Two-factor authentication has been added to OpenSSH
This new feature is currently in an 'experimental' status. It allows the use of very inexpensive hardware keys connected via USB, Bluetooth, and NFC for authentication. For example, the YubiKey Security Key or Thetis FIDO U2F Security Key with Bluetooth costs about 100 euros. Instructions for enabling this authentication can be found in the link. Source: linux.org.ru
