Port 3378: WSICOPY — A Name Without a Protocol

What Range This Port Belongs To

Port 3378 falls in the registered port range (1024–49151), also called user ports. This range is administered by IANA, the Internet Assigned Numbers Authority. Unlike the well-known ports below 1024 (which require root privileges on Unix systems and carry famous protocols like HTTP, SSH, and DNS), registered ports can be claimed by any organization that submits a request. IANA records the name and moves on. They don't verify that the protocol works, that the software ships, or that anyone ever uses it.¹

The WSICOPY Mystery

IANA lists port 3378 as assigned to a service called WSICOPY, for both TCP and UDP. That's the entirety of what's documented.²

No RFC. No company name. No description. No website. No software that announces itself as WSICOPY. Searching for WSICOPY turns up only port database mirrors copying the IANA entry back and forth at each other.

This happens. Someone files for a port assignment, the paperwork goes through, and then the project dies or pivots or simply never ships. The name stays in the registry indefinitely. IANA doesn't reclaim registered ports — once assigned, the entry persists, a placeholder for something that may never have existed in any meaningful form.

What You'll Actually Find on Port 3378

If you see traffic on port 3378, it's almost certainly not WSICOPY (whatever that was). More likely candidates:

• Application-specific usage: Software that picks ports from the registered range arbitrarily, rather than using the assigned service
• Port scanning noise: Automated scanners probe all registered ports looking for open services
• Ephemeral connections: Operating systems sometimes use registered ports as source ports for outbound connections

How to Check What's Listening

If port 3378 is open on your machine and you want to know what's using it:

On Linux/macOS:

ss -tlnp | grep 3378
# or
lsof -i :3378

On Windows:

netstat -ano | findstr :3378

The output will show the process ID. From there, you can identify the specific application using the port — which almost certainly won't call itself WSICOPY.

Why Ghost Registrations Exist

The registered port range has over 48,000 slots. Thousands of them look like this: a name in a table, no documentation behind it. Some are abandoned projects. Some are internal tools from companies that never published anything. Some are bureaucratic artifacts from the early Internet, when registering a port felt like planting a flag.

The system works well enough because most software either uses well-known ports (below 1024) or negotiates ports dynamically. The registered range is more directory than law — useful when it's populated, mostly ignored when it isn't.