This thesis deals with creating of decentralized peer to peer system designed for remote control of computers. P2P network and single nodes in this network is inspired by hybrid peer-to-peer network architecture used by Skype application. The application uses terminal services available in operation system Windows for remote control of computers. Namely, MS Remote Desktop and MS Remote Assistance is used. The entire application is created in programing language C#.

Made available in DSpace on 2016-06-02T19:06:28Z (GMT). No. of bitstreams: 1 DissMAS.pdf: 1097300 bytes, checksum: 0523c552783284a2613a52f0ce2a4cc1 (MD5) Previous issue date: 2005-08-19 / In this work the problem of the multimedia content distribution to a large number of computers is addressed. Specifically, we consider the problem of the server overloading that occurs due to the increase of the volume of requests to receive content. The consequence is the increase of response time and denial of service. As solution a communication model complementing the traditional client-serve is presented. It is based on the cooperative networks, where the clients cooperate to distribute the media, where they act as a kind of temporary server, until the server come back to a normal stage. Using such redirectioning scheme, the data networked traffic on server is decreased which alleviates its load. The proposed solution is shown in detail, pointing the modifications in the traditional model. / Neste trabalho discutimos o problema da distribuição de conteúdo multimídia para um grande número de computadores. Especificamente, consideramos o problema da sobrecarga do servidor, que ocorre devido ao rápido aumento do volume de requisições para receber conteúdo. Como conseqüência tem-se o aumento do tempo de resposta e até negação de serviço. Apresentamos como solução um modelo de comunicação para complementar o tradicional cliente-servidor. Ele é baseado nas redes cooperativas, onde os clientes cooperam para distribuir a mídia, fazendo com que eles atuem como uma espécie de servidor temporário a novos clientes. Com esse redirecionamento, reduz-se o tráfego no servidor, o que alivia a sua carga. A solução proposta é apresentada em detalhes, mostrando as modificações no sistema tradicional.

Com o advento da internet, surgem no campo da filantropia plataformas digitais que utilizam o poder de mobilização de indivíduos da web 2.0 para apoiar financeiramente projetos socioambientais. Esta dissertação tem por base as experiências da startup Eventos do Bem, que utiliza o método de angariação online Peer-to- Peer (P2P). A abordagem digital do método de captação de recursos P2P consiste na elaboração de campanhas promovidas por indivíduos online os quais podem utilizar seus eventos pessoais prol de uma causa social - como aniversários, casamentos entre outros - para mobilizar sua rede de contatos propondo que seus conhecidos doem para sua campanha ao invés de os presentearem no aniversário. As experiências na realização de campanhas digitais em prol de organizações sociais no referido empreendimento, elucubraram problemas relativos à performance financeira das campanhas. Logo, esta pesquisa foi realizada com o objetivo de propor diretrizes e práticas que potencializem o sucesso deste tipo de arrecadação online. Visto ser um modelo aplicado de forma pioneira no país, como metodologia, optou-se pela estratégia de estudos de caso múltiplos com base em YIN (1994) na qual, em conjunto com o estudo da startup Eventos do Bem, selecionou-se a plataforma estadunidense Charity:Water, referência em angariação P2P. Como unidades de análise, foram abordadas as campanhas de angariação realizadas em ambas as plataformas, focando na categoria de campanhas de aniversário. Logo, o trajeto desta pesquisa delineou-se nas fases: (a) análise da experiência da startup Eventos do Bem, em paralelo com a leitura do referencial teórico pertinente; (b) pesquisa e seleção da plataforma Charity:Water; (c) estudo e realização de 46 entrevistas, compondo-se em 6 entrevistas com funcionários do Charity:Water e 40 efetivadas com criadores de campanhas de aniversário em ambas as plataformas; (d) análise de fatores e práticas influenciadoras das campanhas promovidas nos casos abordados; (e) estudo cross- case e análise dos resultados obtidos. Como resultado da pesquisa, foi delineado um procedimento de boas práticas para potencializar a performance das campanhas digitais, destacando-se ações referentes à interação individual do criador da campanha com toda a sua rede de contatos, a persistência no pedido e a realização de um discurso do pedido de doação com qualidade, isto é, que apresente argumentos para persuadir doadores mais emocionais como também os mais racionais e lógicos. Desta forma, o estudo contribuiu para expandir o debate de captação de recursos online e aponta inovações da técnica P2P no que tange à mecânica do processo de decisão para doar e demonstra que a técnica pode fornecer resultados que vão além da angariação de recursos, estimulando maior engajamento social dos participantes. / With the advent of the Internet, philanthropy is emerging in digital platforms that use the mobilization power of web 2.0 individuals to financially support social and environmental projects. This dissertation is based on the experiences of the startup Eventos do Bem, which uses the Peer-to-Peer (P2P) online raising method. The digital approach of the P2P method of fundraising consists of the elaboration of campaigns promoted by individuals online who can use their personal events for a social cause - such as anniversaries, weddings and others - to mobilize their network of contacts by proposing that their acquaintances ache for their campaign instead of giving them on their birthday. The experiences in the accomplishment of digital campaigns in favor of social organizations in the mentioned enterprise, they have presented problems related to the financial performance of the campaigns. Therefore, this research was carried out with the objective of proposing guidelines and practices that will enhance the success of this type of online collection. As a model pioneered in the country, as a methodology, we chose the strategy of multiple case studies based on YIN (1994) in which, together with the study of the startup Eventos do Bem, we selected the platform American Charity: Water, reference in P2P fundraising. As units of analysis, the campaigns of raising were carried out in both platforms, focusing on the category of birthday campaigns.Therefore, the study\'s path was delineated in the phases: (a) analysis of the startup experience of the Good Events, in parallel with the reading of the relevant theoretical reference; (B) research and selection of the Charity: Water platform; (C) study and performance of 46 interviews, comprising 6 interviews with Charity: Water employees and 40 interviews with fundraisers on both platforms; (D) analysis of factors and practices influencing the campaigns promoted in the cases addressed; (E) cross-case study and analysis of the results obtained. As a result, a procedure of good practices was designed to potentiate fundraising P2P performance, highlighting actions regarding the individual interaction of the campaigner with his entire network of contacts, a persistence without request and realization of a speech of the Request Of giving with quality, is, and presents arguments to persuade donors more emotional as also the most rational and logical. In this way, the study contributed to expand the online fundraising debate and points out innovations of the P2P technique regarding the mechanics of the decision process to donate and demonstrates that the technique can provide results that go beyond fundraising, Stimulating greater social engagement of participants.

