Asks the user for authentication before they are permitted to use the proxy.
Authentication headers are stripped from the flows, so they are not passed to
upstream servers. For now, only HTTP Basic authentication is supported. The
proxy auth options are ignored if the proxy is in transparent or reverse proxy
mode.

<table class="table">
    <tbody>
        <tr>
            <th width="20%">command-line</th>
            <td>
                <ul>
                    <li>--nonanonymous</li>

                    <li>--singleuser USER</li>

                    <li>--htpasswd PATH</li>
                </ul>
            </td>
        </tr>
    </tbody>
</table>