It is now possible to retrieve mac addresses under BSD operating systems. (merged into master branch, not yet released)
As far as I know, at least FreeBSD, NetBSD and OpenBSD don’t implement the SIOCGIFHWADDR ioctl, so a getifaddrs() fallback was needed.
Before, only mac_unknown hard class was reported:
# cf-promises -v|hcgrep mac
mac_unknown
Now:
# cf-promises -v|hcgrep mac
mac_08_00_d5_84_88_00
Of course, sys.hardware_addresses and [sys.hardware_macinterface_name] variables are populated.