Port 1011 — The Unassigned Port

The Port Range

Port 1011 belongs to the well-known ports range (0-1023), established by IANA as system and reserved ports. These 1024 ports are supposed to be assigned to standardized, widely-used services. HTTP gets 80, HTTPS gets 443, SSH gets 22. The system was designed so network engineers worldwide would know: if port X is open, service Y is likely running.

Port 1011 is in the reserved band but has no official assignment. It exists in the space where infrastructure meets uncertainty.

What's Actually Listening

Port 1011 has no legitimate, standardized service. The documented uses are exclusively malicious:

• Doly Trojan — A backdoor trojan that listens on TCP 1011, documented in security databases since the early 2000s
• Backdoor.Win32.Augudor.a — Creates a listener on port 1011 to allow remote execution of arbitrary code

This is the actual history of the port. It's not a busy Internet backbone. It's a vector for compromise.

Why Unassigned Ports Matter

The genius of the original port system was predictability. You know port 25 runs mail, port 53 runs DNS, port 443 runs HTTPS. This predictability made networks navigable—you could see what was running just by scanning for open ports.

But unassigned ports in the well-known range create a problem: they're officially "yours to use" but socially "you probably shouldn't." They're too low to be dynamic ephemeral ports (49152-65535), too standardized to claim for new applications, and too visible to ignore if they're open. They become dead space in the port address space.

And dead space, in networking, gets filled with quiet threats.

Checking What's Listening

To see if something is listening on port 1011:

On macOS/Linux:

lsof -i :1011
netstat -an | grep 1011

On Windows:

netstat -ano | findstr :1011

If you see anything here, ask yourself: Did I start that? If not, you have a real problem to solve.

The Bigger Picture

Port 1011 teaches something important: not every port is designed for elegance or clarity. Some ports are just... unfinished business. Reserved but never claimed. And when something does claim an unassigned port, it's usually not asking permission.

This is why network administrators scan. This is why threat detection exists. Port 1011 may not carry the Internet's critical traffic, but it carries a warning: know what's listening on your network, or know nothing.