Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major de Automação). Faculdade de Engenharia. Universidade do Porto. 2009

Border Gateway Protocol (BGP) prefix hijacking is a serious problem in the Internet today. Although there are several services being offered to detect a prefix hijack, there has been little work done to prevent a hijack or to continue providing network service during a prefix hijack attack. This thesis proposes a novel framework to provide defense against prefix hijacking which can be offered as a service by Content Distribution Networks and large Internet Service Providers. Our experiments revealed that the hijack success rate reduced from 90.36% to 30.53% at Tier 2, 84.65% to 10.98% at Tier 3 and 82.45% to 8.39% at Tier 4 using Autonomous Systems (ASs) of Akamai as Hijack Prevention Service Provider. We also observed that 70% of the data captured by Hijack Prevention Service Provider (HPSP) can be routed back to Victim. However if we use tunneling, i.e. trying to route data to neighbors of Victims which in turn sends the traffic to Victims, we observed that data can be routed to Victim 98.09% of the time. Also, the cost of such redirection is minimal, since the average increase in path length was observed to be 2.07 AS hops.

VoIP(Voice over IP) is one of the most important applications on the Internet. As the voice coding enhancing, VoIP provides a good voice quality with low bandwidth. Therefore, the IP telephony services have a price advantage with PSTN. In the near future, VoIp may replace with the PSTN to provide a better telephony service. In this paper, we discuss how to design and implement an embedded VoIp user agent system. With the help of DSP(Digital Signal Processor), we speed up the voice data processing. We use Linux as the embedded operating system and other open source library to implement a VoIP user agent base on SIP(Session Initiation Protocol) standard. With the hardware and software co-design, we build up an embedded VoIP Integrated Access Device.

Border Gateway Protocol (BGP) prefix hijacking is a serious problem in the Internet today. Although there are several services being offered to detect a prefix hijack, there has been little work done to prevent a hijack or to continue providing network service during a prefix hijack attack. This thesis proposes a novel framework to provide defense against prefix hijacking which can be offered as a service by Content Distribution Networks and large Internet Service Providers. Our experiments revealed that the hijack success rate reduced from 90.36% to 30.53% at Tier 2, 84.65% to 10.98% at Tier 3 and 82.45% to 8.39% at Tier 4 using Autonomous Systems (ASs) of Akamai as Hijack Prevention Service Provider. We also observed that 70% of the data captured by Hijack Prevention Service Provider (HPSP) can be routed back to Victim. However if we use tunneling, i.e. trying to route data to neighbors of Victims which in turn sends the traffic to Victims, we observed that data can be routed to Victim 98.09% of the time. Also, the cost of such redirection is minimal, since the average increase in path length was observed to be 2.07 AS hops.

International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The technologies used for flight test are evolving. Trusted standards like CAIS and IRIG106 PCM are giving way to new “trusted standards” (and proven technologies/protocols) found in telecommunication and networking such as Ethernet, fiber channel, TCP/IP, UDP, ATM and so on. Currently there is $100Ms+ invested in CAIS and IRIG compliant equipment in the world. A key challenge in this evolution is to provide a reliable solution that allows the FTI engineer to immediately take advantage of these advanced technologies while protecting prior investment in equipment, knowledge, and resources during this transition. This paper presents an analysis of how to protect existing assets while still leveraging the power of the latest technologies. It looks at the characteristics of a “bridge” system, and suggests solutions for merging and linking data from and to different transmission protocols using data synchronization and deterministic data management cycles.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / The majority of currently operating flight test programs around the world utilize PCM-based airborne instrumentation systems. Most instrumentation engineers are very comfortable with PCM-based data acquisition systems, and feel uncomfortable when talking about network implementations and the adoption of iNET. In order for these engineers to embrace this new technology, migrating from a PCM to network topology must be done in an evolutionary manner that provides for the preservation of capital investment while introducing new system concepts that enhance current instrumentation systems. This paper describes hardware components that enable instrumentation engineers to migrate their existing PCM-based instrumentation system to a network-based system. Several of these components are discussed to illustrate how they provide a controlled migration path to a network-based system. These components include time distribution, gateways, network data selectors, network switches, transmitters, transceivers, and recorders.

