Global network | EPFL Graph Search

A global network is any communication network which spans the entire Earth. The term, as used in this article refers in a more restricted way to bidirectional communication networks, and to technology-based networks. Early networks such as international mail and unidirectional communication networks, such as radio and television, are described elsewhere. The first global network was established using electrical telegraphy and global span was achieved in 1899. The telephony network was the second to achieve global status, in the 1950s. More recently, interconnected IP networks (principally the Internet, with estimated 2.5 billion users worldwide in 2014 ), and the GSM mobile communication network (with over 6 billion worldwide users in 2014) form the largest global networks of all. Setting up global networks requires immensely costly and lengthy efforts lasting for decades. Elaborate interconnections, switching and routing devices, laying out physical carriers of information, such as land and submarine cables and earth stations must be set in operation. In addition, international communication protocols, legislation and agreements are involved. Global networks might also refer to networks of individuals (such as scientists), communities (such as cities) and organizations (such as civil organizations) worldwide which, for instance, might have formed for the management, mitigation and resolval of global issues. Communication satellites are an important part of global networks. However, there are specific low Earth orbit (LEO) global satellite constellations, such as Iridium, Globalstar and Orbcomm, which are comprised by dozens of similar satellites which are put in orbit at regularly spaced positions and form a mesh network, sometimes sending and receiving information directly among themselves. Using VSAT technology, satellite internet access has become possible. It is estimated that 80% of the global mobile market uses the GSM standard, present in more than 212 countries and territories.

AntispamLab - A Tool for Realistic Evaluation of Email Spam Filters

Jean-Yves Le Boudec, Slavisa Sarafijanovic, Raphaël Naefen, Luis Hernández

The existing tools for testing spam filters evaluate a filter instance by simply feeding it with a stream of emails, possibly also providing a feedback to the filter about the correctness of the detection. In such a scenario the evaluated filter is disconnected from the network of email servers, filters, and users, which makes the approach inappropriate for testing many of the filters that exploit some of the information about spam bulkiness, users' actions and social relations among the users. Corresponding evaluation results might be wrong, because the information that is normally used by the filter is missing, incomplete or inappropriate. In this paper we present a tool for testing spam filters in a very realistic scenario. Our tool consists of a set of Python scripts for unix/linux environment. The tool takes as inputs the filter to be tested and an affordable set of interconnected machines (e.g., PlanetLab machines, or locally created virtual machines). When started from a central place, the tool uses the provided machines to build a network of real email servers, installs instances of the filter, deploys and runs simulated email users and spammers, and computes the detection results statistic. Email servers are implemented using Postfix, a standard linux email server. Only per-email-server filters are currently supported, whereas per-email-client filters testing would require additional tool development. The size of the created emailing network is constrained only by the number of available PlanetLab or virtual machines. The run time is much shorter then the simulated system time, due to a time scaling mechanism. Testing a new filter is as simple as installing one copy of it in a real emailing network, which unifies the jobs of a new filter development, testing and prototyping. As a usage example, we test the SpamAssassin filter.

2007

AntispamLab - A Tool for Realistic Evaluation of Email Spam Filters

Jean-Yves Le Boudec, Slavisa Sarafijanovic, Raphaël Naefen, Luis Hernández

2007