No IANA registration and no common software — an open 9098 is whatever someone put there.
9098 is unassigned in the IANA service name and port number registry, and nmap's services file lists it as unknown with a very low observed frequency. There is no standard protocol, no default daemon, and no well-documented malware association to report. If you find it open, the answer comes from the host itself: a service-version scan or the process listening on the box.
Expose with care
The verdict depends entirely on what is actually bound there; identify the service before deciding, and do not assume an unregistered high port is harmless.
$ nmap -sV -Pn -p 9098 TARGETSeen 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.