Concepts like peer-to-peer networks and distributed computing are not new. They have been available in different forms for a long time. This thesis examines the possibility of merging these concepts. The assumption is that non-centralized peer-to-peer networks can be used for effective sharing of computing resources. While most peer-to-peer systems today concentrate on sharing of data in various forms, this thesis concentrates on sharing of clock cycles instead of files.

Abstrakt: Den illegala fildelningen har blivit ett omdiskuterat ämne runt om i världen sedan fildelningstjänsten Napster skapades av unge Shawn Fanning. På senare år har flera nya fildelningstekniker utvecklas och upphovsrättskyddat material delas ut och laddas ner av hundratusentals tals personer runt om i Sverige. Syftet med rapporten är att ge en beskrivning av tekniker och lagar som tillämpas inom illegal fildelning. Samt att beskriva olika aktörer som figurerar inom den illegala fildelningen och vilka åtgärder de tillämpar för att fortsätta och skydda sin verksamhet. / Abstract: Illegal file sharing has become a hot topic around the world. The topic has been heavily discussed since the young Shawn Fanning created the file-sharing service Napster. In recent years many new file sharing technologies has been developed and copyrighted files is now shared and downloaded by hundreds of thousands of peoples in Sweden. The thesis purpose is to give a description of technology and laws which are applied in the area of illegal file sharing. And also to describe different actors which appear within the area of illegal file sharing and which measures they apply to continue and protect their activities.

We developed a diffusive load balancing scheme that equalizes the available capacities of nodes in a peer-to-peer (P2P) system. These nodes may have different resource capacities, geographic locations, or availabilities (i.e., length of time being part of the peer-to-peer system). The services on these nodes may have different service times and arrival rates of requests. Using the diffusive scheme, the system is able to maintain similar response times for its services. Our scheme is a modification of the diffusive load balancing algorithms proposed for parallel computing systems. This scheme is able to handle services with heterogeneous resource requirements and P2P nodes with heterogeneous capacities. We also adapted the diffusive scheme to clustered peer-to-peer system, where a load balancing operation may move services or nodes between clusters. After a literature survey of this field, this thesis investigates the following issues using analytical reasoning and extensive simulation studies. The load balancing operations equalize the available capacities of the nodes in a neighborhood to their averages. As a result, the available capacities of all nodes in the P2P system converge to a global average. We found that this convergence is faster when the scheme uses neighborhoods defined by the structure of the structured P2P overlay network rather than using randomly selected neighbors. For a system with churn (i.e. nodes joining and leaving), the load balancing operations maintain the standard deviation of the available capacities of nodes within a bound. This bound depends on the amount of churn and the frequency of load balancing operations, as well as on the capacities of the nodes. However, the sizes of the services have little impact on this bound. In a clustered peer-to-peer system, the size of the bound largely depends on the average cluster size. When nodes are moved among clusters for load balancing, the numbers of cluster splits and merges are reduced. This may reduce the maintenance cost of the overlay network.

