Design and evaluation of interconnecting structured peer-to-peer networks with a hierarchical topology

El tráfico en Internet está evolucionando continuamente. En el siglo XX, la mayor parte del tráfico en Internet soportado por los Proveedores de Servicios de Internet (ISP’s en terminología anglosajona) estaba relacionado con el tráfico web. Sin embargo, actualmente, el tráfico en Internet ha evolucionado drásticamente. La mayor parte del tráfico en Internet es tráfico Peer-to-Peer. Este cambio cambia completamente la situación en comparación con el siglo anterior, de ahí la relevancia del paradigma de las redes Peer-to-Peer. La adopción de las redes Peer-to-Peer está principalmente motivada por su uso en aplicaciones de compartición de ficheros pero la aplicación de las redes Peer-to-Peer no está sólo limitada al paradigma de compartición de ficheros. De hecho, las redes Peer-to-Peer son adecuadas para el desarrollo de cualquier servicio o aplicación distribuida ya que permiten almacenar información de manera distribuida entre un conjunto de nodos. Además, también permiten recuperar esa información cuando sea necesario. Una aplicación relevante basada en redes Peer-to-Peer es Skype la cual permite un servicio de VoIP entre varios millones de personas. Sin embargo, la interoperabilidad entre diferentes redes Peer-to-Peer no ha sido resuelta todavía. Cada red Peer-to-Peer define su propio mecanismo y su propio formato de paquete. Por lo tanto, sería deseable definir algún mecanismo que permita el intercambio de información entre diferentes redes Peer-to-Peer. Esta Tesis define un mecanismo que permite el intercambio de información entre diferentes redes Peer-to-Peer estructuradas, concretamente redes overlay basadas en DHT’s (Distributed Hash Tables). Este mecanismo está basado en un formato común de paquete, que asegura la interoperabilidad entre diferentes redes overlay, y en una arquitectura jerárquica. Esta arquitectura jerárquica está compuesta por dos niveles de jerarquáa. El nivel más bajo de la jerarquía está compuesto por las diferentes redes overlay que desean estar interconectadas. Cada una de estas redes overlay puede usar cualquier DHT, no existe ninguna restricción al respecto. Al menos un super-peer existe en cada una de estas redes overlay del nivel inferior; además, estos super-peer también participan en el nivel superior. Al nivel superior se le conoce como Red de Interconexión y está compuesto sólo por una red overlay. Su función es similar al servicio de DNS pero en el área de las redes Peer-to-Peer. En la Red de Interconexión se guarda la información de localización de cada uno de los super-peers y también el dominio o la overlay a la que representan. Por lo tanto, si un recurso de otra red quiere ser recuperado, un peer tiene que reenviar la petición a su super-peer. El super-peer consulta a la Red de Interconexión para localizar al super-peer que se hace cargo de la red destino donde se encuentra el recurso deseado y una vez que se localizar al super-peer, se le reenvía la petición. Finalmente, el super-peer en la red destino buscar el recurso deseado y lo envía de vuelta al peer que originó la petición. La arquitectura propuesta ha sido estudiada analíticamente para asegurar que el rendimiento es razonable en comparación con otras redes Peer-to-Peer. Además, la propuesta es validada con una herramienta de simulación para asegurar que las asunciones en el modelo analítico no afectan en un escenario más general. Finalmente, una implementación real sobre un entorno controlado es mostrada para demostrar la aplicabilidad y viabilidad de la propuesta. Los escenarios para las simulaciones y la verificación de la implementación han sido diseñados con especial cuidado para tener unas condiciones lo más cercanas posibles a escenarios reales.---------------------------------------------------------------------------------------------------------------------The traffic in the Internet is evolving continuously. In the 20th century, the most traffic supported by Internet Service Providers (ISP’s) was related with web traffic. However, nowadays, the traffic in the Internet has evolved drastically; now, most of the traffic in the Internet is Peer-to-Peer traffic. This fact changes completely the situation in comparison with the end of the previous century, thus the relevance of the Peer-to-Peer paradigm nowadays is evident. The adoption of Peer-to-Peer overlay networks was firstly motivated for its usage in file-sharing applications but the applicability of Peer-to-Peer overlay networks is not only limited to this kind of applications. In fact, Peer-to-Peer overlay networks are suitable for the development of any distributed application or service since they allow the allocation and retrieval of information in a distributed fashion among a set of nodes. However, each overlay network has its own structure and mechanisms to distribute the information among all nodes. Additionally, each Peer-to-Peer overlay network implementation usually defines its own packet format. Therefore, the interoperability among different overlay networks is not possible. This Thesis defines a mechanism to allow the exchange of information among different structured Peer-to Peer overlay networks, concretely DHT (Distributed Hash Table) overlay networks. This mechanism is based on both a common packet format, which assures the interoperability among different overlay networks, and on a hierarchical architecture. This hierarchical architecture has two levels of hierarchy. The lower level of the hierarchy is composed by the different overlay networks that want to be interconnected. Each one of these overlay networks can use any DHT overlay network with no restrictions. In addition, each overlay network in the lower level has at least one special peer, called super-peer. These super-peers are attached to the top level. This top level is named Interconnection Overlay and it is composed by just one overlay network. The purpose of super-peers is to route the queries among different overlay networks and they use the Interconnection Overlay to achieve this objective. In this Interconnection Overlay, the location information of each one of the superpeers and the overlay network represented by them are stored. Therefore, super-peers can forward the queries with the information stored in the Interconnection Overlay. If a resource placed in other overlay network wants to be obtained, a peer has to forward the query to its super-peer. The super-peer gets from the Interconnection Overlay the information about the super-peer that takes care of the destination overlay network and forwards this request. Finally, the super-peer in the destination overlay network looks for the desired resource and once is retrieved the answer is sent back to the requester. The proposed architecture is mathematically analysed to obtain is performance in term of hops and number of overlay routing entries in peers. Furthermore, the proposal is validated with a simulation tool to assure that the assumptions in the analytical model have been enough accurate. Finally, a real implementation over a controlled environment demonstrates the applicability and viability of the proposal and allows removing many of the original assumptions. The scenarios for the simulation analysis and the evaluation of the implementation have been designed carefully in order to define conditions as similar as possible to the real world

