How to monitor Systems Up or Down with ping disabled on them?

Hello,
For security reasons, ping is disabled across servers in organization, Now in order to monitor system status (up/down) hence Heartbeat or Uptime are ruled out (as both work on ping mechanism) .
Currently a basic OS level monitoring of a process (systemd) being monitored i.e. if that process on these servers is running then server is up else down.
Now considering this scenario, I am seeking an advice on , If any one came across and implemented a workaround OR any expert advice would be of a real help .
Thanks in advance, looking for response and if any clarification please let me know .