Where Adobe Flash asked permission before opening a raw socket — a relic of a dead plugin.
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.
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.
$ printf '<policy-file-request/>\0' | nc TARGET 843Seen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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Corrections or a missing port? Reply @rimrocksystems.