Also called: Host Intrusion Prevention and Network Intrusion Prevention
Intrusion prevention is a defensive approach to network security used to identify potential threats and respond to them swiftly. Like an intrusion detection system, an intrusion prevention software system monitors network traffic. Based on a set of rules established by the network administrator, intrusion prevention systems take immediate action after the the unauthorised person gains access to the network.
More complex monitoring & analysis should also be performed by an effective intrusion prevention solution, such as watching and responding to traffic patterns as well as individual packets. "Intrusion Detection & prevention mechanisms can include address matching, HTTP string and substring matching, generic pattern matching, TCP connection analysis, packet anomaly detection, traffic anomaly detection and TCP/UDP port matching."
Thus, an intrusion prevention system can be said to include any product or practice used to keep attackers from gaining access to a network, such as firewalls and anti-virus software.