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ThorX — Android phone
Device Samsung Galaxy A05 (SM-A055M), Android 15
Address thorx.technet, 10.100.100.5 over WireGuard
Configured On the device; nothing here is built by Nix

ThorX's Syncthing is set up on the phone itself; see syncthing.nix.

adb from Odin

Odin reaches ThorX over adb on a fixed port, with no pairing after the first time:

adb connect 10.100.100.5:<port>

The port is the one set in ADB Auto Enable on the phone. It is kept out of this public repo; the app's status screen shows it.

How it works

  • Odin has adb from android-debug-bridge.nix. Its private key is the sops secret adb_private_key in secrets/3-laptop/android-debug-bridge.yaml, and ~/.android/adbkey is a link to the decrypted copy. ThorX trusts that key, so the pairing survives reboots and a reinstall of Odin. The rest of ~/.android is persisted under /Storage/Apps/Tools/Android-Debug-Bridge.
  • ThorX runs ADB Auto Enable (com.tpn.adbautoenable). At every boot it switches wireless debugging on, finds the random port Android gives it, and moves adb to the fixed port.

Android picks a new random wireless debugging port each time it is switched on, and nixpkgs' adb cannot discover it, since it is built without mDNS. The app's fixed port is what makes adb connect work without looking the port up.

Setting it up again

After a factory reset of ThorX, or for a new key:

  1. On ThorX, open Developer options, then Wireless debugging, and turn it on.
  2. Pair Odin: tap Pair device with pairing code, then on Odin run adb pair 10.100.100.5:<pairing port> <code>. For a new key, generate one with adb keygen, replace adb_private_key with it in the sops file, and switch Odin before pairing.
  3. Connect once on the random port shown on the Wireless debugging screen: adb connect 10.100.100.5:<port>. If the screen is out of reach, nix run nixpkgs#nmap -- -Pn -p 30000-50000 --open 10.100.100.5 finds it.
  4. Install the app's APK from its GitHub releases with adb install, and open it.
  5. Pair the app: start a second Pair device with pairing code and enter that code and port in the app. The app pairs with the phone's own adb over loopback.
  6. Grant it the settings permission from Odin: adb shell pm grant com.tpn.adbautoenable android.permission.WRITE_SECURE_SETTINGS. The app tries to grant this to itself, but that fails while the VPN is up (below).
  7. Set the target port in the app, then tap Test to run its boot routine. Its log should end with Successfully configured ADB on port <port>!.
  8. Turn the app's web server off. Its control page on port 9093 has no password.

Hazards

  • The VPN hides the phone from the app. WireGuard is ThorX's active network, so the app takes 10.100.100.5 as its own address. The phone advertises adb only on its Wi-Fi address, so the app skips that advertisement. The Discover button then fails, and so does the app's self-grant of the permission. The boot routine still works, because it falls back to scanning every port.
  • The fixed port is open on every network ThorX joins, including public Wi-Fi, and the connection is not encrypted. A computer still needs its key approved on the phone before adb lets it in.
  • The app holds adb access to the phone itself. That is how it switches the port, so it can run shell commands on ThorX.