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Re: [mosquitto-dev] Tracking down the publisher of a message

IF you start mosquitto in verbose mode it will log the length of the message it received.

e.g. The following show 2 mosquitto_pub clients connect, the first published a payload of "ben" shown as 3 bytes, the second published a null payload shown as 0 bytes.

The log line has the client id which can be matched to the earlier log entry with the ip address.

$ mosquitto -p 1888 -v
1636624290: mosquitto version 2.0.13 starting
1636624290: Using default config.
1636624290: Starting in local only mode. Connections will only be possible from clients running on this machine. 1636624290: Create a configuration file which defines a listener to allow remote access. 1636624290: For more details see
1636624290: Opening ipv4 listen socket on port 1888.
1636624290: Opening ipv6 listen socket on port 1888.
1636624290: mosquitto version 2.0.13 running
1636624309: New connection from on port 1888.
1636624309: New client connected from as auto-66D62DF4-D085-B93E-A3F7-859C745218AD (p2, c1, k60).
1636624309: No will message specified.
1636624309: Sending CONNACK to auto-66D62DF4-D085-B93E-A3F7-859C745218AD (0, 0) 1636624309: Received PUBLISH from auto-66D62DF4-D085-B93E-A3F7-859C745218AD (d0, q0, r0, m0, 'foo', ... (3 bytes)) 1636624309: Received DISCONNECT from auto-66D62DF4-D085-B93E-A3F7-859C745218AD
1636624309: Client auto-66D62DF4-D085-B93E-A3F7-859C745218AD disconnected.
1636624323: New connection from on port 1888.
1636624323: New client connected from as auto-B3D3304F-9E2D-2A3D-29BB-0D3F213DE0F9 (p2, c1, k60).
1636624323: No will message specified.
1636624323: Sending CONNACK to auto-B3D3304F-9E2D-2A3D-29BB-0D3F213DE0F9 (0, 0) 1636624323: Received PUBLISH from auto-B3D3304F-9E2D-2A3D-29BB-0D3F213DE0F9 (d0, q0, r0, m0, 'foo', ... (0 bytes)) 1636624323: Received DISCONNECT from auto-B3D3304F-9E2D-2A3D-29BB-0D3F213DE0F9
1636624323: Client auto-B3D3304F-9E2D-2A3D-29BB-0D3F213DE0F9 disconnected.

On 11/11/2021 09:45, Andrew Holt wrote:

It's my own fault.

On my (dev) network, somewhere, I have a client that is publishing a message with a NULL topic.

What I would like to do is to find the IP address of the publisher.

If there is some way to get the broker to log the source of a message that would be ideal, but I'm open to other suggestions.


P.S. It's my own fault.

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