Reserved at IANA; older service tables still call it esp, the eSilo Storage Protocol.
The current IANA registry marks 6567 as Reserved, with no service name and no assignee. Legacy service tables, including nmap-services, still print it as esp, "eSilo Storage Protocol" — a name that outlived its vendor and now survives mostly as a scanner label. Nothing in common use listens here, so a scanner reporting "esp" on 6567 is guessing from a name table, not from a probe response.
Expose with care
Do not trust the service name your scanner prints for this one; identify the actual process before deciding what the exposure is.
$ sudo lsof -nP -iTCP:6567 -sTCP:LISTENSeen 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.