Port 3650: PRISMIQ VOD Plug-in — A Registered Ghost

What This Port Is

Port 3650 is officially registered with IANA under the service name prismiq-plugin, assigned to the PRISMIQ VOD plug-in in January 2003.¹

PRISMIQ made a set-top box in the early 2000s that bridged your PC and your TV—MP3s, video, photos, streaming from your computer room to your living room. It was an early attempt at what we'd now call a media streamer. Port 3650 was registered to support its video-on-demand component.²

PRISMIQ is gone. The product is gone. The IANA registration remains—a placeholder with no tenant.

What Range This Port Belongs To

Port 3650 sits in the registered ports range (1024–49151). These ports are not reserved by the operating system the way well-known ports (0–1023) are. Any application can bind to them without elevated privileges. IANA maintains a registry of assigned names to prevent collisions, but registration is voluntary and enforcement is nonexistent.

When a company registers a port and then disappears, nothing reclaims it. The registry entry persists. The port becomes what you might call a registered ghost: officially assigned, practically available.

What's Actually on This Port Today

Almost certainly nothing, by default.

If you're seeing traffic on port 3650 on your network, it isn't PRISMIQ. Possible explanations:

• A custom application or internal service someone configured to use it
• Malware or a backdoor (uncommon on non-standard ports, but not unheard of)
• A misconfigured or legacy piece of software

Check what's listening before assuming.

How to Check What's Using Port 3650

Linux / macOS:

# Show the process listening on port 3650
ss -tlnp sport = :3650

# Or with lsof:
lsof -i :3650

Windows:

# Show all listening ports with process IDs
netstat -ano | findstr :3650

# Then look up the PID:
tasklist | findstr <PID>

If nothing returns, nothing is listening. That's the expected result.

Why Ghost Ports Matter

The registered port range has 48,128 slots. Many of them are like port 3650—registered by companies or individuals who no longer exist, for products no longer running. IANA doesn't expire registrations. There's no mechanism to reclaim them.

This is mostly harmless. The Internet is large; ports are plentiful. But it means the registry is partly a historical artifact rather than a live map of what's actually in use. When you're troubleshooting or choosing a port for an internal service, treat any port you don't recognize as potentially unoccupied, regardless of what the registry says—then verify.