Abstract: An intrusion detection system (IDS) is capable of identifying the source of traffic, filtering the traffic to classify it as either safe or suspect and then applying sophisticated detection techniques such as stateful pattern recognition, protocol parsing, heuristic detection or anomaly detection either singularly or in combination based on the traffic type. In a network environment, each traffic source is provided with at least one IDS sensor that is dedicated to monitoring a specific type of traffic such as RPC, HTTP, SMTP, DNS, or others. Traffic from each traffic source is filtered to remove known safe traffic to improve efficiency and increase accuracy by keeping each IDS sensor focused on a specific traffic type.