Mosquitto: Starting in local only mode

Question

I have a virtual machine that is supposed to be the host, which can receive and send data. The first picture is the error that I'm getting on my main machine (from which I'm trying to send data from). The second picture is the mosquitto log on my virtual machine. Also I'm using the default config, which as far as I know can't cause these problems, at least from what I have seen from other examples. I have very little understanding on how all of this works, so any help is appreciated.

What I have tried on the host machine:

1. Disabling Windows defender
2. Adding firewall rules for "mosquitto.exe"
3. Installing mosquitto on a linux machine

Answer 1

By default, the Mosquitto broker will only accept connections from clients on the local machine (the server hosting the broker). Therefore, a custom configuration needs to be used with your instance of Mosquitto in order to accept connections from remote clients.

1. On your Windows machine, run a text editor as administrator and paste the following text:

listener 1883
allow_anonymous true

2. This creates a listener on port 1883 and allows anonymous connections. By default the number of connections is infinite. Save the file to "C:\Program Files\Mosquitto" using a file name with the ".conf" extension such as "your_conf_file.conf".

3. Open a terminal window and navigate to the mosquitto directory. Run the following command:

mosquitto -v -c your_conf_file.conf

where

-c : specify the broker config file.

-v : verbose mode - enable all logging types. This overrides any logging options given in the config file.

Answer 2

You have to run with

mosquitto -c mosquitto.conf

mosquitto.conf, which exists in the folder same with execution file exists (C:\Program Files\mosquitto etc.), have to include following line.

listener 1883 ip_address_of_the_machine(192.168.1.1 etc.)

Answer 3

Starting with the release of Mosquitto version 2.0.0 (you are running v2.0.2) the default config will only bind to localhost as a move to a more secure default posture.

If you want to be able to access the broker from other machines you will need to explicitly edit the config files to either add a new listener that binds to the external IP address (or 0.0.0.0) or add a bind entry for the default listener.

By default it will also only allow anonymous connections (without username/password) from localhost, to allow anonymous from remote add:

allow_anonymous true 

More details can be found in the 2.0 release notes here