{
  "port": 9091,
  "protocol": "tcp",
  "service": "Transmission RPC / Prometheus Pushgateway",
  "oneLiner": "Usually a Transmission BitTorrent web UI or a Prometheus Pushgateway — both default here.",
  "whatItIs": "IANA has 9091 registered to a private assignment called xmltec-xmlmail that you will essentially never meet. In practice the port belongs to two popular pieces of software: Transmission's RPC and web interface (the /transmission/web/ UI behind transmission-daemon), and the Prometheus Pushgateway, which listens on 9091 by default for metrics pushed by batch jobs. On a home or lab network a listener here is almost always Transmission on a NAS or seedbox; in a monitoring stack it is the Pushgateway.",
  "exposure": {
    "verdict": "never",
    "note": "Transmission's RPC lets a caller add torrents and set the download directory, and older builds shipped with weak or absent authentication; the Pushgateway accepts unauthenticated metric writes and deletes. Keep both on the LAN or behind an authenticating reverse proxy."
  },
  "checkCommand": "curl -sS -m 5 -o /dev/null -w '%{http_code}\\n' http://TARGET:9091/",
  "links": [
    {
      "title": "transmission/transmission",
      "url": "https://github.com/transmission/transmission",
      "kind": "github"
    },
    {
      "title": "prometheus/pushgateway (default listen port 9091)",
      "url": "https://github.com/prometheus/pushgateway",
      "kind": "github"
    },
    {
      "title": "IANA port registry — 9091 (xmltec-xmlmail)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=9091",
      "kind": "iana"
    }
  ]
}