Meshtastic Relay

A hybrid internet/LoRa mesh relay daemon written in Go. Fixed Meshtastic nodes (Raspberry Pi + LoRa radio) are deployed at homes, offices, and public places. Users connect via WiFi or BLE from their phone to the nearest node. Their cryptographic identity (Ed25519 keypair) is portable -- they are recognized network-wide regardless of which node they are connected to.

Messages route over the internet (MQTT) when available, and fall back to LoRa radio mesh when internet connectivity is lost.

Architecture

Phone (WiFi/BLE) --> [Relay Node (RPi + LoRa)] --MQTT--> [Relay Node] --> Phone
                                                   |
                                                   +--LoRa--> [Relay Node] --> Phone

Core Components

Package	Description
identity/	Ed25519/X25519 cryptographic identity system
announce/	Presence announcement and propagation
message/	Wire format, end-to-end encryption (NaCl crypto_box)
transport/	Transport abstraction with MQTT and Meshtastic serial backends
transport/router/	Path selection with internet-first, LoRa fallback
node/	Multi-user relay daemon and connection management
store/	Store-and-forward message queue (BoltDB)
config/	YAML configuration loading
cmd/relayd/	Main daemon entry point

Identity System

Every user has an Ed25519 keypair. Their identity hash is SHA-256(public_key)[:16] (truncated to 16 bytes). Key exchange uses X25519 ECDH with HKDF-SHA256 key derivation, and messages are encrypted with XSalsa20-Poly1305 (NaCl crypto_box).

Transport Layer

The relay daemon maintains two transport paths:

• MQTT (primary): Connects to a shared MQTT broker for internet-based message relay between nodes.
• Meshtastic Serial (fallback): Communicates with a locally attached Meshtastic LoRa radio over serial protobuf for off-grid mesh routing.

A router component monitors health of each transport and selects the best path, with automatic failover when internet connectivity degrades.

Building

# Build for current platform
make build

# Cross-compile for Raspberry Pi (ARMv7)
make build-arm

# Cross-compile for Raspberry Pi 4+ (ARM64)
make build-arm64

# Run tests
make test

# Run tests with coverage
make test-cover

# Lint
make lint

Configuration

Copy and edit the example configuration:

cp config.example.yaml config.yaml

See config/ package documentation for all available options.

Running

./bin/relayd -config config.yaml

Project Status

This project is in early development. The core cryptographic identity system, message format, and transport abstractions are implemented. Integration testing and production hardening are ongoing.

Acknowledgments

This project implements protocol concepts inspired by the Reticulum Network Stack, which is released under the MIT License. Meshtastic Relay is a clean-room reimplementation of these public-domain protocol concepts in Go -- it does not fork or copy any Reticulum source code.

Meshtastic Relay also integrates with Meshtastic LoRa radios for off-grid mesh communication.

License

See LICENSE file for details.