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Spam detection methods
Rickwood, Michal ; Horváth, Tomáš (referee) ; Oujezský, Václav (advisor)
Hlavním cílem této práce je navrhnout a implementovat detekční algoritmus na spam, který využívá výhradně záznamy provozu v podobě Netflow zpráv. Poskytovatelé internetových služeb musí spam detekovat, aby zabránili označování celých jejich subnetů za spammery. Algoritmus byl navržen na základě analýzy mnohých datasetů obsahující Netflow záznamy. Tyto datasety obsahovaly validní emaily, spam a také běžný internetový provoz. Algoritmus v prvním kroku využívá domain name system blacklistů pro verifikaci spammovací stanice. Veškerá komunikace ze stanic, které se objeví na některém ze seznamů jsou okamžitě zahozeny. Filtrační kritéria algoritmu jsou aplikována pouze na stanice, které nejsou blacklisty označeny. Tato kritéria byla rozdělena na akceptační a seřaďovací. Akceptační kritérium bylo navrženo k nalezení potenciálně významných stanic. Bylo formulováno pět kritérií určených k seřazování těchto vybraných IP adresy dle pravděpodobnosti, že se jedná o spamovací stanice. Za každým kritérium stojí matematická rovnice vracející hodnotu mezi 0 a 1. Celkový součet takto vrácených hodnot se u spamovacích stanic blíží k pěti, zatímco legitimní stanice mají hodnoty znatelně nižší. Výstupem vyvinutého algoritmu je seznam potenciálních spamovacích stanic seřazených podle pravděpodobnosti, že se jedná o spamovací stanice.
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Nonlinear phenomena in optical fibers
Burian, Radek ; Horváth, Tomáš (referee) ; Münster, Petr (advisor)
The subject of this thesis is to describe nonlinear phenomena in the optic fiber. The theoretical part describes a principle of transmission in optical fibers. Optics modules, fibers and their parameters are described marginally. Except nonlinear phenomena, there is also described linear phenomena such as attenuation, dispersion, scattering. In terms of nonlinear phenomena there is described second order phenomena such as Second harmonic generation (SHG), Sum and difference harmonic generation (SFG and DFG) and third order phenomena, such as Kerr effect, Third harmonic generation (THG), Four-wave mixing (FWM) and Cross phase modulation (XPM). There are also described nonlinear scattering, such as Raman´s and Brillouin´s scattering. The Four-wave mixing is simulated in the first half of the practical part. Four-wave mixing occurs in DWMD systems, where can invoke cross-talks between channels. In the second half of the practical part is measured this nonlinear phenomenon. The aim of the measurement is to understand the behaviour of the FWM and find the way how to eliminate its power. The Four-wave mixing measurement is based on the simulation. Second measurement is designed for Brillouin scattering. The conclusion from simulated and laboratory part from both measurements are compared with theoretical knowledge.
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Optical network design
Polaček, Adam ; Tomašov, Adrián (referee) ; Horváth, Tomáš (advisor)
This bachelor thesis deals with the design of a technological optical network for the area of Hradec Králové, for the company ČEZD Distribuce. The theoretical part of the thesis describes the current network design and discusses network protocols. The practical part of the thesis describes the passive part and the logical part of the network. An important part of the thesis, is the fiber scheme and configuration design for router and switch. In the last part of the thesis, simulation in GNS-3 program is shown.
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Optical access network management
Bartko, Samuel ; Ružička, Michal (referee) ; Horváth, Tomáš (advisor)
This Bachelor thesis is concerned about optical access network in theoretical part, where it describes working principle of optical network. The main concern is put on passive optical networks, where it describes XGS-PON standard. In practical parts describes connection and making functional network with XGS-PON. In the last part there is a manual for laboratory task, which has a goal of making students understand the issue of activating end point unit in XGS-PON network.