Aus der Einleitung: "Neben „klassischen“ virtuellen Gemeinschaften, die einen gemeinsamen Netzort für die Interaktion benutzen und die auf technischer Ebene vornehmlich durch den Einsatz von Client-Server-Architekturen gekennzeichnet sind, lassen sich Gemeinschaftsformen identifizieren, deren Ursprung in vollkommen dezentralen Peer-to-Peer (P2P)-Netzen liegt. Diese P2P-Gemeinschaften haben in einigen Anwendungsgebieten wie dem Filesharing großen Erfolg [SF02]."

Um die ständig wachsenden Anforderungen zur Übertragung von Live Video Streams im Internet zu erfüllen werden kosteneffektive und resourceneffiziente Lösungen benötigt. Eine adäquate Lösung bietet die Peer-to-Peer (P2P) Streaming Architektur an, welche bereits heute in unterschiedlichsten Systemen zum Einsatz kommt. Solche Systeme erfordern von der Streaming Quelle nur moderate Bandbreiten, da die Nutzer (bzw. Peers) ihre eigene Bandbreite zur Verbreitung des Streams einbringen. Dazu werden die Peers oberhalb der Internetarchitektur zu einem Overlay verbunden. Das geplante Verlassen, sowie der ungewollte Absturz von Peers (genannt Churn) kann das Overlay schädigen und den Empfang einiger Peers unterbrechen. Weitaus kritischer sind Angriffe auf die Verfügbarkeit des Systems indem relevante Knoten des Overlays von Angreifern attackiert werden, um die Verteilung des Streams gezielt zu stören. Um Overlays zu konstruieren, die robust gegenüber Churn sind, nutzen so genannte pull-basierte P2P Streaming Systeme eine Mesh Topologie um jeden Peer über mehrere Pfade mit der Quelle zu verbinden. Peers fordern regelmäßig Teile des Videos, sog. Chunks, von ihren Partnern im Overlay an. Selbst wenn einige Partner plötzlich nicht mehr im System verfügbar sind kann ein Peer alle Chunks von den verbleibenden Nachbarn beziehen. Um dies zu ermöglichen tauschen Peers regelmäßig sog. Buffer Maps aus. Diese kleinen Pakete enthalten Informationen über die Verfügbarkeit von Chunks im Puffer eines Peers. Um dadurch entstehende Latenzen und den zusätzlichen Mehraufwand zu reduzieren wurden hybride Systeme entwickelt. Ein solches System beginnt pull-basiert und formt mit der Zeit einen Baum aus einer kleinen Untermenge aller Peers um Chunks ohne explizite Anfrage weiterzuleiten. Unglücklicherweise sind sowohl pull-basierte, als auch hybride Systeme anfällig gegenüber Denial-of-Service Angriffen (DoS). Insbesondere fehlen Maßnahmen zur Abschwächung von DoS Angriffen auf die Partner der Quelle. Die genannten Angriffe werden weiterhin dadurch erleichtert, dass die Identität der Quelle-nahen Knoten akkurat aus den ausgetauschten Buffer Maps extrahiert werden kann. Hybride Systeme sind außerdem anfällig für Angriffe auf den zugrundeliegenden Baum. Aufgrund der schwerwiegenden Auswirkungen von DoS Angriffen auf pull-basierte, sowie hybride Systeme stellen wir drei Gegenmaßnahmen vor. Zuerst entwickeln wir das Striping Schema zur Abschwächung von DoS Angriffen auf die Partner der Quelle. Hierbei werden Peers dazu angeregt ihre Chunk-Anfragen an unterschiedliche Partner zu senden. Als zweites entwickeln wir das SWAP Schema, welches Peers dazu bringt proaktiv ihre Partner zu wechseln um Angreifer daran zu hindern die Quellenahe zu identifizieren. Als drittes entwickeln wir RBCS, einen widerstandsfähigen Baum zur Abschwächung von DoS Angriffen auf hybride Systeme. Da bisher kein Simulator für die faire Evaluation von P2P-basierten Live Video Streaming Algorithmen verfügbar war, entwickeln wir OSSim, ein generalisiertes Simulations-Framework für P2P-basiertes Video Streaming. Des weiteren entwickeln wir etliche Angreifermodelle sowie neuartige Resilienzmetriken on OSSim. Ausgiebige Simulationsstudien zeigen, dass die entwickelten Schemata signifikant die Widerstandsfähigkeit von pull-basierten und hybriden Systemen gegenüber Churn und DoS Angriffen erhöhen. / The constantly growing demand to watch live videos over the Internet requires streaming systems to be cost-effective and resource-efficient. The Peer-to-Peer (P2P) streaming architecture has been a viable solution with various deployed systems to date. The system only requires a modest amount of bandwidth from the streaming source, since users (or peers) contribute their bandwidth to disseminate video streams. To enable this, the system interconnects peers into an overlay. However, churn–meaning the leaving and failing of peers–can break the overlay, making peers unable to receive the stream. More severely, an adversary aiming to sabotage the system can attack relevant nodes on the overlay, disrupting the stream delivery. To construct an overlay robust to churn, pull-based P2P streaming systems use a mesh topology to provide each peer with multiple paths to the source. Peers regularly request video chunks from their partners in the overlay. Therefore, even if some partners are suddenly absent, due to churn, a peer still can request chunks from its remaining partners. To enable this, peers periodically exchange buffer maps, small packets containing the availability information of peers’ video buffers. To reduce latency and overhead caused by the periodic buffer map exchange and chunk requests, hybrid systems have been proposed. A hybrid system bootstraps from a pull-based one and gradually forms a tree backbone consisting of a small subset of peers to deliver chunks without requests. Unfortunately, both pull-based and hybrid systems lack measures to mitigate Denial-of-Service (DoS) attacks on head nodes (or the source’s partners). More critically, they can be identified accurately by inferring exchanged buffer maps. Furthermore, hybrid systems are vulnerable to DoS attacks on their backbones. Since DoS attacks can badly affect both pull-based and hybrid systems, we introduce three countermeasures. First, we develop the striping scheme to mitigate DoS attacks targeting head nodes. The scheme enforces peers to diversify their chunk requests. Second, to prevent attackers from identifying head nodes, we develop the SWAP scheme, which enforces peers to proactively change their partners. Third, we develop RBCS, a resilient backbone, to mitigate DoS attacks on hybrid systems. Since a simulator for a fair evaluation is unavailable so far, we develop OSSim, a general-purpose simulation framework for P2P video streaming. Furthermore, we develop several attacker models and novel resilience metrics in OSSim. Extensive simulation studies show that the developed schemes significantly improve the resilient of pull-based and hybrid systems to both churn and DoS attacks.

