# WHATPORT(843)

## NAME

port 843 — Flash socket policy server — Where Adobe Flash asked permission before opening a raw socket — a relic of a dead plugin.

Protocol: TCP  
IANA registry

## DESCRIPTION

Flash Player 9 and later required a cross-domain policy before a SWF could open a socket to a host: it connected to TCP 843 on that host, sent the literal string `<policy-file-request/>` followed by a NUL byte, and expected an XML policy document in reply. Sites running Flash chat, games or sockets-based apps therefore ran a tiny policy daemon such as flashpolicyd on 843 alongside the real service. The port was never IANA-registered — it was Adobe's convention. Flash reached end of life in December 2020, so a listener here today is a forgotten leftover process.

## EXPOSURE

**Expose with care.** The daemon only ever emits a static XML policy, but a permissive `<allow-access-from domain="*"/>` was a real cross-domain hole; with Flash dead, the right move is to turn it off.

## CHECK

```sh
printf '<policy-file-request/>\0' | nc TARGET 843
```

## SEE ALSO

- source — [flashpolicyd — Flash socket policy daemon (listens on 843)](https://github.com/ripienaar/flashpolicyd) (github.com)
- 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/843/> · JSON: <https://whatport.net/843.json> · full dataset: <https://whatport.net/ports.json>