{
  "port": 1027,
  "protocol": "both",
  "service": "Reserved (TCP) / 6a44 (UDP)",
  "oneLiner": "Reserved by IANA on TCP; the UDP side belongs to 6a44, an experimental IPv6-behind-NAT44 mechanism.",
  "whatItIs": "IANA marks TCP 1027 simply \"Reserved\" — there is no service name and no assignee, so nothing is entitled to it. UDP 1027 is assigned to `6a44` (RFC 6751, Experimental), a scheme for giving hosts native ISP-prefixed IPv6 addresses from behind IPv4-only CPE by tunnelling IPv6 in UDP/IPv4; it saw essentially no deployment. Anything actually listening on TCP 1027 is therefore unregistered, and on pre-Vista Windows it is most often another dynamically allocated RPC endpoint from the old 1025-5000 range.",
  "exposure": {
    "verdict": "careful",
    "note": "There is no standard service here, so you cannot reason about it from the port number — identify the owning process before deciding whether it should be reachable at all."
  },
  "checkCommand": "sudo lsof -nP -iTCP:1027 -sTCP:LISTEN",
  "links": [
    {
      "title": "RFC 6751 — Native IPv6 behind IPv4-to-IPv4 NAT CPE (6a44)",
      "url": "https://www.rfc-editor.org/rfc/rfc6751.html",
      "kind": "spec"
    },
    {
      "title": "IANA Service Name and Transport Protocol Port Number Registry",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml",
      "kind": "iana"
    }
  ]
}