A Survey on Routing in Anonymous Communication Protocols

The Internet has undergone dramatic changes in the past 15 years, and now forms a global communication platform that billions of users rely on for their daily activities. While this transformation has brought tremendous benefits to society, it has also created new threats to online privacy, ranging from profiling of users for monetizing personal information to nearly omnipotent governmental surveillance. As a result, public interest in systems for anonymous communication has drastically increased. Several such systems have been proposed in the literature, each of which offers anonymity guarantees in different scenarios and under different assumptions, reflecting the plurality of approaches for how messages can be anonymously routed to their destination. Understanding this space of competing approaches with their different guarantees and assumptions is vital for users to understand the consequences of different design options. In this work, we survey previous research on designing, developing, and deploying systems for anonymous communication. To this end, we provide a taxonomy for clustering all prevalently considered approaches (including Mixnets, DC-nets, onion routing, and DHT-based protocols) with respect to their unique routing characteristics, deployability, and performance. This, in particular, encompasses the topological structure of the underlying network; the routing information that has to be made available to the initiator of the conversation; the underlying communication model; and performance-related indicators such as latency and communication layer. Our taxonomy and comparative assessment provide important insights about the differences between the existing classes of anonymous communication protocols, and it also helps to clarify the relationship between the routing characteristics of these protocols, and their performance and scalability

Including context in a routing algorithm for the internet of things

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia InformáticaThe “Internet of Things” assumes that a large number of devices which are used on a daily basis will eventually become connected to the Internet. This scenario will provide room for a large set of new applications, however the network connections of an enormous set of nodes, which can be connected and disconnected, can move around and which have limitations with regards to their processing and communication capabilities, raises the need for the development of new message routing algorithms, different from those being in use today. In this thesis, a contribution is made towards the development of this type of algorithms. In particular, the idea which is tested is whether routing algorithms can improve their performance at various levels, such as, message delivery time, number of messages lost, power consumption, etc., if in the routing decisions these algorithms can make use of the concept of “Context”. Within the framework of this thesis, the “Context” is the organized collection of information which the routing algorithm collects from the environment surrounding the network nodes, and which allows it to make better routing decisions. This information can be related to low-level issues, such as, node location, power required to send a message, etc., as well as, with constraints related to the application, such as, message priority, maximum delivery time, etc. In order to evaluate this approach, this thesis proposes a routing algorithm called C-AODV. As the name suggests, it is based on the ADOV algorithm, however it is modified in several aspects; in particular, the possibility of using information collected from the context can be utilized to improve message routing. In order to test the proposed solution, several tests were performed on the NS-3 simulator which allowed the evaluation of the algorithm functionalities. The tests performed indicate that the proposed solution is valid

