Introduction

Every organization, using networked computers and deploying an information system to perform its activity, faces the threat of hacking from individuals within the organization and from its outside. Employees (and former employees) with malicious intent can represent a threat to the organization's information system, its production system, and its communication networks. At the same time, reported attacks start to illustrate how pervasive the threats from outside hackers have become. Without proper and efficient protection, any part of any network can be prone to attacks or unauthorized activity. Routers, switches, and hosts can all be violated by professional hackers, company's competitors, or even internal employees. In fact, according to various studies, more than half of all network attacks are committed internally.

One may consider that the most reliable solution to ensure the protection of organizations' information systems is to refrain from connecting them to communication networks and keep them in secured locations. Such a solution could be an appropriate measure for highly sensitive systems.