Grâce à l’émergence dans la vie quotidienne des appareils de plus en plus populaires que sont les smartphones et les tablettes, la tâche de postionner l'utilisateur par le biais de son téléphone est une problématique fortement étudiée dans les domaines non seulement de la recherche mais également des communautés industrielles. Parmi ces technologies, les approches GPS sont devenues une norme et ont beaucoup de succès pour une localisation en environnement extérieur. Par contre, le Wi-Fi, les capteurs inertiels et le Bluetooth sont plutôt préférés pour les tâches de positionnement dans un environnement intérieur.Pour ce qui concerne le positionnement des smartphones, les approches basées sur les « empreintes digitales » (fingerprint) Wi-Fi sont bien établies. D'une manière générale, ces approches tentent d'apprendre la fonction de correspondance (cartographie) des caractéristiques du signal Wi-Fi par rapport à la position de l’appareil dans le monde réel. Elles nécessitent généralement une grande quantité de données pour obtenir une bonne cartographie. Lorsque ces données d'entraînement disponibles sont limitées, l'approche basée sur les empreintes digitales montre alors des taux d’erreurs élevés et devient moins stable. Dans nos travaux, nous explorons d’autres approches, différentes, pour faire face à cette problématique du manque de données d'entraînement. Toutes ces méthodes sont testées sur un ensemble de données public qui est utilisé lors d’une compétition internationale à la Conférence IPIN 2016.En plus du système de positionnement basé sur la technologie Wi-Fi, les capteurs inertiels du smartphone sont également utiles pour la tâche de suivi. Les trois types de capteurs, qui sont les accéléromètres, le gyroscope et la boussole magnétique, peuvent être utilisés pour suivre l'étape et la direction de l'utilisateur (méthode SHS). Le nombre d'étapes et la distance de déplacement de l'utilisateur sont calculés en utilisant les données de l'accéléromètre. La position de l'utilisateur est calculée par trois types de données avec trois méthodes comprenant la matrice de rotation, le filtre complémentaire et le filtre de Madgwick. Il est raisonnable de combiner les sorties SHS avec les sorties de Wi-Fi, car les deux technologies sont présentes dans les smartphones et se complètent. Deux approches combinées sont testées. La première approche consiste à utiliser directement les sorties Wi-Fi comme points de pivot pour la fixation de la partie de suivi SHS. Dans la deuxième approche, nous comptons sur le signal Wi-Fi pour construire un modèle d'observation, qui est ensuite intégré à l'étape d'approximation du filtre à particules. Ces combinaisons montrent une amélioration significative par rapport au suivi SHS ou au suivi Wi-Fi uniquement.Dans un contexte multiutilisateur, la technologie Bluetooth du smartphone pourrait fournir une distance approximative entre les utilisateurs. La distance relative est calculée à partir du processus de numérisation du périphérique Bluetooth. Elle est ensuite utilisée pour améliorer la sortie des modèles de positionnement Wi-Fi. Nous étudions deux méthodes. La première vise à créer une fonction d'erreur qui permet de modéliser le bruit dans la sortie Wi-Fi et la distance approximative produite par le Bluetooth pour chaque intervalle de temps spécifié. La seconde méthode considère par contre cette relation temporelle et la contrainte de mouvement lorsque l'utilisateur se déplace. Le modèle d'observation du filtre à particules est une combinaison entre les données Wi-Fi et les données Bluetooth. Les deux approches sont testées en fonction de données réelles, qui incluent jusqu'à quatre utilisateurs différents qui se déplacent dans un bureau. Alors que la première approche n'est applicable que dans certains scénarios spécifiques, la deuxième approche montre une amélioration significative par rapport aux résultats de position basés uniquement sur le modèle d'empreintes digitales Wi-Fi. / With the popularity of smartphones and tablets in daily life, the task of finding user’s position through their phone gains much attention from both the research and industry communities. Technologies integrated in smartphones such as GPS, Wi-Fi, Bluetooth and camera are all capable for building a positioning system. Among those technologies, GPS has approaches have become a standard and achieved much success for the outdoor environment. Meanwhile, Wi-Fi, inertial sensors and Bluetooth are more preferred for positioning task in indoor environment.For smartphone positioning, Wi-Fi fingerprinting based approaches are well established within the field. Generally speaking, the approaches attempt to learn the mapping function from Wi-Fi signal characteristics to the real world position. They usually require a good amount of data for finding a good mapping. When the available training data is limited, the fingerprinting-based approach has high errors and becomes less stable. In our works, we want to explore different approaches of Wi-Fi fingerprinting methods for dealing with a lacking in training data. Based on the performance of the individual approaches, several ensemble strategies are proposed to improve the overall positioning performance. All the proposed methods are tested against a published dataset, which is used as the competition data of the IPIN 2016 Conference with offsite track (track 3).Besides the positioning system based on Wi-Fi technology, the smartphone’s inertial sensors are also useful for the tracking task. The three