The terminal ‘ping’ command is often used to see whether or not a server at a given IP address is running and responsive. This is accomplished by sending data packets using the IP/ICMP protocol between your computer and the destination server (which then mirrors them back again).
Most clouds, however, block inbound ICMP packets as a security measure. If you would like to be able to ping your VMs, you need to edit the VM’s external firewall to allow receiving of ICMP type 8 packets.
What follows is an example of how to do so on Microsoft Azure, though the process will look very similar regardless of what cloud you are using:
- Click the name of the VM you want to allow ICMP traffic to:
- Click the ‘Networking’ item on the left menu:
- Click the blue ‘Add inbound port rule’ button:
- In the pane that slides in on the right, select ‘ICMP’ from protocol and click ‘Add’ to allow all ICMP traffic:
- Replace the “*” in both the ‘Source port ranges’ and ‘Destination port ranges’ fields with the value 8. You can also skip this step, to allow all ICMP traffic to reach your VM.