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MQTT | Integrations Overview

Public MQTT Server​

Common MQTT Layout

The Meshtastic project provides a public MQTT service that users can connect to, with certain restrictions in place to ensure network stability. This service allows Meshtastic devices to bridge over the internet, providing global connectivity for remote networks.

For instructions on connecting to the public MQTT server, please refer to Connect to the Default Public Server.

Restrictions on the Public MQTT Server​

To maintain optimal performance and protect LoRa meshes, traffic restrictions are currently applied to the public MQTT server.

Zero-Hop Policy​

Traffic from the public MQTT server does not fully propagate through local mesh networks. Directly connected nodes will receive the data, but due to the zero-hop policy, it will not spread further to other nodes within the local mesh network.

Optimized Traffic Filtering​

Only specific portnums are prioritized for transmission over the public MQTT server when using the default PSK:

  • NodeinfoApp
  • TextMessageCompressedApp
  • TextMessageApp
  • PositionApp
  • TelemetryApp
  • MapReportApp
  • RoutingApp

Location Precision Filtering​

On the default PSK, the public server also limits the precision of location data to help protect user privacy. Only position packets containing imprecise location data (10-16 bits) are shared on the topic, ensuring that precise location details are not exposed. For more information on how location precision works, see the Position Precision section.

This filtering focuses network resources on critical traffic, improving overall performance and reducing unnecessary data flow. Since these restrictions are applied at the network level, no firmware updates are required. As Meshtastic networks continue to grow, further traffic reduction measures may become necessary to manage network load and maintain reliable performance across all channels.

Using Private Brokers​

It is not recommended to use the default key (PSK) on a private broker. Doing so potentially allows security vulnerabilities and can flood the mesh with traffic, as private brokers do not enforce the zero-hop policy needed for public channels. Private brokers are intended for use with private channels, where custom PSKs provide secure, isolated communication.

Software Integrations​

Using or emitting packets directly in/from smart home control software such as Home Assistant or other consumers that can work with JSON messages.

When MQTT is enabled, the Meshtastic device simply uplinks and/or downlinks every raw protobuf MeshPacket that it sees to the MQTT broker, encapsulated in a ServiceEnvelope protobuf. In addition, some packet types are serialized or deserialized from/to JSON messages for easier use in consumers. All packets are sent to the broker, whether they originate from another device on the mesh, or the gateway node itself.

MQTT Topics​

If no specific root topic is configured, the default root topic will be msh/REGION.

For each channel where uplink and/or downlink is enabled, two topics might be used:

Protobufs topic​

A gateway node will uplink and/or downlink raw (protobuf) MeshPackets to the topic:

msh/REGION/2/e/CHANNELNAME/USERID, where CHANNELNAME is the name of the channel (firmware versions prior to 2.3.0 will publish to a topic with /c/ in the place of /e/).

For example: msh/US/2/e/LongFast/!abcd1234

The payload is a raw protobuf, whose definitions for Meshtastic can be found here. Reference guides for working with protobufs in several popular programming languages can be found here. Looking at the MQTT traffic with a program like mosquitto_sub will tell you it's working, but you won't get much useful information out of it. For example:

苓????"!
	!937bed1cTanksTnk"D???05??=???aP`
	ShortFast	!937bed1c

If encryption_enabled is set to true, the payload of the MeshPacket will remain encrypted with the key for the specified channel.

JSON topic​

備註

JSON is not supported on the nRF52 platform.

If JSON is enabled, packets from the following port numbers are serialized to JSON: TEXT_MESSAGE_APP, TELEMETRY_APP, NODEINFO_APP, POSITION_APP, WAYPOINT_APP, NEIGHBORINFO_APP, TRACEROUTE_APP, DETECTION_SENSOR_APP, PAXCOUNTER_APP and REMOTE_HARDWARE_APP. These are then forwarded to the topic:

msh/US/2/json/CHANNELNAME/USERID.

