Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The way in which people consume video is changing with the adoption of new technologies such as tablet computers and smart televisions. These new technologies, along with the Internet, are moving video distribution away from satellite and terrestrial broadcast to distribution over the Internet. Services online now offer the same content that originally was only available on satellite broadcast television. However, these services are only viable in countries with high speed, inexpensive Internet bandwidth. The need therefore exists for alternative services to deliver content in countries where bandwidth is still expensive and slow. These include many of the developing nations of Africa. In this thesis we design and develop a video distribution platform that relies on peer-to-peer networking to deliver high quality video content. We use an existing video streaming peer-to-peer protocol as the primary distribution mechanism, but allow users to share video over other protocols and services. These can include BitTorrent, DC++ and users sharing hard drives with one another. In order to protect the video content, we design and implement a security scheme that prevents users from pirating video content, while allowing easy distribution of video data. The core of the security scheme requires a low bandwidth Internet connection to a server that streams keys to unlock the video content. The project also includes the development of a custom video player application to integrate with the security scheme. The platform is not limited to, but is aimed at high speed local area networks where bandwidth is free. In order for the platform to support feasible business models, we provision additional services, such as video cataloging and search, video usage monitoring and platform administration. The thesis includes a literature study on techniques and solutions to secure video entertainment, specifically in a peer-to-peer environment. / AFRIKAANSE OPSOMMING: Die wyse waarvolgens mense video verbruik is aan die verander met die ingebruikneming van nuwe tegnologie soos tabletrekenaars en slim televisiestelle. Hierdie nuwe tegnologie tesame met die Internet maak dat die verspreiding van video al hoe minder plaasvind deur middel van satellietuitsendings en al hoe meer versprei word deur die Internet. Aanlyn-Internetdienste bied deesdae dieselfde inhoud aan as wat voorheen slegs deur beeldsending versprei is. Hierdie dienste is egter slegs lewensvatbaar in lande met hoëspoed- en goedkoop Internetbandwydte. Daar is dus ’n behoefte aan alternatiewe tot hierdie dienste in lande waar bandwydte steeds duur en stadig is. Baie lande in Afrika kan in hierdie kategorie ingesluit word. In hierdie tesis word ’n videoverspreidingsplatform ontwerp en ontwikkel, wat van portuurnetwerke gebruik maak om hoëkwaliteit-beeldmateriaal te versprei. Die stelsel gebruik ’n bestaande portuurnetwerk-datavloeiprotokol as die premêre verspreidingsmeganisme, maar laat gebruikers ook toe om videoinhoud direk met ander gebruikers en dienste te deel. BitTorrent, DC++ en gebruikers wat hardeskywe met mekaar deel word hierby ingesluit. Ten einde die videoinhoud te beskerm ontwerp en implimenteer ons ’n sekuriteitstelsel wat verhoed dat gebruikers die videoinhoud onregmatig kan toe-eien, maar wat terselfdertyd die verspreiding van die data vergemaklik. Hierdie sluit die ontwikkeling van ’n pasgemaakte videospeler in. Die kern van die sekuriteitstelsel benodig ’n lae-bandwydte-Internetverbinding na ’n bediener wat sleutels uitsaai om die videoinhoud te ontsluit. Alhoewel nie daartoe beperk nie, is die platform gemik op hoëspoed-plaaslikegebiedsnetwerke met gratis bandwydte. Om die platvorm aan ’n haalbare sakemodel te laat voldoen het ons vir addisionele dienste soos videokatalogisering met soekfunksies, videoverbruikersmonitering en platvormadministrasie voorsiening gemaak. Die tesis sluit ’n literatuurstudie oor tegnieke en oplossings vir die beskerming van video data, spesifiek in die portuurnetwerke omgeving, in.

