, orchestrated by a tester script that will automatically start, stop and do all the required API calls. As to where to find all these machines, I will make use of Amazon EC2 cloud services and their on-demand instances.

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Content providers from the music industry argue that peer-to-peer (P2P) networks such as KaZaA, Morpheus, iMesh, or Audiogalaxy are an enormous threat to their business. They furthermore blame these networks for their recent decline in sales figures. For this reason, an empirical investigation was conducted during a period of 6 weeks on one of the most popular files-sharing systems, in order to determine the quantity and quality of pirated music songs shared. We present empirical evidence as to what extent and in which quality music songs are being shared. A number of hypotheses are outlined and were tested. We studied, among other things, the number of users online and the number of flies accessible on such networks, the free riding problem, and the duration per search request. We further tested to see if there are any differences in the accessibility of songs based on the nationality of the artist, the language of the song, and the corresponding chart position. Finally, we outline the main hurdles users may face when downloading illegal music and the probability of obtaining high quality music tracks on such peer-to-peer networks.

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Currently, wireless technology is revolutionizing the way we share information and communicate. The demands for mobility have made wireless technology the primary source for voice communication. Code-division multiple-access (CDMA) is a very popular spread spectrum application due to its claims of low transmission power, higher system capacity, ability to mitigate multipath fading and user interference. In that case, frequency-hopping code-division multiple access (FH-CDMA) has received considerable attention over the past few years. This technique will allow a better performance over a fading channel, message privacy, and immunity to narrowband interference. This paper addresses the characteristics of FH-CDMA in WPAN networks, with an emphasis on frequency-hopped Bluetooth systems. A performance evaluation of FH-CDMA is discussed and simulated. The analysis shows the interaction between the designed parameters and their effect on the network system. Most specifically, the FH-CDMA scheme provides frequency and temporal diversity to combat the effects of interference.

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Whereas Lessig's recent work engages with questions of culture and creativity in society, this paper looks at the role of culture and creativity in the law. The paper evaluates the Napster, DeCSS, Felten and Sklyarov litigation in terms of the new social, legal, economic and cultural relations being produced. This involves a deep discussion of law's economic relations, and the implications of this for litigation strategy. The paper concludes with a critique of recent attempts to define copyright law in terms of first amendment rights and communicative freedom.

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As the virtual world grows more complex, finding a standard way for storing data becomes increasingly important. Ideally, each data item would be brought into the computer system only once. References for data items need to be cryptographically verifiable, so the data can maintain its identity while being passed around. This way there will be only one copy of the users family photo album, while the user can use multiple tools to show or manipulate the album. Copies of users data could be stored on some of his family members computer, some of his computers, but also at some online services which he uses. When all actors operate over one replicated copy of the data, the system automatically avoids a single point of failure. Thus the data will not disappear with one computer breaking, or one service provider going out of business. One shared copy also makes it possible to delete a piece of data from all systems at once, on users request. In our research we tried to find a model that would make data manageable to users, and make it possible to have the same data stored at various locations. We studied three systems, Persona, Freenet, and GNUnet, that suggest different models for protecting user data. The main application areas of the systems studied include securing online social networks, providing anonymous web, and preventing censorship in file-sharing. Each of the systems studied store user data on machines belonging to third parties. The systems differ in measures they take to protect their users from data loss, forged information, censorship, and being monitored. All of the systems use cryptography to secure names used for the content, and to protect the data from outsiders. Based on the gained knowledge, we built a prototype platform called Peerscape, which stores user data in a synchronized, protected database. Data items themselves are protected with cryptography against forgery, but not encrypted as the focus has been disseminating the data directly among family and friends instead of letting third parties store the information. We turned the synchronizing database into peer-to-peer web by revealing its contents through an integrated http server. The REST-like http API supports development of applications in javascript. To evaluate the platform’s suitability for application development we wrote some simple applications, including a public chat room, bittorrent site, and a flower growing game. During our early tests we came to the conclusion that using the platform for simple applications works well. As web standards develop further, writing applications for the platform should become easier. Any system this complex will have its problems, and we are not expecting our platform to replace the existing web, but are fairly impressed with the results and consider our work important from the perspective of managing user data.

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As the virtual world grows more complex, finding a standard way for storing data becomes increasingly important. Ideally, each data item would be brought into the computer system only once. References for data items need to be cryptographically verifiable, so the data can maintain its identity while being passed around. This way there will be only one copy of the users family photo album, while the user can use multiple tools to show or manipulate the album. Copies of users data could be stored on some of his family members computer, some of his computers, but also at some online services which he uses. When all actors operate over one replicated copy of the data, the system automatically avoids a single point of failure. Thus the data will not disappear with one computer breaking, or one service provider going out of business. One shared copy also makes it possible to delete a piece of data from all systems at once, on users request. In our research we tried to find a model that would make data manageable to users, and make it possible to have the same data stored at various locations. We studied three systems, Persona, Freenet, and GNUnet, that suggest different models for protecting user data. The main application areas of the systems studied include securing online social networks, providing anonymous web, and preventing censorship in file-sharing. Each of the systems studied store user data on machines belonging to third parties. The systems differ in measures they take to protect their users from data loss, forged information, censorship, and being monitored. All of the systems use cryptography to secure names used for the content, and to protect the data from outsiders. Based on the gained knowledge, we built a prototype platform called Peerscape, which stores user data in a synchronized, protected database. Data items themselves are protected with cryptography against forgery, but not encrypted as the focus has been disseminating the data directly among family and friends instead of letting third parties store the information. We turned the synchronizing database into peer-to-peer web by revealing its contents through an integrated http server. The REST-like http API supports development of applications in javascript. To evaluate the platform s suitability for application development we wrote some simple applications, including a public chat room, bittorrent site, and a flower growing game. During our early tests we came to the conclusion that using the platform for simple applications works well. As web standards develop further, writing applications for the platform should become easier. Any system this complex will have its problems, and we are not expecting our platform to replace the existing web, but are fairly impressed with the results and consider our work important from the perspective of managing user data.