# WHATPORT(7402)

## NAME

port 7402 — RTPS data-distribution meta-traffic — 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.

Protocol: TCP/UDP  
IANA registry

## DESCRIPTION

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

**Do not expose.** 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.

## CHECK

```sh
sudo tcpdump -ni any 'udp portrange 7400-7500'
```

## SEE ALSO

- iana — [IANA port registry — 7402 (rtps-dd-mt)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=7402) (iana.org)
- source — [eProsima Fast DDS — RTPS/DDS implementation used by ROS 2](https://github.com/eProsima/Fast-DDS) (github.com)

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HTML: <https://whatport.net/7402/> · JSON: <https://whatport.net/7402.json> · full dataset: <https://whatport.net/ports.json>