# WHATPORT(1100)

## NAME

port 1100 — MCTP (IANA) / JBoss HA-JNDI — Registered to MCTP, but in the field this is the clustered JBoss HA-JNDI naming port sitting one above 1099.

Protocol: TCP  
IANA registry

## DESCRIPTION

IANA registers 1100 as mctp. What actually shows up on scans is JBoss Application Server's clustered naming service: the HA-JNDI configuration guide states that the Port attribute "to which the HA-JNDI server will bind waiting for JNP clients" defaults to 1100, with the RMI stub port defaulting to 1101. So finding 1100 open usually means a clustered legacy JBoss/EAP node, and 1098, 1099 and 1101 are typically open alongside it. HA-JNDI lets clients read and write the JNDI tree, which is why it has a long CVE history.

## EXPOSURE

**Do not expose.** A reachable JNDI naming service lets attackers manipulate bindings and pull in remote objects; keep the whole 1098-1101 cluster range on a private network.

## CHECK

```sh
nmap -Pn -p 1098-1101 -sV TARGET
```

## SEE ALSO

- docs — [JBoss Server Configuration Guide — Clustered JNDI (HA-JNDI) configuration](https://docs.jboss.org/jbossas/docs/Server_Configuration_Guide/4/html/clustering-jndi-jboss.html) (docs.jboss.org)
- iana — [IANA Service Name and Transport Protocol Port Number Registry](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml) (iana.org)

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HTML: <https://whatport.net/1100/> · JSON: <https://whatport.net/1100.json> · full dataset: <https://whatport.net/ports.json>