A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / Data-intensive research computing requires the capability to transfer les over long distances at high throughput. Stateful rewalls introduce su cient packet loss to prevent researchers from fully exploiting high bandwidth-delay network links [25]. To work around this challenge, the science DMZ design [19] trades o stateful packet ltering capability for loss-free forwarding via an ordinary Ethernet switch. We propose a novel extension to the science DMZ design, which uses an SDN-based rewall. This report introduces NFShunt, a rewall based on Linux's Net lter combined with OpenFlow switching. Implemented as an OpenFlow 1.0 controller coupled to Net lter's connection tracking, NFShunt allows the bypass-switching policy to be expressed as part of an iptables rewall rule-set. Our implementation is described in detail, and latency of the control-plane mechanism is reported. TCP throughput and packet loss is shown at various round-trip latencies, with comparisons to pure switching, as well as to a high-end Cisco rewall. Cost, as well as operations and maintenance aspects, are compared and analysed. The results support reported observations regarding rewall introduced packet-loss, and indicate that the SDN design of NFShunt is a technically viable and cost-e ective approach to enhancing a traditional rewall to meet the performance needs of data-intensive researchers / GS2016

A research report submitted to the Faculty of Engineering and the Built Environment of the University of the Witwatersrand in partial fulfilment of the requirements for the degree of Master of Science in Engineering February 2017 / Software-defined networking (SDN) is the physical separation of the control and data planes in networking devices. A logically centralised controller plane which uses a network-wide view data structure to control several data plane devices is another defining attribute of SDN. The centralised controllers and the network-wide view data structure are difficult to scale as the network and the data it carries grow. Solutions which have been proposed to combat this challenge in SDN lack the use of the statistical properties of the workload or network traffic seen by SDN controllers. Hence, the objective of this research is twofold: Firstly, the statistical properties of the controller workload are investigated. Secondly, Autoregressive Integrated Moving Average Models (ARIMA) and Artificial Neural Network (ANN) models are investigated to establish the feasibility of forecasting the controller workload signal. Representations of the state of the controller plane in the network-wide view in the form of forecasts of the controller workload will enable control applications to detect dwindling controller resources and therefore alleviate controller congestion. On the other hand, realistic statistical traffic models of the controller workload variable are sought for the design and evaluation of SDN controllers. A data center network prototype is created by making use of an SDN network emulator called Mininet and an SDN controller called Onos. It was found that 1–2% of flows arrive within 10 s of each other and more than 80% have inter-arrival times in the range of 10 s–10ms. These inter-arrival times were found to follow a beta distribution, which is similar to findings made in Machine Type Communications (MTC). The use of ARIMA and ANN to forecast the controller workload established that it is feasible to forecast the workload seen by SDN controllers. The accuracy of these models was found to be comparable for continuously valued time series signals. The ANN model was found to be applicable even in discretely valued time series data. / MT2017

