Random MAC address on an fake ASIX USB ethernet device

22 June 2017 by Lincoln Ramsay

I have 2 USB ethernet adapters at work. They are cheap chinese things. I’m pretty sure they are the same thing this guy examined in detail.

They had been working just fine for quite some time but today, one of them broke. I don’t know what happened, but I suspect there must be some NAND used to store configuration that has gone bad. The primary symptoms I can see are that some of the USB things are different (eg. serial number is now 1 instead of 2) and most annoyingly, the MAC address cannot be read.

The main problem this causes that on every insert, the device is given a random MAC address so I can’t associate permanent network settings with it anymore. But since it does show up slightly differently to the working adapter, I can fix it with a udev rule.

Before it broke, it came up with MAC address 00:90:9A:9A:A9:39 and (through a udev rule) was assigned the name eth4. That udev rule no longer works so I had to make this rule to set both things in one go.

# This fake ASIX USB ethernet device is broken and forgets its MAC address
ATTRS{idProduct}==”772a”, ATTRS{idVendor}==”0b95″, ATTRS{serial}==”000001″, NAME=”eth4″, RUN+=”/usr/bin/macchanger -m 00:90:9A:9A:A9:39 %k”