{
  "port": 89,
  "protocol": "tcp",
  "service": "SU/MIT Telnet Gateway",
  "oneLiner": "Registered to an ancient Stanford/MIT Telnet gateway; nothing runs it today.",
  "whatItIs": "IANA records port 89 as `su-mit-tg`, the SU/MIT Telnet Gateway, registered by Mark Crispin. It was a gateway service between Stanford and MIT networks in the early Internet and has no surviving specification or implementation. Modern scans that report \"su-mit-tg\" are just echoing `/etc/services`. In practice an open 89 is an unrelated service parked one port above 88.",
  "exposure": {
    "verdict": "careful",
    "note": "No standard service claims this port in practice, so an open 89 needs fingerprinting before you trust it."
  },
  "checkCommand": "nc -vz TARGET 89",
  "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"
    }
  ]
}