Grades computacionais oportunistas utilizam recursos ociosos de máquinas compartilhadas para executar aplicações que necessitam de um alto poder computacional e/ou trabalham com grandes quantidades de dados. Mas a execução de aplicações paralelas computacionalmente intensivas em ambientes dinâmicos e heterogêneos, como grades computacionais oportunistas, é uma tarefa difícil. Máquinas podem falhar, ficar inacessíveis ou passar de ociosas para ocupadas inesperadamente, comprometendo a execução de aplicações. Um mecanismo de tolerância a falhas que dê suporte a arquiteturas heterogêneas é um importante requisito para estes sistemas. Neste trabalho, analisamos, implementamos e avaliamos um mecanismo de tolerância a falhas baseado em checkpointing para aplicações paralelas em grades computacionais oportunistas. Este mecanismo permite o monitoramento de execuções e a migração de aplicações entre nós heterogêneos da grade. Mas além da execução, é preciso gerenciar e armazenar os dados gerados e utilizados por estas aplicações. Desejamos uma infra-estrutura de armazenamento de dados de baixo custo e que utilize o espaço livre em disco de máquinas compartilhadas da grade. Devemos utilizar somente os ciclos ociosos destas máquinas para armazenar e recuperar dados, de modo que um sistema de armazenamento distribuído que as utilize deve ser redundante e tolerante a falhas. Para resolver o problema do armazenamento de dados em grades oportunistas, projetamos, implementamos e avaliamos o middleware OppStore. Este middleware provê armazenamento distribuído e confiável de dados, que podem ser acessados de qualquer máquina da grade. As máquinas são organizadas em aglomerados, que são conectados por uma rede peer-to-peer auto-organizável e tolerante a falhas. Dados são codificados em fragmentos redundantes antes de serem armazenados, de modo que arquivos podem ser reconstruídos utilizando apenas um subconjunto destes fragmentos. Finalmente, para lidar com a heterogeneidade dos recursos, desenvolvemos uma extensão ao protocolo de roteamento em redes peer-to-peer Pastry. Esta extensão adiciona balanceamento de carga e suporte à heterogeneidade de máquinas ao protocolo Pastry. / Opportunistic computational grids use idle resources from shared machines to execute applications that need large amounts of computational power and/or deal with large amounts of data. But executing computationally intensive parallel applications in dynamic and heterogeneous environments, such as opportunistic grids, is a daunting task. Machines may fail, become inaccessible, or change from idle to occupied unexpectedly, compromising the application execution. A fault tolerance mechanism that supports heterogeneous architectures is an important requisite for such systems. In this work, we analyze, implement and evaluate a checkpointing-based fault tolerance mechanism for parallel applications running on opportunistic grids. The mechanism monitors application execution and allows the migration of applications between heterogeneous nodes of the grid. But besides application execution, it is necessary to manage data generated and used by those applications. We want a low cost data storage infrastructure that utilizes the unused disk space of grid shared machines. The system should use the machines to store and recover data only during their idle periods, requiring the system to be redundant and fault-tolerant. To solve the data storage problem in opportunistic grids, we designed, implemented and evaluated the OppStore middleware. This middleware provides reliable distributed storage for application data, which can be accessed from any machine in the grid. The machines are organized in clusters, connected by a self-organizing and fault-tolerant peer-to-peer network. During storage, data is codified into redundant fragments, allowing the reconstruction of the original file using only a subset of those fragments. Finally, to deal with resource heterogeneity, we developed an extension to the Pastry peer-to-peer routing substrate, enabling heterogeneity-aware load-balancing message routing.

