The role of topology and contracts in internet content delivery

The Internet depends on economic relationships between ASes (Autonomous Systems), which come in different shapes and sizes - transit, content, and access networks. CDNs (Content delivery networks) are also a pivotal part of the Internet ecosystem and construct their overlays for faster content delivery. With the evolving Internet topology and traffic growth, there is a need to study the cache deployments of CDNs to optimize cost while meeting performance requirements. The bilateral contracts enforce the routing of traffic between neighbouring ASes and are applied recursively: traffic that an AS sends to its neighbour is then controlled by the contracts of that neighbour. The lack of routing flexibility, little control over the quality of the end-to-end path are some of the limitations with the existing bilateral model, and they need to be overcome for achieving end-to-end performance guarantees. Furthermore, due to general reluctance of ASes to disclose their interconnection agreements, inference of inter-AS economic relationships depend on routing and forwarding data from measurements. Since the inferences are imperfect, this necessitates building robust algorithmic strategies to characterize ASes with a significantly higher accuracy. In this thesis, we first study the problem of optimizing multi-AS deployments of CDN caches in the Internet core. Our work is of significant practical relevance since it formalizes the planning process that all CDN operators must follow to reduce the operational cost of their overlay networks, while meeting the performance requirements of their end users. Next, we focus on developing a temporal cone (TC) algorithm that detects PFS (Provider-free ASes). By delivering a significant portion of Internet traffic, PFS is highly relevant to the overall resilience of the Internet. We detect PFS from public datasets of inter-AS economic relationships, utilizing topological statistics (customer cones of ASes) and temporal diversity. Finally, we focus on a multilateral contractual arrangement and develop algorithms for optimizing the cost of transit and access ASes. In particular, we implement Bertsekas auction algorithm for the optimal cost assignment of access ASes to transit ASes. Furthermore, we implement an epsilon-greedy bandit algorithm for optimizing the price of transit ASes and show its learning potential.This work has been supported by IMDEA Networks Institute.Programa Oficial de Doctorado en Ingeniería TelemáticaPresidente: Jordi Domingo Pascual.- Secretario: Francisco Valera Pintor.- Vocal: Pedro Andrés Aranda Gutiérre

Routing-Verification-as-a-Service (RVaaS): Trustworthy Routing Despite Insecure Providers

Computer networks today typically do not provide any mechanisms to the users to learn, in a reliable manner, which paths have (and have not) been taken by their packets. Rather, it seems inevitable that as soon as a packet leaves the network card, the user is forced to trust the network provider to forward the packets as expected or agreed upon. This can be undesirable, especially in the light of today's trend toward more programmable networks: after a successful cyber attack on the network management system or Software-Defined Network (SDN) control plane, an adversary in principle has complete control over the network. This paper presents a low-cost and efficient solution to detect misbehaviors and ensure trustworthy routing over untrusted or insecure providers, in particular providers whose management system or control plane has been compromised (e.g., using a cyber attack). We propose Routing-Verification-as-a-Service (RVaaS): RVaaS offers clients a flexible interface to query information relevant to their traffic, while respecting the autonomy of the network provider. RVaaS leverages key features of OpenFlow-based SDNs to combine (passive and active) configuration monitoring, logical data plane verification and actual in-band tests, in a novel manner

Policy issues in interconnecting networks

To support the activities of the Federal Research Coordinating Committee (FRICC) in creating an interconnected set of networks to serve the research community, two workshops were held to address the technical support of policy issues that arise when interconnecting such networks. The workshops addressed the required and feasible technologies and architectures that could be used to satisfy the desired policies for interconnection. The results of the workshop are documented

Secure Inter-domain Routing and Forwarding via Verifiable Forwarding Commitments

The Internet inter-domain routing system is vulnerable. On the control plane, the de facto Border Gateway Protocol (BGP) does not have built-in mechanisms to authenticate routing announcements, so an adversary can announce virtually arbitrary paths to hijack network traffic; on the data plane, it is difficult to ensure that actual forwarding path complies with the control plane decisions. The community has proposed significant research to secure the routing system. Yet, existing secure BGP protocols (e.g., BGPsec) are not incrementally deployable, and existing path authorization protocols are not compatible with the current Internet routing infrastructure. In this paper, we propose FC-BGP, the first secure Internet inter-domain routing system that can simultaneously authenticate BGP announcements and validate data plane forwarding in an efficient and incrementally-deployable manner. FC-BGP is built upon a novel primitive, name Forwarding Commitment, to certify an AS's routing intent on its directly connected hops. We analyze the security benefits of FC-BGP in the Internet at different deployment rates. Further, we implement a prototype of FC-BGP and extensively evaluate it over a large-scale overlay network with 100 virtual machines deployed globally. The results demonstrate that FC-BGP saves roughly 55% of the overhead required to validate BGP announcements compared with BGPsec, and meanwhile FC-BGP introduces a small overhead for building a globally-consistent view on the desirable forwarding paths.Comment: 16 pages, 17 figure