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100G passive optical network
Sporni, Alex ; Tomašov, Adrián (referee) ; Horváth, Tomáš (advisor)
This diploma thesis deals with the current state of development of passive optical networks, with the main emphasis on high-speed passive optical networks of 50 Gb/s and higher. The opening part of the thesis provides a theoretical introduction to optical access networks, their division, elements of passive optical networks and the subsequent analysis of the latest standards. As part of the implementation, simulation topologies for various simulation scenarios are designed in the VPIphotonics Transmission Maker tool. The proposed simulations are properly evaluated in the next chapter. The quality of the proposed simulation topology is assessed using bit/symbol error rate and in some cases in combination with an eye diagram (quality factor). The output of the work are simulation scenarios for various configurations and modulation formats of the proposed optical networks. The output of the work is also a laboratory task, which will be used for teaching purposes.
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Optical fiber polygon for testing of services
Frolka, Jan ; Horváth, Tomáš (referee) ; Dejdar, Petr (advisor)
Bachelor’s thesis describes the types of optical fibers, their structures and properties. The basic parameters of optical fibers and standards for single-mode fibers are defined. The differences between the various connectors and the polishing of the ferrules are also described. The next section describes the multichannel transmission technology and its modifications, as well as the FFTx technology. In the next part, the work deals with measurements on optical fibers, the most common measurement methods are listed. The reader will learn what to do and also what not to do when manipulating with optical elements. The attached diagrams show the test polygon, as well as the measured and calculated values of the attenuation of its parts.
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Quantum key distribution over optical fibre infrastructure
Klíčník, Ondřej ; Horváth, Tomáš (referee) ; Münster, Petr (advisor)
The aim of this bachelor thesis is to create a comprehensive view of the current technology of quantum key distribution (QKD) over optical fiber, in theoretical terms, a completely secure key exchange. The thesis can be divided into theoretical and practical parts. The theoretical part illuminates the reasons for the use of these systems and the fundamentals of quantum mechanics needed to understand the function of individual QKD protocols. Furthermore, the principles of operation of both the protocols and related services such as post-quantum cryptography (PQC) and quantum number generation (QRNG) are described. The last chapter is devoted to the architecture of QKD networks and describes current standards for QKD communications. In the practical part, a detailed analysis of commercially available devices is performed. Subsequently, simulation results of selected QKD protocols are presented and a custom QKD polygon is designed, built and tested.
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Leakage of information through active and passive elements in optical fibre infrastructures
Spurný, Vladimír ; Horváth, Tomáš (referee) ; Münster, Petr (advisor)
This bachelor thesis deals with the problem of information leakage from optical fiber infrastructures, both from the fibers themselves and from passive and active elements. The first part is devoted to a theoretical description of the transmission of information over an optical fiber and the function of individual components. The next part is focused on the theoretical analysis of possible information leaks. In the last - practical part, there will be an examination of some of the previously described possibilities of information leakage with subsequent analysis and a proposal for risk minimization.
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Interface for management of optical line termination in passive optical network
Kováč, Dávid ; Holík, Martin (referee) ; Horváth, Tomáš (advisor)
This bachelors thesis deals with the creation of a graphic user interface for the configuration of optical line terminal for passive optical networks. The aim of the thesis was to make the configuration of optical line terminal easier and more convenient. The graphic user interface allows the user to configure ONTs, display all connected ONTs, show the event log and to configure alarm profiles. The theoretical part of the thesis deals with getting acquainted with passive optical networks and getting familiar with how the graphical interface was created. Furthermore, there are the programming tools and the extension used to create the GUI, an explanation of how and why each part of the GUI was created, including the classes and the methods which were used, how the testing went and the results. At the end of the thesis is a manual of what needs to be installed to make the GUI work and how to use it.
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Notification robot
Hudák, Filip ; Horváth, Tomáš (referee) ; Holík, Martin (advisor)
The bachelor thesis focuses on the creation of notification bot for appropriate communication channel. In theoretical part, different communication channels are compared based on price, privacy, encryption, popularity etc. Practical part describes registration and application setting of communication, tests of data acquisition and sending messages to the communication channel. It deals with the design of a communication module, which stores a token and secret key, with simplified method for sending messages. It states design and a structure of the notification bot, as well as the design of communication interfaces for the communication with third party applications. It places importance on fast and secure encryption via created communication interfaces using best practices. Next point in the pratical part describes tracking individual web pages with easy addition of web pages. In conclusion it describes Docker images installation, which is followed by own containers deployment.
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