OSSEC
OSSEC is an open-source host-based intrusion detection system performing log analysis, integrity checking and rootkit detection.
Legal & ethical use. Use this tool only on systems, networks and data that you own or have explicit written permission to test. Unauthorised access or scanning can break computer-misuse laws (for example Pakistan's Prevention of Electronic Crimes Act, 2016, and equivalents elsewhere). Practise in your own lab or in authorised environments such as CTFs.
What it is used for
- Monitor file changes on a server
- Alert on suspicious log patterns
Key features
- Log analysis
- File integrity monitoring
- Active response
Installation
See the OSSEC documentation for installation.
Beginner usage guide
Install the agent on a test server, modify a monitored file and observe the alert.
Example commands
Run these only against your own lab or authorised targets. Placeholder addresses such as 192.0.2.x are documentation ranges.
Check agent status (typical)
sudo /var/ossec/bin/ossec-control statusPath may differ by installation.
References
Source verification
Last reviewed: 2026-10-27
Links checked over HTTP: 2026-10-27 07:51 UTC — official: 200, docs: 200, repo: 200
Commands were written from the official documentation and have not been executed on this site; test them in your lab.