Registered to DEC's distributed lock manager, but on a Mac it is Open Directory Proxy.
IANA registers 625 as dec-dlm (previously spelled dec_dlm), the Digital Equipment Corporation Distributed Lock Manager from the VMS cluster era, which you will not encounter today. The number is widely reported on macOS as Open Directory Proxy — odproxyd, which relays directory lookups for a Mac bound to an Open Directory domain — but Apple publishes no documentation for the port, so treat that as a field observation and confirm it against the running process rather than the registry name.
Do not expose
If this is Open Directory Proxy, it answers questions about your account namespace and belongs on a managed LAN; if it is something else, you do not know what it is until you identify the process.
$ nc -vz -w 3 TARGET 625Seen 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.