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Analysis of the dependence of communications services to the delay and QoS optimization
Schön, Martin ; Číka, Petr (referee) ; Hošek, Jiří (advisor)
This thesis discusses wireless network standards 802.11a/b/g/n. First part explains basic principles of networks and media access. Next the standard IEEE 802.11, general QoS parameters and their application in wireless networks, according to standard 802.11e are analyzed. Second part of the thesis verifies the acquired knowledge in simulating program Opnet - effects of the delay, jitter and packet loss on VoIP call are tested. In the last part of the thesis a network for video streaming has been designed. The video was streamed in different qualities and the influence of other network traffic (with and without the support of QoS) on the video streaming was tested.
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Analysis of delay dependence of modern communication services and channels, QoS optimization
Rozman, Jiří ; Szőcs, Juraj (referee) ; Endrle, Pavel (advisor)
The main aim of this thesis is to familiarize with options of services using real-time data transfer in wireless networks. Theoretical part presents wireless network based on IEEE 802.11 standard and its practical use. Large part is focuses on 802.11e standart, that provides support for quality of service in wireless networks. Furthemore this thesis deals with transport and applicaton protocols supporting multimedia streaming over computer network. Second chapter is focused on analyzing real computer network with purpose in measuring parametrs influencing quality of service such as bandwith, delay, jitter and loss. Last part deals with the design of wireless network in OPNET Modeler enviroment with focus on simulating parameters that influence quality of service.
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Multimedia services in wireless networks
Bučina, Peter ; Martinásek, Zdeněk (referee) ; Mácha, Tomáš (advisor)
The main topic of my diploma thesis is dedicated to the issue of wireless networks mostly aimed at IEEE 802.11 standard. Theoretical part of the thesis is divided into three main chapters. It deals with basic overview of standards, architecture, utilization of radio spectrum and modulating techniques in signal processing. Further, it describes basic security measures and quality of service requirements in WLAN networks. The thesis is complemented by two separate laboratory assignments focused on procedure related to the chosen problematic. The first assignment handles common steps to break ciphered protocols WEP and WPA in WLAN’s. Linux software called Back Track 5 was used to provide complete package of tools for WLAN security tests. The second one is aimed at practical options on video streaming in converged wireless networks and also at remote access of mobile users to wireless IP camera video stream.
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Optimization of hand-over process in real network environment
Hornyak, Tomáš ; Skořepa, Michal (referee) ; Molnár, Karol (advisor)
This Master´s thesis deals especially with exploration of the handover process and with searching for ways of in?uencing this process. The goal of this thesis is to create tools for recording of access point utilization and in?uence the handover of wireless clients based on the obtained data. An access point with open ?rmware, which allows low-level management, was necessary for practical tests. First chapter deals with a survey of current o?er of open ?rmware available for access points and then the appropriate candidate for this thesis is chosen – the OpenWRT project. Second chapter deals with the con?guration of OpenWRT system and basic settings of the chosen wireless router – TP-Link TL-WR1043ND. Next chapter deals with analysis of the handover process in wireless networks. Information obtained by this analysis is used during the creation of the graphic application. The fourth chapter presents the basics of Microsoft Native Wi-Fi API and introduces basic functions used by this API. Those functions were used during the creations of the application. Last two chapters present the created graphic application. The ?fth chapter deals with the application design and examination of its functionality and used functions. Last chapter then documents usability of the application in real environment.
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Efficiency of Wireless Networks from Services View
Buchta, Marek ; Vymazal, Michal (referee) ; Škorpil, Vladislav (advisor)
Subject of this thesis was the issue of effectiveness of wireless networks from the perspective of services. Become acquainted with WiFi network standard IEEE 802.11 with protocols and principles of WiFi networks and services. It should be focused on the quality of service QoS. In teoretical part of this thesis are described problems considering wireless networks, layer model and types of nets used in WiFi. Standard IEEE 802.11 is analysed in details including supplements and used packets. Special attention is paid to the quality of service QoS. Next are discussed the principles and application services as VoIP, videoconferencing, video streaming and others in WiFi network. On the basis of obtained knowledge is designed extensive WiFi network with assured supply of services. For modelling and simulation of wireless network is used software development environment Opnet Modeler. Model of wireless network is used to optimize and analyse this wireless communication network. In thesis are also simulated properties of data which are sensitive to delay. In last part of thesis is created a laboratory work, which contains a submission of task, detailed theory, wiring diagram, instructions for elaboration, guidelines for simulation and example of elaboration of task. Work is about comparison of network with used 802.11b and 802.11e standard, and support of quality of service QoS.
