{
  "port": 7921,
  "protocol": "tcp",
  "service": "Unassigned",
  "oneLiner": "IANA has never assigned this port, and no common service is known to squat it.",
  "whatItIs": "7921 falls inside the block IANA lists as 7914-7931 Unassigned, so there is no registered service name to look up. Nmap's service database has no name for it either and files it as `unknown`, seen on roughly two hundredths of a percent of scanned hosts. In practice that means anything listening here is some application's private choice of port, not a standard protocol. Identify it by its banner rather than by the number.",
  "exposure": {
    "verdict": "careful",
    "note": "An unregistered port tells you nothing about safety — find out what the listener actually is before deciding, and treat an unidentified internet-facing service as untrusted."
  },
  "checkCommand": "nmap -sV -Pn -p 7921 TARGET",
  "links": [
    {
      "title": "IANA Service Name and Transport Protocol Port Number Registry — 7921",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=7921",
      "kind": "iana"
    },
    {
      "title": "nmap/nmap — nmap-services (port frequency database)",
      "url": "https://github.com/nmap/nmap/blob/master/nmap-services",
      "kind": "github"
    }
  ]
}