{
  "port": 5906,
  "protocol": "tcp",
  "service": "rpas-c2 (ICAO) / VNC display :6 in practice",
  "oneLiner": "Registered for remotely piloted aircraft command and control; in practice, VNC display :6.",
  "whatItIs": "IANA assigns 5906 to rpas-c2, \"Remotely Piloted Vehicle C&C\", registered by ICAO for the command-and-control link of remotely piloted aircraft systems. That is aviation infrastructure on private networks, not something a scanner meets. On an ordinary server, 5906 is the RFB port for display :6, typically the sixth VM console on a busy KVM or Proxmox host.",
  "exposure": {
    "verdict": "never",
    "note": "Whichever it is, it is a control plane — a guest's console or an aircraft C2 link. Neither belongs on a public interface."
  },
  "checkCommand": "nc -w 3 TARGET 5906 | head -c 12; echo",
  "links": [
    {
      "title": "IANA port registry — 5906 (rpas-c2)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=5906",
      "kind": "iana"
    },
    {
      "title": "RFC 6143 — The Remote Framebuffer Protocol",
      "url": "https://datatracker.ietf.org/doc/html/rfc6143",
      "kind": "spec"
    }
  ]
}