National Repository of Grey Literature 81 records found  beginprevious65 - 74next  jump to record: Search took 0.00 seconds. 
Selected Extensions of the Albegraic System Octave
Salač, Radek ; Smrčka, Aleš (referee) ; Vojnar, Tomáš (advisor)
This work deals with issues linked to solving system of linear equations in the environment of numerical computer. It describes the fundamental algorithms emphasizing their positive as well as negative sides. The work is devoted to general issues such as time complexity and memory demandingness of given algorithms. In the last part, the process of implementation of selected procedures into the algebraic system Octave is described.
Implementation of an ifplugd Plugin to the BusyBox Project
Kryzhanovskyy, Maksym ; Šimáček, Jiří (referee) ; Vojnar, Tomáš (advisor)
This work deals with porting the ifplugd daemon to BusyBox project. The first part gives introductory information about the BusyBox project, and looks into the structure of the application. The second part deals with the implementation of the ifplugd daemon. As part of this work was carried out partial adjustments in the BusyBox code and ifplugd daemon has been implemented as an applet of the BusyBox package. At the conclusion of this work are discussed the results.
A Tool for Analyzing Performance of Memory Allocators in Linux
Müller, Petr ; Peringer, Petr (referee) ; Vojnar, Tomáš (advisor)
This diploma thesis presents a tool for dynamic memory allocator analysis, focused on their performance. The work identifies the important memory allocator performance metrics, as well as the environment and program factors influencing these metrics. Using this knowledge, a tool was designed and implemented. This tool allows to gather and analyze these metrics. The tool provides the ability to create memory allocator usage scenarios for the purpose of the allocator behavior analysis under different conditions. The tool was tested on several available memory allocators with free license.
An Efficient Finite Tree Automata Library
Lengál, Ondřej ; Konečný, Filip (referee) ; Vojnar, Tomáš (advisor)
Numerous computer systems use dynamic control and data structures of unbounded size. These data structures have often the character of trees or they can be encoded as trees with some additional pointers. This is exploited by some currently intensively studied techniques of formal verification that represent an infinite number of states using a finite tree automaton. However, currently there is no tree automata library implementation that would provide an efficient and flexible support for such methods. Thus the aim of this Mas- ter's Thesis is to provide such a library. The present paper first describes the theoretical background of finite tree automata and regular tree languages. Then it surveys the cur- rent implementations of tree automata libraries and studies various verification techniques, outlining requirements for the library. Representation of a finite tree automaton and algo- rithms that perform standard language operations on this representation are proposed in the next part, which is followed by description of library implementation. Through a series of experiments it is shown that the library can compete with other available tree automata libraries, in certain areas being even significantly superior to them.
Attacks on the Linux Operating System in Theory and Practice
Procházka, Boris ; Hanáček, Petr (referee) ; Vojnar, Tomáš (advisor)
This master's thesis deals with Linux kernel security from the attacker's point of view. It maps methods and techniques of disguising the computing resources used by today's IT pirates. The thesis presents a unique method of attack directed on the system call interface and implemented in the form of two tools (rootkits). The thesis consists of a theoretical and a practical part. Emphasis is placed especially on the practical part, which manifests the presented information in the form of experiments and shows its use in real life. Readers are systematically guided as far as the creation of a unique rootkit, which is capable of infiltrating the Linux kernel by a newly discovered method -- even without support of loadable modules. A part of the thesis focuses on the issue of detecting the discussed attacks and on effective defence against them.
A Fault Injection Bug Hunting Tool Based on Systemtap
Zelinka, Martin ; Smrčka, Aleš (referee) ; Vojnar, Tomáš (advisor)
This work describes different methods of fault injection, the principles of system calls in operating system Linux and the Systemtap tool. The main aim of thesis is design and implementation of the application that work on the principle of fault injection into the system calls using Systemtap tool. Implemented application automatically identifies the existing system calls with the error return values, which are then replaced the original system calls return value.
Model Checking Infinite-State Systems Using Language Inference
Rozehnal, Pavel ; Křena, Bohuslav (referee) ; Vojnar, Tomáš (advisor)
Regular model checking is a method for verifying infinite-state systems based on coding their configurations as words over a finite alphabet, sets of configurations as finite automata, and transitions as finite transducers. We implement regular model checking using inference of regular languages. The method builds upon the observations that for infinite-state systems whose behavior can be modeled using length-preserving transducers, there is a finite computation for obtaining all reachable configurations.   Our new approach to regular model checking via inference of regular languages is based on the Angluin's L* algorithm that is used for finding out an invariant which can answer our question whether the system satisfies some property.   We also provide an intro to the theory of finite automata, model checking, SAT solving and Anguin's L* and Bierman algorithm of learning finite automata.
A Control System for Applications Testing in Linux
Beneš, Eduard ; Vojnar, Tomáš (referee) ; Smrčka, Aleš (advisor)
This thesis discusses the area of a control system for application testing in Linux. There is a need for testing software and its quality using automated software tools. Huge number of testing tools is available, Red Hat Test System (RHTS) being one of them. Dierent approaches to classi cation and evaluation of a testing tools are presented. Selected software testing tools were evaluated and compared with RHTS. The thesis then presents a design of a system for non-interactive application testing in Linux with support for RHTS tests and with focus on future enhancements. Implemented system is nally tested using proposed set of tests and several usage examples are described.
Program Similarity Recognition Based on Behaviour Analysis
Otočka, Dávid ; Vojnar, Tomáš (referee) ; Peringer, Petr (advisor)
The goal of this master thesis was to design an algorithm that will be able to measure the difference between two programs based on their behavioral description. For the algorithm needs, the Levenshtein distance method between two strings and NCD method, were used. Both methods have their implementation approach and test result described. This term also discusses various methods of program analysis in virtual machine environment, as well as explanation of some basic concepts regarding malware analysis.
Static Value Analysis over C Programs
Ďuričeková, Daniela ; Peringer, Petr (referee) ; Vojnar, Tomáš (advisor)
Value-range analysis is a static analysis technique based on arguing about the values that a variable may take on a given program point. It can be used to prove absence of run-time errors such as out-of-bound array accesses. Since value-range analysis collects information on each program point, data-flow analysis can be used in association with it. The main goal of this work is designing and implementing such a value-range analysis tool. The work begins with an introduction into the topic, an explanation of data-flow and value-range analyses and a description of abstract interpretation, which provides the formal basis of the analyser. The core of this work is the design, implementation, testing and evaluation of the analyser. In the conclusion, our personal experience obtained in the area of the thesis is mentioned, along with a discussion of a possible future development of the designed tool.

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