# WHATPORT(6520)

## NAME

port 6520 — Cuttlefish ADB (unassigned at IANA) — Unassigned by IANA; in practice the ADB socket for the first Cuttlefish virtual Android device.

Protocol: TCP  
IANA registry

## DESCRIPTION

IANA leaves 6516-6542 unassigned. The concrete use of 6520 is Android's Cuttlefish virtual device platform: each instance exposes an ADB connection on a TCP server socket, 6520 for instance 1, 6521 for the second, and upward, so `adb connect 127.0.0.1:6520` reaches the first VM. You meet it on Android build and CTS machines running emulated devices. ADB over TCP has no authentication once a host is authorised, which is why Cuttlefish binds it locally.

## EXPOSURE

**Do not expose.** A reachable ADB endpoint is a root-capable shell on the device plus arbitrary file push and pull; keep it on loopback and reach it over an SSH tunnel.

## CHECK

```sh
adb connect 127.0.0.1:6520
```

## SEE ALSO

- docs — [Android Open Source Project — Cuttlefish multi-tenancy (ADB port 6520)](https://source.android.com/docs/devices/cuttlefish/multi-tenancy) (source.android.com)
- iana — [IANA Service Name and Transport Protocol Port Number Registry — 6516-6542 unassigned](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=6520) (iana.org)

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