MQTT broker (Aedes)¶

Alongside the core mqtt in / mqtt out nodes (which connect to a broker), this gateway also ships node-red-contrib-aedes — an embeddable MQTT broker node. Drop an aedes broker node into a flow and the gateway itself becomes an MQTT broker other devices and services can connect to, no separate broker software required.

Double-click the node to configure it, across three tabs.

Connection¶

Aedes broker — Connection tab

Field	Notes
MQTT port	The standard MQTT TCP port — `1883` by default
WS bind	Whether the WebSocket listener is exposed as a URL path or a separate port
WS port	Enables MQTT-over-WebSocket on this port; leave blank to disable WebSocket support entirely
Enable secure (SSL/TLS) connection	Wraps the broker in TLS

Persistence¶

Aedes broker — Persistence tab

Field	Notes
Persistence	`Memory` (default) or `MongoDB`
Persist state across restarts	Saves retained messages and subscriptions as a JSON file in the Node-RED user directory

With persistence on, the broker writes that JSON file on shutdown and every 60 seconds. QoS 1/2 in-flight messages are not persisted, and persistence is disabled automatically if the user directory isn't writable.

Security¶

Aedes broker — Security tab

Field	Notes
Username	Leave blank to disable authentication
Password	Leave blank to disable authentication

Anonymous access by default

With Username and Password both blank — the default — any device that can reach the configured MQTT port can connect and publish/subscribe with no credentials. Set both fields if the broker is reachable beyond a trusted local network.

Using it¶

Once deployed, any node that talks MQTT — this gateway's own mqtt in / mqtt out nodes, or an external device/service — can connect to <gateway-ip>:<MQTT port> as if it were talking to any other MQTT broker. This is useful for collecting readings from field devices that publish over MQTT directly (rather than being polled over Modbus — see Modbus / PLC integration), or as a local message bus between flows without routing everything through a cloud broker.