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Security of wireless computer networks
Jelínek, Martin ; Pelka, Tomáš (referee) ; Doležel, Radek (advisor)
The master's thesis deals with the issue of Wireless Local Area Network (WLAN) from the viewpoint of the security and functional principle of security mechanisms. The transition to the issue concerning the security is accompanied by the methods of wireless data transmission operating on the level of physical layer (FHSS, DSSS, OFDM, MIMO), which is followed by the summary of individual 802.11 standards. The next part deals with the issue of shared transmission medium (CSMA/CA), influence of interference and correcting mechanisms (RTS/CTS). Within the security, the principles of the authentication along with the commonly used methods of security (WEP, WPA, WPA2) are described in detail. The first part concerning security deals with the security in the form of the WEP protocol, which is considered insufficient nowadays and points out the imperfect implementation and the consequent risks. The following part describes the security in the form of WPA which eliminates the implementation weaknesses of the previous WEP security protocol. The description of commonly used mechanisms of authentication (PSK, 802.1x), required temporary key management (PTK, GTK), data integrity (MIC) and encryption which uses TKIP protocol are also included. The last part, possible WLAN security, is aimed at the full support of 802.11i standard, which is called WPA2 (sometimes RSN). That part describes the basic encryption security element CCMP, which is based on the AES block cipher modes. The practical part of the thesis deals with the security verification of current wireless networks. In the process of verification the accessible HW means and programming tools of Open Source Software (OSS) are used. By means of verification it has been pointed out that there are possible security risks resulting from the security method which has been used. Also several recommendations how to reduce the security risks of the used method to minimum are mentioned.
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Wireless Network Security
Sedlák, Břetislav ; Krajsa, Ondřej (referee) ; Lambertová, Petra (advisor)
Master thesis focuses on wireless network security. The thesis is divided in two parts. First part describes today’s used standards and their components, topology and security methods as stealth SSID, MAC addresses filtration, WEP, WPA and WPA2. The last three methods are described in detail. In second part there are realized attacks on above described methods of security. There are described attacks on WEP as KoreK chopchop attack, fragment attack, attack FMS, KoreK and attack PTW. Then is described the dictionary attack on passphrase by WPA/WPA2 with PreShared Key authentication obtaining, precomputed hash tables for faster passphrase finding and for using more core procesors during dictionary browsing. The last attack describes obtaining of keystream used for encrypting of frames by WPATKIP and then sending custom data to client. It is described how to carry out each attack and how to protect against them.
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802.11 standard security techniques and their features
Endrle, Pavel ; Pust, Radim (referee) ; Pfeifer, Václav (advisor)
This master´s thesis is about 802.11 standard security techniques and their features. Particular types of this standard and its features are shown in the introduction. Wireless network security cypher alghoritm types, their features, weaknesses and principles of functions are closely described in next few chapters. Realized attacks on these security alghoritms with their principles are described and shown in the practical part of thesis. One chapter is about effectivity, accessibility and practicability valorization of these attacks in practice.
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VoIP in a wireless network of VŠE
Švarc, Lukáš ; Pavlíček, Luboš (advisor) ; Matuška, Miroslav (referee)
The diploma thesis is focused on exploring the possibility of VoIP service in a wireless network of University of Economics, Prague. This thesis describes the basic principles of VoIP and related wireless technologies necessary for its quality and stable operation. Subsequently, different configurations of wireless network and end clients are tested and compared, including its impact on ordinary users, in a laboratory environment with idle and fully utilized frequency band. Finally, a roaming operation with the use of several advanced 802.11 standards is tested in the real environment of the Old building in Žižkov. In conclusion, the ideal settings for all telecommunication devices are recommended in order to maximize the quality of VoIP operation and to minimize the negative impact on ordinary users.
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Wireless Security Audit
VRÁTNÝ, Jan
This bachelor thesis deals with security problems of wireless networks, also known as Wi-Fi. The purpose of the thesis is to explain the concept of Wi-Fi network, from what components it is composed, introduce safety devices used in wireless networks, and perform a research in a selected city in a specific location with the largest concentration of people if the wireless networks are secured and if they are what type of security is used. In a domestic environment an illustrative attack will be made on a Wi-Fi network secured by 128-bit WEP key. Also I will describe a new security bug that was discovered at the WPS function. Furthermore, this bachelor thesis will focus in detail on a local business, which in addition to conventional LAN extensively uses Wi-Fi network. An analysis of the security of the Wi-Fi network will be performed and the results will be evaluated to show the economic impact on the company if it were to be subjected to an attack in which sensitive data are leaked.
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