Port 964: Unassigned — A reserved number waiting

Port 964 exists in the well-known ports range but has no service assigned to it. It's a number reserved by IANA that nobody ever claimed.

What the Well-Known Range Means

Ports 0-1023 are called well-known ports. They're reserved for system services—the fundamental protocols that make networks work. SSH lives at port 22. HTTP at 80. HTTPS at 443. These ports require superuser privileges to bind to on Unix-like systems because they're supposed to run critical services.

Port 964 is in this range. But it's empty.

Why Unassigned Ports Exist

The Internet Assigned Numbers Authority (IANA) manages port assignments.¹ When the port number system was established, ranges were reserved for different purposes. Not every number from 0-1023 got claimed.

Some protocols never materialized. Some services died before they needed a port. Some numbers were held in reserve for future use that never came. Port 964 is one of these—a placeholder in the well-known range that remains unassigned.

There are hundreds like it. The Internet grew differently than anyone expected in the 1980s. Not all the reserved spaces got filled.

What This Port Can Be Used For

Being unassigned doesn't mean the port is unusable. You can run anything you want on port 964 in your own network. Custom applications. Internal services. Testing. The port number works like any other—it's just not officially allocated to a standard protocol.

But because it's in the well-known range, you'd need superuser privileges to bind to it on most systems. And because it's unassigned, don't expect other devices to know what you're running there.

How to Check What's Listening

On Linux or macOS, you can see if anything is using port 964:

# See what's listening on port 964
sudo lsof -i :964

# Or using netstat
sudo netstat -tulpn | grep :964

On Windows:

netstat -ano | findstr :964

If nothing appears, the port is closed. If you see output, something is bound to that port—probably a custom service or application you installed.

The Landscape of Unassigned Ports

Port 964 is part of a larger pattern. IANA maintains the official registry of port assignments,² and within the well-known range, numerous ports remain unassigned. These gaps exist because:

• The original port allocation was conservative, reserving more numbers than immediately needed
• Some proposed protocols never reached widespread adoption
• The Internet's growth took unexpected paths
• Modern applications often use higher port numbers or dynamic allocation

The well-known range is mostly full of critical services. But the empty spaces—like port 964—remain available for future protocols or private use.