When internet-mediated messaging and social networking applications were introduced in mobile phones, mobile messaging entered a new paradigm. Users can easily create profiles and communicate with other users instantly at anytime of day and anywhere in the world. This paradigm however, has brought forward new privacy issues. Over the course of this exegesis I aimed to explore different aspects of privacy issues related to mobile messaging, including users' awareness and the control of the privacy issues when using social networking messaging. This was demonstrated by conducting a project, which involved development of a mobile phone application and a role-playing game. The project created a frictional scenario of users communicating via mobile messaging. My research revealed that the participants lacked awareness of privacy violations when using mobile messaging, and tended not to modify their behaviours immediately when privacy breaches arose. This research contributes to the existing body of research in the area of mobile messaging privacy, and advocated user awareness of privacy issues in this domain. It could potentially be used as a base for future research.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-03-02T14:42:14Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Antônio_Janael_Pinheiro.pdf: 3669454 bytes, checksum: b097ebe7fc031e2189613f6f98fadd4d (MD5) / Made available in DSpace on 2017-03-02T14:42:14Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação_Antônio_Janael_Pinheiro.pdf: 3669454 bytes, checksum: b097ebe7fc031e2189613f6f98fadd4d (MD5) Previous issue date: 2016-02-24 / FACEPE / Middleboxes são dispositivos de rede essenciais a inúmeras organizações, utilizados primordialmente na adição de serviços à rede. Middleboxes realizam operações complexas e variadas sobre o tráfego, introduzindo vários desafios ao funcionamento das redes atuais. Estes dispositivos são configurados manualmente pelo operador de rede, o que dificulta a aplicação correta das políticas destesmiddleboxes diante de aplicações de rede dinâmicas. Diversas soluções foram propostas para mitigar problemas gerados pela presença demiddleboxes, porém tais soluções não tratam das dificuldades que surgem na operação de aplicações dinâmicas. Muitas destas soluções tornam a rede mais complexa, aumentam o seu custo e exigem a substituição completa dosmiddleboxes existentes. Neste trabalho, é apresentada uma arquitetura baseada em Software-Defined Networking (SDN) que tem como objetivo garantir a aplicação correta de políticas de middleboxes na presença de aplicações dinâmicas. A arquitetura emprega o controle centralizado e a programabilidade dos dispositivos de rede presentes em SDN para tornar osmiddleboxes existentes capazes de aplicar corretamente suas políticas sem introdução de complexidade à rede, sem aumento de seu custo e sem interferência no funcionamento das aplicações. Para avaliar a arquitetura proposta, foi desenvolvido um protótipo no ambiente de emulação Mininet com três middleboxes: um firewall, um Intrusion Detection System (IDS) e um balanceador de carga. As aplicações utilizadas foram Voice over IP (VoIP) e web, e as métricas de desempenho foram o atraso de pacotes, a perda de pacotes e o jitter. Testes de hipóteses baseados noWilcoxonSigned-RankTest aplicados aos resultados atestam que, apesar de adicionar um acréscimo tolerável no atraso de pacotes, a arquitetura proposta não gera perda de pacotes, tampouco impacta o jitter, sendo capaz de configurar corretamente políticas de middleboxes em um cenário de aplicações dinâmicas. / Middleboxes are essential network devices to numerous organizations, primarily to add services to the network. Middleboxes perform complex and varied operations on the traffic, introducing several challenges to the functioning of today’s networks. These devices are manually configured by the network operator, what hinders the correct application of the policies of these middleboxes dynamic network applications. Several solutions have been proposed to mitigate problems caused by the presence of middleboxes, but these solutions do not address the difficulties that arise in the operation of dynamic applications. Many of these solutions make the network more complex, increase its cost and require complete replacement of existing middleboxes. In this work, an architecture based on Software-Defined Networking (SDN) is presented that aim at ensuring the correct application of middlebox policies in the presence of dynamic applications. The architecture employs the centralized control and programmability of network devices present in SDN to make existing middleboxes able to correctly apply their policies without introducing complexity to the network, without increasing their cost and without interfering in the operation of applications. To evaluate the proposed architecture, a prototype in the Mininet emulation environment was developed with three middleboxes: a firewall, an Intrusion Detection System (IDS) and a load balancer. The applications used were Voice over IP (VoIP) calls and HTTP requests, and the performance metrics were packet delay, packet loss and jitter. Hypothesis testing based on Wilcoxon Signed-Rank Test applied to the results show that, while adding a tolerable increase in packet delay, the proposed architecture neither generates packet loss, nor impacts the jitter, being able to correctly configure middleboxes policies in a scenario of dynamic applications.

