{
  "port": 33,
  "protocol": "both",
  "service": "DSP (Display Support Protocol)",
  "oneLiner": "Registered to the Display Support Protocol, a service you will effectively never meet.",
  "whatItIs": "IANA registers port 33 as 'dsp — Display Support Protocol', assigned to Ed Cain, on both TCP and UDP. There is no RFC behind the registration and no reference implementation in common use. Nothing on a modern system binds it, so a listener here is almost certainly unrelated software that picked a free low port. Treat the registration as a name in a table, not as a prediction of what you found.",
  "exposure": {
    "verdict": "careful",
    "note": "The registered protocol is effectively extinct, so whatever answers on 33 is unidentified and should be named before it is exposed."
  },
  "checkCommand": "nc -vz TARGET 33",
  "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"
    }
  ]
}