The first number in an unassigned IANA block, unnamed in Nmap and unclaimed by any product.
IANA's unassigned range 28201-28239 begins at this port, so 28201 is registered to nobody. Nmap lists it as 'unknown' with a small open-frequency, enough to include it in the default 1000-port TCP scan. Nothing in the public record — vendor docs, RFCs, or malware reporting — associates it with a service. An open 28201 is a local decision someone made, and the banner is the only way to find out whose.
Expose with care
Unknown by default. Identify the listener; an unexplained open port on a public IP deserves closing rather than documenting.
$ nmap -Pn -sV -p 28201 --reason 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.