Este trabalho aborda o problema decorrente da necessidade de realizar tráfego multicast em redes ATM. Para isto, foi proposta uma arquitetura para a estrutura de célula da chave, mais especificamente a estrutura de roteamento de células no interior da chave ATM. Como o ATM se propõe a atender a todas as exigências do B-ISDN, a necessidade essencial da chave ATM, é que o transporte de células entre suas portas de entrada e saída se faça o mais rápido possível. Para se conseguir isso, a arquitetura proposta não utiliza buffer nos seus elementos de roteamento. O trabalho não implementa no todo a chave ATM, deixando em aberto o problema da perda de seqüência de células no interior da estrutura de roteamento, que seria uma responsabilidade do módulo de saída da chave. A arquitetura proposta foi modelada e um simulador foi construído para a realização dos testes. Para as simulações foram levados em conta os tráfegos de células unicast e multicast. Como as células unicast e as cópias das células multicast disputavam por um mesmo link de saída, foi proposta uma estratégia para separar estas células. Isto resultou no projeto de posicionar a rede de cópia de células no segundo estágio da estrutura de roteamento, deixando o primeiro estágio para o roteamento das células unicast. O resultado disso foi um segundo estágio agora destinado para as cópias de células multicast absolutamente descongestionado, reduzindo \'drasticamente a possibilidade de disputa por um link de saída. Além disso, a estrutura incorpora os conceitos de TBSF (Tandem Banyan Switch Fabric), e duplicidade de rota, que tornam a estrutura extremamente modular e flexível. Para atender a preocupação em separar o tráfego, foi introduzido entre um estágio e outro da rede Banyan, uma saída de fuga, permitindo que células que tenham atingido a porta de saída desejada possam deixar a estrutura. São apresentados os resultados da simulação, objetivando a validação do trabalho proposto. / This thesis addresses the problem of accomplishing multicast traffic in ATM networks. An architecture is proposed for the cell structure of the switch, more specifically the routing of cells inside an ATM switch. Because ATM tries to satisfy all the demands of the B-ISDN model, an ATM switch must transport cells between its input and output ports as fast as possible. To achieve that, the proposed architecture does not use buffers in its commutation elements. This work does not implement a complete ATM switch, leaving the problem of the loss of sequence of cells inside the routing structure open. This problem must be solved by the output module of the switch. The proposed architecture was modeled and a simulator was built for testing purposes. For the simulations, both the unicast and the multicast traffic were taken into account. As the unicast cells and the copies of the multicast cells disputed for the same output link, a strategy was proposed to separate these cells. This resulted in the positioning of the cell copy network in the second stage of the routing structure, leaving the first stage for the routing of unicast cells. The result was a very free second stage used for copying multicast cells. This new stage reduced the contention for an exit link. The structure incorporates the concepts of TBSF, and route duplicity, which make it extremely modular and flexible. To separate the traffic, it was introduced between the two stages of the Banyan Network an escape exit, allowing cells that have reached the correct output port to leave the structure.

