Both IDS and IPS are designed to identify malicious activity in a network, but the key difference lies in what they do after detection.

IDS = DETECT & ALERT

IPS = DETECT & ACT

What is an IDS(Intrusion Detection System)?

Theoretical Understanding:

An IDS is a passive monitoring system that analyzes network traffic and system activities to identify suspicious behaviour.

It does NOT block traffic — it only:

  • Monitors
  • Detects
  • Alerts

Types:

  • Network-based IDS (NIDS) → monitor network traffic.
  • Host-based IDS(HIDS) → monitors a specific system.

What is an IPS(Intrusion Prevention System)?

Theoretical Understanding:

An IPS is an active security control system placed inline within the network.

It not only detects threats but also:

  • Blocks malicious traffic
  • Drops packets
  • Terminates connections

How it works:

  • Sits between source and destination
  • Inspects traffic in real-time
  • Takes immediate action

Deeper Insight

  • IDS is like a security camera → it watches and reports
  • IPS is like a security guard → it stops intruders

🔎 Key Differences

ROLE

  • IDS → Detection
  • IPS → Prevention

Placement

  • IDS → Out-of-band
  • IPS → Inline

Action

  • IDS → Alerts only
  • IPS → Block threats

Risk

  • IDS → No disruption
  • IPS → May block legitimate traffic(false positives)