I'm having some trouble with my firewall configuration. I have a rule that allows all of my internal networks to communicate over any ports and protocols, which works perfectly fine for ICMP pings between devices. However, when I change the rule to allow only specific destination ports, the pings stop working even though I've confirmed that ICMP is still enabled. Swapping back to allow all ports makes the pings functional again. I'm confused because I thought ports shouldn't impact ICMP traffic. I've also set up both inbound and outbound network security groups to rule out any other issues, but I'm still not getting responses when the ports are restricted. Can anyone shed some light on this?
2 Answers
It's important to note that ICMP doesn't actually use port numbers like TCP/UDP does. So when you change your firewall rule to specify certain ports, those rules may not be applicable to ICMP traffic. I recommend using a tool like Wireshark to see what kind of packets are being sent when you're trying to ping. This can help clarify what's happening under the hood.
You might want to try creating two separate firewall rules: one specifically for ICMP traffic and another for TCP/UDP traffic. This way, you can ensure that ICMP is still allowed regardless of the other port settings.
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