Peer-to-Peer networks are designed to rely on resources of their own users. Therefore, resource management plays an important role in P2P protocols. Therefore, resource management plays an important role in P2P protocols. Early P2P networks did not use proper mechanisms to manage fairness. However, after seeing difficulties and rise of freeloaders in networks like Gnutella, the importance of providing fairness for users have become apparent. In this paper, we propose an incentive based security model which leads to a network infrastructure that lightens the work of Seeders and makes Leechers to contribute more. This method is able to prevent betrayals in Leecher-to-Leecher transactions and more importantly, helps Seeders to be treated more fairly. This is what other incentive methods such as Bittorrent are incapable of doing. Additionally, by getting help from cryptography and combining it with our method, it is also possible to achieve secure channels, immune to spying, next to a fair network. The simulation results clearly show that how our proposed approach can overcome free-riding issue. In addition, our findings revealed that our approach is able to provide an appropriate level of fairness for the users and can decrease the download time.
As a result, the network will be able to identify malicious peers and isolates them from the network. EigenTrust is able to decrease the number of inauthentic files on the network, even under a variety of conditions where malicious peers cooperate in an attempt to subvert the system. In @cite_18 , the authors have introduced an approach to predict a peer's cooperation level, focusing on the cooperation induced by the P2P protocol rather than the cooperation that results from user behavior or bandwidth limitation. This method mainly focuses on live streaming applications. By investigating the correlation between a peer's cooperation level, the authors tried to show that three centrality metrics, namely out-degree, out-closeness, and betweenness, are positively correlated with the cooperation level. Based on this, they proposed a non-linear regression model to measure peer's out-degree in the recent past to predict its cooperation level value in the near future.
@cite_18
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The Peer-to-Peer (P2P) architecture has been successfully used to reduce costs and increase the scalability of Internet live streaming systems. However, the effectiveness of these applications depends largely on user (peer) cooperation. In this article we use data collected from SopCast, a popular P2P live application, to show that there is high correlation between peer centrality--out-degree, out-closeness, and betweenness--in the P2P overlay graph and peer cooperation. We use this finding to propose a new regression-based model to predict peer cooperation from its past centrality. Our model takes only peer out-degrees as input, as out-degree has the strongest correlation with peer cooperation. Our evaluation shows that our model has good accuracy and does not need to be trained too often (e.g., once each 16 min). We also use our model to sketch a mechanism to detect malicious peers that report artificially inflated cooperation aiming at, for example, receiving better quality of service. Peer-to-peer file-sharing networks are currently receiving much attention as a means of sharing and distributing information. However, as recent experience shows, the anonymous, open nature of these networks offers an almost ideal environment for the spread of self-replicating inauthentic files.We describe an algorithm to decrease the number of downloads of inauthentic files in a peer-to-peer file-sharing network that assigns each peer a unique global trust value, based on the peer's history of uploads. We present a distributed and secure method to compute global trust values, based on Power iteration. By having peers use these global trust values to choose the peers from whom they download, the network effectively identifies malicious peers and isolates them from the network.In simulations, this reputation system, called EigenTrust, has been shown to significantly decrease the number of inauthentic files on the network, even under a variety of conditions where malicious peers cooperate in an attempt to deliberately subvert the system. Current peer-to-peer (P2P) systems often suffer from a large fraction of freeriders not contributing any resources to the network. Various mechanisms have been designed to overcome this problem. However, the selfish behavior of peers has aspects which go beyond resource sharing. This paper studies the effects on the topology of a P2P network if peers selfishly select the peers to connect to. In our model, a peer exploits locality properties in order to minimize the latency (or response times) of its lookup operations. At the same time, the peer aims at not having to maintain links to too many other peers in the system. By giving tight bounds on the price of anarchy, we show that the resulting topologies can be much worse than if peers collaborated. Moreover, the network may never stabilize, even in the absence of churn. Finally, we establish the complexity of Nash equilibria in our game theoretic model of P2P networks. Specifically, we prove that it is NP-hard to decide whether our game has a Nash equilibrium and can stabilize. Peer-to-peer content distribution networks can suffer from malicious participants that corrupt content. Current systems verify blocks with traditional cryptographic signatures and hashes. However, these techniques do not apply well to more elegant schemes that use network coding techniques for efficient content distribution. Architectures that use network coding are prone to jamming attacks where the introduction of a few corrupted blocks can quickly result in a large number of bad blocks propagating through the system. Identifying such bogus blocks is difficult and requires the use of homomorphic hashing functions, which are computationally expensive. This paper presents a practical security scheme for network coding that reduces the cost of verifying blocks on-the-fly while efficiently preventing the propagation of malicious blocks. In our scheme, users not only cooperate to distribute the content, but (well-behaved) users also cooperate to protect themselves against malicious users by informing affected nodes when a malicious block is found. We analyze and study such cooperative security scheme and introduce elegant techniques to prevent DoS attacks. We show that the loss in the efficiency caused by the attackers is limited to the effort the attackers put to corrupt the communication, which is a natural lower bound in the damage of the system. We also show experimentally that checking as low as 1-5 of the received blocks is enough to guarantee low corruption rates.