Either a Bacula backup Director or the second raw-print port on a multi-port print server.
IANA registers 9101 to the Bacula Director, the daemon that schedules backup jobs and that bconsole and the Bareos fork's console connect to. The same port is also the second AppSocket/JetDirect print channel on multi-port HP print servers, so nmap labels it both ways. Which one you have is usually obvious from the host: a backup server or a printer.
Do not expose
The Director is the control plane for every backup and restore in the estate; it authenticates with shared secrets from the config files and belongs on a management network, not the internet.
$ nc -vz -w 3 TARGET 9101Seen 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.
Get Beige Box →also available as JSON · Markdown
Corrections or a missing port? Reply @rimrocksystems.