The ZigBee standard is a wireless networking standard created and maintained by the ZigBee Alliance. The standard aims to provide an inexpensive, reliable, and efficient solution for wirelessly networked sensing and control products. The ZigBee Alliance is composed of over 300 member companies making use of the standard in different ways, ranging from energy management and efficiency, to RF remote controls, to health care products. Home automation is one market that greatly benefits from the use of ZigBee. With a focus on conserving home electricity use, a sample design is created to test a home automation network using Freescale's ZigBee platform. Multiple electrical designs are tested utilizing sensors ranging from proximity sensors to current sense transformers. Software is fashioned as well, creating a PC application that interacts with two ZigBee transceiver boards performing different home automation functions such as air conditioner and automatic lighting control. / by Michael G. DiBenedetto. / Thesis (M.S.C.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

by Ka-Po Ma. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 97-105). / Abstracts in English and Chinese. / Acknowledgments --- p.ii / Abstract --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Web-based Education --- p.1 / Chapter 1.2 --- Customized Web-based Learning --- p.3 / Chapter 1.3 --- Thesis Overview --- p.6 / Chapter 2 --- Web-based Education --- p.7 / Chapter 2.1 --- Impact on Traditional Learning --- p.8 / Chapter 2.2 --- Theoretical Perspectives on Teaching and Learning --- p.9 / Chapter 2.2.1 --- Behaviorism Versus Constructivism --- p.10 / Chapter 2.2.2 --- "Categorization of Individual, Group and Collaborative Learn- ing" --- p.12 / Chapter 2.3 --- On-line Eduation and Web-based Learning System --- p.15 / Chapter 2.4 --- Technologies used in Web-based Learning --- p.17 / Chapter 3 --- General Automated Timetabling --- p.21 / Chapter 3.1 --- Timtabling Problem --- p.21 / Chapter 3.2 --- Formulation and Solution Approaches --- p.22 / Chapter 4 --- "Virtual Campus, Customized Web-based Learning Environment" --- p.25 / Chapter 4.1 --- Changing Trend in Learning Process --- p.25 / Chapter 4.2 --- System Design Issue --- p.26 / Chapter 5 --- System Architecture Issue --- p.31 / Chapter 5.1 --- Client-server Model --- p.31 / Chapter 5.1.1 --- Server Side --- p.33 / Chapter 5.1.2 --- Client Side --- p.34 / Chapter 5.2 --- Functional-oriented Design --- p.35 / Chapter 5.3 --- Private Functionality Issue --- p.37 / Chapter 5.3.1 --- Access Authorizing --- p.37 / Chapter 5.3.2 --- Availability Updating --- p.40 / Chapter 5.3.3 --- Personal Information Querying and Modifying --- p.42 / Chapter 5.3.4 --- Status Selecting --- p.42 / Chapter 5.3.5 --- Current Online User Querying --- p.43 / Chapter 5.4 --- Lecture Functionality Issue --- p.44 / Chapter 5.5 --- Personal Scheduling Functionality Issue --- p.45 / Chapter 5.6 --- Collaboration Functionality Issue --- p.50 / Chapter 5.6.1 --- Chatting Room --- p.50 / Chapter 5.6.2 --- Discussion Board --- p.56 / Chapter 5.6.3 --- Personal URL-bookmark Keeping and Sharing --- p.57 / Chapter 6 --- Web-based Learning Scheduler (WL-Scheduler) --- p.59 / Chapter 6.1 --- "Web-based Customized Timetabling Problem, WCTP" --- p.60 / Chapter 6.2 --- Solution Approach - Local Search --- p.61 / Chapter 6.3 --- Algorithm for Approaching Feasible Timetables --- p.63 / Chapter 6.4 --- Evaluating The Best