# WHATPORT(89)

## NAME

port 89 — SU/MIT Telnet Gateway — Registered to an ancient Stanford/MIT Telnet gateway; nothing runs it today.

Protocol: TCP  
IANA registry

## DESCRIPTION

IANA records port 89 as `su-mit-tg`, the SU/MIT Telnet Gateway, registered by Mark Crispin. It was a gateway service between Stanford and MIT networks in the early Internet and has no surviving specification or implementation. Modern scans that report "su-mit-tg" are just echoing `/etc/services`. In practice an open 89 is an unrelated service parked one port above 88.

## EXPOSURE

**Expose with care.** No standard service claims this port in practice, so an open 89 needs fingerprinting before you trust it.

## CHECK

```sh
nc -vz TARGET 89
```

## SEE ALSO

- 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/89/> · JSON: <https://whatport.net/89.json> · full dataset: <https://whatport.net/ports.json>