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 the performance of network model partially or completely. Our proposed method generates a less false positive rate that increase the detection efficiency by reducing the workload and that increase the overall performance of an IDS. The proposed Network Intrusion Detection System is capable of addressing many real issues in network security. To minimize the error rates Finite State Machine model is proposed for the IDS. An efficient user friendly application can be developed based on the proposed system and containing models as per user need.