2,465 research outputs found

    Ein analytisches Framework zur Bewertung der Zuverlässigkeit und Security von fortschrittlichen Netzwerk Systemen

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    Today, anonymous networks such as The Onion Routing (Tor) have been designed to ensure anonymity, privacy and censorship prevention, which have become major concerns in modern society. Although the Tor network provides layered encryption and traffic tunneling against eavesdropping attacks, the jamming attacks and their impact on the network and network services can not be efficiently handled today. Moreover, to defy modern censorship, it is not enough just to use the Tor network to hide the client's identity and the message content as the censorship has become a type of jamming attack, which prevents users from connecting to the censored network nodes by blocking or jamming (Tor) traffic. In network security, the main tools to protect privacy and anonymity as well as integrity and service reliability against eavesdropping and jamming, respectively, are diversity, randomness, coding or encryption and over-provisioning, all less exploit in traditional networks. This thesis provides radical new network concepts to address the needs of traditional networks for privacy, anonymity, integrity, and reliability; and designs \emph{advanced network systems} based on parallel transmission, random routing, erasure coding and redundant configurations as tools to offer diversity, randomness, coding and over-provisioning. Since the network systems designed in this thesis can not be evaluated with existing analytical models due to their rather complex configurations, the main focus of this work is a development of novel analytical approaches for evaluation of network performance, reliability and security of these systems and to show their practicality. The provided analysis is based on combinatorics, probability and information theory. In contrast to current reliability models, the analysis in this thesis takes into account the sharing of network components, heterogeneity of software and hardware, and interdependence between failed components. The significant property of the new security analysis proposed is the ability to assess the level of privacy, anonymity, integrity and censorship success when multiple jamming and eavesdropping adversaries reside in the network.Derzeit werden anonyme Internet Kommunikationssysteme, wie The Onion Routing (Tor), verwendet, um die Anonymität, die Privatsphäre und die Zensurfreiheit der Internetnutzer zu schützen. Obwohl das Tor-Netzwerk einen Schutz vor Lauschangriffe (Eavesdropping) bietet, kann ein beabsichtigtes Stören (Jamming) der Übertragung und den daraus resultierenden Auswirkungen auf die Netzwerkfunktionen derzeit nicht effektiv abgewehrt werden. Auch das moderne Zensurverfahren im Internet stellt eine Art des Jammings dar. Deswegen kann das Tor Netzwerk zwar die Identität der Tor-Nutzer und die Inhalte ihrer Nachrichten geheim halten, die Internetzensur kann dadurch nicht verhindert werden. Um die Netzwerksicherheit und insbesondere Anonymität, Privatsphäre und Integrität zusammen mit der Verfügbar.- und Zuverlässigkeit von Netzwerkservices zu gewährleisten, sind Diversität, Zufallsprinzip, Codierung (auch Verschlüsselung) und eine Überversorgung, die in den konventionellen Netzwerksystemen eher sparsam angewendet werden, die wichtigsten Mittel gegen Security-Angriffe. Diese Arbeit befasst sich mit grundlegend neuen Konzepten für Kommunikationsnetze, die einen Schutz der Anonymität und der Privatsphäre im Internet bei gleichzeitiger Sicherstellung von Integrität, Verfügbarkeit und Zuverlässigkeit ermöglichen. Die dabei verwendeten Konzepte sind die parallele Datenübertragung, das Random Routing, das Erasure Coding und redundante Systemkonfigurationen. Damit sollen Diversität, Zufallsprinzip, Codierung und eine Überversorgung gewährleistet werden. Da die entwickelten Übertragungssysteme komplexe Strukturen und Konfigurationen aufweisen, können existierende analytische Modelle nicht für eine fundierte Bewertung angewendet werden. Daher ist der Schwerpunkt dieser Arbeit neue analytische Verfahren für eine Bewertung von unterschiedlichen Netzwerkleistungsparametern, Zuverlässigkeit und Security zu entwickeln und die Praxistauglichkeit der in der Arbeit aufgeführten neuen Übertragungskonzepte zu beurteilen. Im Gegensatz zu existierenden Zuverlässigkeitsmodellen berücksichtigt der analytische Ansatz dieser Arbeit die Vielfalt von beteiligten Netzwerkkomponenten, deren komplexe Zusammenhänge und Abhängigkeiten im Fall eines Ausfalls

