<p>Recently the society has been turning from the use of paper-based technologies to plastic cards in certain spheres of our life. With the emergence and proliferation of high technologies we cannot content with the security provided bypaper only. Therefore the society has chosen plastic to protect its information because it offers far more security based not only on human perception but also on machine-readable elements. </p><p>The number of plastic cards in circulation in different spheres of our everyday life increases constantly. They replace money, documents and allow easy and safe access to some services. In spite of its security the plastic card however is subjected to fraud. </p><p>Plastic card fraud results in significant losses for the various industries. Since the first appearance of plastic cards methods of committing fraud have changed dramatically. Now there is a wide range of high technologies at the disposal of criminals as well as card manufacturers. </p><p>Therefore we have put the great emphasize of this work on the analysis of the most common card technologies in the Plastic Card World, the magnetic stripe and the chip, existing crimes and main means of their committing. And we also have revealed the weak and strong sides of the prevention techniques, which are currently in use.</p>

El acceso a las redes ATM y el dimensionado de sus recursos son cuestiones clave ya que cada vez hay una mayor demanda de ancho de banda por parte de los usuarios. Sin embargo, se necesitan alternativas económicamente viables. La multiplexación inversa ATM es una técnica con la que se combinan varios enlaces T1/E1 resultando en un único canal lógico de datos con tasa igual al agregado de los anchos de banda T1/E1 menos una pequeña cantidad debida a overhead de control. Resulta de gran interés caracterizar mediante expresiones fácilmente manejables el comportamiento de los nodos de una red de banda ancha en cuanto a los parámetros principales de calidad de servicio ATM. En esta tesis se aportan varios modelos analíticos para evaluar las prestaciones de un conmutador ATM suficientemente genérico y del dispositivo IMUX que permite estimar de manera ajustada los parámetros de calidad de servicio más relevantes para su diseño: tiempo medio de espera de las celdas en el dispositivo y probabilidad de pérdida de las mismas. La finalidad es constituir una herramienta efectiva para el diseño adecuado de los parámetros que definen al nodo ATM y particularmente al IMUX dada su mayor tratabilidad analítica.Para abordar el análisis, en primer lugar se han estudiado sistemas de colas conocidos y en particular se ha aportado un método analítico para aproximar los parámetros de calidad de servicio del sistema de colas más adecuado para modelar un nodo ATM y en concreto un multiplexor inverso ATM. Esto es, cola M/D/s/s+B con tiempo de servicio discreto y un esquema de cinco niveles de prioridad. Por otro lado, se modifica la semi-cadena de Markov para el sistema M/D/1 adaptándola a las características propias del IMUX. Además, se analizan minuciosamente por separado todos los efectos que tienen lugar en el dispositivo IMUX debido a la inserción de las celdas de control y de relleno, de acuerdo con la especificación IMA del ATM Forum.Finalmente se apuntan las líneas de trabajo futuro como son la incorporación de un esquema de cinco prioridades en el IMUX; el estudio y análisis de los efectos que produce el disponer de ancho de banda bajo demanda en las prestaciones que ofrece el IMUX que además está directamente relacionado con el estudio y análisis del comportamiento del IMUX bajo modelos de tráfico de entrada más realista. / The growing demand of network bandwidth users made indicates that user access to high speed (i.e. ATM) networks is a key issue. The Inverse Multiplexing for ATM (IMA) is a technology that combines multiple T1/E1 links to support the transparent transmission of ATM cells over one single logical data trunk which bandwidth is the aggregate of the T1/E1 capacities, minus a small amount due to overhead. That is, it provides high bandwidth by using already deployed WAN infrastructure and at a reasonable cost. Employing this technology, it is possible to dispose of ATM connections with data rates between the T1/E1 (an economical but sometimes too slow option) and T3/E3 ones (with high bandwidth, but expensive for the mass market of users). In this framework, and facing a new technology, it is crucial to have tools (analytical and simulation ones) easy to manipulate that help telecommunication engineers and network planners on the performance evaluation and dimensioning of these systems. In this paper, the fundamentals and major applications of IMA technology are described. Also, the behavior of IMA multiplexers is carefully analyzed and a method to dimension them proposed. An estimate for the Cell Loss Ratio (CLR) and the mean waiting time measured in the IMUX devices are obtained.In this thesis several analytical models are contributed to evaluate the benefits of a sufficiently generic ATM node and of an IMUX device. That allows computing the parameters of quality of service for its design: average waiting time of the cells in the device and cell loss probability. The purpose is to constitute an effective tool for the suitable design of the parameters that define the ATM node and particularly to the IMUX. In order to start with the analysis, firstly we have adapted the well-known queue systems to model a concrete ATM node and an inverse multiplexer for ATM. An analytical method has been contributed to approximate the parameters of quality of service of the queue systems. That is, we have applied a M/D/s/s+B queue with discreet-time service and a scheme of five levels of priority.The last analytical study is based on the comparison with a M/D/1 queue system. In addition, all the effects that take place in IMUX device are analyzed meticulously separately. They are due to the insertion of the control cells and filler cells, in agreement with the IMA specification of the ATM Forum.Even though, we are aware of the weakness of our assumptions, especially concerning to the Poisson input traffic, the model is compact, easy to understand and to manipulate, therefore it can be valuable to validate simulation models developed to evaluate IMUX devices under more realistic input traffic patterns. Finally, the lines of future work are scored: the incorporation of a five priorities scheme in the IMUX; the study and analysis of the effects of having bandwidth under demand as a benefits that the IMUX offers; the study and analysis of the IMUX behavior under more realistic traffic models.

