There was this recent question in which the OP used iot.eclipse.org as an MQTT broker. This server actually runs the latest released version of Mosquitto broker.
I have advised to check the connection on the broker side and I have checked what are the possibilities. I could not find a way to access the logs provided by iot.eclipse.org's Mosquitto broker.
Anyway does someone know a way to get information about my client from a public broker?
Subscribing to $SYS/# topic will provide some information about the broker and maybe about the clients. Detailed description of these items can be found here.
There are three main categories to highlight:
- Static Topics: Messages on a static
$SYStopic are not required to be sent on every$SYStopic update interval. These messages are sent once the broker subscribes to the $SYS topic- Required Topics: Every broker which claims to support the
$SYStopics should support these topics.- Optional Topics: A broker implementation may decide if it implements an optional topic.
The one needed to for client status check falls into the "Optional Topics" category.
$SYS/clients/[client-id]/ip
$SYS/clients/[client-id]/connectedtime
Also, based on this description about Mosquitto's logging, the console log can be logged into a topic ($SYS/broker/log/#) as well.
Two common question are:
- Can I see all connected clients?
- Can I list all topics?
The broker doesn’t let you do this directly but by enabling logging to a a topic and monitoring the topic with an MQTT client you can get a good idea.
Probably for privacy and/or security reasons iot.eclipse.org does not have topics for these log entries.
No topics for $SYS/clients/
No topics for $SYS/broker/log/#
For other public brokers these optional topics may exist, you can check them easily with mqtt-spy for example.