taz wrote:
> Meshtastic and some lesser known systems are a different animal. They do not use an ISP.
There are easier ways. I would use peoples iphones as Nodes. It's easier and cheaper.
--- Send My ---
Send My allows you to upload abritrary data from devices without an internet connection by (##)using Apple's Find My network. The data is broadcasted via Bluetooth Low Energy and forwarded by nearby Apple devices.
https://positive.security/blog/send-my
---
David """
Do you know that my new phone has a 'find my device' that the phone claims can connect via 4-billion devices? how does that work?
"""
Elior-Ai """
Yes. The "4 billion devices" claim is referring to a crowdsourced finding network, rather than your phone somehow having a radio capable of directly reaching billions of devices.
The clever part is that it can potentially locate your phone even when your phone has no mobile data or Wi-Fi connection.
It works roughly like this:
Your missing phone → Bluetooth → somebody else's nearby Android device → Internet → Google's Find Hub → you
Your phone periodically broadcasts a tiny Bluetooth Low Energy (BLE) signal containing an identifier. Other participating Android phones passing nearby can detect that signal. Their phone then reports an encrypted location observation to Google's network. When you use Find Hub, your account can retrieve and decrypt the relevant location information.
So imagine you leave your phone on a seat at a railway station:
📱 Your phone
↓ Bluetooth, perhaps tens of metres
📱 Random person's Android phone
↓ 4G/5G/Wi-Fi
☁️ Google network
↓
💻 You: "There it is."
The person walking past doesn't need to do anything, doesn't learn that your phone is lost, and isn't supposed to learn whose device it is. Their Android device is effectively acting as an anonymous sensor.
Where the "4 billion" comes from
Google has described the Find Hub/Find My Device network as leveraging a network of over a billion Android devices, while Android itself has a worldwide installed base measured in billions. I'd be a little suspicious of taking the exact "4 billion" number literally without seeing what your particular phone displayed—it may be describing the overall potential Android ecosystem rather than four billion currently participating Find Hub nodes.
The underlying concept, though, absolutely is real. Google's explanation of the Find Hub network
There is another particularly interesting feature: supported phones can remain findable for a period after they're switched off. Certain hardware keeps enough of the Bluetooth subsystem operating to participate in the finding network even though Android itself isn't running.
That's conceptually quite close to some of the MQTT/LAN/Tailcat ideas you've been working with: a huge distributed mesh of nodes doing tiny bits of transport work on behalf of one another, except Bluetooth is used for the local discovery hop and the Internet carries the observation back to the owner.
but it suggests that there is some sort of dark internet layer protocol working there? has this been explored by pen testers?
Yes — and your intuition is pointing at something real, although I'd call it an overlay network rather than a "dark Internet."
What's particularly interesting is that security researchers have already reverse-engineered Google's version fairly deeply.
A 2025 PETS paper, Okay Google, Where's My Tracker?, specifically reverse-engineered the proprietary portions of Google's Find My Device Network (now Find Hub). The researchers examined BLE traffic, Android/Google Play Services, and network traffic to Google's servers. They found privacy/security issues including denial-of-service possibilities and a potential device-linkage attack.
And they went considerably further than simply documenting it.
They produced an experimental open-source implementation called GoogleFindMyTools. It can interact with the network, query trackers/Android devices, work with the end-to-end-encryption keys, decrypt location reports belonging to the authenticated user, and even register experimental ESP32/Zephyr-based trackers with Google's network.
GoogleFindMyTools on GitHub
That last part is especially revealing. It demonstrates that, conceptually, the system looks something like:
GOOGLE FIND HUB OVERLAY
BLE beacon
│
▼
┌─────────┐
│ ESP32 / │
│ phone / │
│ tracker │
└────┬────┘
│
│ BLE advertisement
▼
┌───────────────────────┐
│ Arbitrary Android │
│ device passing nearby │
└──────────┬────────────┘
│
│ encrypted observation
│ via normal Internet
▼
┌───────────────────────┐
│ Google Find Hub │
│ backend │
└──────────┬────────────┘
│
│ authenticated query
▼
Device owner
So there's an important distinction.
It isn't an alternative packet-routing Internet where arbitrary machines can establish sockets and send IP traffic through four billion phones. Google deliberately constrains what gets relayed.
But architecturally it has a fascinating property:
A device without Internet access can cause information to travel globally through an unknown third party's Internet connection.
That's very much an overlay/relay network.
And the remarkable bit is the bottom layer. There doesn't need to be an ISP relationship, Wi-Fi credentials, SIM, IP address, or prior relationship between your lost device and the phone that discovers it.
For a distributed-systems person, that is a rather interesting piece of infrastructure: billions of privately owned devices participating in a largely invisible store/observe-and-forward network.
And yes—the security research community is very much poking at what else that primitive can be made to do.
"""
