You can configure as many listeners as you wish in the vernemq.conf file. In addition to this, the vmq-admin listener command let's you configure, start, stop and delete listeners on the fly. Those can be MQTT, WebSocket or Cluster listeners, in the command line output they will be tagged mqtt, ws or vmq accordingly.

Status of all listeners

vmq-admin listener show

    +----+-------+------------+-----+----------+---------+
    |type|status |     ip     |port |mountpoint|max_conns|
    +----+-------+------------+-----+----------+---------+
    |vmq |running|192.168.1.50|44053|          |  30000  |
    |mqtt|running|192.168.1.50|1883 |          |  30000  |
    +----+-------+------------+-----+----------+---------+
`

Starting a new listener

vmq-admin listener start address=192.168.1.50 port=1884 --mountpoint /test --nr_of_acceptors=10 --max_connections=1000

This will start an MQTT listener on port 1884 and IP address 192.168.1.50. If you want to start a WebSocket listener, just tell VerneMQ by adding the --websocket flag. There are more options, mainly for configuring SSL (use vmq-admin listener start --help).

You can isolate client connections accepted by a certain listener from other clients by setting a mountpoint.

To start an MQTT listener using defaults, just set the port and IP address as a minimum.

Stopping a listener

vmq-admin listener stop address=192.168.1.50 port=1884

You can add the -k or --kill_sessions switch to that command. This will disconnect all client connections setup by that listener. In combination with a mountpoint, this can be useful for terminating clients for a specific application, or to force re-connects to another cluster node (to prepare for a cluster leave for your node).

Restarting a stopped listener

vmq-admin listener restart address=192.168.1.50 port=1884

Deleting a stopped listener

vmq-admin listener delete address=192.168.1.50 port=1884