The standard way most people configure Nagios is by simply copying the samples included and modify them with a text editor as needed. Setting up Nagios to monitor even a modest sized network is where most of the work lies. Even though it does take some work, the Nagios configuration files can be "streamlined" using includes and object definitions, this is covered in a separate topic.
I will be covering how to configure Nagios using a text editor. Since we’ll be using FreeBSD, my editor of choice is ee. You can use vi, joe, pico or even Notepad on Windows (via FTP or SCP) if you wish.