# WHATPORT(1027)

## NAME

port 1027 — Reserved (TCP) / 6a44 (UDP) — Reserved by IANA on TCP; the UDP side belongs to 6a44, an experimental IPv6-behind-NAT44 mechanism.

Protocol: TCP/UDP  
IANA registry

## DESCRIPTION

IANA marks TCP 1027 simply "Reserved" — there is no service name and no assignee, so nothing is entitled to it. UDP 1027 is assigned to `6a44` (RFC 6751, Experimental), a scheme for giving hosts native ISP-prefixed IPv6 addresses from behind IPv4-only CPE by tunnelling IPv6 in UDP/IPv4; it saw essentially no deployment. Anything actually listening on TCP 1027 is therefore unregistered, and on pre-Vista Windows it is most often another dynamically allocated RPC endpoint from the old 1025-5000 range.

## EXPOSURE

**Expose with care.** There is no standard service here, so you cannot reason about it from the port number — identify the owning process before deciding whether it should be reachable at all.

## CHECK

```sh
sudo lsof -nP -iTCP:1027 -sTCP:LISTEN
```

## SEE ALSO

- spec — [RFC 6751 — Native IPv6 behind IPv4-to-IPv4 NAT CPE (6a44)](https://www.rfc-editor.org/rfc/rfc6751.html) (rfc-editor.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/1027/> · JSON: <https://whatport.net/1027.json> · full dataset: <https://whatport.net/ports.json>