types of sensors, which are accelerate, gyroscope and magnetic, can be employed to create a Step-And-Heading (SHS) system. Several methods are tested in our approaches. The number of steps and user’s moving distance are calculated from the accelerometer data. The user’s heading is calculated from the three types of data with three methods, including rotation matrix, Complimentary Filter and Madgwick Filter. It is reasonable to combine SHS outputs with the outputs from Wi-Fi due to both technologies are present in the smartphone. Two combination approaches are tested. The first approach is to use directly the Wi-Fi outputs as pivot points for fixing the SHS tracking part. In the second approach, we rely on the Wi-Fi signal to build an observation model, which is then integrated into the particle filter approximation step. The combining paths have a significant improvement from the SHS tracking only and the Wi-Fi only. Although, SHS tracking with Wi-Fi fingerprinting improvement achieves promising results, it has a number of limitations such as requiring additional sensors calibration efforts and restriction on smartphone handling positions.In the context of multiple users, Bluetooth technology on the smartphone could provide the approximated distance between users. The relative distance is calculated from the Bluetooth inquiry process. It is then used to improve the output from Wi-Fi positioning models. We study two different combination methods. The first method aims to build an error function which is possible to model the noise in the Wi-Fi output and Bluetooth approximated distance for each specific time interval. It ignores the temporal relationship between successive Wi-Fi outputs. Position adjustments are then computed by minimizing the error function. The second method considers the temporal relationship and the movement constraint when the user moves around the area. The tracking step are carried out by using particle filter. The observation model of the particle filter are a combination between the Wi-Fi data and Bluetooth data. Both approaches are tested against real data, which include up to four different users moving in an office environment. While the first approach is only applicable in some specific scenarios, the second approach has a significant improvement from the position output based on Wi-Fi fingerprinting model only.

Submitted by Fernando Souza (fernandoafsou@gmail.com) on 2017-08-16T11:08:57Z No. of bitstreams: 1 arquivototal.pdf: 14592184 bytes, checksum: e1af48f8997b6af87f0fc91dd6d4a697 (MD5) / Made available in DSpace on 2017-08-16T11:08:57Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 14592184 bytes, checksum: e1af48f8997b6af87f0fc91dd6d4a697 (MD5) Previous issue date: 2016-08-31 / One of the most important aspects concerning the implementation of a Wireless Local Area Network (WLAN) is that in an area covered by several Access Points (APs), there must exist mechanisms to keep the user connected at any time, regardless of his/her physical location in the network and, primarily, ensure that the applications do not suffer from loss of connectivity. In this context, handoff performance, which consists of changing the AP as the station moves within the same area, is a preponderant factor when it comes to applications that are delay-sensitive. The process is usually started by the stations that once disconnected from an AP, start scanning the existing channels searching for other available APs in a smooth fashion, but in the order of seconds, which makes it difficult to use real-time applications. The challenge is to create a more efficient mechanism to manage this process, providing the required Quality of Service (QoS) for the applications. This work presents the use of mechanisms to improve the performance of the handoff process by employing an approach based on the a Software DefinedWireless Network (SDWN), which was implemented to validate the proposal. The tests performed showed a decrease in the time spent in the handoff, contributing to guarantee the QoS of the applications. / Um dos aspectos mais importantes na implantação de uma rede local sem fio Wireless Local Area Network (WLAN) é que em uma área coberta por vários Access Points (APs), devem existir mecanismos que sejam suficientes para que o usuário possa se manter conectado a qualquer hora independentemente de sua localização física dentro da rede e, principalmente, garantir que as aplicações não sofram com falhas ou perdas de conexão. Neste contexto, o desempenho do handoff, que consiste na troca de AP à medida que uma estação se move dentro de uma mesma área, é fator determinante para o uso de aplicações sensíveis ao atraso. Normalmente o processo é iniciado pelas estações, que ao se desconectarem de um AP iniciam uma varredura nos canais existentes buscando outros APs disponíveis de forma suave, porém na ordem de segundos, o que dificulta o uso de aplicações em tempo real. O desafio é criar um mecanismo mais eficiente para gerenciar este processo provendo a Qualidade de Serviço (QoS) necessária para as aplicações. Este trabalho apresenta uma solução denominada Detection and dIScovery Control in Handoff (DISpatCH) que utiliza mecanismos para melhorar o desempenho do processo de handoff utilizando uma abordagem baseada na arquitetura Software Defined Wireless Network (SDWN) os quais foram implementados para validar a proposta. Testes realizados demonstraram uma diminuição no tempo gasto no handoff contribuindo para garantir o QoS das aplicações.

