{
  "port": 2020,
  "protocol": "tcp",
  "service": "xinupageserver",
  "oneLiner": "Registered to the Xinu teaching operating system; a historical name with no live protocol.",
  "whatItIs": "IANA registers 2020 as xinupageserver, from Xinu, Douglas Comer's teaching operating system at Purdue, whose remote page server used this port. It is a museum registration: no shipping software binds it today. An open 2020 is an application that took the port, or reverse telnet to line 20 on a Cisco terminal server.",
  "exposure": {
    "verdict": "careful",
    "note": "Unidentified listener: identify it before allowing it through a firewall."
  },
  "checkCommand": "nc -vz TARGET 2020",
  "links": [
    {
      "title": "IANA port registry — 2020 (xinupageserver)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=2020",
      "kind": "iana"
    }
  ]
}