Hi
      I have a rather basic mosquitto
          configuration issue that I am going round in circles with... I
          clearly have some fundamental misunderstanding  that I would
          grateful if someone could sort out.
      For the time being I am ignoring
          encryption - that's for later. So everything on port 1883 for
          now.
        
      I can get mosquitto to work fine with a
          single (default) listener. So "port 1883" + "bind_interface
          localhost" = no problem. Testing with mosquitto_sub/pub allows
          me to exchange messages perfectly. Alternatively, just
          omitting all port/bind_interface/listener directives works,
          presumably due to the default listener starting.
        
      But anything involving "listener" seems
          to give me a "Connection refused" error with mosquitto_sub .
          So omitting "bind_interface" but adding "listener 1883" or "listener 1883
            localhost" with or without "port 1883" gives me the same
            "Connection refused " error. I can see from the log that I
            am also getting an error on daemon startup saying "Error:
            Address already in use". 
          
      What
            fundamental thing am I missing? I ask because eventually I
            want to create two listeners, one bound to localhost and a
            second to a network card with a static IP address out to a
            wireless access point, and then ignore MQTT traffic on the
            main, public internet-connected network. I then want to add
            encryption to (at least) the wireless connection. But since
            I am stumbling on two unencrypted connections...
          
      On Linux Mint 19.
      Peter