DNS issue with random MAC device

[SecAficionado]

Hello,

I have an issue that I have seen reported by others, but I think I was able to identify opnsense as the culprit, not my device.

I have a small IoT device that, for whatever reason, does not have a hardware MAC address. It generates a random address every time it boots up. I am looking into writing a custom u-boot for it to hard-code an address, but for now it has a new address each time it boots.

As an initial temporary measure, I created a startup script that brings down the interface, assigns a fixed MAC address and brings the interface back up. That is successful in getting the DHCP server to assign the static IP address that I want to use, but as others have reported, the IoT device does not have internet access after that change.

I was able to trace the issue to a logging problem. I am using Unbound DNS and when looking at the logs, I see entries for dhcp reporting a new dynamic IP address for the device as it boots up, but no report for the static assignment when the MAC address changes. It's as if Unbound does not realize there was a change and does not reply to requests from the static IP/MAC.

If the dhcp server is supposed to notify Unbound, then it would appear it is a dhcp server bug or misconfiguration. If Unbound is supposed to notice the change and respond accordingly, then the issue is there.

Any assistance is appreciated.