In the age of information and communication technology, network models centralized or distributed systems are the good way to connect the user with a single platform.However,when such model and systems are implemented, different types of threat from system surrounding and from the boundary of a system are faced.Therefore we need to introduce new methods and techniques to avoid the threat faced by the systems.In this book we proposed new multi-tier techniques including soft computing, stochastic, hardware implementation and statistical approaches to avoid and minimize the attacks which affect...