Graylog helps you can observe any established or rejected network connection, find those that are unusual to tighten rules and mitigate attacker activity. Developed by TORCH GmbH
License: Open Source
Nagios Log Server is focused on log management with powerful alerting and monitoring capabilities, while Graylog offers a more user-friendly interface with advanced search and analysis features. Both tools are suitable for log management, but their strengths lie in different areas.