I have a standalone application which is running in a box(GCP virtual box). I need to check whether the box is alive or not(running or not). I need a centralised monitoring machine which will run as a daemon and get status of my box every time. If there is no response from the box, Then the centralised machine should send an email notification to the system admin. It should also monitor the network status, network slow or not. So, What best open source monitoring tool helps my requirement.
Any help is appreciated.