Vortragsfolge Prof. Uwe Huebner: Metacomputing - neue Aufgabenverteilung im Netz Dr. Wolfgang Riedel: Was nuetzt uns SGML Sven Graupner: What's up in Operating System Research Sven Koehler: IP Security (nach RFC 1825) Holger Trapp: Kryptographisch gesicherte Kommunikation und Datenhaltung Dr. Joerg Anders: ATM-Eine kritische Betrachtung Guenther Fischer: Cacheserver-Hierarchien Frank Richter: Ein neuer WWW-Server fuer www.tu-chemnitz.de Steffen Brose: Web-Zugang zu DQS Jens Kraizci, Volker Holfeld: Wie weiter mit dem CSN? Jan Wunderlich: Harvest Michael Hasenstein: Datenbank-Klienten auf Java-Basis Andreas Koehler: Form-based File Upload in HTML Gerd Heide: BROADWAY - Interaktivitaet im WWW mittels X-Protokoll Matthias Ehrig: NFS 2 - Moeglichkeiten und Grenzen Ronald Koehler: NFS 3 Christoph Ziegler: HSM - Was verbirgt sich dahinter? Kai Zscheile: Hardware-Loesungen fuer HSM Matthias Clauss: Vergleich und Bewertung von HSM-Loesungen Thomas Mueller: Fileserving an der TUCZ Karsten Baensch: AFS-Loesung fuer die Softwareumgebung der Parsytec-Maschinen Joern Wohlrab: Alternative verteilte Filesysteme Jens Junghaenel: Integration von PC's mittels Samba Merten Schumann: Archivierung elektronisch publizierter Dokumente Michael Tautenhahn: Fast Ethernet Jens Wagner: Firmenadressverwaltung am URZ Dr . Wolfgang Riedel: Neues aus der TeX-Welt (METAPOST, lyx) Carsten Mund: Untersuchung von Einflussfaktoren auf SPEC CINT- und CFP-Benchmarks

Vortragsfolge: Karsten Priemer: Integration heterogener Applikationsumgebungen in Intranets mit Web - Technologien Swen Gerber: Netzcomputer-Konzepte Sven Graupner: JavaOS - Ein Betriebssystem für Intranets? Patrick Voigt: Netscape Internet Foundation Classes (IFC) Christoph Ziegler: MONARCH - Stand und künftige Aufgaben Holger Trinks: WWW-Robots Frank Richter: ¨Das richtige Mailprogramm¨ Bert Auerbach: Internet-Suchsysteme Frank Richter: Directories - Technologien und Datenadministration Ralph Sontag: Aufbau einer Certification Authority Jörg Hüttmann: Digitales Geld Mario Küchler: Internet-Telefonie Torsten Naumann: Ressourcensteuerung für Internet-Zugänge Michael Hasenstein: Eine zentrale Faxserverlösung auf Basis Hylafax+Web-Frontend Ronald Wahl: Intranet-Nutzermanagement Wolfgang Riedel: Konzepte der Software-Refinanzierung Marco Günther: Linux kontra NT - ¨strategische Plattformen¨? - Teil I Thomas Riedel: Linux kontra NT - ¨strategische Plattformen¨? - Teil II Dietmar Grunewald: WINDOWS-NT im öffentlichen PC-Pool Teil I: Servereinsatz und Nutzerverwaltung Jens Wagner: WINDOWS-NT im öffentlichen PC-Pool Teil II: Anwendungssoftware Matthias Ehrig: Diskless Linux - Möglichkeiten der SysAdmin Matthias Clauß: Skalierbare Systemadministration von LINUX-Rechnern Christian Bobber: WWW-Sicherheitsaspekte Thomas Müller: Authentisierung und Verteilung von Konfigurationsfiles Thomas Förster: Verzeichnissysteme für neue Anwendungen Jürgen Winkler: MathLink - der Kommunikations-Standard von Mathematica Ludwig Wolf: Ethernet - neue Normen, neue Perspektiven Thomas Schier: ATM - Standards und deren praktischer Einsatz Günther Fischer: IP-Routing in unserem (ATM-)Netz Prof. Uwe Hübner: Intranet - Erwartungen und Entwicklungen