Made available in DSpace on 2014-12-17T14:55:18Z (GMT). No. of bitstreams: 1 ViniciusSVS_TESE.pdf: 2375594 bytes, checksum: e3d85d405a408eb605711ffd55dbe760 (MD5) Previous issue date: 2014-03-17 / The monitoring of patients performed in hospitals is usually done either in a manual or semiautomated way, where the members of the healthcare team must constantly visit the patients to ascertain the health condition in which they are. The adoption of this procedure, however, compromises the quality of the monitoring conducted since the shortage of physical and human resources in hospitals tends to overwhelm members of the healthcare team, preventing them from moving to patients with adequate frequency. Given this, many existing works in the literature specify alternatives aimed at improving this monitoring through the use of wireless networks. In these works, the network is only intended for data traffic generated by medical sensors and there is no possibility of it being allocated for the transmission of data from applications present in existing user stations in the hospital. However, in the case of hospital automation environments, this aspect is a negative point, considering that the data generated in such applications can be directly related to the patient monitoring conducted. Thus, this thesis defines Wi-Bio as a communication protocol aimed at the establishment of IEEE 802.11 networks for patient monitoring, capable of enabling the harmonious coexistence among the traffic generated by medical sensors and user stations. The formal specification and verification of Wi-Bio were made through the design and analysis of Petri net models. Its validation was performed through simulations with the Network Simulator 2 (NS2) tool. The simulations of NS2 were designed to portray a real patient monitoring environment corresponding to a floor of the nursing wards sector of the University Hospital Onofre Lopes (HUOL), located at Natal, Rio Grande do Norte. Moreover, in order to verify the feasibility of Wi-Bio in terms of wireless networks standards prevailing in the market, the testing scenario was also simulated under a perspective in which the network elements used the HCCA access mechanism described in the IEEE 802.11e amendment. The results confirmed the validity of the designed Petri nets and showed that Wi-Bio, in addition to presenting a superior performance compared to HCCA on most items analyzed, was also able to promote efficient integration between the data generated by medical sensors and user applications on the same wireless network / O monitoramento de pacientes realizado nos hospitais normalmente ? feito de forma manual ou semi-automatizada, em que os membros da equipe de sa?de precisam constantemente se deslocar at? os pacientes para verificarem o estado de sa?de em que eles se encontram. A ado??o desse procedimento, todavia, compromete a qualidade do monitoramento realizado, uma vez que a escassez de recursos f?sicos e humanos nos hospitais tende a sobrecarregar os membros da equipe de sa?de e assim impedir que os mesmos se desloquem aos pacientes com a freq??ncia adequada. Diante disso, diversos trabalhos existentes na literatura especificam alternativas voltadas ? melhoria desse monitoramento mediante o uso de redes sem fio. Nesses trabalhos, a rede ? destinada apenas ao tr?fego de dados gerados por sensores m?dicos e n?o existe a possibilidade da mesma ser alocada para o envio de informa??es oriundas de aplica??es presentes nas esta??es de usu?rio existentes no hospital. Todavia, em se tratando de ambientes de automa??o hospitalar, esse aspecto constitui-se em um ponto negativo, haja vista que os dados gerados nessas aplica??es podem estar diretamente relacionados ao monitoramento de pacientes realizado. Desse modo, esta tese define o Wi-Bio como sendo um protocolo de comunica??o voltado ao estabelecimento de redes de monitoramento de pacientes IEEE 802.11 capazes de permitir a conviv?ncia harmoniosa entre os tr?fegos gerados por sensores m?dicos e esta??es de usu?rio. A especifica??o e verifica??o formal do Wi-Bio foram feitas mediante o projeto e an?lise de modelos em redes de Petri e sua valida??o foi realizada atrav?s simula??es efetuadas na ferramenta Network Simulator 2 (NS2). As