I was playing about with a different project that uses BLE. I noticed that I was seeing some devices being discovered that I wasn't explictly searching for. So, I was curious what you could passively find out about the devices around you.
Hence, this small project.
There are other projects that look nicer, but I was interested in what I could put together myself with the API's that are available, in the style of a Terminal UI.
I've only used it on a Mac, so it may not work as follows on other platforms. The underlying libraries it uses should work on other platforms, so it should compile and run. However, I have not tested those other platforms.
It's fairly simple to use:
cargo run
(The first time you run this on a Mac in a Terminal it will ask for permissions to use Bluetooth)
This will then bring up a simple text UI which shows the named devices that have been discovered. It also shows 'anonymous' devices, where the name is derived from a hash of the "manufacturer data" that is in the BLE advertisement.
Each device is shown with:
-
how long ago it was last seen
-
the RSSI (Received Signal Strength Indicator)
-
a change indicator:
- '↑' = stronger
- '=' = same strength
- '⌄' = weaker
- '*' = newly-discovered (so nothing to compare to)
Scans update every second, and are always sorted by age (newest-first) then by RSSI strength (strongest-first). Anonymous devices are colored arbitrarily, but consistently, to help identify them as they move in the list.
To see all options, do:
cargo run -- -h
To record all discovery events to a file, do:
cargo run -- --record prefix.suffix
This will save all discovery events (what signatures are seen, when, and with what rssi) to a new file.
The file prefix can be anything you want but suffix must end be one of the following.
Save in jsonl format.
Same as .jsonl except output is gzip-compressed.
Saves events to an SQLite DB. If the file doesn't already exist, this will create the DB file with the correct table schema.