Intrusion prevention is a pre-emptive approach to network security used to identify potential threats and respond to them swiftly and it examines network traffic flows to detect and prevent vulnerability exploits. Legitimate traffic should be forwarded to the recipient with no apparent disruption or delay of service. Intrusion Prevention System protects against network and application-level attacks, securing organizations against intrusion attempts, expliots, Reconnaissance, DoS and DDoS attacks, malicious code transmission, backdoor activity and blended threats Now Intrusion Prevention Systems (IDS/IPS) have evolved into the Next Generation Intrusion Prevention Systems with some new aspects like Network Awareness, Application Awareness, Identity Awareness, Behaviour Awareness , Real Time Automated Response, Automatic IPS Tuning