Nagios Installation

Nagios is a host and service monitor designed to inform you of network problems before your clients, end-users or managers do. It has been designed to run under the Linux operating system, but works fine under most *NIX variants as well. The monitoring daemon runs intermittent checks on hosts and services you specify using external "plugins" which return status information to Nagios. When problems are encountered, the daemon can send notifications out to administrative contacts in a variety of different ways (email, instant message, SMS, etc.). Current status information, historical logs, and reports can all be accessed via a web browser.

You can use apt-get to install these packages by running the following commands:

sudo apt-get install apache2
sudo apt-get install build-essential
sudo apt-get install libgd2-dev


Become the root user.

sudo -s

Create a new nagios user account and give it a password.

/usr/sbin/useradd nagios
passwd nagios

On Ubuntu server edition (6.01 and possible newer versions), you will need to also add a nagios group (it's not created by default). You should be able to skip this step on desktop editions of Ubuntu.

/usr/sbin/groupadd nagios
/usr/sbin/usermod -G nagios nagios

Create a new nagcmd group for allowing external commands to be submitted through the web interface. Add both the nagios user and the apache user to the group.

/usr/sbin/groupadd nagcmd
/usr/sbin/usermod -G nagcmd nagios
/usr/sbin/usermod -G nagcmd www-data


Create a directory for storing the downloads.

mkdir ~/downloads
cd ~/downloads

Download the source code tarballs of both Nagios and the Nagios plugins (visit http://www.nagios.org/download/ for links to the latest versions). At the time of writing, the latest versions of Nagios and the Nagios plugins were 3.0b3 and 1.4.7, respectively.

wget http://osdn.dl.sourceforge.net/sourceforge/nagios/nagios-3.0b3.tar.gz
wget http://osdn.dl.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.7.tar.gz


Extract the Nagios source code tarball.

cd ~/downloads
tar xzf nagios-3.0b3.tar.gz
cd nagios-3.0b3

Run the Nagios configure script, passing the name of the group you created earlier like so:

./configure --with-command-group=nagcmd

Compile the Nagios source code.

make all

Install binaries, init script, sample config files and set permissions on the external command directory.

make install
make install-init
make install-config
make install-commandmode


Sample configuration files have now been installed in the /usr/local/nagios/etc directory. These sample files should work fine for getting started with Nagios. You'll need to make just one change before you proceed...

Edit the /usr/local/nagios/etc/objects/contacts.cfg config file with your favorite editor 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


Install the Nagios web config file in the Apache conf.d directory.

make install-webconf

Create a nagiosadmin account 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

Restart Apache to make the new settings take effect.

/etc/init.d/apache2 reload



Extract the Nagios plugins source code tarball.

cd ~/downloads
tar xzf nagios-plugins-1.4.7.tar.gz
cd nagios-plugins-1.4.7

Compile and install the plugins.

./configure --with-nagios-user=nagios --with-nagios-group=nagios
make
make install



Configure Nagios to automatically start when the system boots.

ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios

Verify the sample Nagios configuration files.

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

If there are no errors, start Nagios.

/etc/init.d/nagios start



You should now be able to access the Nagios web interface at the URL below. You'll be prompted for the username (nagiosadmin) and password you specified earlier.

The main page link is: http://localhost/nagios