Can i monitor multiple mysql servers from one agent?

My current setup contains 3 mysql servers. Mysql1, mysql2, mysql3. None of them have access to an internet connection. They are however connected to an internal network. 
My nginx server has a connection to the internal network and the internet. I've already installed an agent on the nginx server and I would like to monitor my mysql servers from there.

When I try to set up the monitor for mysql it asks for a port a username and a password, but I cannot supply a hostname or ip address. I'm guessing the monitor always assumes the mysql server is on localhost.

How do I go about configuring this?

Kind regards
Matthias