esp_mqtt: lwmqtt_connect: -5 with mosquitto broker

[donatoaz]

Hi, first off, thanks so much for the work, it is much appreciated.

I managed to get this library to work with the shiftr.io MQTT broker and now I wanted to use my own broker, however I keep getting this error when I try and connect:

I (19834) esp_mqtt: esp_mqtt_process: begin connection attempt
E (20094) esp_mqtt: lwmqtt_connect: -5
W (20094) esp_mqtt: esp_mqtt_process: connection attempt failed

And on the mosquitto log, it shows:

mqtt    | 1521896205: New connection from 177.97.217.166 on port 1883.
mqtt    | 1521896205: Socket error on client <unknown>, disconnecting.

How can I debug this? It seems error -5 is: LWMQTT_NETWORK_FAILED_READ

It it works with shiftr.io brokers, it must be some broker-side configuration I need to change... My mosquitto.conf file is very simple:

pid_file /var/run/mosquitto.pid

persistence false
persistence_location /mqtt/data/

user mosquitto
allow_anonymous true

# Port to use for the default listener.
port 1883

log_dest file /mqtt/log/mosquitto.log
log_dest stdout

include_dir /mqtt/config/conf.d

[donatoaz]

Using Wireshark I was able to get some relevant info and solve the issue. Apparently, I was sending a user and password on the connection packet and the broker was not happy with that. After changing the code not to send any user or password data it worked.

I know it is a stupid thing, but it would have been nice if the mqtt broker would send back something in the likes of a 403 http, saying it's something related to credentials. Or am I completely off?