Port 2806 sits in the registered ports range (1024–49151). These ports are managed by IANA — the Internet Assigned Numbers Authority — which coordinates the global pool of port numbers so that different applications don't collide. To get a port registered here, you request it, name it, and provide contact information.
Port 2806 is registered. Its official service name is cspuni. Nobody knows what that means.
The IANA entry lists no assignee, no contact address, no description, and no RFC.1 The name "cspuni" appears in the registry the way a name appears on a door that no one answers.
The Wireshark Confusion
Port 2806 is most often encountered in Wireshark traces, not because something important is happening there, but because of how Wireshark works.
Wireshark maintains a services file mapping port numbers to their registered names. When it sees traffic on port 2806 — even if that port is just being used as an ephemeral outbound port by a client making an FTPS connection — it labels the traffic "cspuni." Users see the label, don't recognize it, and open forum threads asking what it is.2
The answer is always the same: it's not your problem. Wireshark found a name, applied it, and the name means nothing actionable. If you're seeing "cspuni" in a capture, look at what the other port in the connection is doing. That's the real story.
You can turn this off in Wireshark under View → Name Resolution → Transport Layer if the label is causing confusion.
What Range This Port Belongs To
Registered ports (1024–49151) occupy the middle of the port number space:
- Well-known ports (0–1023): Reserved for core protocols — HTTP, HTTPS, SSH, DNS. Binding here requires root/administrator privileges.
- Registered ports (1024–49151): Where applications register to avoid conflicts. IANA tracks these, but enforcement is loose.
- Dynamic/ephemeral ports (49152–65535): Temporary ports assigned by the OS for outbound connections. No registration required.
Port 2806 is registered, but registration doesn't guarantee activity. Many registered ports were claimed and never used, or were used by software that no longer exists.
Checking What's Actually on Port 2806
If you see port 2806 active on your system, you can find out what's using it:
Linux/macOS:
Windows:
If something unexpected is listening on port 2806, identify the process before assuming the worst. Ephemeral port assignments are essentially random — your browser or any client application might briefly use 2806 as an outbound port for an unrelated connection.
Why Ghost Registrations Exist
IANA's port registry is not a live system with automatic cleanup. Ports get registered, software gets abandoned, companies get acquired, and the entry stays. The result is a registry with hundreds of ports like 2806: technically claimed, practically vacant.
This isn't a failure of the system. It's the cost of coordination at scale. A port that sits unused hurts nothing. A port conflict between two applications — both assuming they have exclusive use of a number — breaks things. The ghost registration is the lesser problem.
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