Nagios is one of the most widely used open source monitoring tool for monitoring the services and application that run’s on Windows and Linux. It also has the capability to monitor routers and other network devices.
With the help of Nagios, you can monitor basic services and attributes. We can access the Nagios using web interface coming with the bundle, but the configurations need to be done on the file level.
Services List
Nagios can monitor your “private” services and attributes of Linux/UNIX servers, such as:
Attributes
- CPU load
- Memory usage
- Disk usage
- Logged in users
- Running processes
- etc.
Private Services
- HTTP
- FTP
- SSH
- SMTP
- etc
Install Nagios Server
Prerequisites
Get the Latest version of Nagios (v 4.3.4) from the official page. Before compiling the Nagios from the source, you would need to install dependent packages for Nagios.
Let’s switch to root user.
sudo su -
Update the repository cache and install the dependencies for Nagios.
apt-get update apt-get install build-essential apache2 php openssl perl make php-gd libgd-dev libapache2-mod-php libperl-dev libssl-dev daemon wget apache2-utils unzip
Create nagios user and nagcmd group (allowing the external commands to be executed through the web interface), add the nagios and apache user to the part of the nagcmd group.
useradd nagios groupadd nagcmd usermod -a -G nagcmd nagios usermod -a -G nagcmd www-data cd /tmp wget https://assets.nagios.com/downloads/nagioscore/releases/nagios-4.3.4.tar.gz tar -zxvf nagios-4.3.4.tar.gz cd /tmp/nagios-4.3.4/
Compile and Install Nagios
Perform the below steps to compile the Nagios from the source code.
./configure --with-nagios-group=nagios --with-command-group=nagcmd --with-httpd_conf=/etc/apache2/sites-enabled/ make all make install make install-init make install-config make install-commandmode make install-webconf
Configure Nagios
The installer has now placed configuration files in the /usr/local/nagios/etc directory. These default configuration files should work fine for now to start Nagios. All you need to make just one change before you proceed.
Edit the /usr/local/nagios/etc/objects/contacts.cfg file and change the email address associated with the nagiosadmin contact definition to the address you’d like to use for receiving alerts.
vi /usr/local/nagios/etc/objects/contacts.cfg
Change the email address field to receive the notification.
define contact{
contact_name nagiosadmin ; Short name of user
use generic-contact ; Inherit default values from generic-contact template (defined above)
alias Nagios Admin ; Full name of user
email nagios@itzgeek.com ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
} Configure Web Interface
Create a user account (nagiosadmin) for logging into the Nagios web interface. Remember the password you assign to this account – you’ll need it later.
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
Run the following command.
a2enmod cgi
Restart Apache to make the new settings take effect.
systemctl restart apache2
Download and Install Nagios Plugins
Now, it’s time to download Nagios plugins for monitoring the services. Place it into /tmp directory.
cd /tmp wget https://nagios-plugins.org/download/nagios-plugins-2.2.1.tar.gz tar -zxvf /tmp/nagios-plugins-2.2.1.tar.gz cd /tmp/nagios-plugins-2.2.1/
Compile and install the plugins.
./configure --with-nagios-user=nagios --with-nagios-group=nagios make make install
Starting Nagios
Verify the sample Nagios configuration files.
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Enable Nagios to start automatically at system startup.
systemctl enable nagios
Now, start Nagios service.
systemctl start nagios
Access Nagios Web Interface
Now access the Nagios web interface using the following URL.
You’ll be prompted for the username (nagiosadmin) and password you specified earlier.
Upon successful login, you would get the Nagios’s home page.
You can monitor the services by clicking on Services in the left pane.
By default, Nagios can monitor only the localhost, i.e., Nagios server. If you want to monitor remote machines, then you need to install and configure NRPE plugin.
READ: How To Add Linux Host To Nagios Monitoring Using NRPE Plugin
Interested in Other Server Monitoring Tools
READ: How To Install Zabbix Server 3.2 on CentOS 7 / Ubuntu 16.04 / Debian 8
READ: Install Icinga2 on Ubuntu 16.04 / 14.04, Debian, and Mint
READ: Netdata – Real-Time Performance Monitoring Tool for Linux
That’s All.
