a href="mod_auth_file.html"><code>mod_auth_file</code></a> module
  <dd>Handles authentication using <code>AuthUserFile</code> and
      <code>AuthGroupFile</code>
  </dd>

  <p>
  <dt>The <a href="mod_auth_pam.html"><code>mod_auth_pam</code></a> module
  <dd>Provides additional authentication checks via PAM
  </dd>

  <p>
  <dt>The <a href="mod_auth_unix.html"><code>mod_auth_unix</code></a> module
  <dd>Handles authentication using the system files, <i>e.g.</i>
      <code>/etc/passwd</code> and <code>/etc