title: mosquitto_sub with TLS enabled
body: <p>I am new to MQTT and I have a frustrating problem.</p>
  
  <p>I have been using MQTT.fx to subscribe to a topic; I have set the:</p>
  
  <ul>
  <li>Broker Address</li>
  <li>Port</li>
  <li>Client ID</li>
  <li>Enable SSL/TLS 
  <img src="https://i.stack.imgur.com/JZZjL.jpg" alt="link to image"></li>
  <li>Topic</li>
  </ul>
  
  <p>This works well, however I would like to use mosquitto_sub.
  I am attempting to subscribe to the same topic in the following way:</p>
  
  <pre><code>mosquitto_sub -h  host -p 8883 -t topic -i client id
  </code></pre>
  
  <p>This is not working for me. I am using it on a Ubuntu VM.<br/>
  My powers of observation tell me that I should enable TLS, however I'm not quite sure how to do that, I have stuffed around with certificates and enabling TLS in may ways but have not got the right combo. I know it is required as if I uncheck the SSL/TLS box in MQTT.fx I am unable to connect.</p>
  
  <p>I would really like to replicate what I have in MQTT.fx with mosquitto.</p>