{
  "port": 6520,
  "protocol": "tcp",
  "service": "Cuttlefish ADB (unassigned at IANA)",
  "oneLiner": "Unassigned by IANA; in practice the ADB socket for the first Cuttlefish virtual Android device.",
  "whatItIs": "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": {
    "verdict": "never",
    "note": "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."
  },
  "checkCommand": "adb connect 127.0.0.1:6520",
  "links": [
    {
      "title": "Android Open Source Project — Cuttlefish multi-tenancy (ADB port 6520)",
      "url": "https://source.android.com/docs/devices/cuttlefish/multi-tenancy",
      "kind": "official-docs"
    },
    {
      "title": "IANA Service Name and Transport Protocol Port Number Registry — 6516-6542 unassigned",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=6520",
      "kind": "iana"
    }
  ]
}