2,465 research outputs found
Practical issues for the implementation of survivability and recovery techniques in optical networks
Ein analytisches Framework zur Bewertung der Zuverlässigkeit und Security von fortschrittlichen Netzwerk Systemen
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
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Social network support for data delivery infrastructures
Network infrastructures often need to stage content so that it is accessible to consumers. The standard solution, deploying the content on a centralised server, can be inadequate in several situations.
Our thesis is that information encoded in social networks can be used to tailor content staging decisions to the user base and thereby build better data delivery infrastructures. This claim is supported by two case studies, which apply social information in challenging situations where traditional content staging is infeasible. Our approach works by examining empirical traces to identify relevant social properties, and then exploits them.
The first study looks at cost-effectively serving the ``Long Tail'' of rich-media user-generated content, which need to be staged close to viewers to control latency and jitter. Our traces show that a preference for the unpopular tail items often spreads virally and is localised to some part of the social network. Exploiting this, we propose Buzztraq, which decreases replication costs by selectively copying items to locations favoured by viral spread. We also design SpinThrift, which separates popular and unpopular content based on the relative proportion of viral accesses, and opportunistically spins down disks containing unpopular content, thereby saving energy.
The second study examines whether human face-to-face contacts can efficiently create paths over time between arbitrary users. Here, content is staged by spreading it through intermediate users until the destination is reached. Flooding every node minimises delivery times but is not scalable. We show that the human contact network is resilient to individual path failures, and for unicast paths, can efficiently approximate flooding in delivery time distribution simply by randomly sampling a handful of paths found by it. Multicast by contained flooding within a community is also efficient. However, connectivity relies on rare contacts and frequent contacts are often not useful for data delivery.
Also, periods of similar duration could achieve different levels of connectivity; we devise a test to identify good periods. We finish by discussing how these properties influence routing algorithms.This work was supported by a St. John's College Benefactor's Scholarship and a Research Studentship from the Cambridge Philosophical Society
ENTERPRISE SECURITY ANALYSIS INCLUDING DENIAL OF SERVICE COUNTERMEASURES
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]
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Global Data Plane: A Widely Distributed Storage and Communication Infrastructure
With the advancement of technology, richer computation devices are making their way into everyday life. However, such smarter devices merely act as a source and sink of information; the storage of information is highly centralized in data-centers in today’s world. Even though such data-centers allow for amortization of cost per bit of information, the density and distribution of such data-centers is not necessarily representative of human population density. This disparity of where the information is produced and consumed vs where it is stored only slightly affects the applications of today, but it will be the limiting factor for applications of tomorrow.The computation resources at the edge are more powerful than ever, and present an opportunity to address this disparity. We envision that a seamless combination of these edge-resources with the data-center resources is the way forward. However, the resulting issues of trust and data-security are not easy to solve in a world full of complexity. Toward this vision of a federated infrastructure composed of resources at the edge as well as those in data-centers, we describe the architecture and design of a widely distributed system for data storage and communication that attempts to alleviate some of these data security challenges; we call this system the Global Data Plane (GDP).The key abstraction in the GDP is a secure cohesive container of information called a DataCapsule, which provides a layer of uniformity on top of a heterogeneous infrastructure. A DataCapsule represents a secure history of transactions in a persistent form that can be used for building other applications on top. Existing applications can be refactored to use DataCapsules as the ground truth of persistent state; such a refactoring enables cleaner application design that allows for better security analysis of information flows. Not only cleaner design, the GDP also enables locality of access for performance and data privacy—an ever growing concern in the information age.The DataCapsules are enabled by an underlying routing fabric, called the GDP network, which provides secure routing for datagrams in a flat namespace. The GDP network is a core component of the GDP that enables various GDP components to interact with each other. In addition to the DataCapsules, this underlying network is available to applications for native communication as well. Flat namespace networks are known to provide a number of desirable properties, such as location independence, built-in multicast, etc. However, existing architectures for such networks suffer from routing security issues, typically because malicious entities can claim to possess arbitrary names and thus, receive traffic intended for arbitrary destinations. GDP network takes a different approach by defining an ownership of the name and the associated mechanisms for participants to delegate routing for such names to others. By directly integrating with GDP network, applications can enjoy the benefits of flat namespace networks without compromising routing security.The Global Data Plane and DataCapsules together represent our vision for secure ubiquitous storage. As opposed to the current approach of perimeter security for infrastructure, i.e. drawing a perimeter around parts of infrastructure and trusting everything inside it, our vision is to use cryptographic tools to enable intrinsic security for the information itself regardless of the context in which such information lives. In this dissertation, we show how to make this vision a reality, and how to adapt real world applications to reap the benefits of secure ubiquitous storage
BALANCING PRIVACY, PRECISION AND PERFORMANCE IN DISTRIBUTED SYSTEMS
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
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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