title: Why is it needed to set `pam_loginuid` to its `optional` value with docker?
body: <p>In order to run ssh daemon service, <code>pam_loginuid</code> entry has to be set to optional in /etc/pam.d/sshd as described in the <a href="https://docs.docker.com/engine/examples/running_ssh_service/" rel="nofollow noreferrer">official example</a> for Ubuntu 13.10. </p>
  
  <p>Was this entry optional for previous versions of Ubuntu? Did it even exist before Ubuntu 13.10?</p>
  
  <p>What does setting <code>pam_loginuid</code> to <code>optional</code> mean, anyway? </p>
  
  <p>Is my ssh configuration much less secure in this respect?</p>