{
  "port": 9,
  "protocol": "both",
  "service": "Discard",
  "oneLiner": "Discard — a black hole that accepts everything you send and replies with nothing.",
  "whatItIs": "RFC 863 defines Discard as a service that reads and throws away all data with no response, on TCP and UDP alike. It was built as a throughput and sink test for network stacks, and it shipped alongside echo, daytime and chargen as an inetd built-in. It is disabled by default on modern systems. Port 9 is also the conventional destination for Wake-on-LAN magic packets over UDP, which is why WoL tooling references it even though no discard server is involved.",
  "exposure": {
    "verdict": "careful",
    "note": "Harmless in content since it never replies, but it is an unnecessary listener; there is no reason to expose it deliberately."
  },
  "checkCommand": "printf 'sink this\\n' | nc -v TARGET 9",
  "links": [
    {
      "title": "RFC 863 — Discard Protocol",
      "url": "https://www.rfc-editor.org/rfc/rfc863.html",
      "kind": "spec"
    },
    {
      "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"
    }
  ]
}