Tese de mestrado. Redes e Serviços de Comunicação. Faculdade de Engenharia. Universidade do Porto. 2007

With advancing technology, Chip Multi-processor (CMP) architectures have emerged as a viable solution for designing processors. Networks-On-Chip (NOCs) provide a scalable communication method for CMP architectures with increasing numbers of cores. Although there has been significant research on NOC designs for unicast traffic, the research on the multicast router design is still in its infant stage. Considering that one-to-many (multicast) and one-to-all (broadcast) traffic are more common in CMP applications, it is important to design a router providing efficient multicasting. In this thesis, a lookahead multicast routing algorithm with limited area overhead is proposed. This lookahead algorithm reduces network latency by removing the need for a separate routing computation (RC) stage. An efficient area optimization technique is put forward to achieve minimal area overhead for the lookahead RC stage. Also, a novel compression scheme is proposed for multicast packet headers to alleviate their big overhead in large networks. Comprehensive simulation results show that with the new route computation logic design and area overhead optimization, providing lookahead routing in the multicast router only costs less than 20 percent area overhead and this percentage keeps decreasing with larger network sizes. Compared with the basic lookahead routing design, our design can save area by over 50 percent. With header compression and lookahead multicast routing, the network performance can be improved on an average by 22 percent for a (16 x 16) network.

abstract: E-Mail header injection vulnerability is a class of vulnerability that can occur in web applications that use user input to construct e-mail messages. E-Mail injection is possible when the mailing script fails to check for the presence of e-mail headers in user input (either form fields or URL parameters). The vulnerability exists in the reference implementation of the built-in “mail” functionality in popular languages like PHP, Java, Python, and Ruby. With the proper injection string, this vulnerability can be exploited to inject additional headers and/or modify existing headers in an e-mail message, allowing an attacker to completely alter the content of the e-mail. This thesis develops a scalable mechanism to automatically detect E-Mail Header Injection vulnerability and uses this mechanism to quantify the prevalence of E- Mail Header Injection vulnerabilities on the Internet. Using a black-box testing approach, the system crawled 21,675,680 URLs to find URLs which contained form fields. 6,794,917 such forms were found by the system, of which 1,132,157 forms contained e-mail fields. The system used this data feed to discern the forms that could be fuzzed with malicious payloads. Amongst the 934,016 forms tested, 52,724 forms were found to be injectable with more malicious payloads. The system tested 46,156 of these and was able to find 496 vulnerable URLs across 222 domains, which proves that the threat is widespread and deserves future research attention. / Dissertation/Thesis / Masters Thesis Computer Science 2016

Tese de mestrado. Redes e Serviços de Comunicação. Faculdade de Engenharia. Universidade do Porto, INESC Porto. 2009

The frequency of on-site systems for treatment of domestic wastewater is increasing with new residential development in both rural and low-density suburban areas. Subsurface flow constructed wetlands (SFCW) have emerged as a viable option to achieve advanced or secondary treatment of domestic wastewater. The pollutant removal efficiency in SFCW depends on design parameters. Many of these factors have been investigated while others such as aspect ratio, design of water inlet structure and method of dosing the wetland have yet to be fully examined. This study examined the effect of aspect ratio and header design on BOD5 removal efficiency as well as the impact of flow rate on flow distribution in a SFCW. An aspect ratio of 4:1 achieved 10% greater removal of organic matter than a 1:1 ratio. Tracer studies demonstrated that wetlands loaded at a constant rate of 3.8 L/min and 7.6 L/min experienced preferential flow. In addition, tracer studies showed wetlands with leaching chambers as headers failed to achieve equal flow distribution. An improvement in effluent water quality was achieved by replacing the leaching chamber for a perforated manifold as the inlet structure. This study demonstrated the importance of the careful selection of aspect ratio and means by which water is introduced to the wetland in the design of SFCW.

