Writing a chapter on network security is something like writing a brief introduction to flying a commercial airliner. Dissimilar, data communications of the past, today's networks incorporate varied devices that handle the data because it passes from the sender to the receiver. The first question to address is what we mean “network security”. Network security consists of the provisions and policies adopted by a network administrator to prevent and monitor unauthorized access, misuse, modification, or denial of a computer network and network-accessible resources. A generic definition of security is “freedom from risk or danger and safety”. However it is not only human errors that can cause problem to network security, problems can also be caused by natural forces like fire breakouts, earthquakes, floods lightning etc. The ways network administrators think about securing networks has been changed by an increasingly dynamic and technically challenging risk environment. Security is an assessment of risk. Secure environments are designed and developed through an intentional effort.
Evaluation of computer network security using attack undirected geography