Approved for public release, distribution is unlimited / This thesis studies and discusses the development of the API, called the persistency API, for supporting the persistent data sessions. Without persistent session support, network applications often need to be restarted from the beginning when intermittent physical connection loss happens. Application programmers can use the persistency API to achieve the service continuity. The persistency API provides the interface that allows a program to continue retrieve data from the point the connection is lost after the physical connection is restored. The focus of this thesis is to develop a generalized persistency API that supports various types of applications. This thesis studies the persistent session support for two types of transport protocols, TCP and UDP, which are used by major network applications. An application that performs text file and video file transfer is implemented to demonstrate the persistent data transfer sessions for TCP and UDP, respectively. The study shows that the proposed APIs can support the data transfer continuity in the reconnection process. / Captain, Royal Thai Army

In the wake of major disasters, the failure of existing communications infrastructure and the subsequent lack of an effective communication solution results in increased risks, inefficiencies, damage and casualties. Currently available options such as satellite communication are expensive and have limited functionality. A robust communication solution should be affordable, easy to deploy, require little infrastructure, consume little power and facilitate Internet access. Researchers have long proposed the use of ad hoc wireless networks for such scenarios. However such networks have so far failed to create any impact, primarily because they are unable to handle network transience and have usability constraints such as static topologies and dependence on specific platforms. LifeNet is a WiFi-based ad hoc data communication solution designed for use in highly transient environments. After presenting the motivation, design principles and key insights from prior literature, the dissertation introduces a new routing metric called Reachability and a new routing protocol based on it, called Flexible Routing. Roughly speaking, reachability measures the end-to-end multi-path probability that a packet transmitted by a source reaches its final destination. Using experimental results, it is shown that even with high transience, the reachability metric - (1) accurately captures the effects of transience (2) provides a compact and eventually consistent global network view at individual nodes, (3) is easy to calculate and maintain and (4) captures availability. Flexible Routing trades throughput for availability and fault-tolerance and ensures successful packet delivery under varying degrees of transience. With the intent of deploying LifeNet on field we have been continuously interacting with field partners, one of which is Tata Institute of Social Sciences India. We have refined LifeNet iteratively refined base on their feedback. I conclude the thesis with lessons learned from our field trips so far and deployment plans for the near future.

There are a number of known architectural patterns for TCP/IP server design. I present a survey of design choices based on some of the most common of these patterns. I have demonstrated, with working code samples, that most of these architectural patterns are readily portable between UNIX and Windows NT platforms without necessarily incurring significant performance penalties. / Computing / M. Sc. (Computer Science)

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

Port scanning is the first activity an attacker pursues when attempting to compromise a target system on a network. The aim is to gather information that will result in identifying one or more vulnerabilities in that system. For example, network ports that are open can reveal which applications and services are running on the system. How a port responds when probed with data can reveal which protocol the port utilises and can also reveal which implementation of that protocol is being employed. One of the most valuable pieces of information to be gained via scanning and probing techniques is the operating system that is installed on the target. This technique is called operating system fingerprinting. The purpose of this research is to alert computer users of the dangers of port scanning, probing, and operating system fingerprinting by exposing these techniques and advising the users on which preventative countermeasures to take against them. Analysis is performed on the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Internet Protocol (IPv4 and IPv6), and the Internet Control Message Protocol (ICMPv4 and ICMPv6). All the software used in this project is free and open source. The operating system used for testing is Linux (2.4 and 2.6 kernels). Scanning, probing, and detection techniques are investigated in the context of the Network Mapper and Xprobe2 tools. / Thesis (M.Sc. - Computer)-University of KwaZulu-Natal, Durban, 2007.

It is recognized that security services in information-processing systems require access to finite resources in the execution of their duties. In response to the changing threats faced by a system and/or the availability of system resources, it is desired that the system be able to adjust its operational security policies automatically while continuing to function under an acceptable global security policy. This work involves the analysis and integration of a dynamic security service (DSS)-enabled IPsec implementation into a form ready for installation into the MYSEA environment. The feasibility of dynamic security services is demonstrated with support for secrecy and/or integrity protection of MLS server-to-end-user communication via a Trusted Path Extension. This is accomplished through the modulation of the IPsec security associations to adapt to operational needs. The result of this research is beneficial to Homeland Security, the Department of Defense, and the intelligence community by enabling remote distributed computing clients to operate in a secure manner that remains flexible to adapt to changing requirements of protection on the network and the availability of resources on terminating hosts. Furthermore, these methods can aid the realization of high-assurance edge-client connectivity in the creation and extension of the Global Information Grid (GIG).

