Can anyone tell me why and for what reason the original MAC address of red0 was restored without my intervention?
And is it possible to change it permanently without it being restored automatically?
Or even better, is there a way to rotate the MAC address with random values?
No, I did nothing. I only see a new IP for red, then checked the system log and there were some entries, after I checked the MAC Address, it was automatically restored.
Ipfire uses the Assign MAC-Address WUI page to know that you want an alternative MAC Address.
If you just manually change the ifconfig then when your red IP lease time is up then the network update code will accept the new IP and set the mac address to the physical value unless there is a replacement value defined in the /var/ipfire/mac/settings file.