title: Can I create a listener in mosquitto, bound to a device which may not be present?
body: <p>I am running mosquitto on a raspberry pi and it all functions fine with an ethernet connection. I have two listeners, one limited to localhost for most of the functionality and another limited to the vpn ip address so that I can do some administration over vpn, all others are then excluded. The problem is that once this device goes out into the world it may or may not have an internet connection, but if the internet connection is not there, the vpn address does not exist and mosquitto fails to start.</p>
  <p>I am using mosquitto v2.0.4, but I can update if required.</p>
  <p>Does anyone have any suggestions on how I can solve this?</p>
  <pre><code>per_listener_settings true
  retain_available true
  
  log_dest stdout
  
  
  listener 1883 localhost
  allow_anonymous true
  
  listener 1886 10.8.0.100
  max_connections 1
  allow_anonymous true
  </code></pre>