# WHATPORT(2021)

## NAME

port 2021 — servexec — Registered as servexec (xinuexpansion1 on UDP); no current standard service.

Protocol: TCP  
IANA registry

## DESCRIPTION

IANA registers 2021/tcp as servexec and 2021/udp as xinuexpansion1, another pair of undocumented early registrations. Nothing maintained implements them. Because it sits one digit above the FTP control port, 2021 is also a common manual choice for an alternate FTP or SFTP listener, so fingerprint rather than assume.

## EXPOSURE

**Expose with care.** If it turns out to be FTP moved off 21, that is cleartext authentication and should be never — replace it with SFTP or FTPS.

## CHECK

```sh
nc -vz TARGET 2021
```

## SEE ALSO

- iana — [IANA port registry — 2021 (servexec)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=2021) (iana.org)

---

HTML: <https://whatport.net/2021/> · JSON: <https://whatport.net/2021.json> · full dataset: <https://whatport.net/ports.json>