{
  "port": 4242,
  "protocol": "tcp",
  "service": "OpenTSDB / Quassel core (unregistered convention)",
  "oneLiner": "A popular round-number port: OpenTSDB's metrics daemon and Quassel's IRC core both default here.",
  "whatItIs": "IANA has no individual entry for 4242 — it sits inside the 4200–4299 block registered as vrml-multi-use — so everything here is convention. OpenTSDB's time-series daemon leaves tsd.network.port required-but-empty in its source config and sets it to 4242 in the packaged one, and serves its HTTP API and metrics ingest there. Quassel's always-on IRC core also defaults to 4242 for its clients, and Code42's CrashPlan backup client used it as well. Fingerprint before assuming: an HTTP answer on /api/version is OpenTSDB, a binary handshake is more likely Quassel.",
  "exposure": {
    "verdict": "careful",
    "note": "Which occupant it is decides everything. OpenTSDB has no built-in authentication at all, so a public tsd is an open read/write metrics store and should never face the internet; a Quassel core is designed for remote clients and is reasonable to expose, but only with TLS and a strong password."
  },
  "checkCommand": "curl -s --max-time 5 http://TARGET:4242/api/version",
  "links": [
    {
      "title": "OpenTSDB/opentsdb — packaged opentsdb.conf, tsd.network.port = 4242",
      "url": "https://github.com/OpenTSDB/opentsdb/blob/master/build-aux/rpm/opentsdb.conf",
      "kind": "github"
    },
    {
      "title": "Quassel IRC — changing the core's default port 4242",
      "url": "https://quassel-irc.org/node/61",
      "kind": "official-docs"
    },
    {
      "title": "IANA port registry — 4200-4299 (vrml-multi-use)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=4242",
      "kind": "iana"
    }
  ]
}