Comment 0 for bug 1574483

Originally from https://bugs.debian.org/812575: Our current /lib/systemd/network/90-mac-for-usb.link assigns MAC-based names to all USB devices. However, this is wrong and pointless for locally administered MAC addresses (with the second bit set to '1', see https://en.wikipedia.org/wiki/MAC_address#Address_details).

The old 75-persistent-net generator had this rule:

   ENV{MATCHADDR}=="?[2367abef]:*", ENV{MATCHADDR}=""

which ignored these devices. We need to adjust 90-mac-for-usb.link to do the same, and only apply to universally administered MAC addresses (at least until https://lists.ubuntu.com/archives/ubuntu-devel/2016-April/039302.html gets concluded).

We should simply fall through the default policy of assigning location based names. The kernel assigned ones have no meaning whatsoever, so this at least provides name stability for use cases where you can rely on plugging the device into the same port.