How to change MAC address on RPI-B?

[John W. Kitz]

diffusae (if that's your name),

I'm not contradicting the possibility that the sys/dev/usb/net/if_smsc.c
driver needs a patch to set the mac address runtime, as you quoted a Hans
Petter in one of the emails in this thread. But in general if I were you I
would have a good look at the relevant documentation at
"https://www.freebsd.org/cgi/man.cgi?query=ifconfig&apropos=0&sektion=0&manp
ath=FreeBSD+11.0-stable&arch=default&format=html" and compare that to:

ifconfig ue0 down delete
ifconfig ue0 promisc
ifconfig ue0 ether 00:FF:CC:00:11:11

as you state you've tried and came to conclude that it doesn't do what you
intend or expect it to.

Success and regards, Jk.