Nagios is a powerful open-source monitoring system designed to oversee networks, servers, applications, and services. It provides comprehensive monitoring, alerting, and reporting capabilities, enabling administrators to detect and resolve issues proactively before they impact critical systems or users.

Features of Nagios:

• Monitors network devices, servers, and applications for availability and performance.
• Customizable alerting system to notify administrators of potential issues.
• Extensive plugin ecosystem for monitoring various protocols, services, and metrics.
• Scalable architecture for large and complex environments.
• Supports historical data tracking for performance analysis and capacity planning.
• Web-based interface for centralized management and reporting.

Credentials for accessing the Nagios admin panel are typically stored securely in configuration files within the installation directory.

    
To set the admin password for Nagios, run the following command on your VM:
    # sudo su
    # htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
  

To access the Nagios web interface, navigate to http://your-server-ip/nagios.

Disclaimer: Nagios is available in both open-source and enterprise editions. Users are responsible for understanding the licensing terms and selecting the version that meets their requirements. Nagios is provided "as is," without any warranty, express or implied.