simula??es realizadas no NS2 foram projetadas para retratarem um ambiente real de monitoramento de pacientes correspondente a um andar do setor de enfermarias do Hospital Universit?rio Onofre Lopes (HUOL), localizado na cidade de Natal/RN. Al?m disso, no intuito de verificar a viabilidade do Wi-Bio quanto aos padr?es de redes sem fio vigentes no mercado, o cen?rio de testes tamb?m foi simulado sob uma perspectiva em que os elementos da rede utilizavam o mecanismo de acesso HCCA descrito na emenda IEEE 802.11e. Os resultados obtidos atestaram a validade das redes de Petri projetadas e mostraram que o Wi-Bio, al?m de apresentar um desempenho superior ao do HCCA na maioria dos quesitos analisados, tamb?m se mostrou capaz de promover uma integra??o eficiente entre os dados gerados por sensores m?dicos e aplica??es de usu?rio sob a mesma rede sem fio

Made available in DSpace on 2014-12-17T14:55:54Z (GMT). No. of bitstreams: 1 CarlosGM_DISSERT.pdf: 4338321 bytes, checksum: 5834ff97d013cae154b31036fbc6dbe6 (MD5) Previous issue date: 2011-12-29 / Even living in the XXI century are still some difficulties in access to broadband Internet in several Brazilian cities, due to the purchasing power of people and lack of government investment. But even with these difficulties, we seek to encourage the use of wireless technology, which is based on the IEEE 802.11b protocol - also known as Wi-Fi (Wireless Fidelity) Wireless Fidelity Communications, having wide range of commercial applications in the world market, nationally and internationally. In Brazil, this technology is in full operation in major cities and has proved attractive in relation to the access point to multipoint and point-to-point. This paper is a comparative analysis of prediction field, using models based on the prediction of propagation loss. To validate the techniques used here, the Okumura-Hata models, modified Okumura-Hata, Walfisch-Ikegami model, were applied to a wireless computer network, located in the neighborhood of Cajupiranga in the city of Melbourn, in Rio Grande do Norte . They are used for networking wireless 802.11b, using the Mobile Radio to measure signal levels, beyond the heights of the antennas and distances from the transmitter. The performance data versus distance are added to the graphs generated and compared with results obtained through calculations of propagation models / Mesmo vivendo em pleno s?culo XXI ainda encontram-se dificuldades no acesso ? internet banda larga nos diversos munic?pios brasileiros, em decorr?ncia do poder aquisitivo dos habitantes bem como falta de investimento do governo. A tecnologia das redes de acesso sem fio baseadas no protocolo IEEE 802.11b - tamb?m denominada de Wi Fi, (Wireless Fidelity) Fidelidade em Comunica??es sem Fio, possui larga gama de aplica??es atualmente no mercado mundial comercial, nacional e internacional. No Brasil, esta tecnologia encontra-se em plena opera??o nas principais cidades e tem-se mostrado atrativa no que concerne aos acessos ponto multiponto e ponto-a-ponto. Neste trabalho s?o elaborados, uma an?lise comparativa de predi??o de campo, e analisados modelos de predi??o das perdas de propaga??o, Modelo Okumura-Hata, Lee, Modelo de Ikegami-Walfisch, para uma rede de computadores sem fio, no bairro de Cajupiranga e no Centro, no munic?pio de Parnamirim, no Rio Grande do Norte. S?o usados equipamentos de redes sem fio do padr?o 802.11b, analisador de espectro, onde os n?veis de sinais s?o medidos, al?m das alturas das antenas e das dist?ncias em rela??o ao transmissor. Os dados de pot?ncia versus dist?ncia s?o adicionados nos gr?ficos gerados e comparados com os resultados obtidos

Esta tese analisa aplicações de transmissão de voz e vídeo sobre redes Wi-Fi (IEEE 802.11). Os principais problemas observados foram a maior incidência de tráfegos em rajada e os problemas associados à execução de handoffs. Foram propostos algoritmos adaptativos para monitorar e contornar esses problemas. / This thesis examines applications for transmitting voice and video over Wi-Fi (IEEE 802.11). The main problems observed were the higher incidence of bursty traffic and disconnection during handoffs. Adaptive algorithms have been proposed to monitor and work around these problems.

