This master thesis deals with all types of wireless networks security – in personal, local, metropolitan and also mobile networks. This work is mostly focused on wireless local area networks (WLANs), which are the most widespread at nowadays. This work describes attacks to the wireless local area network, attackers steps and possible protection against it. Some of these attacks are tested in practical part of this work. In this master thesis there were also designed and created two laboratory exercises. One of them is a simulation in the wireless network using Opnet Modeler application. The other exercise is strictly practical type.

Master´s thesis „Security risks of wireless access networks“ deals with wireless access networks, which are the most widespread in this time. The main target is realization of attacks wireless access networks protected by various using methods. This thesis shows main securities gaps, which originate from project this networks. These securities gaps are used for realization attacts in practical part. In the next part I took attention of network´s monitoring possibilities.

Nowadays every wireless radio-communication services encompass huge type of technology used for transfer video, voice or data. Wireless communication is the most expanded branch and many companies are using this technology because of low cost and simply management. The biggest advantage is easy connection to shared wireless medium and allows users of network to move around whole covered area. The most expanded types of wireless networks are called Wireless LAN (WLAN). With rising number of WLANs is rising chance to attack shared wireless medium by hacker and many sensitive information can be stolen or modified. To avoid this chance was created the first security protocol used in WLAN called WEP. Its goal was protect data transmitted trough WLAN as strong as were protected in wired networks. Unfortunately WEP was hiding a big weakness which can be used in a crack of WLAN in a minute with the aid of special software. Example of this kid of software can be Airsnort constructed to monitor shared medium and captured every packet transferred trough this medium. Based on statistical method Airsnort can obtain hidden password in a few minutes. The second type of this software can be Aircrack-ng, which can crack hidden password without any user connected to WLAN. Aircrack-ng uses active techniques to generate network load and can obtain password more effectively and faster. The result of both cases was successful and protection of WLAN was completely cracked. Later was created new security protocol called WPA, which had to fix the cryptography weakness of previous WEP. WPA was only temporary security protocol, during standard 802.11 was developing which had to offer highest security and integrity protection of transferred data trough WLAN. For this reasons was created new version of WPA called WPA2 which satisfy requirements of standard 802.11i. Both protocols WPA/WPA2 contain weakness, which can crash security of WLAN. This crack is based on authentication PSK. Attacker during authentication is using information from four-way handshake between user of WLAN and access point. Based on this information attacker can crack password with the aid of password list attack which took approximately 30 minutes. Based on previous result is important to chose strong password contains alphanumeric string or special strings with satisfy length.

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.

This document provides overview of commonly used standards and mechanisms for securing the wireless network based on Wi-Fi protocol. It is covering all important security areas including confidentiality, integrity and authentication. We can find here also detailed analysis and description of functionality of listed mechanisms. Description of possible attacks against listed security mechanisms. There is a measurement of influence of encryption to transfer speed in the another section. It's followed by attacks against particular security mechanisms. And finally, description of deployment of central authentication system.

This thesis deals with the monitoring of wireless nets in terrain. The author will be browsing terrain and there will be extracted some information about accessible wireless nets. For parameters of wireless nets we consider for example the name of wireless net, signal strength, type of security etc. These parameters (of wireless nets and position) are going to be recorded and saved into the database. Using this database it will be possible to perform some further operations like generation maps of wireless networks or detection positions of access points, etc..

The 802.11 standard defines the Wired Equivalent Privacy (WEP) and encapsulation of data frames. It is intended to provide data privacy to the level of a wired network. WEP suffered threat of attacks from hackers owing to certain security shortcomings in the WEP protocol. Lately, many new protocols like WiFi Protected Access (WPA), WPA2, Robust Secure Network (RSN) and 802.11i have come into being, yet their implementation is fairly limited. Despite its shortcomings one cannot undermine the importance of WEP as it still remains the most widely used system and we chose to address certain security issues and propose some modifications to make it more secure. In this thesis we have proposed a modification to the existing WEP protocol to make it more secure. We achieve Message Privacy by ensuring that the encryption is not breached. The idea is to update the shared secret key frequently based on factors like network traffic and number of transmitted frames. We also develop an Initialization Vector (IV) avoidance algorithm that eliminates IV collision problem. The idea is to partition the IV bits among different wireless hosts in a predetermined manner unique to every node. We can use all possible 224 different IVs without making them predictable for an attacker. Our proposed algorithm eliminates the IV collision ensuring Message Privacy that further strengthens security of the existing WEP. We show that frequent rekeying thwarts all kinds of cryptanalytic attacks on the WEP.

