This thesis will address a problem concerning availability of information systems at an enterprise within the financial sector and its external suppliers, so called trusted third party. The information system resides on the internal network of the enterprise and must be available to both employees of the enterprise and the trusted third party simultaneously. This contradicts the company policy which disallows third parties access to the internal network. The HAVECA-model introduced in this thesis provides a framework of methods, each solving a sub problem identified in the model. The identified methods are hardening, verification, control and assurance, together supplying a method for continuously securing the internal network against a trusted third party. The HAVECA-model will be applied to a scenario, providing real-world examples of techniques of allowing the trusted third party to a restricted number of servers on the network. / Robert Karlsson e-mail: robert@iron.se Aron Rydquist e-mail: aaron@linux.se

This thesis deals with the transmission of information over the Ethernet network. In this work a suitable microcontroller and a communication module were selected. The Module provides data transfer from Ethernet to SPI bus. Furthermore an optimal digital temperature sensor DS1820 was chosen. Theoretically it describes the model TCP / IP and the Ethernet type network . In this thesis a block circuit diagram is created, further an electrical wiring diagram and a printed circuit board were constructed. In the programming environment BascomAVR a program is compiled, which is used to transfer information from the microcontroller via Ethernet to a website.

The diploma thesis is focused on the basic properties of network protocols. The main task is to create laboratory tasks that deal with the basic features of network protocols and communication techniques, along with detailed instructions for students of communication technologies. The theoretical part of thesis acquaints the reader with the topic of computer networks and the basic network protocols of the TCP/IP architecture, which occur within the created lab. The practical part contains a selection of testing environment and subsequent description of installation and preparation of selected GNS3 environment. Finally are presented labs, which have been created. First lab deals with the basic differences between TCP and UDP. The second lab is focused on the issue of multicast and the third deals with the basics of penetration testing.

This dissertation deals with the generating of data units at different levels of TCP/IP network model in OPNET Modeler environment. A part of the dissertation is a brief introduction to the simulation environment OPNET Modeler where important components of this comprehensive simulation software are elucidated. The structure of my dissertation reflects individual layers of the model TCP/IP, whereas the function of the process model OPNET Modeler and the data unit used at corresponding levels of TCP/IP is always described. Particular parts of communication models that were created in the simulation environment OPNET Modeler at selected layers of the network model TCP/IP are closely documented in each chapter. Relevant scenarios are described in such a way that they can be later re-arranged by eventual customers.

The aim of this thesis was to get acquainted with the technology of routing data in a computer network. Thesis described in the theoretical level properties of current and past routing protocols and their use in information systems. Based on the acquired knowledge was created a simulation model of network communication in programming environment OPNET Modeler. This model analyzes the received parameters of the current protocols and their subsequent implementation in the real transmission technology using operating system Debian Linux. Finally, the transfer parameters are discussed between the simulation model and real transfer technology.

This thesis deals with the transmission of information over the Ethernet network. In this work a suitable microcontroller and a communication module were selected. The Module provides data transfer from Ethernet to SPI bus. Furthermore an optimal digital temperature sensor DS1820 was chosen. Theoretically it describes the model TCP / IP and the Ethernet type network . In this thesis a block circuit diagram is created, further an electrical wiring diagram and a printed circuit board were constructed. In the programming environment BascomAVR a program is compiled, which is used to transfer information from the microcontroller via Ethernet to a website.

This thesis solves possibility of using entropy for anomaly detection in data communication and especially for security attacks. The main advantage of using entropy is ability to identify unknown attacks because entropy detects changes in network traffic but not the content as existing methods. In this work was tested the suitability of different models entropy (Shannon, Renyi, Tsallis). Also been tested the effect of Renyi and Tsallis parameter on resulting entropy. From the resulting values, I found that all tested entropy achieve good result in the identification of anomalies in network traffic.

Theme of the Master's thesis is issue of backup power units and its attributes. There is also complete proposal of UPS power unit which can be used to control and monitor backup batteries. Power supply is fully controlled via Ethernet interface using TCI/IP protocol. The other chapter describes complete development of TCI/IP GSM unit which can be used for communication interface between GSM and Ethernet protocol. UPS and GSM modules are developed in details. The Master.s thesis includes all needed information for HW unit development and also for controlling software as well. Universal solution of the modules allows number possibilities of further development.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Broadband wireless access (BWA) is a promising emerging technology. In the past, most BWA systems were based on proprietary implementations. The Institute of Electrical and Electronics Engineers (IEEE) 802.16 task group recently standardized the physical (PHY) and medium-access control (MAC) layers for BWA systems. To operate in a wide range of physical channel conditions, the standard defines a robust and flexible PHY. A wide range of modulation and coding schemes are defined. While the standard provides a framework for implementing link adaptation, it does not define how exactly adaptation algorithms should be developed. This thesis develops a link adaptation algorithm for the IEEE 802.16 standard's WirelessMAN air interface. This algorithm attempts to minimize the end-to-end delay in the system by selecting the optimal PHY burst profile on the air interface. The IEEE 802.16 standard recommends measuring C/(N+I) at the receiver to initiate a change in the burst profile, based on the comparison of the instantaneous the C/(N+I) with preset C/(N+I) thresholds. This research determines the C/(N+I) thresholds for the standard specified channel Type 1. To determine the precise C/(N+I) thresholds, the end-to-end(ETE) delay performance of IEEE 802.16 is studied for different PHY burst profiles at varying signal-to-noise ratio values. Based on these performance results, we demonstrate that link layer ETE delay does not reflect the physical channel condition and is therefore not suitable for use as the criterion for the determination of the C/(N+I) thresholds. The IEEE 802.16 standard specifies that ARQ should not be implemented at the MAC layer. Our results demonstrate that this design decision renders the link layer metrics incapable of use in the link adaptation algorithm. Transmission Control Protocol (TCP) delay is identified as a suitable metric to serve as the link quality indicator. Our results show that buffering and retransmissions at the transport layer cause ETE TCP delay to rise exponentially below certain SNR values. We use TCP delay as the criterion to determine the SNR entry and exit thresholds for each of the PHY burst profiles. We present a simple link adaptation algorithm that attempts to minimize the end-to-end TCP delay based on the measured signal-to-noise ratio (SNR). The effects of Internet latency, TCP's performance enhancement features and network traffic on the adaptation algorithm are also studied. Our results show that delay in the Internet can considerably affect the C/(N+I) thresholds used in the LA algorithm. We also show that the load on the network also impacts the C/(N+I) thresholds significantly. We demonstrate that it is essential to characterize Internet delays and network load correctly, while developing the LA algorithm. We also demonstrate that TCP's performance enhancement features do not have a significant impact on TCP delays over lossy wireless links. / Master of Science