Step by step Install & configure Nagios

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.


Nagios has a lot of features, making it a very powerful monitoring tool. Some of the major features are listed below:

Monitoring of network services (SMTP, POP3, HTTP, NNTP, PING, etc.)

Monitoring of host resources (processor load, disk and memory usage, running processes, log files, etc.)

Monitoring of environmental factors such as temperature

Simple plugin design that allows users to easily develop their own host and service checks

yum install httpd
yum install gcc

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

/usr/sbin/useradd nagios
passwd nagios

/usr/sbin/groupadd nagcmd

/usr/sbin/usermod -G nagcmd nagios
/usr/sbin/usermod -G nagcmd apache

Create a directory for storing the downloads.

mkdir ~/downloads
cd ~/downloads

wget http://osdn.dl.sourceforge.net/sourceforge/nagios/nagios-3.0.tar.gz

wget http://osdn.dl.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4...

cd ~/downloads

tar xzf nagios-3.0.tar.gz
cd nagios-3.0

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

Don't start Nagios yet - there's still more that needs to be done...

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.

service httpd restart

cd ~/downloads

tar xzf nagios-plugins-1.4.11.tar.gz
cd nagios-plugins-1.4.11

Compile and install the plugins.

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

chkconfig --add nagios

chkconfig nagios on

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.

service nagios start