Wireless local area networks (WLAN) are beginning to play a much larger role in corporate network environments and are already very popular for home networking applications. This increase in accessibility has created large security holes for hackers and thieves to abuse, which is finally being addressed by stronger security methods such as advanced encryption algorithms and efficient authentication processes. However, these security methods often hamper network performance unbeknownst to engineers and users. This research examines the effects of Wired Equivalent Privacy (WEP), Temporal Key Integrity Protocol (TKIP), and Counter Mode/CBC-MAC Protocol (CCMP) encryption algorithms on throughput rates for IEEE 802.11 networks as well as the authentication times for Lightweight Extensible Authentication Protocol (LEAP) and Protected Extensible Authentication Protocol (PEAP). The research shows that today's wireless hardware is capable of reducing overhead of even the most advanced encryption schemes to less than five percent of the total bandwidth. / Master of Science

Made available in DSpace on 2016-04-04T18:31:27Z (GMT). No. of bitstreams: 1 Manoel Peluso de Carvalho Filho.pdf: 1548469 bytes, checksum: 813f063c4ea17788aa795465c9e6e6f5 (MD5) Previous issue date: 2008-11-24 / Nowadays, the use of the wireless network technology has grown mainly motivated by the price of equipments, ease of installation, network maintenance and expansion of technical safety. The more you use the wireless network resource, the better should be the treatment related to its safety aspect. As the security level increases, the amount of information transmitted between the equipment decreases. This thesis aims to analyze the performance of WLAN network with the implementation of WEP and WPA / TKIP security protocols in an environment that uses applications whose characteristic is to generate small packets on the network. The LanTraffic TM software is used to generate traffic and also to capture the transmission rate in Kbps that flows through the stations. Three scenarios are simulated varying in the distance between the equipments. For each scenario, a comparative study was made and the WLAN behavior without the security resource analyzed, then it was analyzed with the WEP fitted and finally with the WPA/TKIP configured. To develop the experiments it was used a WLAN network in a controlled environment in the Laboratory Research on Radio System in PUC Campinas. Therefore, there is not external interference in the signal transmitted by equipments. / A utiliza??o da tecnologia de rede sem fio tem crescido ultimamente motivado principalmente pelo pre?o dos equipamentos, facilidade de instala??o, manuten??o da rede e amplia??o das t?cnicas de seguran?a. Quanto mais se utiliza o recurso de rede sem fio maior tem de ser o tratamento em rela??o ao aspecto de seguran?a. A medida que aumenta o n?vel de seguran?a, decresce a quantidade de informa??o transmitida entre os equipamentos. Esse trabalho visa analisar o desempenho de rede WLAN(Wireless Local ?rea Network) com a implementa??o dos protocolos de seguran?a WEP(Wired Equivalent Privacy) e WPA/TKIP(WI-FI Protected Access / Temporal Key Integrity Protocol). ? utilizado o software LanTrafficTM para gerar tr?fego na rede e tamb?m para capturar a taxa de transmiss?o em Kbps trafegados entre as STAs. S?o emulados tr?s cen?rios variando a dist?ncia entre os equipamentos. Para cada cen?rio foi confeccionado um comparativo e analisado o comportamento da WLAN configurado sem seguran?a, com o WEP habilitado e finalmente com o WPA/TKIP configurado. Para executar os experimentos utilizou-se uma rede WLAN no laborat?rio de pesquisa em sistema de r?dio (LP-SiRa) da PUC Campinas em um ambiente controlado. Com isso n?o h? interfer?ncias na transmiss?o dos sinais emitidos pelos equipamentos Ou seja, sem interfer?ncia externa no sinal transmitido entre os equipamentos.

Trådlosa nätverk är av naturen sårbara for avlyssning för att kommunikationen sker med radiovagor. Därfor skyddas trådlosa nätverk med kryptering. WEP var den första krypteringsstandarden som användes av en bredare publik som senare visade sig innehålla flera sårbarheter. Följden blev att krypteringen kunde förbigås på ett par minuter. Därför utvecklades WPA som ett svar till sårbarheterna i WEP. Kort därefter kom WPA2 som är den standard som används i nutid. Den svaghet som kan påvisas med WPA2 finns hos WPA2-PSK när svaga lösenord används. Mjukvaror kan med enkelhet gå igenom stora uppslagsverk för att testa om lösenord går att återställa. Det är en process som tar tid och som därför skyddar nätverken i viss mån. Dock har grafikprocessorer börjat användas i syfte för att återställa lösenord. Grafikkorten är effektivare och återställer svaga lösenord betydligt snabbare än moderkortens processorer. Det öppnar upp for att jämföra lösenord med ännu större uppslagsverk och fler kombinationer. Det är vad denna studie avser att belysa; hur har grafikkortens effektivitet påverkat säkerheten i trådlösa nätverk ur ett verksamhetsperspektiv. / Wireless networks are inherently vulnerable for eavesdropping since they use radio waves to communicate. Wireless networks are therefore protected by encryption. WEP was the first encryption standard that was widely used. Unfortunately WEP proved to have several serious vulnerabilities. WEP could be circumvented within few minutes. Therefore WPA was developed as a response to the weak WEP. Shortly thereafter WPA2 was released and are now being used in present. The only weakness with WPA2 is in the subset WPA2-PSK when weak passwords are being used. Software could easily go through large dictionaries to verify if a password could be recovered. But that is time consuming and therefore providing wireless networks limited protection. However a new area of use with advanced graphic cards has showed that it is providing a faster way of recovering passwords than the ordinary processor on the motherboard. That opens up for the larger use of dictionaries and the processing of words or combinations of words. That is what this study aims to shed light on. How the efficiency of the graphic cards have affected security in wireless networks from a corporate perspective of view.