1. Introduction to IDS

• An Intrusion Detection System (IDS) is software or hardware that monitors networks and systems for malicious activities.
• Types of IDS:

1. Network-Based IDS (NIDS)
2. Host-Based IDS (HIDS)
3. Protocol-Based IDS (PIDS)
4. Hybrid IDS

2. Network-Based IDS (NIDS)

• Definition: Monitors network traffic for signs of malicious activity.
• Key Features:
  • Detects attack patterns using signature-based or anomaly-based detection.
  • Monitors all network traffic for threats.
• Pros:
  • Covers multiple devices in a network.
  • Detects external threats before reaching endpoints.
• Cons:
  • Cannot monitor internal (host-based) threats.
  • May miss encrypted traffic attacks.
• Example: Snort (open-source NIDS).
  • Real-time traffic monitoring and protocol analysis.

3. Host-Based IDS (HIDS)

• Definition: Monitors a specific device (host) for malicious behavior.
• Key Features:
  • Detects anomalies in system calls, logs, and applications.
  • Alerts admins of suspicious activity.
• Pros:
  • Identifies attacks that bypass network defenses.
  • Works even when offline.
• Cons:
  • Only protects one host at a time.
  • Consumes system resources.
• Example: OSSEC (open-source HIDS).
  • Features include log analysis, integrity checking, and real-time alerts.

4. Protocol-Based IDS (PIDS)

• Definition: Focuses on monitoring specific network protocols (e.g., HTTP, DNS, FTP) for anomalies.
• Key Features:
  • Detects protocol-specific attacks.
  • Monitors for protocol inconsistencies.
• Pros:
  • Effective against protocol-based vulnerabilities.
  • Provides deep packet inspection.
• Cons:
  • Limited scope (only checks specific protocols).
• Example: ModSecurity (Web Application Firewall with IDS capabilities).
  • Detects SQL injection, XSS, and other web-based attacks.

5. Hybrid IDS

• Definition: Combines NIDS and HIDS for more comprehensive security.
• Key Features:
  • Monitors both network traffic and host activities.
  • Uses both signature and anomaly detection.
• Pros:
  • Covers internal and external threats.
  • Ideal for complex environments.
• Cons:
  • Complex to deploy and manage.
  • Requires high system resources.
• Example: Suricata (open-source hybrid IDS).
  • Provides multi-threaded scalability and real-time alerting.

6. Comparison of IDS Types

7. Conclusion

• IDS plays a crucial role in cybersecurity by detecting and alerting against threats.
• Organizations may combine multiple IDS types for better security coverage.
• Future IDS solutions are integrating AI and automation for enhanced threat detection.