Nagios is an open-source monitoring tool that helps you monitor your network, servers, and applications. In this tutorial, you'll learn how to install Nagios on Clear Linux Latest.
Before we begin, ensure that:
Nagios requires several packages to be installed on the system. Run the following command to install them:
sudo swupd bundle-add development python3-basic
Nagios requires a web server to serve its web interface. Apache is one such web server that we can use. Run the following command to install Apache on Clear Linux:
sudo swupd bundle-add c-basic apache
First, download the Nagios Core source code from the Nagios website using the following command:
curl -SL https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.6.tar.gz | sudo tar -xzf - -C /opt
This command downloads the Nagios Core source code archive and extracts it to the /opt directory.
Next, navigate to the Nagios Core source directory:
cd /opt/nagioscore-nagios-4.4.6/
Run the following commands to compile and install Nagios Core:
sudo ./configure --with-nagios-group=nagios --with-command-group=nagcmd --with-httpd-conf=/etc/apache2/sites-enabled
sudo make all
sudo make install
sudo make install-init
sudo make install-commandmode
sudo make install-config
These commands will compile Nagios Core and install it on your system.
Nagios runs its processes as a separate user and group, so we need to create them before we start the Nagios service. Run the following commands to create the Nagios user and group:
sudo useradd nagios
sudo groupadd nagcmd
sudo usermod -a -G nagcmd nagios
To configure Apache to serve Nagios, you need to create a virtual host configuration for Nagios. Run the following command to create the configuration file:
sudo tee /etc/apache2/sites-available/nagios.conf <<EOF
<VirtualHost *:80>
ServerName localhost
DocumentRoot /opt/nagios/share
<Directory /opt/nagios/share>
Options FollowSymLinks
AllowOverride None
Require all granted
</Directory>
<Directory /opt/nagios/libexec>
Options ExecCGI
AllowOverride None
Require all granted
</Directory>
ScriptAlias /cgi-bin/nagios /opt/nagios/sbin
<Directory "/opt/nagios/sbin">
Options ExecCGI
AllowOverride None
Order allow,deny
Allow from all
AuthName "Nagios Access"
AuthType Basic
AuthUserFile /usr/local/nagios/etc/htpasswd.users
Require valid-user
</Directory>
ErrorLog /var/log/apache2/nagios_error.log
LogLevel warn
CustomLog /var/log/apache2/nagios_access.log combined
</VirtualHost>
EOF
This command creates a new virtual host that listens on port 80 and serves Nagios from the /opt/nagios/share directory. It also configures Apache to use /opt/nagios/sbin as the CGI directory.
Next, enable the new Nagios virtual host and disable the default virtual host:
sudo a2dissite default
sudo a2ensite nagios
Restart the Apache service for the new configuration to take effect:
sudo systemctl restart apache2
Before we start the Nagios service, we need to configure it. First, copy the sample configuration files:
sudo cp /opt/nagios/etc/nagios.cfg-sample /opt/nagios/etc/nagios.cfg
sudo cp /opt/nagios/etc/cgi.cfg-sample /opt/nagios/etc/cgi.cfg
Now, edit the /opt/nagios/etc/nagios.cfg file and change the cgi.cfg file location. Uncomment the following line:
cfg_file=/opt/nagios/etc/cgi.cfg
Next, create an Apache user and password for Nagios:
sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
This command creates a new file /usr/local/nagios/etc/htpasswd.users and adds a user nagiosadmin with a password.
Now, test the configuration files:
sudo /opt/nagios/bin/nagios -v /opt/nagios/etc/nagios.cfg
This command will validate the configuration files. If there are no errors, you will see the following output:
Total Warnings: 0
Total Errors: 0
Things look okay - No serious problems were detected during the pre-flight check
Finally, start the Nagios service:
sudo systemctl start nagios
You can now access the Nagios web interface by navigating to http://your-ip-address/nagios/ or http://localhost/nagios/ if you're accessing it from the same machine.
In this tutorial, you learned how to install Nagios on Clear Linux Latest. You can use Nagios to monitor your network and servers and get alerts if anything goes wrong.
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