Fault Management in Distributed Systems

In the past decade, distributed systems have rapidly evolved, from simple client/server applications in local area networks, to Internet-scale peer-to-peer networks and large-scale cloud platforms deployed on tens of thousands of nodes across multiple administrative domains and geographical areas. Despite of the growing popularity and interests, designing and implementing distributed systems remains challenging, due to their ever- increasing scales and the complexity and unpredictability of the system executions. Fault management strengthens the robustness and security of distributed systems, by detecting malfunctions or violations of desired properties, diagnosing the root causes and maintaining verifiable evidences to demonstrate the diagnosis results. While its importance is well recognized, fault management in distributed systems, on the other hand, is notoriously difficult. To address the problem, various mechanisms and systems have been proposed in the past few years. In this report, we present a survey of these mechanisms and systems, and taxonomize them according to the techniques adopted and their application domains. Based on four representative systems (Pip, Friday, PeerReview and TrInc), we discuss various aspects of fault management, including fault detection, fault diagnosis and evidence generation. Their strength, limitation and application domains are evaluated and compared in detail

A software defined networking architecture for secure routing

Tese de mestrado, Segurança Informática, Universidade de Lisboa, Faculdade de Ciências, 2014O tamanho e aceitação que a internet ganhou veio ajudar à inovação e a partilha entre utilizadores, mas em contrapartida aumentou o risco de tanto a infraestrutura da internet como as pessoas que a utilizam serem alvos de ciber-ataques. Esta é apenas uma visão parcial do problema, pois para suportar a crescente utilização da internet a infraestrutura cresceu sem a maturação de vários protocols e algoritmos que executam alguns dos serviços mais básicos com que convivemos todos os dias na internet. Um dos melhores exemplos ´e o do Border Gateway Protocol, um protocolo de troca de informação de roteamento que está em uso há mais de 20 anos mas possui vários problemas de segurança conhecidos. O desenho inicial do protocolo, aliado à ineficiência das redes tradicionais impediram a adoção das várias adições de segurança já propostas para o protocolo. O protocolo não possui atualizações de segurança que o protejam contra os vários tipos de ataques já descobertos, como prefix hijacking, intercepção e ataques no plano de dados. Estes ataques podem ter consequências graves durante períodos de tempo não negligenciáveis, como reportado em [33, 19]. As propostas já existentes, como o S-BGP[27], soBGP[48] e Origin Authentication[12], apesar de eficazes na proteção contra um ou mais ataques contra o BGP, não foram adoptadas na prática devido aos seus elevados requisitos computacionais ou de implementação. Neste trabalho resumimos os problemas para adopcão de soluções de segurança em três pontos principais: 1. Algumas soluções requerem poder computacional ou capacidade de memória que nem todos os dispositivos de rede que correm BGP em funcionamento conseguem suportar; 2. A solução requer alterações ao protocolo BGP em funcionamento; 3. A solução não garante benefícios de segurança imediatos ao AS que a adoptar; A investigação actual tem chegado à conclusão que muitos dos problemas das redes tradicionais surgem devido `a necessidade de os dispositivos de rede participarem em protocolos complexos para executar funções de rede que vão além do seu objetivo: encaminhar pacotes [24]. Como consequência, as redes tornaram-se bastante complexas e portanto difíceis de gerir e escalar. A falta de segurança radica também neste problema. Em alternativa às redes tradicionais, a comunidade científica e a indústria têm vindo a adoptar um novo tipo de redes, as Software Defined Networks (SDN). Estas redes sepathe datapathram o plano de controlo do plano de dados, passando toda a lógica e estado de rede para um controlador logicamente centralizado, mantendo nos dispositivos de rede apenas a tarefa de encaminhar pacotes. Os controladores SDN implementam funções de rede através de aplicações que executam no próprio ambiente do controlador em vez de obrigar os dispositivos de rede a implementarem esses protocolos. Um desses controladores é o OpenDaylight, que tem o apoio de alguns dos maiores nomes da indústria como a Cisco, IBM, HP e Juniper, e espera-se ser a principal referência no futuro. Neste trabalho propomos duas aplicações SDNs para o controlador OpenDaylight: RFProxy e BGPSec. O RFProxy é um dos três componentes base da aplicação Route- Flow, uma plataforma de servic¸os de roteamento para SDN. O RFProxy é o único componente da aplicação a executar no controlador e é responsável por gerir e configurar os switches de acordo com as decisões tomadas pelo RFServer. Esta aplicação vem aumentar o número de opções para a utilização do RouteFlow e proporciona uma plataforma de roteamento avançada e eficiente para o OpenDaylight. A aplicação BGPSec tem como objetivo garantir proteção contra ataques de prefix hijacking, onde um atacante tenta redireccionar todo o tráfego destinado a um AS para si. Esta proteção é conseguida através da validação dos dados recebidos do BGP. Ao utilizar uma aplicação para a validação dos anúncios BGP em vez de obrigar os dispositivos de rede a executarem este processamento, o desenho e implementação tornam-se mais simples e permitem um maior conjunto de opções quando comparado com as implementações necessárias em redes tradicionais. A utilização de uma aplicação SDN para este efeito é algo inovador e traz vantagens quando comparada com as redes tradicionais. Em particular, o ambiente SDN permite mitigar os dois primeiros problemas de adopção de uma extensão de segurança, ao passar o processamento para o controlador e a não requerer uma alteração protocolo BGP. As contribuições principais deste trabalho podem ser resumidas da seguinte forma: 1. Implementação e avaliação de um serviço avançado de roteamento em ambiente SDN, nomeadamente ao controlador OpenDaylight; 2. Análise dos problemas de segurança do BGP e das extensões de segurança já propostas para redes tradicionais; 3. Desenho, implementação e avaliação de uma aplicação de segurança para o BGP baseada em SDN;The Internet has evolved from a small group of interconnected computers to an infrastructure that supports billions of devices including computers, smartphones, etc, all with increasing demands in terms of network requirements. The architecture of traditional networks hinders their capability of fulfilling these demands, mainly due to the tight coupling of the data and control planes. Network devices are required to handle and participate in complex distributed protocols to perform network tasks such as routing, making networks very complex and thus affecting their scalability, performance, management and innovation ease. The Border Gateway Protocol, the de facto protocol for routing between Autonomous Systems (ASes) is one of the fundamental protocols for the operation of the internet. However, it was created in a time where the internet was composed of fewer ASes that trusted each other and in the information they provided, which is now unsafe to assume. The internet growth also resulted in an increase in the attacks against the internet routing infrastructure, and several misbehaviors have been detected, either due to attacks against the protocol or misconfiguration. Although several solutions have been presented to solve the security issues of BGP, no proposal has yet been adopted due to three main reasons:_ The solution requires either a computational power or memory size that not all currently deployed BGP speakers will be able to withstand; _ The solution incurs changes to the BGP protocol currently in use; _ The solution does not bring immediate security benefits for the adopting AS; Software-Defined Networking (SDN) is an emerging network paradigm that aims to solve the problems of traditional networks by decoupling the data and control planes, moving the latter to a logically centralized controller while making network devices execute solely the former. All network tasks and applications run on top of the controller, which abstracts the network and greatly simplifies the development and testing of new applications and protocols. Forwarding rules are installed and removed using OpenFlow, a vendor-independent communications protocol for SDNs. Several SDN controllers have been developed by different companies and researchers, several of them open-source. One of such kind is the OpenDaylight (ODL) controller, supported by some of the top names in the IT industry (e.g. Cisco, IBM, HP). The goal of ODL is to create a controller of reference and help accelerate SDN evolution and adoption. Although the controller is the core component of a SDN, network logic is performed by an application running on top of it. An example is RouteFlow, a routing platform that provides flexible and scalabe IP routing services to a SDN. Routing decisions are made by creating a virtual network that mimics the topology of the physical infrastructure and by analyzing the routing tables of the virtual devices. RouteFlow is composed by three components: RFClient, RFServer and RFProxy, with the latter running in the controller. The first contribution of this work is the implementation and evaluation of the RFProxy module for the OpenDaylight controller. An SDN architecture provides a new environment to improve BGP security through the creation of an application to run on top of the controller. Such approach mitigates the first two adoption problems mentioned above by offloading the additional processing to the controller and by not requiring changes to the BGP protocol. The other contribution of this work is the study and analysis of the BGP security problems and traditional solutions, and how to address them in a SDN environment. We implemented and evaluated BGPSec, a security application for the OpenDaylight controller that provides the network with protection against prefix hijacking attacks, where a malicious AS tries to direct the traffic destined to an AS onto itself