Timetable --- p.66 / Chapter 7 --- Multimedia Web Presentation System (MWPS) --- p.67 / Chapter 7.1 --- Overview --- p.67 / Chapter 7.2 --- System Components --- p.68 / Chapter 7.2.1 --- The MWPS Server Machine --- p.69 / Chapter 7.2.2 --- The MWPS Client Machine --- p.69 / Chapter 7.2.3 --- The Student Machine --- p.69 / Chapter 7.3 --- Presentation Flow --- p.69 / Chapter 7.4 --- Highlighed Features --- p.72 / Chapter 7.4.1 --- Slides Sequence Capturing --- p.72 / Chapter 7.4.2 --- Audio/Video Capturing --- p.72 / Chapter 7.4.3 --- Script-Text On Playback --- p.72 / Chapter 7.4.4 --- Student Feedbacking --- p.73 / Chapter 7.4.5 --- White Board Facility --- p.73 / Chapter 8 --- Illustration via Screen-shots --- p.74 / Chapter 8.1 --- Login Screen --- p.74 / Chapter 8.2 --- Functionality provided for Students --- p.75 / Chapter 8.2.1 --- Personalized Learning Timetable --- p.76 / Chapter 8.2.2 --- Lecture Delivery --- p.78 / Chapter 8.2.3 --- Checking active users in Virtual Campus --- p.78 / Chapter 8.2.4 --- View and Update Personal Information --- p.79 / Chapter 8.2.5 --- Taking An Entry Test for Interesting Subject --- p.81 / Chapter 8.2.6 --- Changing Current State --- p.84 / Chapter 8.2.7 --- Discussion Board --- p.84 / Chapter 8.2.8 --- Chatting Room --- p.85 / Chapter 8.3 --- Functionality provided for Teachers --- p.85 / Chapter 8.4 --- Functionality provided for Administrators --- p.92 / Chapter 9 --- Conclusion --- p.94 / Appendix --- p.106 / Chapter A --- Appendix --- p.106 / Chapter A.1 --- Internet Technology --- p.106 / Chapter A.2 --- Web Server --- p.107 / Chapter A.3 --- Web Client/Server Example --- p.108

by Ma Chun Ho Eric. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 102-105). / Abstracts in English and Chinese. / INTERNET ROUTING AND PRICING --- p.1 / ABSTRACT --- p.I / ACKNOWLEDGEMENTS --- p.III / LIST OF FIGURES --- p.IV / LIST OF TABLES --- p.VI / CONTENTS --- p.VII / Chapter CHAPTER1 --- Introduction --- p.1 / Chapter 1.1 --- What is Internet? --- p.1 / Chapter 1.2 --- Internet Routing and Pricing --- p.3 / Chapter 1.3 --- Overview of QoS Routing --- p.4 / Chapter 1.3.1 --- Classification of Routing --- p.6 / Chapter 1.3.2 --- Optimal Routing --- p.7 / Chapter 1.4 --- An Introduction to Internet Economics --- p.8 / Chapter 1.4.1 --- Internet Externality --- p.9 / Chapter 1.4.2 --- Current Pricing Practice --- p.10 / Chapter 1.4.3 --- Network Interconnection --- p.14 / Chapter 1.4 --- Organization of Thesis --- p.16 / Chapter CHAPTER2 --- Economic Theory for Interconnection Model --- p.18 / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- Demand and Supply --- p.20 / Chapter 2.2.1 --- Consumer Behavior --- p.20 / Chapter 2.2.2 --- Demand Curve --- p.25 / Chapter 2.2.3 --- Price Elasticity --- p.30 / Chapter 2.2.4 --- Estimation of Market Demand --- p.32 / Chapter 2.3 --- Market Structure --- p.33 / Chapter 2.3.1 --- Competitive Firm --- p.34 / Chapter 2.3.2 --- Monopoly --- p.35 / Chapter 2.3.3 --- Oligopoly --- p.35 / Chapter 2.4 --- Game Theory --- p.35 / Chapter 2.4.1 --- The Payoff Matrix of a game --- p.36 / Chapter 2.4.2 --- Nash Equilibrium --- p.37 / Chapter 2.4.3 --- Mixed Strategies --- p.38 / Chapter 2.4.4 --- Existence of Nash Equilibrium --- p.39 / Chapter 2.5 --- Summary --- p.39 / Chapter CHAPTER3 --- Problem Formulation Interconnection Network for Pricing and Routing in Internet --- p.40 / Chapter 3.1 --- Introduction --- p.40 / Chapter 3.2 --- Problem Formulation --- p.41 / Chapter 3.2 --- Existence of NEP Interconnection Network --- p.46 / Chapter 3.3 --- "A ""Cookbook"" Procedure" --- p.53 / Chapter 3.4 --- Cookbook Examples --- p.54 / Chapter 3.5 --- Summary --- p.65 / Chapter CHAPTER4 --- Price Competition for Interconnection Models --- p.66 / Chapter 4.1 --- Introduction --- p.66 / Chapter 4.2 --- Competitive Pricing of Parallel Networks --- p.66 / Chapter 4.2.1 --- Model and Problem Formulation --- p.67 / Chapter 4.2.2 --- Existence of Nash Equilibrium Point --- p.68 / Chapter 4.2.3 --- Numerical Example and Properties --- p.71 / Chapter 4.3 --- Price Collusion for Serial Networks --- p.75 / Chapter 4.3.1 --- Model and Problem Formulation --- p.75 / Chapter 4.3.2 --- Existence of Nash Equilibrium Point --- p.77 / Chapter 4.3.3 --- Numerical Example and Properties --- p.79 / Chapter 4.4 --- Summary --- p.83 / Chapter CHAPTER5 --- Price Distortion for Series-Parallel Networks with Dominant Carriers --- p.85 / Chapter 5.1 --- Problem Motivation and Formulation --- p.85 / Chapter 5.2 --- Properties under NEP --- p.90 / Chapter 5.3 --- A Simple Simulation --- p.95 / Chapter 5.5 --- Summary --- p.98 / Chapter CHAPTER6 --- Conclusion --- p.99 / BIBLIOGRAPHY --- p.102

by Chung Ling Chi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 74-76). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Motivation and Proposed Solution --- p.2 / Chapter 1.3 --- Organization of the Thesis --- p.4 / Chapter Chapter 2 --- Background --- p.5 / Chapter 2.1 --- Basics of Transmission Control Protocol --- p.5 / Chapter 2.1.1 --- Slow Start and Congestion Avoidance --- p.5 / Chapter 2.1.2 --- Fast Retransmit and Fast Recovery --- p.7 / Chapter 2.2 --- SACK TCP Mechanism --- p.8 / Chapter 2.2.1 --- SACK-permitted Option during Three-way Handshake --- p.8 / Chapter 2.2.2 --- SACK blocks in SACK Option --- p.9 / Chapter 2.2.3 --- Interpreting the SACK Option using Scoreboard --- p.10 / Chapter 2.2.4 --- Retransmission Strategy --- p.11 / Chapter 2.3 --- TCP Veno Mechanism --- p.13 / Chapter 2.3.1 --- Refined Additive Increase --- p.13 / Chapter 2.3.2 --- Refined Multiplicative Decrease --- p.14 / Chapter Chapter 3 --- SACK TCPVeno --- p.16 / Chapter 3.1 --- Distinguishing between Types of Packet Loss --- p.17 / Chapter 3.2 --- Refined Multiplicative Decrease --- p.21 / Chapter 3.2.1 --- Algorithm --- p.21 / Chapter 3.2.2 --- Recovery in Consecutive packet Losses --- p.22 / Chapter 3.2.3 --- Recovering Multiple Packet Losses within a Single Window --- p.26 / Chapter 3.3 --- Refined Additive Increase --- p.37 / Chapter 3.3.1 --- Algorithm --- p.37 / Chapter 3.3.2 --- Advantages --- p.40 / Chapter 3.4 --- Other Issues --- p.43 / Chapter 3.4.1 --- Two Side Modifications --- p.43 / Chapter Chapter 4 --- Experiments --- p.44 / Chapter 4.1 --- The Network Scenario --- p.44 / Chapter 4.1.1 --- Dummynet --- p.45 / Chapter 4.2 --- Experiment Results --- p.47 / Chapter 4.2.1 --- Single Connection --- p.47 / Chapter 4.2.1.1 --- Congestion Window Evolution --- p.47 / Chapter 4.2.1.2 --- Sending Rate and Throughput Evolution --- p.49 / Chapter 4.2.1.2.1 --- Impact of Packet Loss Rate Due to Lossy Link --- p.49 / Chapter 4.2.1.2.2 --- Impact of Buffering --- p.52 / Chapter 4.2.1.2.3 --- Impact of Propagation Delay --- p.57 / Chapter 4.2.2 --- Multiple Connections --- p.62 / Chapter 4.2.2.1 --- Fairness --- p.62 / Chapter 4.2.2.2 --- Compatibility --- p.67 / Chapter Chapter 5 --- Conclusion --- p.72 / Bibliography --- p.74

