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QoS assurance in wireless networks
Kolmačka, Jan ; Vychodil, Petr (referee) ; Vymazal, Michal (advisor)
The diploma thesis gives the overall information about the field of wireless networks of standards 802.11 and Quality of Service (QoS). The practical measurements describe the reactions of multimedia dataflows in the networks 802.11a/b/g/n. The individual standards, offered services, access methods and the network architecture are analyzed in the theoretical part. In the following part there is written about QoS and its basic parameters. Moreover, the standard 802.11e and the question of QoS in the wireless networks are explained in a detailed way. The first part of the practical measurement is focused on the networks 802.11b/g/n. All main network statistics are measured when using the wireless stations and routers. The projection and implementation of the wireless network in the Opnet Modeler is included in the next part. The individual simulations WLAN in the Opnet Modeler are comparing the networks 802.11a/b/g. The analysis of the key QoS statistics is undertaken; the measured data are clearly displayed in the charts and schemes. The interpreted results are concluded and justified.
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Free-Space Optics data link
Šála, Jakub ; Číž, Radim (referee) ; Šporik, Jan (advisor)
In this thesis, shows a current issue for free space optics, limiting their use in practice with regard to the availability and reliability. They conducted measurements on wireless optical links and the observed values is calculated by the availability of the connection. Subsequently, measurements are performed on alternate versions of wireless and copper connections. Observed values were compared with a wireless optical link. It is made of optical design of wireless connections at home.
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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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Security protection techniques of wireless networks of internet providers
Žiško, Róbert ; Pelka, Tomáš (referee) ; Burda, Karel (advisor)
This master’s thesis can be used as the guidebook for Wi-Fi networks provider in non-licensed zones 2,4GHz and 5GHz. It is good tool to understand wireless technology area and its protection. Reader can follow network design and avoid mistakes that are mentioned in work. This text shouldn’t be a tool or a guide for possible attackers, but an impulse for small providers who provide their networks in unsecured form. In the opening chapter of my work, matters of Wi-Fi networks are thoroughly analyzed. As they are able to get internet connection in a lot of inaccessible places, they are considered to be crucial for the present times. The basic procedure describing Wi-Fi planning is written in thesis and also its legislative that has to be strictly observed. The big disadvantage is riskiness of the wireless connection that allows attackers to attack network in many ways. For mentioned reason it is very important to take utmost account of Wi-Fi network’s security and attack resistance. Unfortunately a lot of networks are either secured partially or unsecured at all. These types of networks are frequently attacked in order to get “free” Internet access or because of competitors fight. In the text below we can find possible Wi-Fi attack forms using by attackers to get Internet access or destroy network hardware what can cause big financial loss to providers. I described design and realization of little-town network using safety tools implementation based on my experience. For that purpose I implemented benchmark tests in graphics as well as practical format.
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Model of the metropolitan optical network
Prudík, Jiří ; Hudcová, Lucie (referee) ; Křivák, Petr (advisor)
The purpose of this master’s thesis is foremost to provide a simple guide how to build elements of optical metropolitan area network. The basic model consists to sequence of construction, network topology, passive and active parts. The collection contains examples of alternative technology such as Wireless LAN with different frequency. The optical network construction based on optical cable, fibres, splices, trays, adapters, connectors and active parts for example a lot of media convertor models. After that there are demonstrating type of wavelength division multiplexer used in metropolitan area network – passive planar PCL splitter. One of the passive planar splitter are used to increase optical fibre channel. At the end of the collection a simplified examples of used measurements – optical time domain reflectometry and optical fibre transmission. Contains standard protocols or reflectogram. The conclusion of this thesis summarizes costs of FTTb (Fibre To The Building) model of optical metropolitan area network in Czech republic and future contribution for society.
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Minimizing the effect of interference on wireless network
Doležal, Jan ; Kyselák, Martin (referee) ; Škorpil, Vladislav (advisor)
This thesis is concerned the technology with technologies of transfer through wireless devices. It is about possibilities of optimization of transfer in wireless net, especially of the reduction of interference influence. The first part is about theory and the standards development of wireless technology. There are methods and principles used in wireless technologies. The second part is a practical measuring and testing of an internal wireless net, with the emphasis being on the source of interference influence. Measuring was focused on interference between access points and was not about meteorological influence. It continues with theory and testing of interference of the microwave oven in our wireless net. Then, it is a practical demonstration of interference in an external environment. There are practical examples of interference between different providers’ nets on the same area and solutions to prevent or to cancel this interference. In next part of work the wireless net is parsed and described in a given territory. Here is described the way how to precede the reciprocal interference and eventually how this mutual disturbance suppress. Consequently, our net is optimized for customer growth and for today’s options of newer and more powerful components for wireless transfer. Finally there are two laboratory tasks. The first one is about practical measuring and testing of wireless net’s parameters and the second one is about simulation of wireless networks in the Opnet program.
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Security of wireless computer networks IEEE 802.11
Škodák, Jaroslav ; Jeřábek, Jan (referee) ; Koutný, Martin (advisor)
This work describes available and used standards, protocols and mechanisms used to secure IEEE 802.11 wireless networks. In the next section are listed vulnerabilities and possible attacks against different types of security. The principles of individual attacks on authentication, WEP security and WPA/WPA2 personal mode are described and realized using various software especially linux program aircrack-ng. Password for WEP security is obtained by passive eavesdropping data, using ARP replay injection and by creating own frames. The last two methods are used to generate traffic on the network, which is captured and then used to derive the WEP password. By injecting ARP frames, password was found in the number 60 000 captured frames and about 180 000 frames of data was needed for passive method. Decryption of WEP frame was done by fragment and KoreK chopchop attacks. This decrypted frame could be used to create fake frames and obtain WEP password. Brute force attack is realized for security WPA (WPA2) personal mode (often due to lack of strong password) by comparing password (passphrase) from password list. Speed of comparing is about 200 passwords/s.
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Quality of services support in the end applications
Zelinka, Jiří ; Novotný, Vít (referee) ; Hošek, Jiří (advisor)
The topic of this diploma thesis has been chosen for a discussion and implementation of quality of service on the application and link layer of the OSI model. At the beginning of this thesis the general parameters and basic technologies of the OSI model network layer has been explained. This part was chosen as a resource for explanation of the basic parameters in the quality of services. Basic part is followed by the introduction to the Ethernet technology, which became as a ground for the real model in this diploma thesis. As a part of this section has been written a block which contains a analysis of quality of services in the Ethernet, which means the implementation of IEEE 802.1Q/p. This analysis is followed by structured descrition of the controlling and functionality of quality of services parameters on the link layer with the system tool in the Windows XP, description of Win XP link layer drivers and its modification with system tool tcmon. The end of the theoretical part is represented by introduction to the implementation of quality of service in the wireless networks especially the 802.11e standard. At the beginning of the practical part is specified the description of the topology design which is dedicated to the quality of services implementation. This section is developed to well-founded analysis of applications which were used during topology creating. The last segment of this thesis is dedicated to evolving the practical informations which were obtained during the measurement.
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