No IANA registration and no default service — ordinary Linux ephemeral space.
32783 is inside IANA's unassigned 32778–32800 block: no service name, no assignee, no reference. Nmap carries it only as an unknown TCP port, at a lower frequency than the RPC-named ports below it. Its practical identity is that it is part of the Linux default ephemeral port range, documented as 32768–60999, so the kernel hands it out to outbound sockets, to programs that bind port 0, and to Docker when publishing a container port without a fixed host port. Finding it open means a process took a free port, not that a known service is running.
Expose with care
An anonymous dynamically assigned port — identify the owning process locally; do not firewall-allow the number on the assumption it means something.
$ sudo lsof -nP -iTCP:32783 -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.