IDS vs IPS - Intrusion Detection and Prevention
About 2 min read
IDS/IPS (Intrusion Detection System / Intrusion Prevention System) are security systems that detect and block unauthorized intrusions into networks and systems. An IDS detects malicious activity and notifies administrators, while an IPS goes a step further and automatically blocks malicious traffic. Combined with a firewall, they are an important component for building defense in depth. As of 2024, cloud-based IDS/IPS are spreading rapidly and are available as managed services on AWS and Azure.
Real-World Use Case
"Through an IPS alert, we detected and blocked an SQL injection attempt from an external IP against our internal web server. We added the attacking IP to the blocklist and reinforced the WAF rules as well."
Comparison of IDS and IPS
| Item | IDS (detection) | IPS (prevention) |
|---|---|---|
| Action | Detect and notify | Detect and block automatically |
| Deployment position | Mirror port (out-of-band) | Inline (in-path) |
| Impact of false positives | Excessive alerts | Blocking of legitimate traffic |
| Deployment difficulty | Low | Requires tuning |
The Difference Between IDS and IPS
IDS and IPS are often confused, but their roles are clearly different. An IDS specializes in "detection and notification": even when it discovers malicious traffic, it does not block it but sends an alert to administrators. An IPS, on the other hand, performs "detection and blocking," automatically blocking malicious traffic in real time. While an IDS is placed outside the network (on a mirror port) to monitor a copy of the traffic, an IPS is placed in the network path (inline) to control traffic directly. Because an IPS carries the risk of blocking legitimate traffic due to false positives, tuning at deployment is important. Many organizations adopt a phased approach, starting monitoring with an IDS and migrating to an IPS once operations stabilize.
Detection Methods
Signature-based detection matches traffic against known attack patterns; it offers high accuracy but cannot handle unknown attacks. Anomaly-based detection identifies deviations from normal traffic patterns and can even detect zero-day attacks, but tends to produce more false positives.intrusion detection books on Amazon offer detailed coverage.
Relevance to Password Security
IDS/IPS are also used to detect brute-force attacks and credential stuffing. By detecting and blocking large volumes of login attempts in a short period, they prevent password guessing attacks. Setting a unique, strong password for each service and combining it with IDS/IPS protection greatly improves account security.security operations books (Amazon) are also helpful references.
Was this article helpful?