Η τεράστια και ραγδαία ανάπτυξη στην επιστήμη και στην τεχνολογία σε αυτήν την υφήλιο, τέτοια όπως τα ΓΣΠ και η δορυφορική ψηφιακή χαρτογράφηση οφείλεται στην επιτακτική ανάγκη της ανάπτυξης των χωρών να την προλάβουν και να την αξιοποιήσουν. Η χρήση της τεχνολογίας των ΓΣΠ είναι ουσιώδης, καθώς εξελίσσεται σε ένα από τα καλύτερα και γρηγορότερα εργαλεία ως προς την αξιοποίηση των παραγωγικών πόρων και βοηθά στην απόφαση υποστήριξης της διαδικασίας. Τα ΓΣΠ χρησιμοποιούν την τεχνολογία των ηλεκτρονικών χαρτών δημιουργώντας αλληλεπίδραση με πολύ-επίπεδους χάρτες έτσι ώστε να βρεθούν βέλτιστες λύσεις για τα προβλήματα. Συνδυάζει χωρικά και μη-χωρικά δεδομένα για να κατασκευάσει πληροφορίες που μπορούν εύκολα να αναλυθούν από αυτούς που παίρνουν αποφάσεις. Χρησιμοποιώντας την τεχνολογία των ΓΣΠ έχουμε ένα ισχυρό εργαλείο για την επίτευξη του σχεδιασμού αφού ο ψηφιακός χάρτης θα μπορούσε να χρησιμοποιηθεί στην εύρεση καλύτερων τοποθεσιών για διαφορετικούς σκοπούς όπως στις τράπεζες, στα ΑΤΜ, στα νέα σχολεία, εστιατόρια κτλ. Η εργασία συζητά τα κριτήρια που χρησιμοποιήθηκαν στη στατική ανάλυση και επίσης αναφέρεται στην επιτυχία της GIS ανάλυσης στο να προτείνει τοποθεσίες για τα ΑΤΜ. / The huge and rapid advancement in science and technology in this globe such as GIS and Satellite digital mapping makes it a must for developing countries to catch-up and utilize it. Usage of GIS-technology is essential, as it is becoming one of the better and faster tools to manage resources and helps in the decision support process .A GIS uses electronic mapping technology in producing interactive multi-layer maps so that queries are set to find optimal solutions for problems. It combines spatial and non-spatial data to construct visualized information that can be easily analyzed by decision makers.Using GIS technology is a powerful tool to help in planning since the digital map could be used in defining best positions for different purposes such as banks, ATMs, new schools, restaurant, etc. The paper discusses the criteria used in the spatial analysis, and also, reports on the success of the resultant GIS analysis to suggest proper locations for ATM’s.

Οι κατανεμημένοι αλγόριθμοι δρομολόγησης για switches βασισμένα σε κελιά (=πακέτα σταθερού μεγέθους - π.χ. ΑΤΜ) που χρησιμοποιούν την αρχιτεκτονική Virtual Output Queueing έχουν οδηγήσει στη κατασκευή δρομολογητών υψηλών επιδόσεων. Στην παρούσα διπλωματική παρουσιάζουμε μια νέα ιδέα για την κατασκευή τέτοιων αλγορίθμων που λέγεται "αμοιβαία προτεραιότητα". Οι αλγόριθμοι της οικογένειας αυτής, που λέγεται οικογένεια "MPE", πετυχαίνουν βέλτιστη εγγύηση εξυπηρέτησης για κάθε ουρά εισόδου (καθυστέρηση το πολύ N κύκλων για switch ΝχΝ). Επίσης όσον αφορά τη μέση καθυστέρηση των πακέτων , ξεπερνούν σε απόδοση όλους τους γνωστούς αλγορίθμους. Οι βελτιώσεις που επιτυγχάνονται είναι αρκετά σημαντικές (π.χ. μέχρι και 78% μικρότερη καθυστέρηση πακέτων σε σύγκριση με τον καλύτερο υπάρχοντα αλγόριθμο, για μια επανάληψη). / Distributed scheduling algorithms for cell-based (e.g. ATM) Virtual Output Queuing (VOQ) switches have led to high performance schedulers. In this thesis we introduce a new concept in making such algorithms called "mutual priority" . Algorithms of this family , called "MPE" , achieve optimal service guarantee (N in a NxN switch) and lead to packet delays that outperform all existing algorithms. The improvements achieved are quite significant (i.e. up to 78% less packet delay compared to the best existing algorithm for a single iteration).

