Summary of Intrusion Prevention Systems (IPS)
2025, March 7
1. What is an IPS?
- An Intrusion Prevention System (IPS) is a proactive network security solution.
- It detects and prevents intrusions in real-time by blocking or mitigating malicious activity.
- Difference from IDS:
- IDS only detects and alerts.
- IPS both detects and acts (e.g., blocks or isolates).
2. How IPS Works
- Traffic Monitoring: Inspects all incoming/outgoing traffic.
- Signature Matching: Compares traffic to known attack patterns.
- Anomaly Detection: Flags deviations from normal behavior.
- Response Actions: Blocks or mitigates threats immediately.
3. Types of IPS
- Network-Based IPS (NIPS): Secures entire network segments.
- Host-Based IPS (HIPS): Protects individual systems.
- Wireless IPS (WIPS): Detects threats in wireless networks.
- Application Layer IPS (AL-IPS): Protects applications (e.g., SQLi, XSS).
4. Limitations of IPS
- Performance Impact: May cause latency due to deep inspection.
- False Positives: Legitimate traffic may get blocked.
- Bypassing: Encrypted or polymorphic attacks may evade detection.
- Complexity: Requires constant updates and tuning.
5. Detection Methods
| Method | Pros | Cons |
|---|---|---|
| Signature-Based | Fast detection of known threats | Fails against unknown threats |
| Anomaly-Based | Detects new attacks | Higher false positives |
| Stateful Protocol | Detects protocol-specific anomalies | Configuration is complex |
6. IPS Response Actions
- Block: Stops malicious traffic immediately.
- Alert: Notifies admins while allowing traffic.
- Redirect: Sends traffic to decoys or honeypots.
- Quarantine: Isolates the compromised system or segment.
7. IPS Architecture
- Sensors: Gather data from network.
- Analysis Engine: Detects threats from data.
- Response System: Executes mitigation (block/quarantine).
- Management & Reporting: Handles configurations and generates reports.
8. Deployment Strategies
| Type | Pros | Cons |
|---|---|---|
| Inline | Real-time blocking | May affect performance |
| Out-of-Band | Minimal performance impact | Cannot block traffic in real-time |
9. IPS Integration
- With Firewalls: Catches threats missed by firewalls.
- With SIEM: For centralized analysis and correlation.
- With Endpoint Protection: For layered defense.
10. Real-World Example
- IPS blocked a DDoS attack by filtering out malicious IP traffic in real-time, protecting core systems.
11. Challenges in IPS Deployment
- Cost: High initial investment.
- Resources: Needs powerful infrastructure.
- Evasion: Attackers may use advanced techniques like encryption or fragmentation.