by Hui Chi Chun Ronald. / Thesis submitted in: December 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 62-66). / Abstract also in Chinese. / Chapter Chapter 1. --- Introduction --- p.1 / Chapter Chapter 2. --- AON Architecture --- p.7 / Chapter 2.1 --- WCC Dimension Reduction Node Architecture --- p.10 / Chapter 2.2 --- Restoration of a Survivable AON --- p.13 / Chapter Chapter 3. --- Network Dimensioning Problem --- p.15 / Chapter 3.1 --- Problem Setting --- p.16 / Chapter 3.2 --- Two Solution Approaches --- p.16 / Chapter 3.2.1 --- Minimum Variance Algorithm (MVA) --- p.17 / Chapter 3.2.2 --- Minimum Variance Subroutine (MVS) --- p.19 / Chapter 3.3 --- Shortest Path Algorithm (SPA) --- p.21 / Chapter 3.4 --- An Illustrative Example --- p.22 / Chapter 3.5 --- Performance Comparisons --- p.26 / Chapter Chapter 4. --- Network Management for AON Restoration --- p.31 / Chapter 4.1 --- Surveillance Network --- p.31 / Chapter 4.2 --- Signaling Network --- p.32 / Chapter 4.3 --- Network Management System --- p.32 / Chapter 4.4 --- CCS7 Adaptation for Supporting AON Restoration --- p.34 / Chapter Chapter 5. --- Complete Restoration Algorithm for AON --- p.40 / Chapter 5.1 --- Link-Based Restoration Algorithm --- p.43 / Chapter 5.2 --- Source-Based Restoration Algorithm --- p.44 / Chapter 5.3 --- Case Studies --- p.45 / Chapter 5.3.1 --- Case I and II --- p.45 / Chapter 5.3.2 --- Case III --- p.50 / Chapter 5.4 --- Completely Restorable Network planning --- p.52 / Chapter 5.5 --- A Summary on Problem Formulations --- p.55 / Chapter Chapter 6. --- Conclusion --- p.57 / Reference --- p.62

Lau Kwok Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 66-67). / Abstracts in English and Chinese. / Acknowledgement --- p.1 / Abstract --- p.2 / 摘要 --- p.3 / Chapter Chapter 1 --- Introduction --- p.6 / Chapter Chapter 2 --- Background and Related Work --- p.9 / Chapter 2.1 --- Application-Layer Bandwidth Differentiation --- p.9 / Chapter 2.2 --- Related Work --- p.14 / Chapter 2.2.1 --- Bandwidth Differentation --- p.14 / Chapter 2.2.2 --- Shared Congestion Management --- p.15 / Chapter 2.2.3 --- Flow Partition --- p.16 / Chapter Chapter 3 --- VPS Protocol Architecture --- p.17 / Chapter 3.1 --- Virtual and Actual Flows --- p.18 / Chapter 3.2 --- VPS Controller --- p.21 / Chapter Chapter 4 --- ACK Translation --- p.25 / Chapter 4.1 --- Fast Retransmit and Fast Recovery --- p.27 / Chapter 4.2 --- Timeout --- p.30 / Chapter 4.3 --- Packet and ACK Reordering --- p.33 / Chapter 4.4 --- False Duplicate ACK Suppression --- p.35 / Chapter 4.5 --- Maxburst --- p.37 / Chapter 4.6 --- Memory Overhead and Computation Complexity --- p.38 / Chapter Chapter 5 --- Bandwidth Differentiation --- p.41 / Chapter 5.1 --- Distribution of Virtual Packets --- p.41 / Chapter 5.2 --- Temporary Suspension of Actual Flows --- p.43 / Chapter 5.3 --- Receive Window Limit --- p.44 / Chapter 5.4 --- Limited Data Transmission --- p.44 / Chapter Chapter 6 --- Performance Evaluatoin --- p.45 / Chapter 6.1 --- Performance Metric --- p.45 / Chapter 6.2 --- Simulation Setup --- p.46 / Chapter 6.3 --- Performance over Different Time Scales --- p.47 / Chapter 6.4 --- Performance over Different Bottleneck Bandwidth --- p.53 / Chapter 6.5 --- Performance over Different Application-specified Ratios --- p.54 / Chapter 6.6 --- Performance over Different Number of Flows --- p.57 / Chapter 6.7 --- Heterogeneous Receivers --- p.60 / Chapter Chapter 7 --- Conclusions and Future Work --- p.65 / Bibliography --- p.66

