Installed BM in HP server with two NIC.
Public Interface bind with 9 public IP's, mapped with private IP's.
All clients connect to private IP's.

Question:
I create a rule so users from outside can ping one of my server that mapped
with private IP.
Ex:
202.xxx.xxx.xxx <-> 172.16.1.12

But sometime it can ping, and sometime it can't. What is the problem?

What is the rules should look like?

Thanks