meshtastic

Overview ¶

Package meshtastic decodes the Meshtastic LoRa-mesh radio packet header — the 16-byte plaintext header that prefixes every Meshtastic packet on the 868/915 MHz LoRa channel, before the AES-encrypted payload. Meshtastic is the dominant off-grid LoRa mesh-comms project, and the header is sent in the clear: decoding it from a Flipper Sub-GHz / SDR LoRa capture enumerates the nodes in mesh range (source and destination node IDs), reveals the channel hash (which channel a packet belongs to), and exposes the hop / want-ack / via-MQTT routing flags — passive mesh reconnaissance without touching the air.

Wrap-vs-native judgement ¶

Native. The header is a fixed wire structure defined by the
Meshtastic firmware (RadioInterface.h PacketHeader, "has to exactly
match the wire layout when sent over the radio link"): little-endian
uint32 destination, uint32 source, uint32 packet ID, then a flags
byte, the channel-hash byte, and the next-hop / relay-node bytes.
Pure byte-field extraction and bit-masking — reimplemented from the
firmware, no new dependency, no shell-out.

What this covers ¶

• Destination and source node IDs (the !xxxxxxxx form Meshtastic displays; 0xFFFFFFFF is the broadcast address).
• The packet ID.
• The flags byte: hop limit (bits 0-2), want-ack (bit 3), via-MQTT (bit 4) and hop start (bits 5-7) — so hops-taken = start − limit.
• The channel hash (the per-channel hint byte) and the next-hop / relay-node ID bytes.
• The encrypted payload, surfaced as hex with its length.

Deliberately deferred ¶

The payload is the AES-256-CTR-encrypted (or, for DMs, PKI-encrypted)
protobuf MeshPacket; decrypting it needs the channel pre-shared key
(or the node key pair), which is not on the wire, so it is surfaced
as ciphertext. The LoRa physical layer (CRC, coding rate, preamble)
is upstream — feed the decoded payload bytes.