I hope you guys could add an option to allow red tie to device name such as usb0, eth2… or etc instead of mac address as mac address no longer unique (mobile usb tethering generate mac randomly every time it connects)
Device names are much less unique than MAC addresses.
The fact, that these identities are faked by some mobile devices doesn’t urge to change the naming scheme.
MAC address is defined as the identifying property for a long time now. There existed all the time the possibilty to change the address ( temporarily! ). What is new with these mobile devices is the fact to hide the identity by default.
What about the (W)LAN part? If I configure DHCP with fixed leases only, empty dynamic list, a device with changing MAC will not get an IP and so no internet access.
I’m suggesting an option to turn on such feature, so if you don’t need such feature you don’t turn it on.
Oh yes, that’s a nice thought. 
Why don’t you realize it with your mobile device? Because the “feature” is turned on by default and the setting is hidden somewhere in the configuration?
IMHO, this feature isn’t necessary, whether in IPFire nor the mobile device.
If I want receive mail, I don’t change my name and address every day.
It is needed else usb tethering can’t be used as RED OR WAN. You can’t turn off the random mac generation feature as there’s no option to turn it off, the one that can be turn off is wifi tethering not usb tethering.
There should be such feature in IPFIRE to adapt to the randomised mac trend.
No, there should not be that a ‘feature’!
If a device hides its identity it should not be used. My opinion.