Submitted by bruna ortiz (brunaortiz.f@gmail.com) on 2016-07-04T15:34:48Z No. of bitstreams: 1 Dissertação-Laura Michaella Batista Ribeiro.pdf: 5196443 bytes, checksum: 44f8d0ba69aa5d5fb4454331819feaa4 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-07-18T13:11:02Z (GMT) No. of bitstreams: 1 Dissertação-Laura Michaella Batista Ribeiro.pdf: 5196443 bytes, checksum: 44f8d0ba69aa5d5fb4454331819feaa4 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-07-18T13:25:46Z (GMT) No. of bitstreams: 1 Dissertação-Laura Michaella Batista Ribeiro.pdf: 5196443 bytes, checksum: 44f8d0ba69aa5d5fb4454331819feaa4 (MD5) / Made available in DSpace on 2016-07-18T13:25:46Z (GMT). No. of bitstreams: 1 Dissertação-Laura Michaella Batista Ribeiro.pdf: 5196443 bytes, checksum: 44f8d0ba69aa5d5fb4454331819feaa4 (MD5) Previous issue date: 2014-04-07 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With the significant utilization of the Wi-Fi networks as one of the main mass media and transmission of data, some problems of traffic reliability have been related and increasing day by day. The unplanned use of Access’ Points – AP, chained to the interferences resulting from coexistence of other technologies occupying the same frequency spectrum 2.4GHz, has constantly affected the performance of these networks. In order to propose a solution to interference’s problem between networks 802.11, this work describe an approach of attribution of channels based in many aspects such as received signal strength indicator, signal-to-noise ratio, link quality and channels overlap factor. This approach, named MFDCA (Multi-Factor Dynamic Channel Assignment) is composed by detection interferences modules, as well as selection and attribution of channels. The approach attributes in a dynamic way operation of channels in the networks 802.11, considering the characteristics noted in the spectral environment where which AP is inserted. The MFDCA was developed so that to operate in low cost of access points, as long as they withstand an installation of a firmware based in Linux. The results of the tests accomplished in a pilot network show that a MFDCA is able to benefit the network as a whole, including non-administered networks, by increasing its throughput and decreasing the rate losses of packages. / Com a utilização significativa das redes Wi-Fi como um dos principais meios de comunicação e transmissão de dados, problemas relacionados à confiabilidade no tráfego dessas redes foram surgindo. O uso não planejado de pontos de acesso (do inglês, Access Point - AP), aliado com as interferências decorrentes da coexistência de outras tecnologias compartilhando o mesmo espectro de frequências 2,4GHz, tem constantemente afetado o desempenho das redes sem fio. Com o intuito de propor uma solução para o problema de interferência entre redes sem fio 802.11, este trabalho descreve uma abordagem para atribuição de canais baseada em múltiplos fatores como a indicação da intensidade do sinal recebido, a relação sinal-ruído, a qualidade de link e o fator de sobreposição de canais. Esta abordagem, denominada de MFDCA (Multi-Factor Dynamic Channel Assignment) é composta pelos módulos de detecção de interferências e de seleção e atribuição de canais. A abordagem atribui de forma dinâmica canais de operação nas redes 802.11, considerando as características presentes no ambiente espectral onde cada AP está inserido. AMFDCA foi projetada para operar em pontos de acesso de baixo custo, desde que suportem a instalação de um firmware baseado em Linux. Os resultados dos testes realizados em uma rede piloto mostram que a MFDCA é capaz de beneficiar as redes como um todo, incluindo redes não administradas, proporcionando um aumento na vazão de dados e a diminuição das taxas de perdas de pacotes.

