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Detection of Peer-to-Peer Communication
Letý, Pavel ; Kováčik, Michal (referee) ; Bartoš, Václav (advisor)
This thesis is focused on issues in detection of P2P network from NetFlow. In the theoretical part of this work are introduced actual techniques in detection of this communication in network. There are presented their advantages and disadvantages too. The biggest attention is focused on the classification scheme of Mr. Bashir which deals with a detection of a protocol BitTorrent and a Skype application from Netflow. Following this scheme is designed a detection module for a modular system of a traffic analysis Nemea, developed by Cesnet organization. In the practical part of this work is introduced the implementation of this module. There are also presented results of experiments with real data.
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Implementation of Asterisk VoIP PBX
Schön, Martin ; Münster, Petr (referee) ; Szőcs, Juraj (advisor)
The thesis is divided into two parts, theoretical and practical. In theory, it analyzed the signaling protocols, the RTP protocol for data transmission, VoIP Asterisk PBX and security options. The practical part describes the installation of the Asterisk PBX, conducted demonstration call forwarding. PBX was associated with an LDAP directory server to manage users and ejabberd for text messaging protocol XMPP. It was configured translation SIP-Skype using the SiSky Gateway and with dialplan SIP-H.323 translation. The study was to develop Dialplan with IVR. It was measured bandwidth of the audio/video codecs in an encrypted/unencrypted connections.
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Identifying Skype Traffic Using NetFlow Data
Šebeň, Patrik ; Veselý, Vladimír (referee) ; Grégr, Matěj (advisor)
NetFlow is a network protocol commonly used for collectiong IP traffic information. But there is a way to use this collected data for indentifying clients in Skype communication. This paper describes identifiable patterns in Skype protocol and how to find them in NetFlow data. This way we can identify nodes and supernodes in Skype network.
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Location of VoIP caller in emergency
Mrník, Martin ; Krajsa, Ondřej (referee) ; Komosný, Dan (advisor)
This master thesis deals with the problem of localization of the caller to the emergency line with focus on VoIP calls. It contains general description of the main active and passive geolocation methods, and explains their function. The paper analyzes market share of different VoIP clients and describes the program Skype. The focus of this work is to create an application for geolocation of the caller using analysis of VoIP transmission. The application gains IP address of the caller by capturing packets and displays his/her location on the map. The coordinates are obtained from the MaxMind GeoLite City database which been chosen by evaluating objective parameters as the most suitable for desired use.
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Speech signal transmission over unreliable networks
Rozman, Jiří ; Krajsa, Ondřej (referee) ; Polívka, Michal (advisor)
This thesis deals with analysis of internet telephony. It is fosuced on analysis of VoIP over metalic and wireless network using virtual telephonic switch-board with hardware and software phones and also alternative programs to transmit voice such as Skype and Windows Messenger. It also deals with simulating parameters that influance voice transmission like jitter, latency packet loss. WANem system was used for this simulation. In the end it is focused on the problem of providing flawless voice communication over internet, specially providing Quality of Service.
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Network-Based Application Recognition
Štourač, Jan ; Barabas, Maroš (referee) ; Malinka, Kamil (advisor)
This thesis introduces readers various methods that are currently used for detection of network-based applications. Further part deals with selection of appropriate detection method and implementation of proof-of-concept script, including testing its reliability and accuracy. Chosen detection algorithm is based on statistics data from network flows of tested network communication. Due to its final solution does not depend on whether communication is encrypted or not. Next part contains several possible variants of how to integrate proposed solution in the current architecture of the existing product Kernun UTM --- which is firewall produced by Trusted Network Solutions a.s. company. Most suitable variant is chosen and described furthermore in more details. Finally there is also mentioned plan for further developement and possible ways how to improve final solution.
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Detection of Dynamic Network Applications
Juránek, Michal ; Kaštil, Jan (referee) ; Tobola, Jiří (advisor)
This thesis describes methods of detection of simple voice communications of encrypted VoIP calls between two Skype clients. The elements of network and its communication principles are described. Three approaches to classification are analyzed. The first approach performs the classification by content of network packets using Pearson's chi2 test of goodness of fit, the second approach by characteristics of network flows by means of naive Bayesian classification. The third approach describes ways of detecting signaling messages. The detector application is implemented on the basis of chosen methods.
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Audio steganography and IP telephony
Hrinčárová, Monika ; Drápal, Aleš (advisor) ; Kozlík, Andrew (referee)
Steganography is a technique which hides secret information. In this work, we will hide a secret information in the packets which are produced during a Skype call. Skype is one of the best known and the most widely used VoIP applications. We will propose, describe and implement a steganography method by which we will send the secret message during the Skype call. For embedding the message into packets and extracting them, we will use steganographic method called matrix encoding. To avoid packet loss, we will increase the robustness of this method by error-correcting and self-synchronising codes. As error-correcting codes, we will use the binary Hamming (7, 4) -codes and for the self-synchronising, we will use T-codes. 1
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Analysis of voice over IP protocols
Boháček, Milan ; El Bashir, Robert (advisor) ; Hojsík, Michal (referee)
In the presented work we focus on both implementation and protocol of the voice over IP application Skype. We analyse several versions of Skype clients and deduce inner workings of the Skype protocol. We present details about the cryptographic primitives used by the Skype clients and their impact on the security of the communication. We emphasize several places of suspicious leaks of the internal states of random generators and deduce rules for the detection of the Skype traffic on the firewall. In the end, we mention a simple enhancement of the current Skype clients that, in practice, can detect an ongoing eavesdropping.
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