Study of the Topology Mismatch Problem in Peer-to-Peer Networks

The advantages of peer-to-peer (P2P) technology are innumerable when compared to other systems like Distributed Messaging System, Client-Server model, Cloud based systems. The vital advantages are not limited to high scalability and low cost. On the other hand the p2p system suffers from a bottle-neck problem caused by topology mismatch. Topology mismatch occurs in an unstructured peer-to-peer (P2P) network when the peers participating in the communication choose their neighbors in random fashion, such that the resultant P2P network mismatches its underlying physical network, resulting in a lengthy communication between the peers and redundant network traffics generated in the underlying network[1] However, most P2P system performance suffers from the mismatch between the overlays topology and the underlying physical network topology, causing a large volume of redundant traffic in the Internet slowing the performance. This paper surveys the P2P topology mismatch problems and the solutions adapted for different applications

Graffiti Networks: A Subversive, Internet-Scale File Sharing Model

The proliferation of peer-to-peer (P2P) file sharing protocols is due to their efficient and scalable methods for data dissemination to numerous users. But many of these networks have no provisions to provide users with long term access to files after the initial interest has diminished, nor are they able to guarantee protection for users from malicious clients that wish to implicate them in incriminating activities. As such, users may turn to supplementary measures for storing and transferring data in P2P systems. We present a new file sharing paradigm, called a Graffiti Network, which allows peers to harness the potentially unlimited storage of the Internet as a third-party intermediary. Our key contributions in this paper are (1) an overview of a distributed system based on this new threat model and (2) a measurement of its viability through a one-year deployment study using a popular web-publishing platform. The results of this experiment motivate a discussion about the challenges of mitigating this type of file sharing in a hostile network environment and how web site operators can protect their resources

A Novel Locality Algorithm and Peer-to-Peer Communication Infrastructure for Optimizing Network Performance in Smart Microgrids

[EN] Peer-to-Peer (P2P) overlay communications networks have emerged as a new paradigm for implementing distributed services in microgrids due to their potential benefits: they are robust, scalable, fault-tolerant, and they can route messages even with a large number of nodes which are frequently entering or leaving from the network. However, current P2P systems have been mainly developed for file sharing or cycle sharing applications where the processes of searching and managing resources are not optimized. Locality algorithms have gained a lot of attention due to their potential to provide an optimized path to groups with similar interests for routing messages in order to get better network performance. This paper develops a fully functional decentralized communication architecture with a new P2P locality algorithm and a specific protocol for monitoring and control of microgrids. Experimental results show that the proposed locality algorithm reduces the number of lookup messages and the lookup delay time. Moreover, the proposed communication architecture heavily depends of the lookup used algorithm as well as the placement of the communication layers within the architecture. Experimental results will show that the proposed techniques meet the network requirements of smart microgrids even with a large number of nodes on stream.This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (ERDF) under Grant ENE2015-64087-C2-2R. This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under BES-2013-064539.Marzal-Romeu, S.; González-Medina, R.; Salas-Puente, RA.; Figueres Amorós, E.; Garcerá, G. (2017). A Novel Locality Algorithm and Peer-to-Peer Communication Infrastructure for Optimizing Network Performance in Smart Microgrids. 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Security in peer-to-peer communication systems

P2PSIP (Peer-to-Peer Session Initiation Protocol) is a protocol developed by the IETF (Internet Engineering Task Force) for the establishment, completion and modi¿cation of communication sessions that emerges as a complement to SIP (Session Initiation Protocol) in environments where the original SIP protocol may fail for technical, ¿nancial, security, or social reasons. In order to do so, P2PSIP systems replace all the architecture of servers of the original SIP systems used for the registration and location of users, by a structured P2P network that distributes these functions among all the user agents that are part of the system. This new architecture, as with any emerging system, presents a completely new security problematic which analysis, subject of this thesis, is of crucial importance for its secure development and future standardization. Starting with a study of the state of the art in network security and continuing with more speci¿c systems such as SIP and P2P, we identify the most important security services within the architecture of a P2PSIP communication system: access control, bootstrap, routing, storage and communication. Once the security services have been identi¿ed, we conduct an analysis of the attacks that can a¿ect each of them, as well as a study of the existing countermeasures that can be used to prevent or mitigate these attacks. Based on the presented attacks and the weaknesses found in the existing measures to prevent them, we design speci¿c solutions to improve the security of P2PSIP communication systems. To this end, we focus on the service that stands as the cornerstone of P2PSIP communication systems¿ security: access control. Among the new designed solutions stand out: a certi¿cation model based on the segregation of the identity of users and nodes, a model for secure access control for on-the-¿y P2PSIP systems and an authorization framework for P2PSIP systems built on the recently published Internet Attribute Certi¿cate Pro¿le for Authorization. Finally, based on the existing measures and the new solutions designed, we de¿ne a set of security recommendations that should be considered for the design, implementation and maintenance of P2PSIP communication systems.Postprint (published version