This master’s thesis investigates the technology and security awareness associated with wireless networks (WLAN). It has been stated by the media and theories that many wireless networks are unprotected. This has sparked an interest to investigate the phenomenon in the Jonkoping region. The study is based on the following research questions: - What security weaknesses are present with the WLAN-technology and how can these be avoided? - How does the wireless infrastructure in the Jonkoping region look like? - Why do companies implement the WLAN-technology? - Are the companies aware of the risks involved with WLAN? We conducted this study in three steps; the first step was to hack a wireless network in a controlled environment in order to investigate the weaknesses of the commonly used security measures. The second step of the study was to scan the wireless networks in Jonkoping, Gnosjo and Nassjo in order to create a picture of the wireless infrastructure of the region. The third step of the study was to contact companies that we found in the second step for interviews to investigate their awareness of the technology and its weaknesses. We found that WLANs and their security measures have weaknesses. The commonly used WEP encryption can quite easily be broken and can lure users into a false sense of security. The study shows that companies are aware of this weakness, but use the encryption be-cause it offers a good level of usability and security. It is a compromise between usability and security. Usability is one of the major factors for companies when implementing wireless networks, companies strive for mobility, easy access and ease of use, which the WLAN technology offers. This has lead to an extended wireless infrastructure in cities within the region where one, with ease, can find wireless networks outside buildings. We have noticed an increase in the security awareness as our empirical findings differ from earlier research conducted in other cities. When these studies are compared you can see a trend where the number of unprotected networks decreases. Our contribution to increased wireless security is a checklist of possible security measures to minimize the security threats. / Denna magisteruppsats undersöker tekniken och säkerhetsmedvetandet gällande trådlösa nätverk (WLAN). Då det tidigare uppmärksammats i media och teori att många trådlösa nätverk står oskyddade har detta skapat intresse att undersöka fenomenet i Jönköpingsregionen. Studien baseras på följande frågeställningar: - Vilka säkerhetsluckor finns i WLAN och hur kan dessa undvikas? - Hur ser WLAN-infrastrukturen ut i Jönköpingsregionen? - Varför implementerar företag WLAN-tekniken? - Är företag medvetna om riskerna med trådlösa nätverk? För att skapa en helhetsbild har vi genomfört studien i tre steg varav vi, i det första steget, genomfört dataintrång i en kontrollerad miljö för att undersöka svagheterna med säkerhetsfunktionerna som används i trådlösa nätverk. I det andra steget undersökte vi med hjälp av bärbar dator trådlösa nätverk i Jönköping, Gnosjö och Nässjö. Detta för att skapa oss en uppfattning om hur WLAN-infrastrukturen ser ut i dagsläget. Steg tre innebar intervjuer med företag som vi funnit i samband med steg två rörande deras medvetenhet om tekniken och dess brister. Teorin och vår empiri gav oss underlag att dra slutsatser utifrån våra frågeställningar. Vi fann att WLAN och dess säkerhetsfunktioner har vissa sårbarheter. Den mest förekommande krypteringstekniken, WEP, kan dekrypteras tämligen enkelt och kan vagga in användarna i en falsk säkerhet. Studien visar att företagen är medvetna om detta, men att det handlar om en medveten kompromiss mellan användarvänlighet och säkerhet. Användarvänligheten står till grund för varför företagen väljer att implementera den trådlösa tekniken. Företag eftersträvar mobilitet, smidighet och enkel access, vilket den trådlösa tekniken erbjuder. Detta har lett till en utökad trådlös infrastruktur i städer runtom i regionen där man med lätthet kan hitta trådlösa nätverk utanför byggnader. Vi har noterat ett ökat säkerhetsmedvetande då våra empiriska resultat skiljer sig något från tidigare undersökningar i andra städer. När dessa ställs mot varandra anar man en trend där antalet oskyddade trådlösa nätverk minskar. Vårt bidrag till ökad trådlös säkerhet är en checklista med möjliga åtgärder för att minimera säkerhetsriskerna.

Konfigurationsprotokollet Wi-Fi protected setup (WPS) har vissa brister idess design gällande hur autentiseringen av den PIN-kod som används för attansluta en enhet till ett trådlöst nätverk är implementerad. Dessa brister kanutnyttjas av en attackerare för att utföra en bruteforce-attack som på enrelativt kort tid kan identifiera den korrekta koden. Detta arbete har tagit frammetoder för att motverka eller fördröja attacker mot WPS-protokollet sommed relativt enkla medel kan implementeras i befintliga nätverk. Genomutförda praktiska experiment där en fristående server upptäckt en attack ochgenomfört olika försvarsmetoder har de mekanismer som presenterats utvärderats. Slutsatsen är att den effektivaste metoden för att avbryta en bruteforce-attackmot protokollet är att automatiskt byta ut PIN-koden då en attack upptäcks. / Wi-Fi protected setup (WPS), a protocol used to configure wireless clients, isflawed in regard to the design of the authentication procedure for the PIN-code used to connect a new device. This flaw can be exploited by an attackerto perform a brute force attack to identify the code. This report presentsmethods to counteract brute force attacks performed against the WPS-protocol. The study has been performed by practical experiments where thecountermeasures have been evaluated and their performance has beenmeasured. With simple means, such as a third party acting on the routersbehalf in implementing countermeasures against the attacker, the attack canbe counteracted. The conclusion is that the most effective way of countering the WPS-bruteforce attack presented is to automatically replace the PIN-code with arandomly generated one when an attack is detected.

