Meshtastic is an open-source LoRa mesh used off-grid by preppers, hikers, event organizers, and amateur radio operators, and increasingly for protest logistics, disaster response, and other high-stakes comms, usually where people assume their traffic is private and their neighbors are who they claim to be. Those two assumptions are the subject of this talk. A shared channel key buys confidentiality for everyone who holds it and nothing else: not message integrity, not sender identity, not header privacy, not availability. The default key ships with every node, so for much of the mesh the wall is not there at all. None of this is a flaw. It is the threat model of a protocol built for simple, low-power text between people who already trust each other, and the talk treats it that way.

To make that concrete, we hunt four beasts, each shown live. The Impersonator forges messages and node identities the mesh accepts as real, through AES-CTR ciphertext forgery and firmware-level source-ID spoofing. The Eavesdropper reads who is talking, when, and the shape of the network from cleartext headers with no key, and their location too on any channel still running the default key. The Saboteur breaks delivery for a chosen target by dropping its packets, rewriting hop limits, or decrypting, modifying, and re-encrypting traffic in transit. The Swarm exhausts the node database, only about a hundred slots on the boards we run, with ghost nodes and poisons the public map through the MQTT bridge. The active attacks run on a custom firmware fork whose features toggle at runtime and default to safe, with an on-device KILL ALL that resets everything to safe, so the live demos stay penned in our own isolated mesh. For the HAMs there is a sharper cut: licensed mode sets your callsign and transmits in the clear, and a callsign maps through public FCC records to a name and often an address, so a by-the-book node beacons your legal identity and rough location to a village full of people who can direction-find it. The point is not the regulation, it is the consequence.

We also tell an honest story about how fast this came together: two developers who do not write firmware for a living built the firmware fork, a Python toolkit, and custom device-UI panels in about 16 working days (well, evenings) with heavy AI assistance. The one part that did not yield was the hardware, a radio regression that took old-fashioned diagnosis and a version pin, not a cleverer prompt. The attacker's effort floor collapsed; the hardware did not care, and that asymmetry applies to every volunteer-run protocol. So we close where it matters, with an opsec playbook drawn straight from the beasts: change the default key, verify identity and content out of band, assume broadcast, do not stake life-safety on availability, and match the tool to the threat (Meshtastic bought simplicity and adoption, Reticulum offers cryptographic identity and authenticated encryption by default, MeshCore sits between). Credit where due: Meshtastic already ships public-key DMs and signed admin messages, with cryptographic node identity in progress, and our hardening is offered as support for that trajectory, not a homework list for volunteers. Come find the beasts, then learn to live alongside them.