{
  "port": 9040,
  "protocol": "tcp",
  "service": "Tor TransPort (convention)",
  "oneLiner": "The number Tor transparent-proxy setups conventionally use for TransPort — not an IANA assignment and not a Tor default.",
  "whatItIs": "Tor's TransPort option accepts TCP connections that a firewall has transparently redirected, so traffic gets torified without the application knowing about SOCKS. Tor ships it disabled (the default is 0) and does not pick a port for you; 9040 is simply the number that torrc examples and Tor-routing gateway configurations settled on, which is why iptables/pf rules everywhere redirect to it. IANA lists 9027–9049 as Unassigned. A listener on 9040 means a Tor transparent proxy is configured on that host or gateway.",
  "exposure": {
    "verdict": "never",
    "note": "A reachable TransPort is an open proxy into the Tor network for anyone who can send it a redirected connection; bind it to the internal interface it is meant to serve."
  },
  "checkCommand": "sudo lsof -nP -iTCP:9040 -sTCP:LISTEN",
  "links": [
    {
      "title": "tor(1) manual — TransPort",
      "url": "https://manpages.debian.org/unstable/tor/tor.1.en.html",
      "kind": "official-docs"
    },
    {
      "title": "IANA Service Name and Transport Protocol Port Number Registry — 9040",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=9040",
      "kind": "iana"
    }
  ]
}