nÃo hà / MyGSI à uma proposta de arquitetura de seguranÃa para ambientes de grades peer-to-peer. Utilizando mecanismos de autenticaÃÃo, controle de acesso e delegaÃÃo de direitos de acesso, MyGSI permite a troca de informaÃÃes e o compartilhamento de recursos de forma segura atravÃs de trÃs mÃdulos: MyAuth, MyAC e MyDel. MyAuth à o mÃdulo responsÃvel pela autenticaÃÃo utilizando a infra-estrutura de chaves pÃblicas. MyAC à o mÃdulo responsÃvel pelo controle de acesso e permite o gerenciamento descentralizado de polÃticas de controle de acesso. MyDel à o mÃdulo responsÃvel pelo processo de delegaÃÃo de direitos de acesso atravÃs de correntes de certificados. MyGSI foi desenvolvido na linguagem JAVA e integrado na grade OurGrid. O processo de integraÃÃo de MyGSI com o OurGrid, alguns cenÃrios de uso e os resultados desta integraÃÃo tambÃm sÃo apresentados nesta dissertaÃÃo. / MyGSI is a proposal of security architecture for peer-to-peer grid environments. MyGSI uses authentication mechanisms, access control and delegation of access rights. MyGSI allows the exchange of information in secure mode, and is composed of three modules: MyAuth, MyAC and MyDel. MyAuth uses public key infrastructure to deal with authentication. MyAC deals with access control, allowing a decentralized access control policies management. MyDel deals with the delegation of access rights implemented through certified chains. MyGSI was developed in JAVA and was integrated to OurGrid successfully. Some examples and results of this integration are also presented

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.

We present a distributed data structure, which we call "RootChord". To our knowledge, this is the first distributed hash table which is able to adapt to changes in the size of the network and answer lookup queries within a guaranteed two hops while maintaining a routing table of size Theta(sqrt(N)). We provide pseudocode and analysis for all aspects of the protocol including routing, joining, maintaining, and departing the network. In addition we discuss the practical implementation issues of parallelization, data replication, remote procedure calls, dead node discovery, and network convergence.

We present a distributed data structure, which we call "RootChord". To our knowledge, this is the first distributed hash table which is able to adapt to changes in the size of the network and answer lookup queries within a guaranteed two hops while maintaining a routing table of size Theta(sqrt(N)). We provide pseudocode and analysis for all aspects of the protocol including routing, joining, maintaining, and departing the network. In addition we discuss the practical implementation issues of parallelization, data replication, remote procedure calls, dead node discovery, and network convergence.

In this thesis, the problems caused by peer behavior in peer-to-peer (P2P) video streaming is investigated. First, peer behaviors are modeled using two dimensional continuous time markov chains to investigate the reliability of P2P video streaming systems. Then a metric is proposed to evaluate the dynamic behavior and evolution of P2P overlay network. Next, a hybrid geographical location-time and interest based clustering algorithm is proposed to improve the success ratio and reduce the delivery time of required content. Finally, Hybrid Fault Tolerant Video Streaming System (HFTS) over P2P networks has been designed and offered conforming the required Quality of Service (QoS) and Fault Tolerance. The results indicate that the required QoS can be achieved in streaming video applications using the proposed hybrid approach.

