Port 552: DeviceShare — The registered protocol that never was

Port 552 belongs to the well-known port range (0-1023), the tier of ports assigned by the Internet Assigned Numbers Authority (IANA) to specific, standardized services. These are the ports that shaped the Internet—HTTP on 80, HTTPS on 443, SSH on 22.

Port 552 was assigned to DeviceShare (service name: devshr-nts), registered by Benjamin Rosenberg for remote device management and monitoring. The protocol was meant to enable efficient communication between networked devices.¹²

But DeviceShare never happened.

The Reality of Reserved Ports

Search for DeviceShare today and you'll find nothing. No RFC. No documentation. No implementation. No community. The protocol either never launched, was abandoned early, or existed only within a company that no longer exists.

Yet port 552 remains officially assigned to it. That's how port registration works—once assigned, ports stay assigned even if the service disappears. The IANA registry is a historical record, not a list of what's actually running.

This happens more often than you'd think. The well-known port range contains hundreds of ports assigned to protocols that never gained adoption, products that were discontinued, or experiments that failed. Port 552 is one of them.

What This Means

If you see traffic on port 552, it's not DeviceShare. It could be:

• A custom application that chose port 552 because it was effectively unused
• Malware or scanning activity probing for open ports
• A misconfigured service running on the wrong port
• An internal tool that repurposed the port for something unrelated

The registration doesn't prevent other software from using port 552. It just means no major, standardized protocol should claim it.

Checking What's Actually Listening

To see what's using port 552 on your system:

Linux/macOS:

sudo lsof -i :552
sudo netstat -tulpn | grep :552

Windows:

netstat -ano | findstr :552

If something's listening, it's not DeviceShare. Investigate what it actually is.

Why Unassigned (or Effectively Unassigned) Ports Matter

The well-known port range is finite. Only 1,024 ports. Once assigned, they're locked to that service forever—even if the service never materializes.

This is why IANA became more conservative about assignments over time. Early in the Internet's history, ports were handed out freely. Later, the realization hit: these are a limited resource. Every ghost protocol like DeviceShare is a port that can't be used for something real.

The registered port range (1024-49151) was created partly to solve this. Applications that don't need well-known status register there instead. But port 552 predates that caution.

The Honest Truth

Port 552 is a monument to a protocol that never was. The registration exists. The protocol doesn't. And the port sits there, reserved for a vision of device management that no one remembers.

If you see it in use, someone else decided the registration didn't matter anymore. And they're probably right.