I am very familiar with cacti and mrtg but nagios seems very professional to me so I installed it in a pc of mine to monitor some windows & linux boxes.
Below is the steps that I followed to install it. Now wants to add some hosts of both windows and linux. How to add those? What files to edit? Any sample file will be great. Also in web I found some are telling to edit the windows.cfg file which was not created in my case.
You'll need to have root access to install Nagios as described in this documentation, as you'll be creating users and group, modifying your web server config files, etc. Either login as root before you begin or use the su command to change to the root user from another account.
Getting the Latest Version
You can download the latest version of Nagios from http://www.nagios.org/download.
Unpacking The Distribution
To unpack the Nagios distribution, use the following command:
tar xzf nagios-2.10.tar.gz
When you have finished executing these commands, you should find a nagios-version directory that has been created in your current directory. Inside that directory you will find all the files that comprise the core Nagios distribution.
Create Nagios User/Group
You're probably going to want to run Nagios under a normal user account, so add a new user (and group) to your system with the following command (this will vary depending on what OS you're running):
Create Installation Directory
Create the base directory where you would like to install Nagios as follows...
Change the owner of the base installtion directory to be the Nagios user and group you added earlier as follows:
chown nagios.nagios /usr/local/nagios
Identify Web Server User
You're probably going to want to issue external commands (like acknowledgements and scheduled downtime) from the web interface. To do so, you need to identify the user your web server runs as (typically apache, although this may differ on your system). This setting is found in your web server configuration file. The following command can be used to quickly determine what user Apache is running as (paths may differ on your system):
grep "^User" /etc/httpd/conf/httpd.conf
Add Command File Group
Next we're going to create a new group whose members include the user your web server is running as and the user Nagios is running as. Let's say we call this new group 'nagcmd' (you can name it differently if you wish). On RedHat Linux you can use the following command to add a new group (other systems may differ):
Next, add the users that your web server and Nagios run as to the newly created group with the following commands (I'll assume apache and nagios are the respective users):
/usr/sbin/usermod -G nagcmd apache
/usr/sbin/usermod -G nagcmd nagios
Run the Configure Script
Run the configure script to initialize variables and create a Makefile as follows...(the last two options: --with-command-xxx are optional, but needed if you want to issue external commands)
./configure --prefix=prefix --with-cgiurl=cgiurl --with-htmurl=htmurl --with-nagios-user=someuser --with-nagios-group=somegroup --with-command-group=cmdgroup