Efficiently and accurately estimating bandwidths in packet networks is a problem that has intrigued researchers for years. There is no simple manner for estimating bandwidths in IPv4 networks that is accurate, efficient, flexible, and suitable for a variety of applications. Many of the available estimation techniques suffer from inherent flaws such as inaccuracy due to simple assumptions about the network or an overall high complexity that makes it inappropriate in all but a few highly specific situations. The next generation Internet Protocol, IP version 6, has the functionality necessary to implement feedback mechanisms to assist in accurate bandwidth estimations. This thesis proposes a timestamp hop-by-hop option for IPv6 and then applies this option to create a new bandwidth estimation technique. Instead of passive observations, the network infrastructure actively assists in bandwidth measurements resulting in a bandwidth estimation technique that is accurate, efficient, flexible, and suitable for many different applications and scenarios. Both analytical and simulation analysis show that the IPv6 bandwidth estimation technique outperforms a comparable IPv4 estimation method.

This thesis describes the design and implementation of the generator frames used for information transfer in wireless networks. At the beginning of the thesis there is described the introduction to the issue of data transmission in wireless networks 802.11 and the analysis of existing tools. Then it is designed language for describing the structure of their own frames and designed their own tools. The work also deals with the subsequent implementation of the resulting tool. Finally the results of the test are mentioned.

Header compression is one of the technologies, which enables packet-switched computer networks to operate with higher efficiency even if the underlying physical link is limited. Since its inception, the compression was meant to improve dial-up Telnet connections, and has evolved into a complex multi-faceted compression library, which has been integrated into the third and fourth generation of cellular networks, among others. Beyond the promised benefit of decreased bandwidth usage, header compression has shown that it is capable of improving the quality of already existing services, such as real-time audio calls, and is a developing hot topic to this day, realising, for example, Internet Protocol (IP) version 6 support on resource constrained low-power devices. However, header compression is ill equipped to handle the stringent requirements and challenges, which are posed by the coming fifth generation of wireless and cellular networks (5G) and its applications. Even though it can be considered as an already well developed area of computer networks that can compress protocol headers with unparalleled efficiency, header compression is still operating under some assumptions and restrictions that could deny its employment outside of cellular Voice over IP transmissions to certain degrees. Albeit some improvements in the latency domain could be achieved with its help, the application of header compression in both largely interconnected networks and very dynamic ones – such as the wireless mesh and vehicular networks – is not yet assured, as the topic, in this perspective, is still relatively new and unexplored. The main goal of my theses is the presentation and evaluation of novel ideas, which support the application of header compression concepts for the future wireless use-cases, as it holds alluring benefits for the coming network generations, if applied correctly. The dissertation provides a detailed treatment of my contribution in the specific research areas of header compression and network coding, which encompass novel proposals for their enhancement in 5G uses, such as broadcastability and online optimisation, as well as their subsequent analysis from various perspectives, including the achievable compression gains, delay reduction, transmission efficiency, and energy consumption, to name a few. Besides the focus on enabling header compression in 5G, the development of traffic-agnostic and various network-coded compression concepts are also introduced to attain the benefits of both techniques at the same time, namely, reduced bandwidth usage and high reliability in latency sensitive heterogeneous and error prone mesh networks. The generalisation of compression is achieved by the employment of various machine learning concepts, which could approximate the compression characteristics of any packet-based communication flow, while network coding facilitates the exploitation of the low-latency benefits of error correcting codes in heavily interconnected wireless networks.