    ENTERPRISE SECURITY ANALYSIS INCLUDING DENIAL OF SERVICE COUNTERMEASURES

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    Computer networks are the nerve systems of modern enterprises. Unfortunately, these networks are subject to numerous attacks. Safeguarding these systems is challenging. In this thesis we describe current threats to enterprise security, before concentrating on the Distributed denial of Service (DDoS) problem. DDoS attacks on popular websites like Amazon, Yahoo, CNN, eBay, Buy, and the recent acts of war using DDoS attacks against NATO ally Estonia [1] graphically illustrate the seriousness of these attacks. Denial of Service (DoS) attacks are explicit attempts to block legitimate users\u27 system access by reducing system availability [2]. A DDoS attack deploys multiple attacking entities to attain this goal [3]. Unfortunately, DDoS attacks are difficult to prevent and the solutions proposed to date are insufficient. This thesis uses combinatorial game theory to analyze the dynamics of DDoS attacks on an enterprise and find traffic adaptations that counter the attack. This work builds on the DDoS analysis in [4]. The approach we present designs networks with a structure that either resists DDoS attacks, or adapts around them. The attacker (Red) launches a DDoS on the distributed application (Blue). Both Red and Blue play an abstract board game defined on a capacitated graph, where nodes have limited CPU capacities and edges have bandwidth constraints. Our technique provides two important results that aid in designing DDoS resistant systems: 1.It quantifies the resources an attacker needs to disable a distributed application. The design alternative that maximizes this value will be the least vulnerable to DDoS attacks. 2.When the attacker does not have enough resources to satisfy the limit in 1, we provide near optimal strategies for reconfiguring the distributed application in response to attempted DDoS attacks. Our analysis starts by finding the feasible network configurations for Blue that satisfy its computation and communications requirements. The min-cut sets [5] of these configurations are the locations most vulnerable to packet flooding DDoS attacks. Red places \u27zombie\u27 processes on the graph that consume network bandwidth. Red attempts to break Blue communications links. Blue reconfigures its network to re-establish communications. We analyze this board game using the theory of surreal numbers [6]. If Blue can make the game \u27loopy\u27 (i.e. move to one of its previous configurations), it wins [7]. If Red creates a situation where Blue can not successfully reconfigure the network, it wins. In practice, each enterprise relies on multiple distributed processes. Similarly, an attacker can not expect to destroy all of the processes used by the enterprise at any point in time. The attacker will try to maximize the number of processes it can disable at any point in time. This situation describes a \u27sum of games\u27 problem [6], where Blue and Red alternate moves. We adapt Berlekamp\u27s strategies for Go endgames, to tractably find near optimal reconfiguration regimes for this P-Space complete problem [6], [7]

    BALANCING PRIVACY, PRECISION AND PERFORMANCE IN DISTRIBUTED SYSTEMS

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    Privacy, Precision, and Performance (3Ps) are three fundamental design objectives in distributed systems. However, these properties tend to compete with one another and are not considered absolute properties or functions. They must be defined and justified in terms of a system, its resources, stakeholder concerns, and the security threat model. To date, distributed systems research has only considered the trade-offs of balancing privacy, precision, and performance in a pairwise fashion. However, this dissertation formally explores the space of trade-offs among all 3Ps by examining three representative classes of distributed systems, namely Wireless Sensor Networks (WSNs), cloud systems, and Data Stream Management Systems (DSMSs). These representative systems support large part of the modern and mission-critical distributed systems. WSNs are real-time systems characterized by unreliable network interconnections and highly constrained computational and power resources. The dissertation proposes a privacy-preserving in-network aggregation protocol for WSNs demonstrating that the 3Ps could be navigated by adopting the appropriate algorithms and cryptographic techniques that are not prohibitively expensive. Next, the dissertation highlights the privacy and precision issues that arise in cloud databases due to the eventual consistency models of the cloud. To address these issues, consistency enforcement techniques across cloud servers are proposed and the trade-offs between 3Ps are discussed to help guide cloud database users on how to balance these properties. Lastly, the 3Ps properties are examined in DSMSs which are characterized by high volumes of unbounded input data streams and strict real-time processing constraints. Within this system, the 3Ps are balanced through a proposed simple and efficient technique that applies access control policies over shared operator networks to achieve privacy and precision without sacrificing the systems performance. Despite that in this dissertation, it was shown that, with the right set of protocols and algorithms, the desirable 3P properties can co-exist in a balanced way in well-established distributed systems, this dissertation is promoting the use of the new 3Ps-by-design concept. This concept is meant to encourage distributed systems designers to proactively consider the interplay among the 3Ps from the initial stages of the systems design lifecycle rather than identifying them as add-on properties to systems

    NetGlance NMS - An integrated network monitoring system

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    Mestrado de dupla diplomação com a Kuban State Agrarian UniversityThis work is about IT infrastructure and, in particular, computer networks in KubSAU and IPB. Also, it is about a network monitoring system “NetGlance NMS” developed for KubSAU System Administration Department. Work objective is to optimize the information structure for KubSAU and IPB. During the work, following tasks were completed: Research the existing IPB information structure, Compare the information structure for KubSAU and IPB, Model the IPB computer network (topology, services), Research bottlenecks and potential pitfalls in the data-center and in the computer network of IPB, Research information security mechanisms in the computer network of IPB, Organize monitoring process for the computer network in KubSAU. The most important impact of the work is an increasing network productivity and user experience as a result of creation and deploy a monitoring software.O trabalho descrito no âmbito desta dissertação incide sobre a infraestrutura TI e, em particular, sobre as redes de computadores da KubSAU e do IPB. Além disso, descreve-se um sistema de gestão integrada de redes, designada “NetGlance NMS”, desenvolvido para o Departamento de Administração de Sistemas da KubSAU. O objetivo do trabalho é desenvolver uma ferramenta para otimizar a gestão da estrutura de comunicações das duas instituições. Durante o trabalho, as seguintes tarefas foram concluídas: levantamento da estrutura de comunicações do IPB, comparação da estrutura de comunicações entre a KubSAU e o IPB, modelação da rede de comunicações do IPB (topologia, serviços), estudo de possíveis estrangulamentos no datacenter e na rede de comunicações doIPB, estudo de mecanismos de segurança na rede de comunicações do IPB, organização do processo de monitorização da rede de comunicações da KubSAU. O contributo mais relevante deste trabalho é o desenvolvimento de uma aplicação de gestão integrada de redes, de forma a contribuir para o aumento da produtividade da rede e da experiência dos utilizadores
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