Port 1691: empire-empuma — A Registered Ghost

Port 1691 sits in the registered ports range (1024–49151). IANA has given it a name: empire-empuma. That name appears in port databases, gets echoed across lookup tools, and means essentially nothing — because no public documentation of the underlying protocol or company has survived.

This is not unusual. It is, in fact, one of the quieter truths about the port registry.

The Registered Ports Range

Ports 1024 through 49151 are called registered ports. Anyone — a company, an open-source project, an individual — could historically contact IANA and request a port number for their application. IANA would assign it, add it to the registry, and move on. No verification that the protocol worked. No requirement that documentation be published. No follow-up if the company later dissolved.

The result is a registry full of entries like port 1691: a name attached to a number, with the actual protocol lost to time.

What "empire-empuma" Might Have Been

The name suggests a product or company called Empire, with a specific component or module called Empuma (or vice versa). No RFC was ever written for it. No open-source implementation exists. No forum post from a sysadmin complaining about it, no Wireshark dissector, no security advisory. The registration is the entire paper trail.

If you find something listening on port 1691, it is almost certainly not empire-empuma. It is more likely a custom application, a development server, a game, or something that chose this port specifically because it was obscure enough to avoid conflicts.

What to Do If You See Port 1691 Open

If port 1691 appears in a port scan or firewall log, the registered name tells you nothing useful. Find out what is actually running:

On Linux/macOS:

# See what process has port 1691 open
sudo ss -tlnp | grep 1691
# or
sudo lsof -i :1691

On Windows:

netstat -ano | findstr :1691

Then look up the process ID to find what application owns it.

Why Unassigned and Ghost Ports Matter

The port namespace is a shared resource. Every port a forgotten protocol claims is a port that modern software has to route around. Most developers avoid ports with existing IANA entries out of courtesy — even if those entries are effectively dead.

Port 1691 is a small artifact of a busier era, when companies were racing to register their slice of the network namespace before someone else could. Most of those companies are gone. Their ports remain.