# WHATPORT(8042)

## NAME

port 8042 — Hadoop YARN NodeManager UI; Orthanc DICOM HTTP — Two well-known defaults share it: YARN's NodeManager web UI and the Orthanc DICOM server's REST API.

Protocol: TCP  
IANA: fs-agent

## DESCRIPTION

IANA assigns 8042 to FireScope Agent, which is not what you will find. In a Hadoop cluster, `yarn.nodemanager.webapp.address` defaults to `${yarn.nodemanager.hostname}:8042`, so every NodeManager serves its web UI here. In medical imaging, Orthanc's default configuration "creates a HTTP server for the REST API that listens on the port 8042", which is also its web interface. Context — a datacentre cluster versus a hospital or research network — tells you which one you found.

## EXPOSURE

**Do not expose.** The YARN NodeManager UI exposes cluster topology, running containers and application logs with no authentication in a default install. Orthanc on 8042 fronts a store of patient DICOM images. Neither should be reachable from the internet.

## CHECK

```sh
curl -sI http://TARGET:8042/
```

## SEE ALSO

- docs — [Apache Hadoop — yarn-default.xml (yarn.nodemanager.webapp.address, :8042)](https://hadoop.apache.org/docs/stable/hadoop-yarn/hadoop-yarn-common/yarn-default.xml) (hadoop.apache.org)
- docs — [Orthanc Book — Configuration (HTTP server on port 8042)](https://orthanc.uclouvain.be/book/users/configuration.html) (orthanc.uclouvain.be)
- iana — [IANA Service Name and Transport Protocol Port Number Registry — 8042 (fs-agent)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=8042) (iana.org)

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