Internet Control Message Protocol (ICMP) is a network layer protocol used to diagnose problems between devices within a network.

ICMP determines whether data is received at its destination and how long it took to transmit the data. It is the default protocol the ping network diagnostic tool uses.

ICMP sends return messages with a success or failure indicator to determine whether data was received at another IP address. The message usually consists of a type, a code, a checksum, and any error information.

The content of the message contains a copy of the IPv4 header and the first eight bytes of data for an IPv4 packet. The first eight bytes of the data for an IPv4 packet is the area that causes the message.

If you want your resources to be able to receive ping requests, you need to specify the protocol in any of your custom inbound firewall rules. However, ICMP has no port abstraction, to allow ICMP traffic, so you will need to select it directly from the New rule dropdown.

To learn more about configuring rules, see How to Configure Firewall Rules.