Approved for public release, distribution is unlimited / With the rapidly growing demand for portable devices such as laptops, handheld computers and Personal Digital Assistants (PDAs) with wireless networking capabilities, the need for reliable wireless data network communication has also increased. Just like in mobile voice communication, users demand uninterrupted, secure wireless data communication as they move from place to place. Mobile IP satisfies some of these demands - it enables mobile devices with fixed IP addresses to be permanently reachable even as their point of attachment to the network changes. This allows for routing of data packets to and from the mobile device irrespective of its location on the network. While uninterrupted data flow can be achieved with Mobile IP, it introduces additional security vulnerabilities, including data privacy, data integrity and authentication. The goal of this thesis is to investigate such vulnerabilities and explore implementations to overcome them. / Civilian, National Science Foundation

Approved for public release, distribution unlimited / Adopting Extensible Markup Language (XML) and Hypertext Transfer Protocol (HTTP) are key steps to accommodate the evolution of Internet technologies. While HTTP is already a proven standard communication protocol responsible for the rapid expansion of the World Wide Web, XML provides general mechanisms for determining validatable documents and addresses several deficiencies of HTML regarding diverse document structure and content. XML and HTTP together provide many of the essential capabilities associated with database engines. The Modeling, Virtual Environments and Simulation (MOVES) Institute of the Naval Postgraduate School (NPS) is continuing to build a database of 3D tactical scenarios and using X3D and VRML tools. The configuration parameters and statistical results of these scenarios are XML documents. For a better understanding and usability of these results by the end users, a Webbased application stores and manipulates these XML document. This thesis develops a server-side application that can store, serve, and annotate tactical scenarios for X3D operational visualization and anti-terrorist training by using XML and HTTP technologies. The experimental demonstration for this work is the prototypical Anti-Terrorism/Force Protection (AT/FP) simulation model developed by Lieutenant James W. Harney, USN, using Extensible 3D Graphics (X3D)/ Virtual Reality Modeling Language (VRML) models. / Captain, Tunisian Army

Approved for public release; distribution is unlimited / Simple Network Management Protocol (SNMP) allows users of network equipment (i.e. Network Administrators) to remotely query the state of any device being tested for system load, utilization and configuration. Windows NT, Windows 2000 and Windows XP Professional are all equipped with SNMP service so that an SNMP manager can communicate with an SNMP agent running on a wireless 802.11b client. However the rest of Windows operating systems, including Windows CE and a Pocket PC, have to run third party proxy SNMP agents in order to be recognized by an SNMP management application. This thesis describes an implementation of a Pocket PC SNMP agent for two Pocket PC mobile devices accessing a wired network via an 802.11b wireless link. As a result of the implementation performed in this thesis, an SNMP manager can wirelessly communicate with a Pocket PC client. However, other results found that only some of the commercially available SNMP managers are able to access the mobile SNMP client and its management information base, due to incompatible implementations of the server and client software. / Lieutenant, Royal Thai Air Force

by Sze Ho Pong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 50-[53]). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Related Work --- p.3 / Chapter 1.2 --- Contributions of the Thesis --- p.3 / Chapter 1.3 --- Organization of the Thesis --- p.4 / Chapter 2 --- Background --- p.5 / Chapter 2.1 --- Best-effort Internet - The Lossy Network --- p.5 / Chapter 2.2 --- Effects of Packet Loss on Streamed Video --- p.7 / Chapter 2.3 --- Loss Recovery Schemes in Video Streaming --- p.8 / Chapter 3 --- Comparison of Two Packet-Loss Detection Schemes --- p.10 / Chapter 3.1 --- Gap Detection (GD) --- p.12 / Chapter 3.2 --- Time-Out (TO) Detection --- p.14 / Chapter 3.3 --- Mathematical Comparison --- p.17 / Chapter 4 --- The Combined Loss-Detection Algorithm --- p.21 / Chapter 4.1 --- System Architecture --- p.22 / Chapter 4.2 --- Loss Detection and Recovery --- p.23 / Chapter 4.2.1 --- Detecting Data Packet Losses Transmitted for First Time --- p.24 / Chapter 4.2.2 --- Detecting Losses of Retransmitted Packet --- p.28 / Chapter 4.3 --- Buffering Techniques --- p.32 / Chapter 4.3.1 --- Determining Packet-Loss Rate in Presentation --- p.33 / Chapter 4.4 --- Mapping Packet-Loss Rate to Degradation of Video Quality --- p.38 / Chapter 5 --- Experimental Results and Analysis --- p.40 / Chapter 5.1 --- Experimental Setup --- p.40 / Chapter 5.2 --- Small Delay Jitter Environment --- p.42 / Chapter 5.3 --- Large Delay Jitter Environment --- p.44 / Chapter 5.3.1 --- Using Low Bit-Rate Stream --- p.44 / Chapter 5.3.2 --- Using High Bit-Rate Stream --- p.44 / Chapter 6 --- Conclusions and Future Work --- p.47 / Chapter 6.1 --- Conclusions --- p.47 / Chapter 6.2 --- Future Work --- p.49 / Bibliography --- p.50