Os produtos naturais marinhos são apontados com uma das fontes de substâncias bioativas mais importantes para a descoberta de novos fármacos. Neste ambiente, os organismos estão em constante interação ecológica por meio da produção de metabólitos secundários. Fungos endofíticos e cianobactérias representam grupos de micro-organismos que realizam a biossíntese de substâncias com características químicas únicas e atividades biológicas potentes. Entretanto, quando retirados de seu habitat natural, esses seres microbianos geralmente perdem sua capacidade metabólica através de um fenômeno denominado silenciamento gênico, no qual genes biossintéticos deixam de ser transcritos devido a motivos ainda indeterminados. Esse mecanismo genético é intermediado, dentre outros fatores, pelas enzimas DNAmetiltransferase (DNA-MT) e Histona-desacetilase (HDAC). Deste modo, seus inibidores têm sido utilizados com sucesso para promover a eliciação de substâncias que não seriam produzidas em condições laboratoriais. Outra importante abordagem na pesquisa de produtos naturais têm sido a desreplicação baseada na fragmentação (MS/MS) para identificação de substâncias ou análogos. As redes moleculares (molecular networking) constituem uma nova abordagem na qual dados de espectrometria de massas são agrupados de acordo com as semelhanças entre os padrões de fragmentação, formando famílias de moléculas, permitindo a rápida visualização do perfil químico de várias amostras ao mesmo tempo. Deste modo, este trabalho apresenta o isolamento e identificação de metabólitos inéditos a partir de fungos endofíticos e cianobactérias oriundos do ambiente marinho. Para isto, técnicas de eliciação epigenética foram utilizadas em ambos os grupos de organismos, e a desreplicação via redes moleculares foi utilizada em cianobactérias. Fungos endofíticos associados à macroalga vermelha Bostrychia tenella foram alvo de estudos químicos e epigenéticos. As linhagens Xylaria sp. e Nigrospora oryzae foram submetidas ao cultivo em meio sólido arroz, o que resultou no isomento da substância citocalasina D e de um derivado potencialmente inédito da griseofulvina. A linhagem Penicillium decaturense foi cultivada em meio líquido PDB resultando no isolamento da 10,11-deidrocurvularina e possíveis análogos. Experimentos com inibidores epigenéticos (butirato de sódio e procaína) promoveram a modulação do perfil químico desta linhagem, ao estimular a produção de metabólitos não expressos em condições normais de cultivo. Ainda, a linhagem Acremonium sp. produziu várias substâncias quando cultivada em meio de líquido Czapek sob a influência de procaína, sendo uma delas potencialmente inédita e derivada da classe de metabólitos das brevianamidas. Frações orgânicas da cianobactéria Schizothrix sp., coletada no Panamá, foram analisadas em LC-MS/MS e os dados gerados foram utilizados para a criação de redes moleculares. Este estudo resultou na identificação dos metabólitos barbamida, hectoclorina, curacinas A e D, curazole, acetato de malingamida D, dolastatina 10 e carmaficina B. Ainda, análogos das substâncias curazole, dolastatina D e dois análogos inéditos das carmaficinas foram propostos. A cianobactéria Moorea producens JHB, coletada na Jamaica, foi submetida ao cultivo sob influência do ii composto butirato de sódio, e produziu dois metabólitos inéditos, propostos de acordo com os dados de fragmentação, como sendo derivados da jamaicamida e da hectoclorina, num tipo de biossíntese cruzada. Portanto, este trabalho confirma os fungos endofíticos e cianobactérias marinhos como promissores quanto a exploração do metabolismo secundário. / Marine natural products are pointed out as one of the most important sources of bioactive compounds for drug discovery. In this environment, organisms are in constantly interaction ecological through the production of secondary metabolites. Endophytic fungi and cyanobacteria represent groups of microorganisms that perform biosynthesis of substances with unique chemical features and potent biological activities. However, when removed from their natural habitat, these microbial beings generally lose their metabolic capacity through a phenomenon called gene silencing, in which biosynthetic genes are no longer transcribed due to reasons still undetermined. This genetic mechanism is brokered, among other factors, by the enzyme DNA methyltransferase (DNA-MT) and histone deacetylase (HDAC). Thus, their inhibitors have been used successfully to promote the elicitation of substances that would not be produced under laboratory conditions. Another important