Meshtastic

Meshtastic is an open-source, off-grid mesh communication platform that turns inexpensive LoRa devices (typically ESP32-based boards costing $20–$60) into long-range text messaging and GPS location-sharing nodes. Devices automatically form a decentralized, self-healing mesh network where each device repeats messages for others. Using Meshtastic, communication is possible over long distances (2-10 miles or 5–15 kilometers per hop) without any cellular towers, wifi, or internet access. The current range record is over 200 miles. Devices can run for weeks or months on small batteries or solar power.

Every device on the network is a node, but nodes come in many forms. Some nodes have keyboards for direct message transmission. Other nodes have no keyboard, but are controlled via a smartphone app connected by Bluetooth or USB. Some nodes are just simple repeaters. It’s especially popular with hikers, preppers, disaster-response teams, and communities in remote areas.

If you are new to mesh networking, Mestastic is one of the easier ones to grasp. If you are looking to DIY your own Arduino-esque off-grid texting device with a 3D printed case, this is the network most hobbyists are doing that on.

If you are just getting started with Meshtastic, and are looking for a cheap and/or easy entry point, give one of these devices a shot:

The simplest kind of Meshtastic node is a glorified repeater, since by default all nodes rebroadcast packets from nearby nodes. These types of nodes you can basically just configure and place somewhere, and it will start repeating whatever it picks up.

These types of nodes can be built all sorts of ways with common off-the-shelf components. Some of them come with cool features like being able to control them from a phone or PC via Bluetooth or USB. If you want a node that is already partially or fully assembled, try one of these:

If you want a single device to use for communicating over Meshtastic, without having to use a smartphone or computer to control it, you will need a sufficiently standalone node: ie, one with a full screen, keyboard and battery power.

Like the repeater nodes, you can build these however you want. But if you want to skip most or all of that, jump right to one of these options:

There are also many Meshtastic-compatible LoRa kits for the Raspberry Pi, if that's something you are into:

As Meshtastic is an open platform, intercepting traffic is trivial - you just need a compatible device within range of the network. Much of it is unencrypted, so anyone can read the messages straight out of the air.

Some messages on Meshtastic are encrypted, which complicates evesdropping. If the source device is left unattended (such as one hanging in a tree, a common deployment) then you can simply pull the encryption key from the device. If not, well, just gather all the encrypted messages so you can at least try to break the encryption at your leisure later.