BLE & Wi-Fi Scanner
S01E04 — "Your phone has been a radio receiver this whole time. We just turned on the screen."
How scanning works
NearTrace uses Android's BluetoothLeScanner and WifiManager APIs to passively receive advertisement packets. It never initiates a connection. Your phone is in receive-only mode — like a radio tuned to a station, not a transmitter.
Every packet received updates the device's entry: last-seen timestamp, signal strength, and any new advertisement data.
Vendor inference
Raw BLE advertisements are full of information that most scanners throw away. NearTrace decodes:
OUI lookup
The first 3 bytes of a MAC address identify the manufacturer (e.g., A4:C3:F0 = Apple). NearTrace resolves these via api.macvendors.com (cached, with a circuit breaker — if the API is slow or down, it fails silently and retries in 5 minutes).
Apple Continuity packets
Apple devices broadcast their entire ecosystem state in Continuity advertisement packets. NearTrace decodes these to surface:
| What you see | What it means |
|---|---|
Apple · AirPods Pro 2 | Continuity identifies the exact model |
Apple · iPhone | NearbyInfo flags indicate device type |
Apple · iPhone (with AirPods) | Companion audio device detected |
Find My (likely AirTag) | Find My network packet detected |
| Continuity badges | Watch, AirDrop active, iCloud, Call in progress |
BT version detection
NearTrace stamps BT 5+ in the badge bar only when it can prove it — extended advertising, 2M PHY, or CODED PHY observed. No guessing.
GPS stamping
If you've granted location permission and pressed Start, every device sighting after that point gets a GPS coordinate. Devices discovered before you pressed Start intentionally get no location — they're pre-scan noise.
Tap a device → Map tab to see all sighting locations.
Plugins
The device detail page runs optional analysis plugins:
| Plugin | What it does |
|---|---|
| Service Inspector | Decodes all advertised BLE services |
| Connectivity Probe | Checks common ports (80, 443, 22, etc.) |
| Vulnerability Advisor | Flags known CVEs for the device type |
| mDNS | Resolves the device's mDNS hostname |
| SSDP | Discovers UPnP service descriptions |
Plugins run on-demand — tap the plugin card to trigger it.