Software-Driven and Virtualized Architectures for Scalable 5G Networks

In this dissertation, we argue that it is essential to rearchitect 4G cellular core networks–sitting between the Internet and the radio access network–to meet the scalability, performance, and flexibility requirements of 5G networks. Today, there is a growing consensus among operators and research community that software-defined networking (SDN), network function virtualization (NFV), and mobile edge computing (MEC) paradigms will be the key ingredients of the next-generation cellular networks. Motivated by these trends, we design and optimize three core network architectures, SoftMoW, SoftBox, and SkyCore, for different network scales, objectives, and conditions. SoftMoW provides global control over nationwide core networks with the ultimate goal of enabling new routing and mobility optimizations. SoftBox attempts to enhance policy enforcement in statewide core networks to enable low-latency, signaling-efficient, and customized services for mobile devices. Sky- Core is aimed at realizing a compact core network for citywide UAV-based radio networks that are going to serve first responders in the future. Network slicing techniques make it possible to deploy these solutions on the same infrastructure in parallel. To better support mobility and provide verifiable security, these architectures can use an addressing scheme that separates network locations and identities with self-certifying, flat and non-aggregatable address components. To benefit the proposed architectures, we designed a high-speed and memory-efficient router, called Caesar, for this type of addressing schemePHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/146130/1/moradi_1.pd