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Student Number :9600874K - MSc research report - School of Electrical Engineering - Faculty of Engineering and the Built Environment / Telecommunication networks have evolved from voice only single service networks to multimedia networks providing bearer services such as voice, data and video transportation. Moreover, these networks, collectively called Next Generation Networks (NGNs), enable rapid creation, deployment and management of advanced services in an efficient manner. However, the initial business model of telcos was to internally develop and provide these advanced services to customers. In this monopolized environment, service development is driven by technological availability rather than customer demands. Furthermore, vendor specific network elements prohibit the development of re-useable service components, which in turn increases the time-to-market of services. Deregulation and advances in Distributed Computing Systems (DCSs) are driving towards open networks and rapid service delivery. Third party Application Service Providers (ASPs) are envisioned to develop and supply the services, with the telco providing bearer services. The use of softswitch architectures such as Open Service Access (OSA) / Parlay (OSA / Parlay) in an open NGN environment abstract services from core network elements through its Application Programming Interface (API). Services are thus decoupled from vendor and protocol specific network equipment and can be provided across a plethora of network architectures. One major advantage of NGN is the ability to provide bearer service in a mobile environment. Location Based Services (LBSs) are envisaged to be an important class of services provided in the NGN environment. For an LBS service to be complete, a geospatial database is necessary to provide location information. This report documents the design and implementation of a Geospatial Data Access Service Capability Feature (GDASCF) as an extension to the OSA / Parlay gateway. The GDASCF encapsulates necessary APIs that offer uniform access to query geospatial databases. One key component of the design is the realization of the Adapter layer which adapts function calls to an appropriate Database Management System (DBMS). The introduction of the GDASCF and Adapter layer provides a solution which results in flexible and rapid service creation.

Esta dissertação apresenta uma solução para a integração do serviço de diretório LDAP com o serviço de nomes CORBA. Descrevemos a implementação de um servidor de nomes CORBA que armazena, num diretório LDAP, as associações entre nomes e referências para objetos. O servidor de nomes CORBA é, portanto, um cliente do serviço de diretório LDAP. Eficiência e flexibilidade são as vantagens desta abordagem. As associações nome–referência ficarão acessíveis tanto para clientes CORBA (através das interfaces do serviço de nomes) como para clientes LDAP (através da API do LDAP). Atributos descritivos poderão ser adicionados às entradas do diretório que representam associações nome-referência. Clientes LDAP poderão utilizar as facilidades de busca no diretório para obter referências cujas entradas satisfaçam determinadas condições. Essas condições podem envolver o nome associado à referência ou outros atributos presentes nas entradas do diretório.

A MANET (Mobile Ad hoc NETwork) is a network with the features of infrastructure-less, multi-hop, self-configuring, and distributed-routing, which are quite different from a traditional wired network. Since nodes in a MANET are free to move, causing the topology of the MANET to change frequently, a routing protocol able to accommodate the rapidly changed topology is required. The MANET routing protocols can be classified into three categories based on routing information update mechanism: (1) proactive/table-driven protocol (2) reactive/on-demand protocol (3) hybrid protocol. Every category has its own advantages and disadvantages. Among these, the hybrid protocol tries to combine the advantages of proactive and reactive ones. This work presents a novel hybrid routing protocol - CG2R (Core Gateway Relay Protocol). The CG2R partitions a network into several regions called zones. The proactive mechanism is used within the zone, while the reactive one is applied outside the zone. Each zone contains one core gateway; the core gateway constitutes the backbone of the routing path. Unlike conventional cluster-based routing protocols which require the algorithm of electing cluster head to get some value such as ID number or Weight to elect cluster heads, the node in CG2R can decide itself a core gateway or not by using the algorithm that we present. The core gateway covers more cells and manages more nodes than the others to reduce the cases of a node moving out the zone. Based on this feature, the backbone of the network can be formed by the gateway nodes. The simulation results reveal that CG2R is more scalable and efficient than CGSR and AODV protocols.