Zheng, Pengxuan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 53-57). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgments --- p.v / Table of Contents --- p.vi / List of Figures --- p.viii / List of Tables --- p.ix / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Related Work --- p.2 / Chapter 1.3 --- Our Contribution --- p.3 / Chapter 1.4 --- Organization of the Thesis --- p.4 / Chapter Chapter 2 --- Background Overview --- p.6 / Chapter 2.1.1 --- Traditional Wireless Networks --- p.6 / Chapter 2.2 --- Exponential Backoff --- p.7 / Chapter 2.2.1 --- Introduction --- p.7 / Chapter 2.2.2 --- Algorithm --- p.8 / Chapter 2.2.3 --- Assumptions --- p.9 / Chapter 2.3 --- System Description --- p.9 / Chapter 2.3.1 --- MPR Capability --- p.9 / Chapter 2.3.2 --- Backoff Slot --- p.10 / Chapter 2.3.3 --- Carrier-sensing and Non-carrier-sensing Systems --- p.11 / Chapter Chapter 3 --- Multipacket Reception in WLAN --- p.12 / Chapter 3.1 --- MAC Protocol Description --- p.13 / Chapter 3.2 --- Physical Layer Methodology --- p.16 / Chapter 3.2.1 --- Blind RTS Separation --- p.17 / Chapter 3.2.2 --- Data Packet Detection --- p.19 / Chapter Chapter 4 --- Exponential Backoff with MPR --- p.21 / Chapter 4.1 --- Analytical Model --- p.22 / Chapter 4.1.1 --- Markov Model --- p.22 / Chapter 4.1.2 --- Relations betweenpt andpc --- p.23 / Chapter 4.2 --- Simulation Settings --- p.26 / Chapter 4.3 --- Asymptotic Behavior of Exponential Backoff --- p.27 / Chapter 4.3.1 --- Convergence ofpt andpc --- p.27 / Chapter 4.3.2 --- Convergence of Npt --- p.29 / Chapter Chapter 5 --- Non-carrier-sensing System --- p.31 / Chapter 5.1 --- Performance Analysis --- p.31 / Chapter 5.1.1 --- Throughput Derivation --- p.31 / Chapter 5.1.2 --- Throughput Analysis --- p.32 / Chapter 5.1.3 --- Convergence of S --- p.36 / Chapter 5.2 --- Infinite Population Model --- p.38 / Chapter 5.2.1 --- Attempt Rate --- p.38 / Chapter 5.2.2 --- Asymptotic Throughput of Non-carrier-sensing System --- p.39 / Chapter Chapter 6 --- Carrier-sensing System --- p.43 / Chapter 6.1 --- Throughput Derivation --- p.43 / Chapter 6.2 --- Asymptotic Behavior --- p.44 / Chapter Chapter 7 --- General MPR Model --- p.48 / Chapter Chapter 8 --- Conclusions --- p.51 / Bibliography --- p.53

O problema das fraudes virtuais em serviços de Internet Banking e comércio eletrônico vem crescendo a cada dia. Em 2005, as fraudes virtuais representaram, no Brasil, uma perda de 300 milhões de reais. Neste trabalho, apresentamos inicialmente o cenário atual das fraudes, especificando quais ataques elas utilizam, como são hoje executadas e quais vulnerabilidades exploram. Cada ataque é classificado conforme uma nova taxonomia criada. São também apresentadas possíveis defesas contra esses ataques, indicando a efetividade de cada uma. Analisamos também o ponto de vista da privacidade do usuário para cada uma dessas soluções. Como contribuição original, esse trabalho apresenta uma solução de curto prazo, que opera sobre a infra-estrutura já existente, que visa reduzir o problema das fraudes. São feitas também considerações sobre possíveis soluções de longo prazo de maior efetividade e que promovam uma defesa mais estrutural. / The problem of virtual frauds in Internet Banking and electronic commerce services is growing each day. In 2005, the virtual frauds represented a damage of 300 million reais in Brazil. In this work, we present initially the current scenario of virtual frauds, specifying what attacks are used, how they are executed and which vulnerabilities they exploit. Each attack will be classified in accordance to a new methodology. We also present defenses against these attacks, indicating the effectiveness and intrusion of each one of them. In the end, a short term and defensive solution is presented to reduce the problem of virtual frauds. We also consider long term solutions that could be used in the future to accomplish structural defenses.