Congestion control is concerned with allocating the resources in a network such that the network can operate at an acceptable performance level when the demand exceeds or is near the capacity of the network resources. These resources include bandwidths of links, buffer space (memory) and processing capacity at intermediate nodes. Although resource allocation is necessary even at low load, the problem becomes more important as the load increases. Without proper congestion control mechanisms, the throughput may be reduced considerably under heavy load. Future applications are expected to require increasingly higher bandwidth and generate a heterogeneous mix of network traffic. ATM network is potentially capable of supporting all classes of traffic (e.g., voice, video, and data) and have multiple service classes allow audio, video and data to share the same network. Of these, the Available Bit Rate (ABR) service class is designed to efficiently support data traffic. Switch algorithms have been the most investigated topic of ABR. This has happened because the specification of ABR given by the ATM Forum allows a diversity of switch algorithms to be implemented. These range from the simplest binary switches to the more complex ER switches. The major part of this thesis has been devoted to ABR. First an introduction to the concept of congestion control and a brief literature survey of congestion control for ABR service of ATM networks are presented. Then two proposed congestion control mechanisms for the ABR service class in ATM networks are examined by means of simulation, showing the different degree of performance and complexity. The simulation results presented in this thesis were obtained using a network simulator written in C++. This network simulator is a small event driven program. Analytical results were derived for different network configurations and different scenarios using this program.

In this thesis, I examined various signalling both in wired and mobile networks, with more emphasis on SIGTRAN. The SIGTRAN is the protocol suite applicable in the current new generation and next-generation networks, most especially as it enables service provider to be able to interpolate both wireline and wireless services within the same architecture. This concept is an important component in today’s Triple-play communication, and hence this thesis has provided a broad view on Signalling and Protocol Gateways in Traditional and Next Generations Networks. Signal flow in a typical new generation network was examined by carrying out discrete event simulation of UMTS network using OPNET modeller 14.5. Through both Packet-Switching (PS) and Circuit-Switching (CS) signalling, I was able to examine the QoS on a UMTS. Precisely, I looked at throughput on UMTS network by implementing WFQ and MDRR scheduling schemes.

Recently the society has been turning from the use of paper-based technologies to plastic cards in certain spheres of our life. With the emergence and proliferation of high technologies we cannot content with the security provided bypaper only. Therefore the society has chosen plastic to protect its information because it offers far more security based not only on human perception but also on machine-readable elements. The number of plastic cards in circulation in different spheres of our everyday life increases constantly. They replace money, documents and allow easy and safe access to some services. In spite of its security the plastic card however is subjected to fraud. Plastic card fraud results in significant losses for the various industries. Since the first appearance of plastic cards methods of committing fraud have changed dramatically. Now there is a wide range of high technologies at the disposal of criminals as well as card manufacturers. Therefore we have put the great emphasize of this work on the analysis of the most common card technologies in the Plastic Card World, the magnetic stripe and the chip, existing crimes and main means of their committing. And we also have revealed the weak and strong sides of the prevention techniques, which are currently in use.

The need for increased safety and efficiency in civil aviation is pushing the introduction of Automatic Dependent Surveillance - Broadcast (ADS-B). The basic principle of ADS-B is that each aircraft is able to communicate its position and status over a radio data link to surrounding aircraft. In this way each aircraft obtains a detailed picture of the surrounding traffic. During a period of transition from today's radar surveillance to ADS-B many aircraft will not be equipped with the new data link technology and will therefore be invisible to the ADS-B equipped aircraft. The Traffic Information Service - Broadcast (TIS-B) has been conceived to be the solution to this problem. TIS-B is defined as a broadcast surveillance service in which data from the ordinary ground radar system is transmitted from a ground station to airborne systems, providing an air situation picture of the non-ADS-B stations. The topics of this thesis are the definition and implementation of a TIS-B server. The presented solution is an evaluation TIS-B server that will receive data from a data-fusing tracker and provide one or several TIS-B ground stations with data filtered according to the settings of the server.