approach in the natural products research field have been dereplication based on the fragmentation (MS/MS) for the identification of substances or analogues. The molecular networking is a new approach in which data from mass spectrometry are grouped according to the similarities between the patterns of fragmentation, forming families of molecules, allowing rapid visualization of the chemical profile of several samples simultaneously. Thus, this work presents the isolation and identification of novel metabolites from endophytic fungi and cyanobacteria originating from the marine environment. For this propose, epigenetic elicitation techniques were used in both groups of organisms and the molecular networks via dereplication was used in cyanobacteria. Endophytic fungi associated with red seaweed Bostrychia tenella were subjected to chemical and epigenetic studies. Xylaria sp. and Nigrospora oryzae strains were cultured in solid medium rice, resulting in isolation of substance of cytochalasin D and a potentially novel derivative of griseofulvin. Penicillium decaturense strain was grown in PDB liquid medium resulting in the isolation of 10,11- deidrocurvularina and possible analogues. Experiments with epigenetic inhibitors (sodium butyrate and procaine) promoted the modulation of the chemical profile of this strain, to stimulate the production of metabolites not expressed under normal culture conditions. Moreover, Acremonium sp. produced various substances when grown in liquid medium under the influence of Czapek procaine, one of novel and potentially derived from the class of metabolites brevianamides. Organic fractions of the cyanobacteria Schizothrix sp., collected in Panama, were analized by LC-MS/MS and the data generated were used to create molecular networks. This study resulted in the identification of metabolites barbamide, hectochlorin, curacins A and D, curazole malyngamide D acetate, dolastatin 10 and carmaphycin B. Also, analogs of curazole, dolastatin 10 and carmaphycins A and B have been proposed. Cyanobacteria Moorea producens JHB, collected in Jamaica, was grown under the influence of sodium butyrate, and produced two new proposed metabolites in accordance with the fragmentation data as being derived from jamaicamide and hectochlorin, in a sort of crossed biosynthesis. Therefore, this work corroborates marine endophytic fungi and cyanobacteria as promising for exploration of secondary metabolism.

Context. A huge majority of the current Internet traffic is information dissemination. Information-Centric Networking (ICN) is a future networking paradigm that focuses on global level information dissemination. In ICN, the communication is defined in terms of requesting and providing Named Data Objects (NDO). NetInf is a future networking architecture based on Information-Centric Networking principles. Objectives. In this thesis, a global routing solution for ICN has been implemented. The authority part of NDO's name is mapped to a set of routing hints each with a priority value. Multiple NDOs can share the same authority part and thus the first level aggregation is provided. The routing hints are used to forward a request for a NDO towards a suitable copy of the NDO. The second level aggregation is achieved by aggregating high priority routing hints on low priority routing hints. The performance and scalability of the routing implementation are evaluated with respect to global ICN requirements. Furthermore, some of the notable challenges in implementing global ICN routing are identified. Methods. The NetInf global routing solution is implemented by extending NEC's NetInf Router Platform (NNRP). A NetInf testbed is built over the Internet using the extended NNRP implementation. Performance measurements have been taken from the NetInf testbed. The performance measurements have been discussed in detail in terms of routing scalability. Results. The performance measurements show that hop-by-hop transport has significant impact on the overall request forwarding. A notable amount of time is taken for extracting and inserting binary objects such as routing hints at each router. Conclusions. A more suitable hop-by-hop transport mechanism can be evaluated and used with respect to global ICN requirements. The NetInf message structure can be redefined so that binary objects such as routing hints can be transmitted more efficiently. Apart from that, the performance of the global routing implementation appears to be reasonable. As the NetInf global routing solution provides two levels of aggregation, it can be scalable as well.