Wireless Protected Setup (WPS) är ett säkerhetsprotokoll för trådlösa nätverk. Dess design medför en allvarlig säkerhetsbrist som kan möjliggöra att obehöriga kan få åtkomst till ett lösenordskyddat trådlöst nätverk. Vid attack finns det olika verktyg tillgängliga att använda. I denna rapport jämförs mjukvaruverktygen Reaver och Bully i attack mot WiFi’s WPS-protokoll, där Bullys prestanda tidigare har påvisats vara mer effektiv och förutsätts snabbare utföra brute-forceattack jämfört med Reaver. Ett praktiskt laborationsexperiment har utförts för att undersöka vilken skillnad i hastighet som kan ses mellan verktygen Reaver och Bully i en brute-forceattack. Experimentet utfördes genom att mäta tiden det tog för de två verktygen att testa 100 PIN-nycklar mot en router utan skyddsmekanismer hos WPS. Resultatet visar att Bully utför en brute-forceattack i högre hastighet jämfört med Reaver. Dock, med den högre attackhastigheten som Bully innehar, kan stabilitetsproblem vid attack medföras, vilket öppnar upp för framtida diskussion om högre hastighet bör prioriteras över stabilitet för lyckade attacker. / Wireless Protected Setup (WPS) is a security protocol for wireless networks. Its design contains a serious security flaw that could allow an attacker access to a password-protected wireless network. An attack can be executed using various tools available. In this report, the software-tools Reaver and Bully are compared in performance against WiFi’s WPS-protocol, where Bully previously has been shown to be more effective and predicted faster to execute a bruteforce-attack. A practical laboration has been executed in order to determine differences in speed that can be seen between the tools Reaver and Bully in a bruteforce-attack. The experiment was done by measuring the time it took both tools to test 100 PIN-numbers against a router without protection for WPS. The result shows that Bully performs a bruteforce-attack in higher speed compared to Reaver. However, with the higher attack-speed that Bully uses, some stability issues may follow, opening the topic of future discussion regarding priorities of speed vs. stability for successful attacks.

Les réseaux sans fil sont en plein développement du fait de la flexibilité de leur interface, qui permet aux utilisateurs de se communiquer directement entre eux ou de se connecter facilement à Internet en onde radio sans mettre en place préalablement d'infrastructures lourdes, telles que des câbles filaires. Parmi les différentes technologies de réseaux sans fil, l'IEEE 802.11/Wi-Fi est devenu une technologie plus connue et plus utilisée pour construire des réseaux sans fil à haut débit dans une zone à forte concentration d'utilisateurs, telle que les aéroports, les campus ou les sites industriels. L'engouement pour les réseaux sans fil et notamment pour les réseaux Wi-Fi a fait émerger de nouvelles nécessités, tel que se déplace dans les réseaux sans fil tout en restant connecté à Internet. Dans les réseaux sans fil, le déplacement d’un utilisateur implique parfois un changement de Point d’accès (AP) au réseau. On désigne généralement ce fait un handover de niveau 2, du fait que le changement d'AP n’implique que les deux premières couches du modèle OSI. Si les deux APs se situent dans des réseaux différents, le changement d'AP implique aussi le changement de réseau pour cet utilisateur. On dénomme généralement cette situation un handover de niveau 3, par le fait que cet utilisateur devrait changer son réseau d’attachement et son adresse IP pour maintenir la connexion à Internet et que ce changement intervient sur la couche réseau du model OSI. La procédure du handover de niveau 2 dans les réseaux Wi-Fi est gérée par la norme IEEE 802.11 et celle de niveau 3 est gérée par le protocole IP Mobile. Le protocole IP Mobile est un protocole standardisé par l'IETF qui permet à l'utilisateur de maintenir ses communications en cours et de rester connecté à Internet tout en masquant d'une manière transparente le changement de réseau. Ainsi, l'utilisateur peut se déplace dans les réseaux Wi-Fi tout en maintenant les communications en cours et restant connecté à Internet grâce à la norme IEEE 802.11 et au protocole IP Mobile. Cependant, le délai introduit par ces deux procédures du handover est trop long, les communications en cours sont interrompus pendant ces procédures, naturellement, cela ne peut pas répondre aux exigences qualitatives des applications temps réel comme la vidéo conférence ou la voix sur IP. Diverses propositions qui ont été faites pour réduire le délai de ces procédures du handover et améliorer leur performance. Cependant, ces propositions sont soit imparfaites, soit non-implémentables