title: MQTT Security - how to prevent abusers subscribing to topics?
body: <p>I've got everything setup and working for MQTT now. I am using the IBM wmqtt.jar and the Mosquitto broker.. </p>
  
  <p>My Java Servlet creates an MQTTConnection to the broker and publishes under the topic "AndroidDeviceID/myAppName" .. </p>
  
  <p>The Android client subscribes to that same topic... </p>
  
  <p>It seems to me that if anyone knew the device name of my user, they could create a simple android app and subscribe to that topic on my MQTT broker. Then they get all the notifications (in this case instant messaging messages) from my users.. </p>
  
  <p>How is this properly avoided?</p>