An Intrusion Prevention System (IPS) extends IDS capabilities by actively blocking detected threats rather than just alerting. Positioned inline with network traffic, IPS can drop malicious packets, terminate connections, or block source addresses in real time. This provides automated response but introduces risk of blocking legitimate traffic.
IPS uses the same detection methods as IDS—signatures, anomaly detection, and behavior analysis. The key difference is the ability to take action. Careful tuning is essential to minimize false positives that could disrupt business operations.
CISSP Relevance
Domain 4 (Communication and Network Security) covers IPS as an evolution of IDS. Understand the tradeoffs between detection-only and prevention modes, inline versus passive deployment, and how IPS integrates with firewalls in next-generation solutions. Know the risks of automated blocking in production environments.
Guidance on IPS deployment is in NIST SP 800-94.
Related terms: Intrusion Detection System, Firewall