A Framework For Efficient Data Distribution In Peer-to-peer Networks.

Peer to Peer (P2P) models are based on user altruism, wherein a user shares its content with other users in the pool and it also has an interest in the content of the other nodes. Most P2P systems in their current form are not fair in terms of the content served by a peer and the service obtained from swarm. Most systems suffer from free rider\u27s problem where many high uplink capacity peers contribute much more than they should while many others get a free ride for downloading the content. This leaves high capacity nodes with very little or no motivation to contribute. Many times such resourceful nodes exit the swarm or don\u27t even participate. The whole scenario is unfavorable and disappointing for P2P networks in general, where participation is a must and a very important feature. As the number of users increases in the swarm, the swarm becomes robust and scalable. Other important issues in the present day P2P system are below optimal Quality of Service (QoS) in terms of download time, end-to-end latency and jitter rate, uplink utilization, excessive cross ISP traffic, security and cheating threats etc. These current day problems in P2P networks serve as a motivation for present work. To this end, we present an efficient data distribution framework in Peer-to-Peer (P2P) networks for media streaming and file sharing domain. The experiments with our model, an alliance based peering scheme for media streaming, show that such a scheme distributes data to the swarm members in a near-optimal way. Alliances are small groups of nodes that share data and other vital information for symbiotic association. We show that alliance formation is a loosely coupled and an effective way to organize the peers and our model maps to a small world network, which form efficient overlay structures and are robust to network perturbations such as churn. We present a comparative simulation based study of our model with CoolStreaming/DONet (a popular model) and present a quantitative performance evaluation. Simulation results show that our model scales well under varying workloads and conditions, delivers near optimal levels of QoS, reduces cross ISP traffic considerably and for most cases, performs at par or even better than Cool-Streaming/DONet. In the next phase of our work, we focussed on BitTorrent P2P model as it the most widely used file sharing protocol. Many studies in academia and industry have shown that though BitTorrent scales very well but is far from optimal in terms of fairness to end users, download time and uplink utilization. Furthermore, random peering and data distribution in such model lead to suboptimal performance. Lately, new breed of BitTorrent clients like BitTyrant have shown successful strategic attacks against BitTorrent. Strategic peers configure the BitTorrent client software such that for very less or no contribution, they can obtain good download speeds. Such strategic nodes exploit the altruism in the swarm and consume resources at the expense of other honest nodes and create an unfair swarm. More unfairness is generated in the swarm with the presence of heterogeneous bandwidth nodes. We investigate and propose a new token-based anti-strategic policy that could be used in BitTorrent to minimize the free-riding by strategic clients. We also proposed other policies against strategic attacks that include using a smart tracker that denies the request of strategic clients for peer listmultiple times, and black listing the non-behaving nodes that do not follow the protocol policies. These policies help to stop the strategic behavior of peers to a large extent and improve overall system performance. We also quantify and validate the benefits of using bandwidth peer matching policy. Our simulations results show that with the above proposed changes, uplink utilization and mean download time in BitTorrent network improves considerably. It leaves strategic clients with little or no incentive to behave greedily. This reduces free riding and creates fairer swarm with very little computational overhead. Finally, we show that our model is self healing model where user behavior changes from selfish to altruistic in the presence of the aforementioned policies

Enhancing Message Privacy In Wired Equivalent Privacy.

The 802.11 standard defines the Wired Equivalent Privacy (WEP) and encapsulation of data frames. It is intended to provide data privacy to the level of a wired network. WEP suffered threat of attacks from hackers owing to certain security shortcomings in the WEP protocol. Lately, many new protocols like WiFi Protected Access (WPA), WPA2, Robust Secure Network (RSN) and 802.11i have come into being, yet their implementation is fairly limited. Despite its shortcomings one cannot undermine the importance of WEP as it still remains the most widely used system and we chose to address certain security issues and propose some modifications to make it more secure. In this thesis we have proposed a modification to the existing WEP protocol to make it more secure. We achieve Message Privacy by ensuring that the encryption is not breached. The idea is to update the shared secret key frequently based on factors like network traffic and number of transmitted frames. We also develop an Initialization Vector (IV) avoidance algorithm that eliminates IV collision problem. The idea is to partition the IV bits among different wireless hosts in a predetermined manner unique to every node. We can use all possible 224 different IVs without making them predictable for an attacker. Our proposed algorithm eliminates the IV collision ensuring Message Privacy that further strengthens security of the existing WEP. We show that frequent rekeying thwarts all kinds of cryptanalytic attacks on the WEP

An Alliance Based Peering Scheme For Peer-To-Peer Live Media Streaming

Peer-to-Peer (P2P) streaming has emerged as a scalable method for media distribution in recent years. While recent measurement studies have shown the effectiveness of P2P network in media streaming, there have been questions raised about the Quality of Service (QoS), reliability of streaming services and sub optimal uplink utilization in particular. We present a new model for P2P media streaming where nodes cluster into groups, called alliances, for a symbiotic association in order to share the media content. We show that alliance formation is an effective way to organize the peers in loosely coupled groups. The node topology formed using alliances generates a Small World Network, which exhibit efficient overlay structures in terms of path lengths between the nodes and robustness to network perturbations like churn. We present a comparative performance evaluation of our model with CoolStreaming/DONet on QoS metrics. © 2007 ACM

