The Oracle/Sun Java Web Console over HTTPS; registered at IANA today as radg.
IANA's current entry for 6789/tcp is radg, "GSS-API for the Oracle Remote Administration Daemon", registered in 2002 and updated in 2016; older service tables, including nmap's, still print the earlier names smc-https and ibm-db2-admin. In practice this is the port of the Oracle Java Web Console on Solaris, reached as https://hostname:6789, and Oracle's documentation notes the console ships configured to refuse remote connections unless the tcp_listen property is turned on. An open 6789 therefore usually means a Solaris box with its administration console deliberately opened up.
Do not expose
A root-capable system administration console. Oracle's default is local-only for a reason; if it must be remote, reach it over a VPN rather than from the internet.
$ curl -skI https://TARGET:6789/Seen 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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