Adding hosts to Nagios Core 4.3.4 on Linux

Nagios wants you to buy Nagios XI which makes it easy to add hosts using the web page.  If you want to use the free Nagios Core and want to add a windows host, edit /usr/local/nagios/etc/objects/windows.cfg, copy the first "define host" section and add it below the first define host.  You then need to change the {IP} "address", the host_name and the "alias" to something new.  Save the file and restart Nagios (systemctl restart nagios?)

If you are adding a linux host, the cheap way is to edit /usr/local/nagios/etc/objects/localhost.cfg and repeat the above with the first defined host.

Adding a switch requires you to edit /usr/local/nagios/etc/nagios.cfg and uncomment the switch.cfg line.  Then edit /usr/local/nagios/etc/objects/switch.cfg.