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RHEL9.x compatible Linux : Nagios Server

Nagios is an open source monitoring solution running on Linux.

Nagios is designed to periodically check critical network, application, or server parameters.
These parameters include microprocessor load, number of running processes, log files, disk and memory usage, as well as many other services such as SMTP (Simple Mail Transfer Protocol), HTTP (Hypertext Transfer Protocol), POP3 (Post Office Protocol 3), etc. can be checked.

These parameters require a microprocessor load, a database such as PHP or MySQL to run Nagois, and a web server such as Apache or Nginx. We will proceed under the assumption that all of these have already been configured.

SELinux must be set to permissive

1. Install necessary packages

Start and enable Apache and PHP-FPM

2. Installing Nagios Core

To download the latest Nagios Core source code, go to the Nagios download page and check for the latest release version (as of 2022.11.3).


It appears as follows


It appears as follows

Install Nagios Core

Install Nagios init script

Install external command files and permissions

Install Nagios Configuration Files

Install Apache configuration files for Nagios

③Create Nagios Users and Groups

Add Apache User to Nagios Group

3. Install Nagios Plugin

①Download the latest code from the Nagios Plugins page


③Create necessary directories

4. Creating a Nagios Web User

Create a user account to access the Nagios Web Dashboard. This user account is used for authentication.
The default name of the user is nagiosadmin, which is defined as the preferred user name in the /usr/local/nagios/etc/cgi.cfg file.

Set ownership and permissions

Restart Apache

Allow HTTP service port in firewall

Start and Enable Nagios Services

Reboot system

Confirmation of service execution

5. Access the Nagios Web Interface

Access http://[IP_Address]/nagios/ with any browser
Username : nagoisadmin
Password : Password specified when the user was created above
Click [Sign in]

After successful login, the following dashboard will appear

Show host availability
Click on [Hosts] in the left menu

Click [Tactical Overview] on the left menu to view the monitoring data

6. Nagios Agent Configuration

To monitor the agent. Install the following
• Nagios plugins for data collection
• NRPE Agent to run plugins

6.1 Installing Nagios plugins
Install using the EPEL repository

Available Nagios Plugins

The following nagios-plugins are available

Install the important Nagios plugin.(Install check the processes, disk space, swap space, dns, users, uptime, httpand load, for example)

After installation, the package is stored in the path /usr/lib64/nagios/plugins/.

6.2 Installing Nagios NRPE Agent
Install from the EPEL repository

Version Check

Start and activate the service

Check if the service is running

Allow services to pass through the firewall

Monitoring of added hosts can now be performed from the Nagios Web UI. It will take some time before the host is available.

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