No registration, no default service — an open 9409 is entirely site-specific.
9409 has no IANA assignment and appears as unknown in nmap's services table with a negligible observed frequency. There is no protocol, product default, or documented malware family to attach to it. Whatever is listening was configured by hand or chosen by an application at random.
Expose with care
Judge it on the service behind it; nothing about the number argues either way.
$ nmap -sV -Pn -p 9409 TARGETSeen 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.