Nitrokey FIDO U2F With Linux Two-Factor Authentication (2FA) Troubleshooting The Nitrokey FIDO U2F supports two-factor authentication (2FA) . With two-factor authentication (2FA), the Nitrokey FIDO U2F is checked in addition to the password. The Nitrokey FIDO U2F can be used with any current browser. Two-Factor Authentication (2FA) Open one of the websites that support FIDO U2F. Log in to the website and enable two-factor authentication in your account settings. (In most cases you will find a link to the documentation of the supported web service at dongleauth.com.) Register your Nitrokey FIDO U2F in the account settings by touching the button to activate the Nitrokey FIDO U2F. After you have successfully configured the device, you must activate the Nitrokey FIDO U2F this way each time you log in. You are now ready to go. Important: The Nitrokey App can not be used for the Nitrokey FIDO U2F. Troubleshooting If the Nitrokey is not accepted immediately, you may need to copy this file 41-nitrokey.rules to etc/udev/rules.d/. In very rare cases, the system will need the older version of this file. After copying the file, restart udev via sudo service udev restart.