M.Comm. / The problem of establishing and controlling remote access to corporate networks has become one of the most difficult issues facing network administrators and information security professionals (Tipton & Krause (b), 2001:99). As the connection devices become more powerful and less expensive, more and more personally owned devices make their way to the connected edge of the network. The rise of the Internet as an accepted vehicle for business use has dramatically increased the points of entry to the corporate network. As employees and third parties gain mobility through the use of laptops, smart phones and Personal Digital Assistants (PDAs), the threat to organisational security grows (Cartwright, 2001). There are three main reasons why remote access connections are often insecure: Lack of awareness regarding security risks associated with remote access; Protecting a remote access connection is a complex task which is unlikely to be done well unless a methodical approach is taken; and Remote locations are not under the direct control of the organisation and are inherently insecure (Information Security Forum (a), 1999). The purpose of this short dissertation is to: Provide an overview of remote access, including concepts and definitions; Identify the risks associated with remote access to corporate networks; Identify possible controls to mitigate these risks; and highlight possible future trends regarding remote access.

Delay tolerant networks (DTNs) are a class of emerging networks that exhibit significantly different characteristics from today's Internet, such as intermittent connectivity, large delay, and high loss rates. DTNs have important applications in disaster relief, military, rural Internet access, environmental sensing and surveillance, interplanetary communication, underwater sensing, and vehicular communication. While not the common case for networking, DTNs represent some of the most critical cases, where the ability to communicate can make a huge difference for human lives. Supporting effective communication in DTNs, however, is challenging. First, with intermittent connectivity, DTNs are often extremely limited in capacity. Second, given resource limitations and uncertainty in DTNs, it is critical to deliver data efficiently and robustly. The situation is especially acute for multicast which sends data to multiple destinations. This thesis seeks to address these two issues. To enhance network capacity in DTNs, we propose a message ferrying scheme that exploits the use of special mobile nodes (called message ferries) and controlled device mobility to deliver data. Message ferries are utilized to transport data via mobility between sources and destinations. We develop a foundation for the control of the mobility of message ferries, and nodes if possible, to cooperatively deliver data under a variety of conditions. We also study another approach which deploys new nodes called throwboxes to enhance capacity. Throwboxes are small and inexpensive wireless devices. By relaying data between mobile nodes, throwboxes are able to create data transfer opportunities that otherwise would not exist. We systematically investigate the issues of deployment and routing, and develop algorithms for various deployment and routing approaches. Based on extensive evaluation, we obtain several findings to guide the design and operation of throwbox-augmented DTNs. To address the issue of efficient and robust data delivery, we focus on DTN multicasting. Given the unique characteristics of DTNs, traditional solutions such as IP multicast can not be simply ported to DTNs. We identify the limitations of IP multicast semantics in DTNs and define new semantic models for DTN multicast. Based on these semantic models, we develop and evaluate several multicast routing algorithms with different routing strategies.