The license-management port of Sassafras KeyServer, used by its KeyAccess clients.
IANA registers 19283 as keysrvr, "Key Server for SASSAFRAS", to Sassafras Software, whose KeyServer product does software-license metering and computer-inventory tracking on university and enterprise fleets. Managed machines run a KeyAccess client that talks to the server on this port, which is why it shows up across a whole lab or campus subnet at once. Nmap sees it more often on UDP than TCP.
Do not expose
An internal asset- and license-management service that every managed endpoint trusts. There is no reason for it to answer outside the organization's network.
$ nc -vz -w 3 TARGET 19283Seen 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.