Made available in DSpace on 2016-04-04T18:31:21Z (GMT). No. of bitstreams: 1 Paulo da Costa.pdf: 1562833 bytes, checksum: 074d86d4ee46703de7c27efeee0966e5 (MD5) Previous issue date: 2008-02-15 / The Internet is one of the most important sources for content and services to which the simple user has become an important collaborator. With the bandwidth improvements in the upload and download transfer rates we realize the peer-to-peer (P2P) communications is growing fast in Brazil. The evolution of the peer-to-peer leads to a scenario where the client-server model will be replaced to a peer-to-peer model with multiple peers over the web. The purpose of this study is to report the evolution of the internet in Brazil, showing the actual scenario and making predictions considering the evolution of the technology and the use of the web in different scenarios, focusing in the peer-to-peer model. During the development of this study, some statistic methods will be used, such as the Gompertz and the linear regression methods to create predictions to be used in the decision making process. Analysis of the results according to quantitative researches done by researches institutes, provide the integration between the presented technique and the performed procedures. / A Internet ? atualmente uma das principais fontes de distribui??o de conte?dos e servi?os em ambientes abertos, da qual o usu?rio comum vem se tornando cada vez mais um importante fornecedor. Com o crescente aumento das taxas de transmiss?o para upload e download que s?o oferecidas pelas operadoras para os usu?rios comuns, ? poss?vel ter uma indica??o de que o modelo de comunica??o peer-to-peer (P2P) caminha para o crescimento. Este modelo, que j? tem sido amplamente utilizado, indica para o futuro um panorama onde o modelo cliente-servidor tende a ser superado pelo modelo peer-to-peer e com a tend?ncia da ado??o de um modelo com m?ltiplos peer-to-peer. O prop?sito deste trabalho ? analisar a evolu??o de demanda da Internet e em especial deste modelo no cen?rio brasileiro, identificando e detalhando seu panorama atual e com predi??es de como ser? em futuro pr?ximo, tomando como base par?metros de evolu??o tecnol?gica e uso da Internet em diversos cen?rios. Ser?o utilizados os m?todos estat?sticos de regress?o linear e Gompertz para gerar as previs?es de demanda como apoio para tomadas de decis?es. An?lises dos resultados com pesquisas quantitativas feitas por institutos de pesquisa fazem a integra??o entre a t?cnica apresentada e os procedimentos executados.