c# - Unable to anonymously connect to Mosquitto 2.0.5 on Ubuntu

Question

I have the Mosquitto 2.0.5 snap (version 511) running on an Ubuntu Core 18 system. I made no modifications to the configuration, nor pass another configuration to Mosquitto.

On that same system I am running a .NET 5 application, that uses MQTTnet to connect to Mosquitto. I do not pass any credentials to connect to Mosquitto. However, I am unable to connect to Mosquitto 2.0.5, where I was able to connect to Mosquitto 1.6.12 before.

I do know of the increased security of Mosquitto 2.0 (and that is also the reason to upgrade), but the upgrade documentation clearly states that in the default configuration (no listeners) anonymous connections are still possible on localhost:1883. The strange thing is, that it all works when I run Mosquitto 2.0.5 and my application on Windows, but it does not work on Ubuntu Core (the target system).

Mosquitto 2.0.5 is logging the following when I attempt to make the connection:

New connection from 127.0.0.1:57362 on port 1883.
Client <unknown> disconnected, not authorised.

I use the following C# code (using MQTTnet) to make the connection:

var factory = new MqttFactory();
var client = factory.CreateMqttClient();
var builder = new MqttClientOptionsBuilder().
            WithTcpServer("localhost", 1883);
client.ConnectAsync(builder.Build(), CancellationToken.None).Wait(MQTTBROKER_TIMEOUT);

Am I not understanding something, am I doing something wrong?

Any help is appreciated.

EDIT: I have been playing around a bit more, and it seems that by default the dynamic security plugin is loaded when using the snap, however I did not find anything in the configuration files about this. I guess that due to this, the authentication fails. Then the next question arises, how can I find out what the default administrator user and its password are in this situation, as I need those to be able to add groups, clients and roles to the plugin.

question from:https://stackoverflow.com/questions/65923604/unable-to-anonymously-connect-to-mosquitto-2-0-5-on-ubuntu

Answer 1

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