Apple AirPort base station administration — the port AirPort Utility configures the router on.
The IANA registration for 5009 is winfs, "Microsoft Windows Filesystem", which you will essentially never meet. What actually answers is Apple's base station admin service: AirPort Utility talks to an AirPort Express, Extreme, or Time Capsule on TCP 5009 to read and write its configuration. Apple discontinued the AirPort line in 2018, so a listener today is an old base station still in service — and the port is a reliable fingerprint for one.
Do not expose
This is the router's configuration plane on hardware that stopped receiving firmware updates. It belongs on the LAN only; never enable base-station administration from the WAN side.
$ nc -vz TARGET 5009Seen 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.
Get Beige Box →also available as JSON · Markdown
Corrections or a missing port? Reply @rimrocksystems.