Fast,Efficient And Secure Bss Transitions

We present a fast and efficient way of switching a wireless node (WN) between different Access Points (AP) in an Infrastructure Wireless Network. Our proposed model adheres to the security standards set by IEEE 802.IIi draft. New architectures like S02.IIi and Robust Secure Network (RSN) mainly depend on the S02.Ix×× communication between a Wireless supplicant node and an Authentication Server (AS) followed by a 4-Way handshake between Wireless Supplicant node and Access Point. Reassociation with another AP also requires a four way handshake. We propose two models for transitions. The first model is based on Distributed approach while the second one is based on Centralized approach. Distributed model involves AP to AP direct communication without the involvement of AS while in Centralized model APs communicate through AS. We show that both the models are very efficient, secure and deny any kind of man in the middle attack, any rogue attack by wireless node or an AP and any kind of Denial of Service attack. Finally, we show that Centralized model has a little edge over the distributed model. © 2005 IEEE

Preferential And Strata Based P2P Model: Selfishness To Altruism And Fairness

Peer to Peer models are based on user altruism, where a user shares his content. Real life p2p systems suffer from free rider\u27s problem. Many nodes contribute much more than they should while others get a free ride for downloading the content. We present a simulation based study of BitTorrent like p2p systems. We propose a self punishing and self healing model that dissuades the users from cheating and encourages them to cooperate. A preferential based scheme is used to group nodes in the same stratum. This protocol uses publish based model and public key cryptography that prevents the nodes from cheating and enforces them to cooperate. Our results show that the node behavior changes from selfish to altruistic. Our proposed model ensures fairness, performs better in link utilization and minimizes the mean download time. © 2006 IEEE

Enhancing Message Privacy In Wep

The Wired Equivalent Privacy (WEP) protocol for networks based on 802.11 standards has been shown to have several security flaws. In this paper we have proposed a modification to the existing WEP protocol to make it more secure. We also develop an IV avoidance algorithm that eliminates Initialization Vector (IV) collision problem by assigning unique pattern of IV bits to each node. We achieve Message Privacy by ensuring that the encryption is not breached. The idea is to update the shared secret key frequently based on factors like network traffic and number of transmitted frames. We show that frequent rekeying thwarts all kinds of cryptanalytic attacks on the WEP

An Alliance Based Peering Scheme For P2P Live Media Streaming

While recent measurement studies have shown the effectiveness of P2P network in media streaming, there have been questions raised about the Quality of Service (QoS), reliability of streaming services and sub optimal uplink utilization in particular. P2P streaming systems are inherently less reliable because of churn, internet dynamics, node heterogeneity and randomness in the swarm. We present a new model for P2P media streaming based on clustering of peers, called alliances. We show that alliance formation is a loosely coupled and an effective way to organize the peers. We show that our model maps to a small-world network, which form efficient overlay structures and are robust to network perturbations such as churn. We present a comparative simulation based study of our model with CoolStreaming/DONet and present a quantitative performance evaluation. Simulation results are promising and show that our model scales well under varying workloads and conditions, delivers near optimal levels of QoS, and for most cases, performs at par or even better than Cool-Streaming/DONet. © 2007 IEEE

Beam: An Efficient Peer To Peer Media Streaming Framework

In this paper, we present a swarm based peer to peer media streaming model. In our approach, nodes that serve the maximum content to their peers have a higher utility to the swarm and become candidates for direct relay of stream from the media server. This reward forms a natural incentive for the nodes to contribute to the swarm. Nodes cluster into small groups, called alliances, for a symbiotic association. Alliance members must exchange pieces to have the complete packet. This policy dissuades non-cooperating members in an alliance from their selfish behavior. We study our model using a simulator and present some initial results. © 2006 IEEE

Security Issues In Bittorrent Like P2P Streaming Systems

We present a streaming protocol that addresses the security issues pertaining to BitTorrent like P2P systems. Any efficient streaming system would not be effective if it cannot withstand security threats. We focus on free rider\u27s, whitewasher\u27s and malicious payload insertion attacks which implicitly affect Quality of Service like important metrics for the streaming system. We propose a novel idea of alliance formation, wherein the nodes collaborate with their preferred participating peers for a symbiotic association. The protocol enforces a strict policy that dissuades free riders and whitewashers from their selfish behavior. We propose a lightweight integrity checking algorithm for malicious garbled payload insertion to guard against security threats to the swarm. We present an evaluative comparison of the system performance in a cheating node free environment versus system with prevalent threats. Our simulation results show that cheating and malicious node problem can be significantly reduced by our proposed protocol. We explore the security vulnerabilities in the contemporary p2p file sharing systems and make security recommendations for the same