The phenomenon that rural residents and people with low incomes lag behind in Internet access is known as the "digital divide." This problem is particularly acute in developing countries, where most of the world's population lives. Bridging this digital divide, especially by attempting to increase the accessibility of broadband connectivity, can be challenging. The improvement of wide-area connectivity is constrained by factors such as how quickly we can dig ditches to bury fibers in the ground; and the cost of furnishing "last-mile" wiring can be prohibitively high.In this paper, we explore the use of digital storage media transported by the postal system as a general digital communication mechanism. While some companies have used the postal system to deliver software and movies, none of them has turned the postal system into a truly generic digital communication medium supporting a wide variety of applications. We call such a generic system a Postmanet. Compared to traditional wide-area connectivity options, the Postmanet has several important advantages, including wide global reach, great bandwidth potential and low cost.Manually preparing mobile storage devices for shipment may appear deceptively simple, but with many applications, communicating parties and messages, manual management becomes infeasible, and systems support at several levels becomes necessary. We explore the simultaneous exploitation of the Internet and the Postmanet, so we can combine their latency and bandwidth advantages to enable sophisticated bandwidth-intensive applications.

Today, even a moderately sized corporate intranet contains multiple firewalls and routers, which are all used to enforce various aspects of the global corporate security policy. Configuring these devices to work in unison is difficult, especially if they are made by different vendors. Even testing or reverse engineering an existing configuration (say when a new security administrator takes over) is hard. Firewall configuration files are written in low level formalisms, whose readability is comparable to assembly code, and the global policy is spread over all the firewalls that are involved. To alleviate some of these difficulties, we designed and implemented a novel firewall analysis tool. Our software allows the administrator to easily discover and test the global firewall policy (either a deployed policy or a planned one). Our tool uses a minimal description of the network topology and directly parses the various vendor-specific low level configuration files. It interacts with the user through a query-and-answer session, which is conducted at a much higher level of abstruction. A typical question our tool can answer is "from which machines can our DMZ be reached and with which services?" Thus, the tool complements existing vulnerability analysis tools, as it can be used before a policy is actually deployed it operates on a more understandable level of abstraction, and it deals with all the firewalls at once.