What This Port Is
Port 2398 sits in the registered port range (1024–49151) — the middle tier of the port numbering system, below the well-known ports reserved for HTTP and SSH, above the ephemeral ports your OS assigns on the fly.
IANA lists it as assigned to a service called "Orbiter" on both TCP and UDP.1 The registration exists. The software, if it ever shipped, is nowhere to be found in common use.
The Registered Port Range
Registered ports are where applications stake their claim. A developer submits a request to IANA, IANA adds the entry, and the port is theoretically "spoken for." The catch: there's no enforcement. An assignment doesn't mean the software is widely deployed, actively maintained, or even still running anywhere.
Port 2398's "Orbiter" entry is a textbook example. It has a name and a registrant but no footprint. This is common in the registered range — it contains thousands of ports assigned to software that shipped in limited quantities, was abandoned, or was registered speculatively and never used.
The Gaming Neighborhood
Port 2398 also falls inside 2300–2400 (UDP), a range that Microsoft's DirectPlay and the MSN Gaming Zone used heavily in the early 2000s. Games like Age of Empires II, Flight Simulator 2000, and Freelancer used ports scattered through this block for peer-to-peer sessions.2
Those games are long past their active networking days, but some legacy installations still open ports in this range. If you see 2398 active on an older Windows machine, a retro gaming setup is worth investigating.
What to Do If You See It Open
An open port you don't recognize is worth five minutes of your time.
On Linux or macOS:
On Windows:
The process ID in the output maps to a running program. On Windows, open Task Manager, go to Details, and find the matching PID.
If nothing in your environment intentionally uses port 2398, there's no reason it should be open. Close it.
Why Unassigned-in-Practice Ports Matter
The registered port range holds over 48,000 ports. Most are lightly used, and a meaningful fraction are ghost registrations like this one. Understanding the range helps you reason about what should and shouldn't be listening on any given machine.
A port appearing in the IANA registry isn't a green light. It means someone once asked for it. What runs on your system is a different question — and one only lsof or netstat can actually answer.
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