Port 279: Unassigned — A Gap in the System Ports

Port 279 is officially unassigned. It sits in the well-known ports range (0-1023)—the Internet's most privileged address space, typically reserved for system services that everyone needs—but no protocol has ever claimed it.

The Unassigned Range

Port 279 is part of a larger block: ports 272-279 are all unassigned.¹ This is unusual. Most numbers in the well-known range received assignments decades ago. SSH claimed 22 in 1995. HTTP took 80 in the 1980s. DNS grabbed 53 even earlier.

But 272-279? Nothing. Not forgotten, not reserved for future use—just never needed.

What Well-Known Means

The well-known ports range (0-1023) is special. On Unix-like systems, only root can bind services to these ports. This restriction exists because these numbers were meant for essential system services—things everyone needs to work the same way everywhere.

IANA (the Internet Assigned Numbers Authority) controls assignments in this range. Getting a well-known port requires IETF Review or IESG Approval—a high bar.² You can't just claim one for your application.

Port 279 is available for that process, but in decades of Internet history, no one has asked for it.

Why Unassigned Ports Matter

Unassigned doesn't mean unused. Any application can listen on port 279 if it wants to. You might find:

• Custom internal applications that picked an arbitrary port
• Malware trying to hide in an unexpected location
• Development servers running on whatever port seemed available
• Nothing at all

The difference between "unassigned" and "assigned" is about coordination, not permission. Assigned ports have a documented purpose everyone agrees on. Unassigned ports are open questions.

Checking What's Listening

To see if anything is using port 279 on your system:

On Linux/Mac:

# Check if anything is listening on port 279
sudo lsof -i :279
sudo netstat -tlnp | grep :279
ss -tlnp | grep :279

On Windows:

netstat -ano | findstr :279

If something is there, it's not a standard service. It's worth investigating what it is and why it chose port 279.

The Geography of Port Numbers

Think of the port number space as a city:

• 0-1023 (Well-known ports): Downtown. High-security buildings. Root access required. Mostly claimed decades ago, except for quiet blocks like 272-279.
• 1024-49151 (Registered ports): Suburbs. IANA tracks who's using what, but enforcement is looser. Your application can request one.
• 49152-65535 (Dynamic/ephemeral ports): The wild edges. Your OS assigns these temporarily for outgoing connections. No one owns them.

Port 279 is downtown property that never got built on.

Related Ports

Port 280 (http-mgmt): Assigned to HTTP management protocol. This is the next port up, and it does have an official assignment.³

Ports 272-278: Also unassigned, forming a continuous block with 279.

Port 280 and above: The unassigned block ends here, with port 280 marking the return to assigned services.