Content Distribution in P2P Systems

The report provides a literature review of the state-of-the-art for content distribution. The report's contributions are of threefold. First, it gives more insight into traditional Content Distribution Networks (CDN), their requirements and open issues. Second, it discusses Peer-to-Peer (P2P) systems as a cheap and scalable alternative for CDN and extracts their design challenges. Finally, it evaluates the existing P2P systems dedicated for content distribution according to the identied requirements and challenges

Secure identity management in structured peer-to-peer (P2P) networks

Structured Peer-to-Peer (P2P) networks were proposed to solve routing problems of big distributed infrastructures. But the research community has been questioning their security for years. Most prior work in security services was focused on secure routing, reputation systems, anonymity, etc. However, the proper management of identities is an important prerequisite to provide most of these security services. The existence of anonymous nodes and the lack of a centralized authority capable of monitoring (and/or punishing) nodes make these systems more vulnerable against selfish or malicious behaviors. Moreover, these improper usages cannot be faced only with data confidentiality, nodes authentication, non-repudiation, etc. In particular, structured P2P networks should follow the following secure routing primitives: (1) secure maintenance of routing tables, (2) secure routing of messages, and (3) secure identity assignment to nodes. But the first two problems depend in some way on the third one. If nodes’ identifiers can be chosen by users without any control, these networks can have security and operational problems. Therefore, like any other network or service, structured P2P networks require a robust access control to prevent potential attackers joining the network and a robust identity assignment system to guarantee their proper operation. In this thesis, firstly, we analyze the operation of the current structured P2P networks when managing identities in order to identify what security problems are related to the nodes’ identifiers within the overlay, and propose a series of requirements to be accomplished by any generated node ID to provide more security to a DHT-based structured P2P network. Secondly, we propose the use of implicit certificates to provide more security and to exploit the improvement in bandwidth, storage and performance that these certificates present compared to explicit certificates, design three protocols to assign nodes’ identifiers avoiding the identified problems, while maintaining user anonymity and allowing users’ traceability. Finally, we analyze the operation of the most used mechanisms to distribute revocation data in the Internet, with special focus on the proposed systems to work in P2P networks, and design a new mechanism to distribute revocation data more efficiently in a structured P2P network.Las redes P2P estructuradas fueron propuestas para solventar problemas de enrutamiento en infraestructuras de grandes dimensiones pero su nivel de seguridad lleva años siendo cuestionado por la comunidad investigadora. La mayor parte de los trabajos que intentan mejorar la seguridad de estas redes se han centrado en proporcionar encaminamiento seguro, sistemas de reputación, anonimato de los usuarios, etc. Sin embargo, la adecuada gestión de las identidades es un requisito sumamente importante para proporcionar los servicios mencionados anteriormente. La existencia de nodos anónimos y la falta de una autoridad centralizada capaz de monitorizar (y/o penalizar) a los nodos hace que estos sistemas sean más vulnerables que otros a comportamientos maliciosos por parte de los usuarios. Además, esos comportamientos inadecuados no pueden ser detectados proporcionando únicamente confidencialidad de los datos, autenticación de los nodos, no repudio, etc. Las redes P2P estructuradas deberían seguir las siguientes primitivas de enrutamiento seguro: (1) mantenimiento seguro de las tablas de enrutamiento, (2) enrutamiento seguro de los mensajes, and (3) asignación segura de las identidades. Pero la primera de los dos primitivas depende de alguna forma de la tercera. Si las identidades de los nodos pueden ser elegidas por sus usuarios sin ningún tipo de control, muy probablemente aparecerán muchos problemas de funcionamiento y seguridad. Por lo tanto, de la misma forma que otras redes y servicios, las redes P2P estructuradas requieren de un control de acceso robusto para prevenir la presencia de atacantes potenciales, y un sistema robusto de asignación de identidades para garantizar su adecuado funcionamiento. En esta tesis, primero de todo analizamos el funcionamiento de las redes P2P estructuradas basadas en el uso de DHTs (Tablas de Hash Distribuidas), cómo gestionan las identidades de sus nodos, identificamos qué problemas de seguridad están relacionados con la identificación de los nodos y proponemos una serie de requisitos para generar identificadores de forma segura. Más adelante proponemos el uso de certificados implícitos para proporcionar más seguridad y explotar las mejoras en consumo de ancho de banda, almacenamiento y rendimiento que proporcionan estos certificados en comparación con los certificados explícitos. También hemos diseñado tres protocolos de asignación segura de identidades, los cuales evitan la mayor parte de los problemas identificados mientras mantienen el anonimato de los usuarios y la trazabilidad. Finalmente hemos analizado el funcionamiento de la mayoría de los mecanismos utilizados para distribuir datos de revocación en Internet, con especial interés en los sistemas propuestos para operar en redes P2P, y hemos diseñado un nuevo mecanismo para distribuir datos de revocación de forma más eficiente en redes P2P estructuradas.Postprint (published version