Nagios is a powerful monitoring system that enables organizations to identify and resolve IT infrastructure problems before they affect critical business processes. http://www.nagios.org/about

Download the latest version of nagios while hot, from http://www.nagios.org/download

$ wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.2.0.tar.gz 
$ cd nagios-3.2.0
$ ./configure
$ make all 
$ useradd nagios
$ make install
$ make install-init
$ make install-commandmode
$ make install-config
$ make install-webconf

Running the following command will create a new file called htpasswd.users in the /usr/local/nagios/etc directory. It will also create an username/password entry for nagiosadmin. You will be asked to provide a password that will be used when nagiosadmin authenticates to the web server.

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

Download and install plugins

$ wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.14.tar.gz
$ tar xfz nagios-plugins-1.4.14.tar.gz
$ cd nagios-plugins-1.4.14
$ ./configure && make && make install 

Edit the configuration files to add host and services to be monitored:

vim /usr/local/nagios/etc/objects/localhost.cfg 

Check remote services http://wiki.nagios.org/index.php/Howtos:checkbyssh_RedHat

http://172.26.0.205:4020/nagios/

with username = "nagiosadmin" and password = "nagios"