This thesis project has studied a number of protocols that could be used to communicate between a vehicle and a remote server in the context of Scania’s connected services. While there are many factors that are of interest to Scania (such as response time, transmission speed, and amount of data overhead for each message), this thesis will evaluate each protocol in terms of how much data overhead is introduced and how packet loss affects this overhead. The thesis begins by giving an overview of how a number of alternative protocols work and what they offer with regards to Scania’s needs. Next these protocols are compared based on previous studies and each protocol’s specifications to determine which protocol would be the best choice for realizing Scania’s connected services. Finally, a test framework was set up using a virtual environment to simulate different networking conditions. Each of the candidate protocols were deployed in this environment and setup to send sample data. The behaviour of each protocol during these tests served as the basis for the analysis of all of these protocols. The thesis draws the conclusion that to reduce the data transmission overhead between vehicles and Scania’s servers the most suitable protocol is the UDP based MQTT SN. / I den här rapporten har jag undersökt ett antal protokoll som kan användas för att kommunicera mellan server och lastbil och därmed användas för Scanias Connected Services. Då det är många faktorer som är intressanta när det kommer till kommunikation mellan lastbil och server för Scania som till exempel responstid, överföringshastighet och mängden extra data vid överföring så har jag valt att begränsa mig till att utvärdera protokollen utifrån hur mycket extra data de använder vid överföring och hur detta påverkas av paketförlust. Rapporten börjar med att ge en överblick över vilka tänkbara protokoll som kan användas och vad de kan erbjuda gällande Scanias behov. Efter det så jämförs protokollen baserat på tidigare studier och protokollens specifikationer för att avgöra vilket protokoll som är bäst lämpat att användas i Scanias Connected Services. Sists så skapas ett virtuellt ramverk för att simulera olike nätverksförhållanden. Här testas varje protokoll och får sända olike datamängder för att sedan få sin prestanda utvärderad baserat på hur mycket extra data som sändes. Dessa resultat ligger sedan till grund för den analys och slutsats angående vilket protokoll som är bäst lämpat att användas av Scania. Rapporten drar slutsatsen att baserat på den information som finns tillgänglig och de resultat som ficks av testerna så skulle den UDP baserade MQTT-SN vara bäst lämpad för att minimera mängden extra data som skickas.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Due to the need to increase in production and to the high rates of losses in the header because of machines with low efficiency in harvesting, it is presented, in this thesis the knowledge systematization needed to develop new header designs to harvest beans. This work presents the machines used for the harvest of beans, the harvesting systems, and a list of influencing factors that determine the knowledge required for new projects. In the patent records, harvesters able to carry out all the harvest s phases, machines for cutting or pulling off plants, addition or replacement parts for harvesters, and machines with different technologies were found. The result of a search for machines in the market showed the main characteristics of headers such as mechanical and hydraulic couplings, dimensions and power transmission systems that are used. A comparison among subsystems was made, and it was noticed that, although the machines are designed for the same culture, and the systems are virtually identical, there are some quite different adjustments, and, in some cases, they do not observe agronomical recommendations, showing that the optimization of designs is possible. It is presented a study on the technologies in harvesting and the size relation of machines that enable their construction followed by the four main categories related to the influencing factors in the project (project scope examination, operating environment characteristics, ratification criteria, and machines available in the market). It was observed that there are still potential improvements in the recorded designs in the patents including the exploration of new concepts. It was observed that many machines recorded in patents are not found in the market. Among the possible reasons for this, there is the fact that the great majority of machines registered in patents carry out the harvest by individualizing the planting lines, which is a characteristic that does not have a good market acceptance. / Em virtude da necessidade de aumento da produção e dos altos índices de perdas na plataforma decorrentes de máquinas com baixa eficiência na colheita, apresenta-se, nesse trabalho, a sistematização de conhecimentos necessários para novos projetos de plataformas de colheita de feijão. O trabalho apresenta as máquinas atualmente utilizadas para colheita de feijão, os sistemas de colheita e a relação dos fatores de influência que determinam a base de conhecimento necessária para projetos. Foram encontrados nos registros de patentes colhedoras capazes de realizar todas as etapas da colheita, máquinas para corte ou arranquio das plantas, peças para adição ou substituição nas colhedoras e máquinas com tecnologias diferenciadas. A pesquisa por máquinas disponíveis no mercado mostrou as características gerais das plataformas como acoplamentos mecânicos e hidráulicos, dimensões e os sistemas de transmissão de potência utilizados. Foi realizada uma comparação entre os subsistemas e notou-se que, embora as máquinas sejam destinadas à mesma cultura e possuem sistemas praticamente idênticos, possuem algumas regulagens bastante distintas, em alguns casos não atendendo às recomendações agronômicas, demonstrando espaço para otimização dos projetos. É apresentado um estudo sobre as tecnologias na colheita e a relação de tamanho das máquinas que viabilizam sua construção, seguida, das quatro principais categorias relacionadas aos fatores de influência no projeto (exame do escopo, características do ambiente operacional, critérios de homologação, e, máquinas disponíveis no mercado). Foi observado que há ainda potencial de melhorias dos projetos depositados em patentes, inclusive com exploração de novas concepções. Muitas máquinas registradas em patentes não são encontradas no mercado. Dentre os prováveis motivos está o fato de que a maioria das máquinas registradas realiza a colheita individualizando as linhas de plantio, característica que não apresta boa aceitação no mercado.