Our work focuses on wireless networks in general, but deals specifically with security in wireless sensor networks and energy consumption in IEEE 802.11 infrastructure WLANs. In the first part of our work, we focus on secure communication among sensor nodes in a wireless sensor network. These networks consists of large numbers of devices having limited energy and memory. Public key cryptography is too demanding for these resource-constrained devices because it requires high computation. So, we focus on symmetric key cryptography to achieve secure communication among nodes. For this cryptographic technique to work, two nodes have to agree upon a common key. To achieve this, many key distribution schemes have been proposed in the literature. Recently, several researchers have proposed schemes in which they have used group-based deployment models and assumed predeployment knowledge of the expected locations of nodes. They have shown that these schemes achieve better performance than the earlier schemes, in terms of connectivity, resilience against node capture and storage requirements. But in many situations expected locations of nodes are not available. We propose a solution which does not use the group-based deployment model and predeployment knowledge of the locations of nodes, and yet performs better than schemes which make the aforementioned assumptions. In our scheme, groups are formed after the deployment of sensor nodes on the basis of their physical locations. Nodes in different groups sample keys from disjoint key pools, so that compromise of a node affects secure links of its group only. Because of this reason, our scheme performs better than earlier schemes as well as the schemes using predeployment knowledge, in terms of connectivity, storage requirement, and security. Moreover, the post-deployment key generation process completes sooner than in schemes like LEAP+. In the second part of our work, we develop analytical models for estimating the energy spent by stations (STAs) in infrastructure WLANs when performing TCP-controlled file downloads. We focus on the energy spent in radio communication when the STAs are in the Continuously Active Mode (CAM), or in the static Power Save Mode (PSM). Our approach is to develop accurate models for obtaining the fractions of times the STA radios spend in idling, receiving and transmitting. We discuss two traffic models for each mode of operation: (i) each STA performs one large file download, and (ii) the STAs perform short file transfers with think times (short duration of inactivity)between two transfers. We evaluate the rate of STA energy expenditure with long file downloads, and show that static PSM is worse than using just CAM. For short file downloads, we compute the number of file downloads that can be completed with a given battery capacity, and show that PSM performs better than CAM for this case. We provide a validation of our analytical models using the NS-2 simulator. Although the PSM performs better than the CAM when the STAs download short files over TCP with think times, its performance degrades as the number of STAs associated to the access point (AP) increases. To address this problem, we propose an algorithm, which we call opportunistic PSM (OPSM). We show through simulations that OPSM performs better than PSM. The performance gain achieved by OPSM increases as the file size requested by the STAs or the number of STAs associated with the AP increases. We implemented OPSM in NS-2.33, and to compare the performance of OPSM and PSM, we evaluate the number of file downloads that can be completed with a given battery capacity and the average time taken to download a file.

The idea of a free network is a myth of the past. Networking costs are expected to remain a burden to future IT budgets, no doubt raising questions regarding the payment of such services. Users do not normally pay to use local area networks, as companies tend to own their LANs. However, when wide area or international networks are considered, the situation is different. It is argued that in these cases the invoicing and payment system should be integral to the network's communication protocol. This implies changes to the networking protocol (to handle invoicing) as well as a new look at customary ideas of representing currency (to handle payment). In this dissertation, an invoicing and payment scheme that uses electronic cash and is implemented as part of the basic ATM protocols is discussed. The main advantages of this scheme can be summarized as a low administrative overhead and user privacy. / Computer Science / M. Sc. (Computer Science)

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Approved for public release; distribution is unlimited. / The purpose of this thesis is to discuss the new features and enhancements of Windows Server 2003. Windows NT and Windows 2000 were known to have numerous security vulnerabilities; hence Microsoft focused on improving security by making Windows Server 2003 "secure by design, secure by default, secure in deployment." This thesis examines the differences between the five unique editions of the Windows Server 2003 family. Some of the pros and cons of migrating to Windows Server 2003 are highlighted. The author hopes this study will assist information technology professionals with their decision on whether or not to upgrade to this latest version of Microsoft's flagship network operating system. / Lieutenant Commander, United States Navy

Approved for public release, distribution is unlimited / Optical fiber has been the preferred cabling technology for certain building and campus network LAN backbones. Until recently, however, the use of fiber as a cabling medium to the desktop has been confined to special environments that require the unique properties of optical fiber such as noise immunity, security, distance, high bandwidth demands (CAD/CAM, video conferencing), and immunity to electrical interference. However, choosing to use optical fiber in a network over other cabling options may present significant advantages in its inherent ability to handle data at higher speeds. Decreasing costs of optical fiber components compared to the increasing electronic costs of carrying Gigabit Ethernet over Cat 5 or Cat 5E UTP copper cabling has also accelerated the migration to optical fiber LAN. The thesis conducts a feasibility study of implementing a Fiber Optic Local Area Network in Software Metrics Laboratory in Ingersoll 158. / Major, Republic of Singapore Air Force

