I am a newbie to MQTT, I was wondering how could one prevent a client who is not running in the same processor, where the broker is also running, to connect with the broker. In other way, restricting non-local MQTT clients from connecting to the broker.
I know there are different measures to security starting from username/password to SSL. But without any of these, are not there some means to define that no remote client shall ever succeed in establishing a connection?