Registered in 2004 as "M2m Services" with no published protocol behind the name.
IANA assigns m2mservices to TCP and UDP 8383, described only as "M2m Services", registered in November 2004. There is no specification, no reference document, and no widely deployed implementation tied to the registration. In practice 8383 is one of the generic high HTTP-alternate ports that application stacks and admin consoles grab because it is memorable, so what answers there is whatever the local software chose. Nmap sees it open on about 0.02% of hosts.
Expose with care
The registry name tells you nothing about what is listening. Identify the service — if it turns out to be an admin console or a dev server, judge it by that, not by the port.
$ sudo lsof -nP -iTCP:8383 -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.