In this thesis I describe my research activities and results of the last 4 years. I also provide an outlook and guidelines on how to proceed with our project, that we named SEDNS - Security-Enhanced Domain Name System. This project’s ambitions are to complement DNS, the Domain Name System, in a way that allows us to keep using it in the future. The main reason for this strategy is, that it has proven to be difficult to change any part of the Internet infrastructure, such as parts of the protocols stack or well established Internet authorities, like ICANN or IANA. The main problems of DNS are twofold. (1) The DNS protocol does not contain any measures to prevent data from being tampered with. (2) Furthermore, it is difficult to configure DNS correctly since most of the configuration is done within the DNS data itself, e.g., delegating authority. It is well known that DNS problems lead to reduced availability of Internet-based services in many different ways. In this thesis, I present four main results. All of them contribute to improvements and deeper understanding of DNS’ dependability issues. First, I discuss, how well established cryptographic tools can be used to enhance DNS’ security without getting into the same problems that prevent DNSSEC from being globally deployed. These problems are explained as well. This is an important topic for the Internet and DNS community, since at the moment most of the protocol improvements are connected to DNSSEC. Second, I thoroughly discuss the technique that was used in the recent years to overcome any problems related to client-server architectures, i.e., peer-to-peer systems. Such solutions have been proposed to improve DNS’ availability and reduce configuration effort. I show, that those systems do not keep up with the expectations, neither as client side tools nor as server infrastructure replacement. To reach this conclusion, a novel DHT scheme has been developed. The evaluation of it is shown as well. Third, results of our DNS data mining show that it is useful to improve the quality of DNS data and therefore, to protect clients from malicious or erroneous information. And fourth, an outlook is presented, which combines all the results of the first three points to suggest an architecture that indeed can improve our supply with DNS data, omitting the shortcomings of the classical client-server-architecture and its peer-to-peer replacements. Note, that although the development of future DNS standards and protocols is subject to political struggle, e.g., on whether or not an international organization should maintain the root zone instead of the USA, this thesis focuses only on technical aspects. / In dieser Dissertation beschreibe ich meine Forschungsaktivitäten und Ergebnisse der letzten 4 Jahre. Ich gebe auch einen Ausblick und Hinweise, wie unser Project, das wir SEDNS - Security-Enhanced Domain Name System genannt haben, fortgesetzt werden sollte. Die Ambitionen dieses Projektes sind, DNS, das Domain Name System, zu in einer Art und Weise zu erweitern, die es uns erlauben soll, dieses System auch in der Zukunft weiter zu benutzen. Der Hauptgrund für diese Strategie ist, dass es sich in der Vergangenheit als schwierig erwiesen hat, Teile der Internet-Infrastruktur, wie zum Beispiel Teile des Protokollstapels oder gut etablierte Internet-Behörden wie ICANN oder IANA, zu ändern bzw. auszutauschen. Daher wollen wir nicht versuchen, DNS komplett zu ersetzen. DNS hat zwei Hauptprobleme: (1) Das DNS Protokoll bietet keinerlei Möglichkeiten, Daten vor Verfälschung zu schützen, und (2) es ist schwierig, DNS korrekt zu konfigurieren, weil ein Großteil der Konfiguration direkt innerhalb der DNS Daten selbst stattfindet, wie zum Beispiel die Delegation von Verantwortungsbereichen, und diese oft nicht global konsistent und korrekt sind. Diese Probleme sind umso bedeutender, weil es allgemein bekannt ist, dass DNS Probleme auf verschiedene Art und Weisen zu reduzierter Verfügbarkeit von wichtigen Internet-basierten Diensten führen. In dieser Arbeit präsentiere ich vier Hauptergebnisse. Zuerst diskutiere ich, wie gut etablierte kryptographische Werkzeuge benutzt werden können um die Sicherheit von DNS zu verbessern, ohne dabei auf dieselben Probleme zu stoßen, die DNSSEC davon abhalten, weltweit benutzt zu werden. Diese Probleme werden dabei erläutert. Es handelt sich dabei um ein wichtiges Thema für die Internet- und DNS-Community, weil im Moment die meisten Weiterentwicklungen des DNS Protokolls mit DNSSEC zusammenhängen. Als zweites diskutiere ich im Detail die Technik, die in den vergangenen Jahren benutzt wurde um Probleme beliebiger Client-Server Anwendungen zu überwinden: Peer-to-Peer Systeme. Derartige Lösungen wurden vorgeschlagen, um DNS' Verfügbarkeit zu verbessern und Konfigurationsaufwand zu reduzieren. Ich zeige allerdings, dass solche Lösungen nicht die in sie gesetzten Erwartungen erfüllen, weder als Client-seitige Tools noch als Ersatz für die Server-Infrastruktur. Um diesen Schluss zu ziehen, wurde ein neues, auf die Bedürfnisse von DNS zugeschnittenes DHT Schema entwickelt und evaluiert im Vergleich zu DNS und existierenden Systemen. Als drittes werden DNS Data Mining Ergebnisse präsentiert, die zeigen, wie sinnvoll es ist, die Qualität der DNS Daten zu verbessern, und somit Clients vor bösartigen oder fehlerhaften Informationen zu schützen. Als viertes wird ein Ausblick präsentiert, der die Ergebnisse der vorherigen drei Punkte kombiniert und eine Architektur vorschlägt, die unsere Versorgung mit DNS Daten tatsächlich verbessern kann und die Nachteile der klassischen Client-Server-Architektur und ihrer Peer-to-Peer Nachfolger vermeidet. Zu beachten ist, dass obwohl die Entwicklung zukünftiger DNS Standards und Protokolle Gegenstand politischer Konflikte ist, z.B. darüber ob anstelle der USA eine internationale Organisation die Root-Zone verwalten sollte, diese Arbeit nur auf die technischen Aspekte ausgerichtet ist.

<p>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.</p> / <p>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.</p><p>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.</p>

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.

Zugl.: Hamburg, Techn. Univ., Diss., 2008

Zugl.: Düsseldorf, Universiẗat, Diss.