pam_yubico yes. You can also use this to secure SSHD on servers by delegating to PAM with keyboard-interactive. I'm waiting for U2F OpenSSH support to trickle

pam_yubico yes. You can also use this to secure SSHD on servers by delegating to PAM with keyboard-interactive. I'm waiting for U2F OpenSSH support to trickle down to stable distros but in the meantime pam_yubico is pretty damn good... not to mention you don't have to worry about terminal support since it relies on the yubikey OTP emulating a keyboard.