I have set the acl_file property in /etc/mosquitto/mosquitto.conf to /home/ubuntu/my.acl. In the ACL file, I have allow_anonymous false to disallow connections from clients that do not have user name.

From MQTT Lens, I tried connecting to this broker without passing user name. I don't see a connect message immediately in the log. However, when I delete the connection from MQTT Lens, I see the message as connected followed by a disconnect message.

ubuntu@ip-172-31-42-207:/var/log/mosquitto$ tail -f mosquitto.log  
1527666604: New connection from 183.xx.xx.xx on port 1883.
1527666604: New client connected from 183.xx.xx.xx as lens_bWIkzTxFSc2BIIUQqqT35ipsiPV (c1, k120).
1527666746: Client lens_bWIkzTxFSc2BIIUQqqT35ipsiPV disconnected.

How can I confirm that allow_anonymous false actually denied the connection?

1 Answer 1


allow_anonymous false needs to be in the mosquitto.conf file not the acl file

IIRC the logging is delayed because of a minor bug in some versions of mosquitto because you are not driving any other load through the broker

  • :facepalm: I misread the man mosquitto.conf page! May 30, 2018 at 8:10
  • Great answer, though I'm not sure I like allow_anonymous false. Grrr! ;)
    – anonymous2
    Jun 1, 2018 at 12:48

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