3

A 'listener' console was setup:

mosquitto_sub -h test.mosquitto.org -t "myTopic" -v

mosquitto_pub returns an error:

pi@raspberrypi:~ $ mosquitto_pub -h test.mosquitto.org  -t 'myTopic' -m 'hello world'
**Error: The connection was lost.**

What steps, from the command line, can be taken to diagnose if there is a syntax problem?

Update:

Replacing the MQTT server with iot.eclipse.org does not suffer the error and returns payloads as expected.

Listener console setup:

mosquitto_sub -h iot.eclipse.org -t "myTopic" -v

Send payload:

mosquitto_pub -h iot.eclipse.org -t 'myTopic' -m 'hello world'

mosquitto_pub returns:

pi@raspberrypi:~ $ mosquitto_sub -h iot.eclipse.org -t "myTopic" -v
myTopic hello world

Publish a payload:

pi@raspberrypi:~ $ mosquitto_pub -h test.mosquitto.org  -t 'myTopic' -m 'hello world'

Changing the MQTT broker demonstrates there is not a syntax error, however, the question remains why there is an error returned in the original testing

gatorback
  • 1,216
  • 20
  • 44
  • 1
    @jsotola This comment is not helpful. For starters, what documentation are you referring to? – Murphy Aug 07 '19 at 07:08
  • the mosquitto.org documentation – jsotola Aug 07 '19 at 07:19
  • @jsotola Comments issued in the imperative (as opposed to the interrogative or declarative) may be construed as disrespectful, especially if they are deemed not helpful. – gatorback Aug 07 '19 at 17:12
  • @gatorback, you wanted to know how to determine if there is a syntax error ... the place to start is to find out what the server expects to receive from your device – jsotola Aug 08 '19 at 02:17
  • @jsotola If you have solution, I suggest posting a response with code examples as an answer below. I am looking forward to constructive solution to the question: enter the bonus round if you can nail down root cause of the error returned. – gatorback Aug 08 '19 at 11:59

2 Answers2

3

From the webpage:

This means that it will often be running unreleased or experimental code and may not be as stable as you might hope.

I experience the same problem, but was able to use iot.eclipse.org successfully. There's much traffic there, so better use a specific topic instead of #. For your tests, just pick one from the public brokers list that doesn't require signup.

Murphy
  • 2,609
  • 1
  • 13
  • 21
0

I found that adding the --insecure option solved this error for me.

mosquitto_pub -t mqtt-topic -m "sample-msg-1" --insecure

My mqtt server is all internal with the port all within docker so, the --insecure option doesn't really add any additional exposure for my case. I'm not sure why that worked for me since I think it should be using mqqt (unencrypted) as opposed to mqqts (encrypted)

Dave Raiman
  • 1
  • 1
  • Can you explain what the `--insecure` option ***does**?* … … … … … … … … … … … … … Please do not respond in comments; [edit] your answer to make it clearer and more complete. – G-Man Says 'Reinstate Monica' Jun 26 '22 at 20:07