How-To Install Nagios on Ubuntu Linux

After many attempts and how-tos, I was finally able to get Nagios installed on (Ubuntu) Linux. My first attempt was downloading an appliance from Jumpbox, then Fedora 10, and finally, Ubuntu. This how-to will be broken out into three parts:

1. Download and install Ubuntu
2. Download, install, and configure Apache
3. Download, install, and configure Nagios

Download and install Ubuntu:

• Download Ubuntu (I used version 8.10 of Ubuntu Desktop)
• In VMWare Server, I booted to the ISO image
• Choose "Install Ubuntu"
• Choose English as the language
• Choose Time Zone
• Keyboard
• Select the Guided (use entire disk) option
• Fill in the user and computer information
• Click Install
• Click Restart
  

Once Ubuntu is installed, you can begin installing the prerequisites.

All commands will be issued with sudo command. If you prefer, you can just su as root and run everything that way.

Download, install and Configure Apache

• sudo apt-get install build-essential :this will install some necessary compilers
• sudo apt-get install libgd2-xpm-dev :Install GD Libraries
• sudo apt-get install apache2 : Install Apache2
• sudo apt-get install php5-common php5 libapache2-mod-php5 :Install PHP for Apache2

Configure Apache to use PHP:

• Run in a terminal: sudo vim /etc/apache2/apache2.con
• Paste the following into the file:
  
  DirectoryIndex index.html index.php index.cgi
  
  
  
• and restart the server with the command
  sudo /etc/init.d/apache2 restart
  
  

At this point, build-essentials, libgd2-xpm-dev and Apache with PHP support should be installed. You can test this by opening a browser and going to http://localhost/ to test Apache.
To test PHP, create a new text file and enter
<?php phpinfo( );?>
Save the file as test.php in your root web directory (should be /var/www). Then go to http://localhost/test.php and this should display the PHP version information in the browser.

If you can view the Apache start page and the PHP version info page, it's time to download and install Nagios.

If you can't view the Apache start page: check that all of the packages are installed and the Apache service is running.

If you can't view the PHP version info page: verify that PHP was installed.

Download, install, and configure Nagios

Change to your home directory:

cd ~/

Download the current version of Nagios: http://sourceforge.net/project/showfiles.php?group_id=26589:

sudo wget http://downloads.sourceforge.net/nagios/nagios-3.1.0.tar.gz?use_mirror=voxel

Download the current version of the Nagios Plugins: http://sourceforge.net/project/showfiles.php?group_id=29880:

sudo wget http://downloads.sourceforge.net/nagiosplug/nagios-plugins-1.4.13.tar.gz?use_mirror=voxel

Extract the Nagios tarball:

sudo tar -zxvf nagios-3.1.0.tar.gz

and change to the nagios-3.1.0 directory

cd nagios-3.1.0

Create a user to run the service and a group to run external commands:

• sudo useradd -m nagios
• sudo passwd nagios
• sudo groupadd nagcmd
• sudo usermod -a -G nagcmd nagios
• sudo usermod -a -G nagcmd www-data

Now install the Nagios tarballs that were downloaded previously:

• sudo ./configure --with-command-group=nagcmd
• sudo make all
• sudo make install
• sudo make install-init
• sudo make install-config
• sudo make install-commandmode
• sudo make install-webconf

Add a user for the Nagios interface:

sudo htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

Add the directives to Apache for Nagios:

In a terminal type:

sudo vim /etc/apache2/apache.conf

Paste the text below into the conf file:

ScriptAlias /nagios/cgi-bin /usr/local/nagios/sbin

<Directory "/usr/local/nagios/sbin">
Options ExecCGI
AllowOverride None
Order allow,deny
Allow from all
AuthType Basic
AuthUserFile /usr/local/nagios/etc/htpasswd.users
Require valid-user
</Directory>

Alias /nagios /usr/local/nagios/share

<Directory "/usr/local/nagios/share">
Options None
AllowOverride None
Order allow,deny
Allow from all
AuthType Basic
AuthUserFile /usr/local/nagios/etc/htpasswd.users
Require valid-user
</Directory>

ServerName localhost



Restart Apache:

sudo /etc/init.d/apache2 restart

Extract and compile the plugins that were downloaded earlier:

• cd ~/
• tar -zxvf nagios-plugins-1.4.13.tar.gz
• cd nagios-plugins-1.4.13
• sudo ./configure --with-nagios-user=nagios --with-nagios-group=nagios
• sudo make
• sudo make install

Create a link to start the service:
sudo ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios
Verify the config:

sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Start Nagios:

sudo /etc/init.d/nagios start

You should now be able to log into the Nagios web interface (http://localhost/nagios) using the nagiosadmin user and password.

This how-to is actually a combination of the Nagios official documentation (Ubuntu Quickstart), Albasit's Nagios/Ubuntu/VMWare how-to, and some of my own work in-between. I appreciate the help I got from all of these documents.