à cause de leur complexité. En partant du principe que les réseaux Wi-Fi et les routeurs d'accès sont déjà massivement implantés dans le monde universitaire et dans les entreprises, nous proposons d'ajouter une nouvelle fonctionnalité, appelé E-HCF (Extended Handover Control Function) dans un routeur sans modifier les autres équipements du réseau. Le routeur pourvu de cette fonctionnalité est dénommé le routeur E-HCF. Pour réduire le délai des procédures du handover, la fonctionnalité E-HCF permet au routeur de générer une topologie des APs en utilisant la théorie des graphes de voisinage et de maintenir un pool d'adresses IP disponibles dans sa base de données. Quand le Nœud mobile (MN) a besoin de changer son AP, le routeur E-HCF peut proposer au MN une liste des APs potentiellement utilisables qui sont choisis et classés par un algorithme de sélection et de classement que nous avons élaboré dans la thèse. Si le changement d'AP implique un changement de réseau, le MN doit changer d'adresse IP. Dans ce cas, le routeur E-HCF peut attribuer une adresse IP unique à ce MN. Le MN peut donc utiliser cette adresse sans exécuter la phase d'Auto-configuration d'adresses ni exécuter la procédure de Détection d'adresse dupliquée. Avec cette nouvelle fonctionnalité E-HCF, nous pouvons réduire le délai des procédures du handover de quelques secondes à une centaine de millisecondes. / Wireless networks are in full development because of the flexibility of their interfaces, which allow users to be easily connected to the Internet. Among various technologies of wireless networks, IEEE 802.11/Wi-Fi technology is becoming better known and more used to construct high speed wireless networks in areas with high concentration of users, such as airports, campuses or industrial sites. The passion for wireless networks and in particular for Wi-Fi networks has given rise to new uses of the Internet, such as moving in wireless networks while still being connected. In Wi-Fi networks, the user's movement may sometimes lead to a change of Access Points (APs) to the network. This fact is generally named the handover of layer 2 because this change involves only the first two layers of the OSI model. If the two APs are located in different networks, the change of AP would entail a change of network for the user. This situation is generally termed, the handover of layer 3 because the user should change his network and his IP address to maintain connection to the Internet. Therefore, this change intervenes on the network layer of the OSI model. The process of the handover of layer 2 is handled by the IEEE 802.11 standard and that of layer 3 is controlled by the Mobile IP protocol. The Mobile IP protocol is a protocol standardized by IETF, which allows users to change network, while maintaining their actual connection to the Internet. Consequently, users can connect to the Internet, while keep moving in Wi-Fi networks in control of the IEEE 802.11 standard and the Mobile IP protocol. However, the delay induced by these procedures of handover is too long. As such, this generally leads to the cut-off of current communications, hence impacting adversely on the qualitative requirements of real-time applications, such as video conferencing or voice over IP. Various proposals have been made to reduce the delay of handover procedures and to improve their performances. However, these proposals are either imperfect, or non-implementable because of their complexity. Based on the premise that Wi-Fi networks and access routers are already massively implanted in academia and in industry, we propose to add a new functionality, called E-HCF (Extended Handover Control Function) in routers, without modifying other network equipments. A router equipped with this functionality is called an E-HCF router. To reduce the delay of handover procedures, the E-HCF functionality allows a router to generate a topology of APs by using the neighbourhood graph theory and to maintain a pool of available IP addresses in its database. When a Mobile Node (MN) needs to change its AP, the E-HCF router may propose to the latter a list of potentially usable APs, which are selected and classified by an algorithm of selection and classification that we developed in the thesis. If the change of APs involves a change of network, the MN must change its IP address. In this case, the E-HCF router can assign a unique IP address to this MN. The MN can thus use this address without engaging in the process of Stateless Address Autoconfiguration or the procedure of Duplicate Address Detection. With this new E-HCF functionality, we can reduce the delay of handover procedures from a few seconds to one hundred milliseconds.