"Permissions tweaks for Linux"

The very last section of the README in the U2F Support Extensions repo is entitled "Permissions tweaks for Linux" and contains a link to a list of uDev rules supplied by Yubico that need to be added for Firefox to be allowed to access Yubikeys on unix systems.

The Where & How

The udev rules required can be copied from the Yubico/libu2f-host repo into /lib/udev/rules.d/70-u2f.rules on your local system. Once copied there the new rules can be reloaded using the following command, which needs to be run as root:

udevadm control --reload-rules && udevadm trigger

Now once Firefox is restarted it should be able to talk to a Yubikey and pass the U2F support checker?