An example of a received NODEINFO_APP message:

{
  "id": 452664778,
  "channel": 0,
  "from": 2130636288,
  "payload": {
    "hardware": 10,
    "id": "!7efeee00",
    "longname": "base0",
    "shortname": "BA0"
  },
  "sender": "!7efeee00",
  "timestamp": 1646832724,
  "to": -1,
  "type": "nodeinfo"
}

The meaning of these fields is as follows:

  • "id" is the unique ID for this message.
  • "channel" is the channel index this message was received on.
  • "from" is the unique decimal-equivalent Node ID of the node on the mesh that sent this message. (The hexadecimal value 7efeee00 represented by an integer in decimal is 2130636288).
  • "id" inside the payload of a NODEINFO_APP message is the hexadecimal Node ID (sometimes called User ID) of the node that sent it.
  • "hardware" is the hardware model of the node sending the NODEINFO_APP message.
  • "longname" is the long name of the device that sent the NODEINFO_APP message.
  • "shortname" is the short name of the device that sent the NODEINFO_APP message.
  • "sender" is the hexadecimal Node ID of the gateway device, which is in this case the same node that sent the NODEINFO_APP message.
  • "timestamp" is the Unix Epoch when the message was received, represented as an integer in decimal.
  • "to" is the decimal-equivalent Node ID of the destination of the message. In this case, "-1" means it was a broadcast message (this is the decimal integer representation of 0xFFFFFFFF).
  • "type" is the type of the message, in this case it was a NODEINFO_APP message.

The from field can thus be used as a stable identifier for a specific node. Note that in firmware prior to 2.2.0, this is a signed value in JSON, while in firmware 2.2.0 and higher, the JSON values are unsigned.

If the message received contains valid JSON in the payload, the JSON is deserialized and added as a JSON object rather than a string containing the serialized JSON.

You can also send a JSON message to the topic msh/US/2/json/mqtt/ to instruct a gateway node to send a message to the mesh.

To make this work, ensure that your node has a Meshtastic channel configured called "mqtt". Enable Downlink. The PSK can be random and doesn't matter. This channel allows the node to listen to messages on the msh/US/2/json/mqtt/ topic.

Reboot your device after creating this channel.

The JSON message should contain the following fields:

{
   "from": <decimal Node ID of MQTT node>,
   "to": <decimal Node ID of recipient for a DM (optional)>,
   "channel": <channel index (optional)>,
   "type": "type",
   "payload": {
       "key":"value"
       ...
    }
}

from and payload fields are required for a valid envelope (note that in firmware <2.2.20 a field sender was required, but this is no longer the case). The from field should be equal to the decimal Node ID of the node that will transmit the message. If the Node ID (sometimes called User ID) is !7efeee00, then the decimal equivalent would be 2130636288. Optionally, you can specify a different channel than the primary channel by setting the channel field to a channel index (0-7). Furthermore, you can send a direct message by setting the to field to the decimal Node ID of the destination. If the to field is not set, the message will be broadcast to all nodes on the mesh.

Currently two types of messages are supported: "sendtext" and "sendposition". For the type sendtext, the payload should be a string containing the text to send. For the type sendposition, the payload should be an object with the fields latitude_i, longitude_i, altitude (optional) and time (optional).

Basic Configuration​

Check out MQTT Settings for full information. For quick start instructions, read on.

  • Connect your gateway node to wifi, by setting the network.wifi_ssid, network.wifi_psk and network.wifi_enabled preferences.
  • Alternatively use the RAK4631 with Ethernet Module RAK13800, by setting network.eth_mode and network.eth_enabled (note that JSON is not supported on the nRF52 platform).
  • Configure your broker settings: mqtt.address, mqtt.username, and mqtt.password. If all are left blank, the device will connect to the Meshtastic broker.
  • Set uplink_enabled and downlink_enabled as appropriate for each channel. Most users will just have a single channel (at channel index 0). meshtastic --ch-index 0 --ch-set uplink_enabled true

uplink_enabled will tell the device to publish mesh packets to MQTT. downlink_enabled will tell the device to subscribe to MQTT, and forward any packets from there onto the mesh.

Gateway nodes​

Any meshtastic node that has a direct connection to the internet (either via a helper app or installed WiFi/4G/satellite hardware) can function as a "Gateway node".

Gateway nodes (via code running in the phone) will contain two tables to whitelist particular traffic to either be delivered toward the internet, or down toward the mesh. Users that are developing custom apps will be able to customize these filters/subscriptions.

Since multiple gateway nodes might be connected to a single mesh, it is possible that duplicate messages will be published on any particular topic. Therefore, subscribers to these topics should deduplicate if needed by using the packet ID of each message.

Examples​