crypto keys.
  Options:
     --pk, --spa              : Technique [&quot;PK&quot;, &quot;SPA&quot;(default)].
     -p, --port &lt;port&gt;        : Port to open/close on the remote host [integer].
     -S, --knock-ip &lt;addr&gt;    : IP to authorize on the remote host [IP or host].
     -f, --field &lt;field&gt;      : Covert channel protocol header field.
     -a, --action &lt;type&gt;      : Action taken by Aldaba server [&quot;Open&quot;, &quot;Close&quot;].
     -t, --target-ports &lt;seq&gt; : Sequenc