If you previously followed my guide on Nagios 4 Setup then you are probably wondering how to add hosts to your Nagios 4 install.

Well below is how I added some basic hosts to Nagios 4 through the command line so continue reading to see how I did it.

Make a new object definition by typing:

sudo nano /usr/local/nagios/etc/objects/newhost.cfg

Now add the following lines to it:

# Define a host for the local machine

define host{
  use linux-server ; Name of host template to use
  ; This host definition will inherit all variables that are defined
  ; in (or inherited by) the linux-server host template definition.
  host_name google.com
  alias google.com
  address www.google.com
  }

###############################################################################
 ###############################################################################
 #
 # SERVICE DEFINITIONS
 #
 ###############################################################################
 ###############################################################################

# Define a service to "ping" the local machine

define service{
  use generic-service ; Name of service template to use
  host_name google.com
  service_description PING
  check_command check_ping!100.0,20%!500.0,60%
  }

# Define a service to check HTTP on the local machine.
 # Disable notifications for this service by default, as not all users may have HTTP enabled.

define service{
  use generic-service ; Name of service template to use
  host_name google.com
  service_description HTTP
  check_command check_http
  notifications_enabled 0
  }

now edit your main config file to tell it the location of the new config file:

sudo nano /usr/local/nagios/etc/nagios.cfg

add the following line to the file:

cfg_file=/usr/local/nagios/etc/objects/newhost.cfg

Now restart your nagios daemon:

sudo /etc/init.d/nagios restart

Check for errors prior to restarting before continuing with last step

sudo /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

Restart nagios after changing any config files with:

sudo /etc/init.d/nagios restart