Network security has now become one of the most important aspects in computer systems and the Internet. Apart from strong encryption, there is no definite method of truly securing network, thus they must be protected at different levels of the OSI model. At the physical layer they can be protected by lock-and-key, and at the data link they can be protected within VLANS (Virtual LANs). With the network and transport layers, networks can be secured by firewalls, which monitor source and destination network addresses, and source and destination ports, respectively. At the session level user names and passwords can be used. Unfortunately all these methods can be prone to methods which can overcome the protection used. This can be overcome by software which tries to detect the malicious moves of users, and try to inform the system administrators when this happen. Unfortunately there are too many factors involved in these systems. An important one is the human operator itself. Many security...
J. Pikoulas, William J. Buchanan, Mike Mannion, K.