title: SSH 2FA authentification
body: <p>I'm trying to enable 2fA authentification on my lighsail server, running ubuntu 20.04.
  I installed google-authenticator and launched it, configured /etc/pam.d/sshd to add the following line :</p>
  <pre><code>auth required pam_google_authenticator.so
  auth required pam_permit.so 
  </code></pre>
  <p>and then /etc/ssh/sshd_config to set :</p>
  <pre><code>ChallengeResponseAuthentication yes
  </code></pre>
  <p>But then nothing happens. If I add the line :</p>
  <pre><code>AuthenticationMethods publickey,keyboard-interactive
  </code></pre>
  <p>Then the ssh client asks for a password that I don't have (I have a keypair, but no password).
  What can I do to enable 2FA ?</p>