Approved for public release; distribution in unlimited. / Complex multilevel secure (MLS) architectures are emerging that require user identification and authentication services not only from multilevel connections, but from pre-existing single level networks. The XTS-400 can be used as a server in such environments. Trusted devices are required for user login via multilevel connections; however, single level remote login facilities do not require such client-side devices. Instead, a more lightweight mechanism is possible. Remote login capabilities do not exist on the XTS-400 for use over the single level networks and this capability is a desired feature for use in complex multilevel architectures. OpenSSH is an application, developed for OpenBSD, that uses the SSH protocol to provide secure remote logins and an interactive command interface. A secure remote login application, OpenSSH, was ported to the XTS-400 in order to provide remote login capabilities. The porting process identified differences between the original development platform for OpenSSH and the XTS- 400. Solutions, in the form of source code modifications, were made to overcome problems resulting from the compatibility differences encountered during the port. Testing was conducted to ensure that the port was successful and did not violate any security policies enforced by the XTS-400. / Civilian, Naval Postgraduate School

M.Comm. / This study was conducted with the intent of understanding and evaluating the commercial use and possibilities that the Internet offers, as well as the strategic approach businesses should take when commencing with electronic commerce on the Internet. The potential value of Intranets and Extranets has also been examined briefly. The Internet is a very useful mechanism for marketing as well as sales of products or services on a domestic or international basis. Various other commercial possibilities and uses exist for the Internet, as well as for its derivatives — the Intranet and Extranet. In the fiercely competitive market of today, companies research, develop and invest resources in various methods and tools in the hope to gain competitive advantage over their rivals. The Internet, Intranet and Extranet, used in isolation or conjunction, pose an extremely attractive alternative to gaining competitive advantage in a specific sector or market niche.The success of the Internet as a business tool depends directly on the overall business strategy that is driving the approach. For optimum success the main business strategy must be aligned with the Information Technology Strategy, and especially include thorough consideration as well as planning when implementing the Internet or one of its derivatives as a business tool.

The world of computers experienced an explosive period of growth toward the end of the 20th century with the widespread availability of the Internet and the development of the World Wide Web. As people began using computer networks for everything from research and communication to banking and commerce, network failures became a greater concern because of the potential to interrupt critical applications. Fault tolerance systems were developed to detect and correct network failures within minutes and eventually within seconds of the failure, but time-critical applications such as military communications, video conferencing, and Web-based sales require better response time than any previous systems could provide. The goal of this thesis was the development and implementation of a Network Fault Tolerance (NFT) system that can detect and recover from failures of network interface cards, network cables, switches, and routers in much less than one second from the time of failure. The problem was divided into two parts: fault tolerance within a single local area network (LAN), and fault tolerance across many local area networks. The first part involves the network interface cards, network cables, and switches within a LAN, which the second part involves the routers that connect LANs into larger internetworks. Both parts of the NFT solution were implemented on Windows NT 4.0 PC's connected by a switched Fast Ethernet network. The NFT system was found to correct system failures within 300 milliseconds of the failure.

"Real-time performance evaluation of wireless local area networks (WLANs) is an extremely challenging topic. The major drawback of real-time performance analysis in actual network installations is a lack of repeatability due to uncontrollable interference and propagation complexities. These are caused by unpredictable variations in the interference scenarios and statistical behavior of the wireless propagation channel. This underscores the need for a Radio Frequency (RF) test platform that provides isolation from interfering sources while simulating a real-time wireless channel, thereby creating a realistic and controllable radio propagation test environment. Such an RF-isolated testbed is necessary to enable an empirical yet repeatable evaluation of the effects of the wireless channel on WLAN performance. In this thesis, a testbed is developed that enables real-time laboratory performance evaluation of WLANs. This testbed utilizes an RF-isolated test system, Azimuthâ„¢ Systems 801W, for isolation from external interfering sources such as cordless phones and microwave ovens and a real-time multipath channel simulator, Elektrobit PROPSimâ„¢ C8, for wireless channel emulation. A software protocol analyzer, WildPackets Airopeek NX, is used to capture data packets in the testbed from which statistical data characterizing performance such as data rate and Received Signal Strength (RSS) are collected. The relationship between the wireless channel and WLAN performance, under controlled propagation and interference conditions, is analyzed using this RF-isolated multipath testbed. Average throughput and instantaneous throughput variation of IEEE 802.11b and 802.11g WLANs operating in four different channels - a constant channel and IEEE 802.11 Task Group n (TGn) Channel Models A, B, and C - are examined. Practical models describing the average throughput as a function of the average received power and throughput variation as a function of the average throughput under different propagation conditions are presented. Comprehensive throughput models that incorporate throughput variation are proposed for the four channels using Weibull and Gaussian probability distributions. These models provide a means for realistic simulation of throughput for a specific channel at an average received power. Also proposed is a metric to describe the normalized throughput capacity of WLANs for comparative performance evaluation."