{
  "port": 30,
  "protocol": "tcp",
  "service": "Unassigned",
  "oneLiner": "Unassigned at IANA — no registered service and no established squatter.",
  "whatItIs": "IANA lists port 30 as Unassigned on TCP and UDP, with no assignee and no reference. No widely deployed daemon binds it by default. It shows up in scan results only as an unidentified listener, and there is no protocol convention to guess from. The useful step is to find the owning process on the host rather than to infer a service from the number.",
  "exposure": {
    "verdict": "careful",
    "note": "Unregistered and unidentified; do not open it without knowing exactly which process is behind it."
  },
  "checkCommand": "sudo lsof -nP -iTCP:30 -sTCP:LISTEN",
  "links": [
    {
      "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"
    }
  ]
}