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New scenarios with Wireshark in communication technologies
Šíma, Jan ; Dvořák, Jan (referee) ; Jeřábek, Jan (advisor)
The aim of this thesis is to design and create scenarios that will be used by students as a basis for laboratory exercises in a course that focuses on communication technologies. These scenarios also need to be accompanied by a theoretical introduction that will introduce the topic under discussion to the students. The created scenarios contain additional tasks that are intended for individual work of students. For the teachers there are prepared separate files summarising the correct solution of these tasks. This thesis starts with a theoretical description of used network protocols. First the TCP/IP model is described and then the protocols that belong to this model. The main ones are those that occur in multiple created scenarios, such as TCP, UDP or DNS. The programs and applications that are used in the scenarios are also described. The main program is Wireshark and also the application called Klient DNS. This is followed by a chapter that deals with the drafting of each scenario. The drafts outline what the scenarios goals are. The drafts also list the protocols, programs, and utilities that are used in the exercise. The first scenario contains tasks based on Network Address Translation and its interaction with other protocols, such as the previously mentioned TCP, UDP, and also ICMP and FTP protocols. The second created scenario is dealing and analyzing protocols that try to secure the translation of domain names. Specifically, the DNSSEC extension and also the DoH protocol. The third scenario is focusing more in detail at the function of recursive servers in DNS and DNSSEC communication. The last created scenario explains the planning and allocation of the address space, where again the NAT topic is encountered and the function of routing tables is also explained here.
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Analysis of the influence of network technologies on the operating parameters of the device
Hynšt, Boris ; Dvořák, Jan (referee) ; Kubánková, Anna (advisor)
This bachelor work is focused on study of networking technologies and their effect on physical performance of router. From all the performance variables, the most important for this work are CPU usage and available bandwidth, also how much can each of the technologies affect these variables. For this purpose simple topology was created and all of the technologies were measured and compared to each others. On top of that there was a simple test, that was put in place to find out, if it is possible to make these performance tests with chosen networking simulator.
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Network Tasks Optimalization
Dražil, Jan ; Korček, Pavol (referee) ; Viktorin, Jan (advisor)
Nowdays, when we are running out of public IPv4 addresses, we rely on techniques that at least postpone their complete exhaustion. One of these techniques is a network address translation (NAT). Internet providers require the highest possible bandwidth from devices that perform this task. This thesis compares NAT DPDK, built on top of DPDK framework, with freely available alternatives. This work also extends NAT DPDK with Application-Level Gateway support.
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Exploration of the jet stream in the civil air transport
Švec, Michal ; Imriš, Pavel (referee) ; Krška, Karel (advisor)
This master’s thesis deals with jet streams. The exploration part describes conditions of jet stream formation, its characteristics, classification on the geographical basis and phenomena attendant on the jet streams. It also contains a description of jet stream measurement methods and methods of its interpretation in aeronautical meteorological charts. Organization of aeronautical traffic in the north Atlantic region within reach of the jet streams is further described. Practical part of this thesis contains author’s own research which compares time and economical profitability of transatlantic flights planned according to the jet streams. The principle of this evaluation was based on assessment of real flights and flights via shortest possible routes. It was proven, that profits mentioned above are gained only in the oceanic parts of flights.
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Secure Remote Computer Management System
Heško, Peter ; Hranický, Radek (referee) ; Polčák, Libor (advisor)
Deployment and management of remote systems poses several problems. Their administration and monitoring is much faster and more cost-effective when done remotely than when physical access to the system is required. Software that allows this is in many cases not freely available or has limited functionality. In this work I deal with the analysis of available solutions and then design and implementation of an application that combines all the required features. The result is software that provides secure access to and monitoring of remote computers running Ubuntu 16.04.
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Laboratory exercises explaining network technologies using various simulation instruments
Vaľuš, Dávid ; Ilgner, Petr (referee) ; Bečková, Zuzana (advisor)
This diploma thesis focuses on the preparation of an operating system, a simulation environment and the creation of two laboratory exercises explaining network technologies. In the theoretical part protocols DHCP, FTP, TFTP, HTTP, and NAT service are described. The practical part focuses on the installation of ns-3 and GNS3 programmes and their utilization and settings on OS Ubuntu 18.10. Moreover, it deals with the preparation of laboratory exercises created in the simulation programmes mentioned above together with tutorials, self-check questions and HTTP server in the Python programming language.
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Port Block Allocation for Network Address Translation
Odehnal, Tomáš ; Podermański, Tomáš (referee) ; Grégr, Matěj (advisor)
Cílem této semestrální práce je nastudovat problematiku Carrier-Grade NAT (CGN) přístupu, který musí provádět záznam o překladu adres každého nového spojení. Protože CGN leží na rozhraních rozsáhlých sítí, může denně zaznamenat statisíce spojení. Toto množšství záznamů má vysoké paměťové nároky a ještě složitější je hledání konkrétního záznamu. Tyto problémy je možné řešit pomocí alokace bloku portů pro překlad adres. Výstupem této práce je vytvoření pravidla do iptables, které provádí tuto alokaci bloků pro překlad adres. To se skládá z uživatelské části, která zpracovává pravidla a kernelovský modul provádějící funkcionalitu pravidla.
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Secure peer-to-peer communication system
Eliáš, Luboš ; Koutný, Martin (referee) ; Cvrk, Lubomír (advisor)
The main aim of this master's thesis is to implement a common, secure and peer-to-peer communication system. The system has ability to automatically establish and run a secure end-to-end connection. It has this ability even if a network address translator is in the way to the destination system, without need of any explicit configuration of this translator. The security procedures of this system are in a transparent manner masked from individual applications, which had to solve this challenge in their own way. A responsibility for a security is delegate to an application-independent subsystem working within the core of an operating system. The security of this subsystem is based on capturing the outbound and inbound IP packets and their authentication and encryption. The system was successfully implemented in MS Windows XP operating system, in programming language C++. Transfer rate of communication tunnel in different network bandwidth speeds was measured. Result shows, that in the case of use the system on standard PC sold nowadays is practically no decrease of the transfer rate in comparison to a common channel.
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Network Synchronization of Data under OS Windows
Hellar, Jan ; Trchalík, Roman (referee) ; Očenášek, Pavel (advisor)
This thesis deals with an implementation of a tool for file synchronization over a network for OS Windows. It also illustrates what issues are associated with synchronization of files, such as collision detection and resolution and the issue of setting up connection between two devices over the internet when connected to the internet via NAT devices. Thesis presents factual implementation of collision resolver and application of methods for NAT traversal. By testing the final solution correctness of collision resolver and NAT traversal technique was verified. Results of testing are discussed and possible extensions are proposed.
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High Availability firewalls
Frátrik, Tibor ; Zeman, Václav (referee) ; Slavíček, Karel (advisor)
This diploma thesis is dedicated to researching the possibility redundancy of firewalls, especially commercial, software or hardware firewalls. The theoretical part describes individual firewalls and their redundancy options. The diploma thesis was more focused on two specific firewalls: ASA and Pfsense. As part of the practical part, topologies were designed and implemented for testing the redundancy of these firewalls. Dynamic address translations (NAT), VPN connection status, either site-to-site or remote-access VPN connections, and TCP connections were selected for testing. Finally, the results for individual firewalls were compared. Where it was mainly researched and compared, how the computer network reacts to redundancy in individual types of firewalls.
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