Editing Nagios Main Config, and adding new hosts: \\
/usr/local/nagios/etc/nagios.cfg

Editing Nagios Host Configurations: \\
/usr/local/nagios/etc/objects

Checking for Config Errors: \\
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Restarting Nagios: \\
service nagios restart

Nagios Web Pages Root: \\
/usr/local/nagios/share

DOCS: \\
http://www.debianhelp.co.uk/nagiospluins.htm

Object configuration options: \\
[[http://nagios.sourceforge.net/docs/3_0/objectdefinitions.html]]

NRPE Daemon Config: \\
<code>
/usr/local/nagios/etc/nrpe.cfg
</code>

Don't forget to add iptables rule: \\
<code>
/sbin/iptables -A INPUT -p tcp -m tcp --dport 5666 -j ACCEPT
</code>