Make sure its above your DENY Inbound Connections policy!
If you dont have one I highly recommend it only if you are not hosting any internal applications required by outside users (ie websites, email, etc).
Make sure you have a Interface Management Policy
If you already have one for external Management its still protected by your security policies (if not create one!).
The security policy for this should only allow ping and icmp is by application.
Make sure you have one for management access with a source IP selected of a static trusted IP address (another office, data center, etc.) for SSL (HTTPS) and SSH applications.
Network -> Interface -> Management
Allow only Ping
If you allow others, its okay as long as you have it protected by source IP!
You dont need to put IP’s in here, your security policy is doing that protection for you.
Setup your Ping monitor on your dashboard dashboard.uptimerobot.com