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Intrusion Prevention System (IPS)

An Intrusion Prevention System (IPS) is an active defense tool that monitors and blocks malicious activity in real time, stopping attacks before they reach their targets.

What is IPS?How it typically works?Common techniquesImpactFurther reading

What is IPS?

While an IDS alerts analysts about suspicious activity, an IPS goes a step further by actively blocking threats. Positioned inline with network traffic, IPS devices or software can drop packets, reset connections, or quarantine hosts. For SecOps teams, IPS is a critical layer of defense that reduces the workload on analysts by automatically mitigating common threats.

How it typically works?

  1. Traffic inspection: packets are analyzed in real time.
  2. Detection: signatures or anomaly detection identify malicious patterns.
  3. Blocking: malicious traffic is dropped or sessions terminated.
  4. Alerting: incidents are logged for SecOps to review.

Common techniques

  • Signature-based IPS: matches traffic against known exploit patterns.
  • Anomaly-based IPS: blocks traffic that deviates from expected baselines.
  • Policy-based IPS: enforces custom security policies, such as protocol restrictions.
  • Inline IPS: deployed directly in the traffic path for immediate prevention.
  • Host-based IPS: deployed on endpoints to prevent malicious actions locally.
  • Next-Generation IPS (NGIPS): integrates with firewalls and advanced analytics.

Impact

IPS reduces the time between detection and response, preventing exploits from reaching vulnerable systems. It is especially effective against known attacks, worms, and brute-force attempts. However, IPS requires careful tuning to avoid blocking legitimate traffic, which can disrupt operations.

For SecOps, IPS offers automation that enhances security posture, but it must be complemented by IDS and SIEM for full visibility and context.

Further reading

Related topics

Intrusion Detection System (IDS)SIEMThreat Intelligence