Port 1674 is registered. Just not to anything you're likely running.
IANA lists it as proshare-mc-2 — the second multicast port for Intel ProShare, a desktop videoconferencing system Intel introduced in January 1994. ProShare let users hold face-to-face video calls while simultaneously editing documents together in real time. At $2,499 a kit (camera and telephone headset included), it was Intel's bet that the PC was about to become a communication platform, not just a productivity tool.
The technology was ambitious enough that NASA used it aboard the Space Shuttle Endeavour — astronauts shared photos and documents with ground control in Houston, a dramatic improvement over the previous method of trading files back and forth between missions.
Intel kept investing. By 1998, the price had dropped to $999. But the market wasn't ready, broadband wasn't ubiquitous, and ProShare eventually faded. The product is gone. The port registration remains.
What This Port Range Means
Port 1674 falls in the registered ports range: 1024 to 49151. These ports aren't claimed by the operating system the way well-known ports (0-1023) are — you don't need root or administrator privileges to bind to them. But they're not random either. IANA maintains a registry so that software vendors can stake a claim on a number and avoid collisions with each other.
The registration is a courtesy system. IANA can't enforce it. Nothing stops you from running your own application on port 1674. But if you do, you're technically squatting on Intel's old real estate.
ProShare used two adjacent ports for its multicast functionality:
- Port 1673 —
proshare-mc-1 - Port 1674 —
proshare-mc-2
Neither is in active use by any modern software. They're fossils in the registry.
Is Anything Actually Using It?
Almost certainly not ProShare. But any application can bind to this port — and some do, informally. If something is listening on port 1674 on your machine, it's not Intel's videoconferencing software from 1994. It's either:
- A game server or custom application that picked a number at random
- A trojan or malware (historical databases flag it occasionally, though no specific threat is well-documented)
- Your own software or a developer tool
Check what's actually there before assuming.
How to Check What's Listening on Port 1674
On Linux or macOS:
On Windows:
Then cross-reference the process ID against Task Manager or ps aux to find out what program owns the socket.
Why Ghost Registrations Matter
The IANA registry has tens of thousands of entries. Many belong to software that was deprecated years ago, companies that no longer exist, or protocols that never shipped. These registrations don't expire — once claimed, a port stays claimed in the registry indefinitely unless someone petitions to remove it.
This matters because the registry is supposed to prevent collisions. When new software needs a port, developers check the registry to find something uncontested. Ghost registrations quietly narrow that space. Not by much — there are 48,127 registered ports — but the pattern adds up.
Port 1674 is a small monument to a product that didn't make it: Intel's conviction that people would pay $2,500 to edit documents over video, a quarter century before Zoom made that mundane.
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