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

A NOVEL LINEAR DIOPHANTINE EQUATION-BAESD LOW DIAMETER STRUCTURED PEER-TO-PEER NETWORK

This research focuses on introducing a novel concept to design a scalable, hierarchical interest-based overlay Peer-to-Peer (P2P) system. We have used Linear Diophantine Equation (LDE) as the mathematical base to realize the architecture. Note that all existing structured approaches use Distributed Hash Tables (DHT) and Secure Hash Algorithm (SHA) to realize their architectures. Use of LDE in designing P2P architecture is a completely new idea; it does not exist in the literature to the best of our knowledge. We have shown how the proposed LDE-based architecture outperforms some of the most well established existing architecture. We have proposed multiple effective data query algorithms considering different circumstances, and their time complexities are bounded by (2+ r/2) only; r is the number of distinct resources. Our alternative lookup scheme needs only constant number of overlay hops and constant number of message exchanges that can outperform DHT-based P2P systems. Moreover, in our architecture, peers are able to possess multiple distinct resources. A convincing solution to handle the problem of churn has been offered. We have shown that our presented approach performs lookup queries efficiently and consistently even in presence of churn. In addition, we have shown that our design is resilient to fault tolerance in the event of peers crashing and leaving. Furthermore, we have proposed two algorithms to response to one of the principal requests of P2P applications’ users, which is to preserve the anonymity and security of the resource requester and the responder while providing the same light-weighted data lookup

Sampling cluster endurance for peer-to-peer based content distribution networks

Several types of Content Distribution Networks are being deployed over the Internet today, based on different architectures to meet their requirements (e.g., scalability, efficiency and resiliency). Peer-to-peer (P2P) based Content Distribution Networks are promising approaches that have several advantages. Structured P2P networks, for instance, take a proactive approach and provide efficient routing mechanisms. Nevertheless, their maintenance can increase considerably in highly dynamic P2P environments. In order to address this issue, a two-tier architecture called Omicron that combines a structured overlay network with a clustering mechanism is suggested in a hybrid scheme. In this paper, we examine several sampling algorithms utilized in the aforementioned hybrid network that collect local information in order to apply a selective join procedure. Additionally, we apply the sampling algorithms on Chord in order to evaluate sampling as a general information gathering mechanism. The algorithms are based mostly on random walks inside the overlay networks. The aim of the selective join procedure is to provide a well balanced and stable overlay infrastructure that can easily overcome the unreliable behavior of the autonomous peers that constitute the network. The sampling algorithms are evaluated using simulation experiments as well as probabilistic analysis where several properties related to the graph structure are reveale

Security protocols suite for machine-to-machine systems

Nowadays, the great diffusion of advanced devices, such as smart-phones, has shown that there is a growing trend to rely on new technologies to generate and/or support progress; the society is clearly ready to trust on next-generation communication systems to face today’s concerns on economic and social fields. The reason for this sociological change is represented by the fact that the technologies have been open to all users, even if the latter do not necessarily have a specific knowledge in this field, and therefore the introduction of new user-friendly applications has now appeared as a business opportunity and a key factor to increase the general cohesion among all citizens. Within the actors of this technological evolution, wireless machine-to-machine (M2M) networks are becoming of great importance. These wireless networks are made up of interconnected low-power devices that are able to provide a great variety of services with little or even no user intervention. Examples of these services can be fleet management, fire detection, utilities consumption (water and energy distribution, etc.) or patients monitoring. However, since any arising technology goes together with its security threats, which have to be faced, further studies are necessary to secure wireless M2M technology. In this context, main threats are those related to attacks to the services availability and to the privacy of both the subscribers’ and the services providers’ data. Taking into account the often limited resources of the M2M devices at the hardware level, ensuring the availability and privacy requirements in the range of M2M applications while minimizing the waste of valuable resources is even more challenging. Based on the above facts, this Ph. D. thesis is aimed at providing efficient security solutions for wireless M2M networks that effectively reduce energy consumption of the network while not affecting the overall security services of the system. With this goal, we first propose a coherent taxonomy of M2M network that allows us to identify which security topics deserve special attention and which entities or specific services are particularly threatened. Second, we define an efficient, secure-data aggregation scheme that is able to increase the network lifetime by optimizing the energy consumption of the devices. Third, we propose a novel physical authenticator or frame checker that minimizes the communication costs in wireless channels and that successfully faces exhaustion attacks. Fourth, we study specific aspects of typical key management schemes to provide a novel protocol which ensures the distribution of secret keys for all the cryptographic methods used in this system. Fifth, we describe the collaboration with the WAVE2M community in order to define a proper frame format actually able to support the necessary security services, including the ones that we have already proposed; WAVE2M was funded to promote the global use of an emerging wireless communication technology for ultra-low and long-range services. And finally sixth, we provide with an accurate analysis of privacy solutions that actually fit M2M-networks services’ requirements. All the analyses along this thesis are corroborated by simulations that confirm significant improvements in terms of efficiency while supporting the necessary security requirements for M2M networks