Apple's discontinued Xgrid distributed-computing service — a live one means a very old Mac.
Xgrid was Apple's cluster-computing framework in Mac OS X and Mac OS X Server: an Xgrid controller accepted job submissions from clients and farmed tasks out to agent machines, and IANA still carries the port under the name xgrid. Apple removed Xgrid in OS X Mountain Lion, so nothing current ships it. Finding 4111 open today points at a Mac left on 10.7 or earlier with Xgrid still enabled.
Do not expose
It accepts job submissions — remote execution — from an unmaintained, end-of-life service stack; there is no configuration that makes this safe to publish.
$ nc -vz -w 3 TARGET 4111Seen 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.