One recent innovation in the networking industry, is the concept of Network FunctionVirtualization (NFV). NFV is based on a networking paradigm in which network functions,which have typically been implemented in the form of dedicated hardware appliances in thepast, are implemented in software and deployed on commodity hardware using modernvirtualization techniques. While the most common approach is to place each virtual networkfunction in a virtual machine - using hardware-level virtualization – the growing influenceand popularity of Docker and other container-based solutions has naturally led to the idea ofcontainerized deployments. This is a promising concept, as containers (or operating systemlevel virtualization) can offer a flexible and lightweight alternative to hardware-levelvirtualization, with the ability to use the resources of the host directly. The main problem withthis concept, is the fact that the default behavior of Docker and similar technologies is to relyon the networking stack of the host, which typically isn’t performant enough to handle theperformance requirements associated with NFV. In this dissertation, an attempt is made toevaluate the feasibility of using userspace networking to accelerate the network performanceof Docker containers, bypassing the standard Linux networking stack by moving the packetprocessing into userspace.

Social networking services are relatively new phenomena and they have attracted so much attention around themselves. These services have been seen by many organizations as a po-tential tool to facilitate knowledge sharing. However, very few have successfully adopted such services. Many problems which lead to failures arise when it comes to developing and implementing social networking services with the goal to facilitate knowledge sharing.The purpose of this thesis is to investigate the failure of one social networking service to satisfy the knowledge sharing needs of the organization that has developed and implement-ed it in-house.Interviews with three employees of the company were arranged. The interviews were done with time intervals in between. This gave us the opportunity to rearrange the questions that were going to be asked to the next interviewee. The interviews were really helpful and gave us a good insight of the problem with the development and implementation of the social networking service that the organization was facing. After the interviews were conducted, a questionnaire was elaborated and sent out to the employees in the organization.The results we came up with were really interesting. A table with failure factors for the so-cial networking service used in the organization was made and a model suggesting the steps an organization should follow for the successful development and implementation of a so-cial networking service that facilitates knowledge sharing internally was developed.We found out that the failure was not in the social networking service itself but in the way it was presented, positioned and communicated to the employees of the company. They never took the service seriously for its intended purpose which was knowledge sharing within the organization and that led to the cancelation of the project.

Physical indoor wireless network testbeds as well as outdoor wireless testbeds have the potential to accelerate the pace of research in the field of wireless ad hoc and mesh networking. They form part of a critical chain of steps needed to develop and test ad hoc networking protocols from concept to eventual uptake by industry. Current research in this area makes use of simulations or mathematical models which oversimplify the physical and Medium Access Control layer. In Africa specifically, wireless mesh networking has the potential to make a substantial impact on the lack of telecommunications infrastructure across the continent. A combination of good theoretical analysis, indoor test facilities and rural testbeds forms a perfect suite to carry out meaningful research in the field. A 7x7 wireless grid of closely spaced computers was constructed, making use of highly attenuated 802.11 radios running in ad hoc mode. Modelling and analysis revealed that a suitably attenuated environment was created with variation in signal strength between node pairs following a Gaussian distribution. This emulates a real outdoor network with normal signal propagation issues such as multi-path fading and lack of Fresnel zone clearance. This testbed was then used to evaluate 3 popular MANET ad hoc routing protocols, namely AODV, DYMO and OLSR. OLSR was tested with the standard hysteresis routing metric as well as the ETX routing metric. OLSR showed the best performance in terms of average throughput and packet loss for a medium size (21 node) and large (49 node) mesh network, with the hysteresis routing metric performing best in large networks and ETX performing best in medium sized networks. DYMO also performed very well, considering its low routing overhead, exhibiting the least amount of delay in a large mesh network (49 nodes). The AODV protocol showed the weakest performance in the grid with close to 60% of possible link pairs achieving no route in a 49-node grid. However, it did present the least amount of routing overhead compared with other routing protocols. Finally, a medium-sized rural mesh network testbed consisting of 9 nodes was built in a