{
  "port": 7402,
  "protocol": "both",
  "service": "RTPS data-distribution meta-traffic",
  "oneLiner": "Registered to the RTPS discovery family behind DDS — but real DDS nodes compute their ports from the domain ID, so 7402 itself is rarely the listener.",
  "whatItIs": "IANA reserves 7400-7402 for RTPS, the Real-Time Publish-Subscribe wire protocol that DDS implementations use: rtps-discovery, rtps-dd-ut (user traffic) and rtps-dd-mt (meta-traffic, this port). In practice implementations such as eProsima Fast DDS — the default middleware under ROS 2 — and RTI Connext derive their actual UDP ports from a base plus an offset for the DDS domain ID and participant index, so a scan of a live robotics or industrial fleet shows a spread of ports in the 7400 range rather than exactly 7402. Discovery traffic is mostly UDP, including multicast, so a TCP listener on 7402 is more likely something unrelated squatting the number.",
  "exposure": {
    "verdict": "never",
    "note": "DDS discovery is unauthenticated unless the DDS Security plugins are explicitly enabled; anything reachable on the RTPS ports can enumerate participants, topics and data. Keep it on a trusted segment or a VPN."
  },
  "checkCommand": "sudo tcpdump -ni any 'udp portrange 7400-7500'",
  "links": [
    {
      "title": "IANA port registry — 7402 (rtps-dd-mt)",
      "url": "https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=7402",
      "kind": "iana"
    },
    {
      "title": "eProsima Fast DDS — RTPS/DDS implementation used by ROS 2",
      "url": "https://github.com/eProsima/Fast-DDS",
      "kind": "github"
    }
  ]
}