Yes it can, I used U2F in CLI apps to sign HTTP requests: https://developers.yubico.com/U2F/Libraries/Using_a_library.html https://developers.yubico.com/U2F/Lib

Yes it can, I used U2F in CLI apps to sign HTTP requests: https://developers.yubico.com/U2F/Libraries/Using_a_library.html https://developers.yubico.com/U2F/Libraries/Using_a_library.... There is also pam-u2f: https://developers.yubico.com/pam-u2f/ https://developers.yubico.com/pam-u2f/ and https://github.com/bluecmd/openssh-u2f https://github.com/bluecmd/openssh-u2f (not in upstream)