mountainous area of about 15 square kilometers around an AIDS clinic using the OLSR routing protocol with ETX as the routing metric. The network provided a good service to the satellite-based Internet with throughput rates ranging between 300 kbps for 4 hops and 11000 kbps for 1 hop and an average throughput rate of 2324 kbps. To encourage fair sharing of Internet connectivity, features were installed to limit each user to 40 MB/month of free Internet traffic. A local web server offers cached pages of Wikipedia and Linux repositories to reduce the need for Internet access. VoIP services were also installed between clinic infrastructure to reduce the the need for making expensive GSM calls. It was shown that a mesh network of this size provides a very satisfactory level of broadband service for users accessing a satellite-based Internet facility as well as local VoIP services. / Dissertation (MEng)--University of Pretoria, 2009. / Electrical, Electronic and Computer Engineering / unrestricted

The etiology of central nervous system tumors (CNSTs) is mainly unknown. Aside from extremely rare genetic conditions, such as neurofibromatosis and tuberous sclerosis, the only unequivocally identified risk factor is exposure to ionizing radiation, and this explains only a very small fraction of cases. Using meta-analysis, gene networking and bioinformatics methods, this dissertation explored the hypothesis that environmental exposures produce genetic and epigenetic alterations that may be involved in the etiology of CNSTs. A meta-analysis of epidemiological studies of pesticides and pediatric brain tumors revealed a significantly increased risk of brain tumors among children whose mothers had farm-related exposures during pregnancy. A dose response was recognized when this risk estimate was compared to those for risk of brain tumors from maternal exposure to non-agricultural pesticides during pregnancy, and risk of brain tumors among children exposed to agricultural activities. Through meta-analysis of several microarray studies which compared normal tissue to astrocytomas, we were able to identify a list of 554 genes which were differentially expressed in the majority of astrocytomas. Many of these genes have in fact been implicated in development of astrocytoma, including EGFR, HIF-1α, c-Myc, WNT5A, and IDH3A. Reverse engineering of these 554 genes using Bayesian network analysis produced a gene network for each grade of astrocytoma (Grade I-IV), and ‘key genes’ within each grade were identified. Genes found to be most influential to development of the highest grade of astrocytoma, Glioblastoma multiforme (GBM) were: COL4A1, EGFR, BTF3, MPP2, RAB31, CDK4, CD99, ANXA2, TOP2A, and SERBP1. Lastly, bioinformatics analysis of environmental databases and curated published results on GBM was able to identify numerous potential pathways and gene-environment interactions that may play key roles in astrocytoma development. Findings from this research have strong potential to advance our understanding of the etiology and susceptibility to CNSTs. Validation of our 'key genes' and pathways could potentially lead to useful tools for early detection and novel therapeutic options for these tumors.

Today, data centers host a wide variety of applications which generate a mix of diverse internal data center traffic. In a data center environment 90% of the traffic flows, though they constitute only 10% of the data carried around, are short flows with sizes up to a maximum of 1MB. The rest 10% constitute long flows with sizes in the range of 1MB to 1GB. Throughput matters for the long flows whereas short flows are latency sensitive. This thesis studies various data center transport mechanisms aimed at either improving flow completion time for short flows or throughput for long flows. Thesis puts forth two data center transport mechanisms: (1) for improving flow completion time for short flows (2) for improving throughput for long flows. The first data center transport mechanism proposed in this thesis, FA-DCTCP (Flow Aware DCTCP), is based on Data Center Transmission Control Protocol (DCTCP). DCTCP is a Transmission Control Protocol (TCP) variant for data centers pioneered by Microsoft, which is being deployed widely in data centers today. DCTCP congestion control algorithm treats short flows and long flows equally. This thesis demonstrate that, treating them differently by reducing the congestion window for short flows at a lower rate compared to long flows, at the onset of congestion, 99th percentile of flow completion time for short flows could be improved by up to 32.5%, thereby reducing their tail latency by up to 32.5%. As per data center traffic measurement studies, data center internal traffic often exhibit predefined patterns with respect to the traffic flow mix. The second data center transport mechanism proposed in this thesis shows that, insights into the internal data center traffic composition could be leveraged to achieve better throughput for long flows. The mechanism for the same is implemented by adopting the Software Defined Networking paradigm, which offers the ability to dynamically adapt network configuration parameters based on network observations. The proposed solution achieves up to 22% improvement in long flow throughput, by dynamically adjusting network element’s QoS configurations, based on the observed traffic pattern.