hi, i’m new to icinga2 and wanted to ask your help to monitor client co-computers through icinga2 web, i’m currently using icinga 2 v2.12.4 and need to configure icinga 2 to notify icinga2 web every time computers are disconnected from the network, I also need to know how long the PCs were connected to the network and how long they were disconnected from the network. I hope you can help me with this configuration.
Hi, and welcome to icinga2.
We generally expect people asking questions here to have read the
documentation about how to set up Icinga2, and to have tried to follow that on
their own systems, and then to ask here about specific aspects they get stuck
with.
In your case it seems that you are really only interested in the Host Checks,
rather than Service Checks, so this would be a pretty simple setup.
Please start with:
Installation - Icinga 2 and
Monitoring Basics - Icinga 2
See how you get on and let us know what specific problems you run into.
When asking further questions please try to give as much information as
possible to help us understand what your system is like - otherwise we do not
know - for example which Operating System are you on, how did you install
icinga 2, if you get an error message, exactly what does it say, etc.
Good luck and thanks for choosing Icinga2 
Antony.