{
  "port": 100,
  "protocol": "tcp",
  "service": "Unassigned (historically \"newacct\")",
  "oneLiner": "Unassigned by IANA; `/etc/services` still lists it as newacct and flags it as unauthorized use.",
  "whatItIs": "IANA marks TCP 100 as Unassigned. Most Unix `/etc/services` files nonetheless carry the line `newacct 100/tcp # [unauthorized use]` — a squatted \"new account\" service that was never registered, and the comment is IANA's own note that the usage is unsanctioned. So a scanner may label an open 100 \"newacct\" while no such protocol is defined. Treat the label as historical trivia and fingerprint whatever is actually listening.",
  "exposure": {
    "verdict": "careful",
    "note": "There is no standard service to reason about here; an open 100 is an unknown listener until you identify it."
  },
  "checkCommand": "nc -vz TARGET 100",
  "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"
    }
  ]
}