MQTT Authentication Not Working with ChirpStack and Mosquitto

[dhanush-ninja]

Description:
I have configured Mosquitto with a username and password and updated both chirpstack.toml and chirpstack-gateway-bridge.toml accordingly, but the Gateway Bridge and ChirpStack fail to connect to the MQTT broker with NotAuthorized errors.

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Configuration:

Mosquitto (mosquitto.conf):

listener 1883
allow_anonymous false
password_file /mosquitto/config/passwd

ChirpStack (chirpstack.toml):

[integration]
enabled=["mqtt"]

[integration.mqtt]
server="tcp://$MQTT_BROKER_HOST:1883/"
username="admin"
password="password@098"
json=true

ChirpStack Gateway Bridge (chirpstack-gateway-bridge.toml):

[integration.mqtt.auth.generic]
servers=["tcp://mosquitto:1883"]
username="admin"
password="password@098"

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Observed behavior:

mosquitto-1                               | 1766123347: Client f578b34a766c0cd4 disconnected, not authorised.
chirpstack-1                              | 2025-12-19T05:49:07.926907Z ERROR chirpstack::gateway::backend::mqtt: MQTT error error=Connection refused, return code: `NotAuthorized`
chirpstack-gateway-bridge-basicstation-1  | time="2025-12-19T05:49:08.415761364Z" level=warning msg="[client]   status is already disconnected" module=mqtt
chirpstack-gateway-bridge-basicstation-1  | time="2025-12-19T05:49:08.418923358Z" level=error msg="[client]   Connecting to tcp://mosquitto:1883 CONNACK was not CONN_ACCEPTED, but rather Connection Refused: Not Authorised" module=mqtt
chirpstack-gateway-bridge-basicstation-1  | time="2025-12-19T05:49:08.418970406Z" level=error msg="[client]   Failed to connect to a broker" module=mqtt
chirpstack-gateway-bridge-basicstation-1  | time="2025-12-19T05:49:08.419641104Z" level=error msg="integration/mqtt: connection error" error="not Authorized"

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Expected behavior:
ChirpStack and the Gateway Bridge should successfully connect to Mosquitto using the configured username and password.

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Additional context / Questions:
Are there additional configuration changes needed in the Gateway Bridge TOML to support authenticated MQTT?

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