# WHATPORT(3390)

## NAME

port 3390 — dsc (Distributed Service Coordinator) — Registered as Distributed Service Coordinator, but in practice the port next door to RDP.

Protocol: TCP/UDP  
IANA registry

## DESCRIPTION

IANA assigns 3390 to dsc, "Distributed Service Coordinator", registered to Charles Honton with no published specification. Nothing in common use implements it. What you actually find on 3390 is usually a second RDP listener: when two Windows hosts sit behind one NAT, or an admin wants RDP off the obvious port, 3390 is the reflexive next choice. That is convention, not registration — confirm by fingerprinting rather than assuming.

## EXPOSURE

**Expose with care.** If a fingerprint shows RDP here, apply the 3389 rule and keep it off the internet; if it is something else, identify the process before deciding.

## CHECK

```sh
nmap -Pn -sV -p 3390 TARGET
```

## SEE ALSO

- iana — [IANA port registry — 3390 (dsc)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=3390) (iana.org)

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HTML: <https://whatport.net/3390/> · JSON: <https://whatport.net/3390.json> · full dataset: <https://whatport.net/ports.json>