Port 867: Unassigned — An empty seat in the well-known range

Port 867 is unassigned. Both TCP and UDP port 867 have no official service registered with the Internet Assigned Numbers Authority (IANA).

What Range This Port Belongs To

Port 867 falls in the well-known port range (0-1023). This range is the most controlled part of the port number system. Ports here are assigned by IANA to specific, standardized services—usually protocols defined in RFCs that the entire Internet depends on.

Port 22 is SSH. Port 80 is HTTP. Port 443 is HTTPS. These are well-known ports with well-known purposes.

Port 867 is... nothing. At least officially.

What This Means

In the well-known range, you'd expect every port to have an assignment. These ports were meant to be carefully managed, with each number representing a specific protocol or service that needed a consistent address across all networks.

But not every port in this range has been claimed. Port 867 is one of the gaps—a number in the registry that no protocol currently owns. It's available for assignment if someone creates a service important enough to warrant an official well-known port, but for now, it sits empty.¹

Unofficial Uses

There's no widely documented unofficial use of port 867. Unlike some unassigned ports that get adopted by specific applications or show up frequently in certain environments, port 867 appears to be genuinely unused in practice.

Some port databases mention vague references to "Mac OS X RPC-based services" or NetInfo, but these references are not substantiated in official documentation and may be outdated or incorrect.²

Why Unassigned Ports Matter

Unassigned ports are important for several reasons:

Room for growth — The Internet still needs new protocols. Having unassigned ports in the well-known range means there's space for future standardized services that need a permanent, globally recognized port.

Flexibility — An unassigned port can be temporarily used for testing, development, or internal services without conflicting with standard protocols. Just know that IANA could assign it at any time.

Historical insight — The gaps in the well-known range show us which parts of the protocol ecosystem filled in first, and which needs were never urgent enough to claim a permanent address.

Checking What's Listening

Even though port 867 has no official assignment, something could still be listening on it on your system—either by mistake or for a custom application.

To check what's listening on port 867:

On Linux/macOS:

sudo lsof -i :867
# or
sudo netstat -tulpn | grep :867

On Windows:

netstat -ano | findstr :867

If you find something listening on this port and you don't recognize it, investigate. Unassigned ports are sometimes used by malware precisely because they're unexpected.

The Empty Seats

The well-known port range was designed to be the organized part of the Internet's addressing system. Every port carefully assigned. Every number accounted for.

But port 867 reminds us that even in the most controlled systems, there are gaps. Numbers waiting for protocols that may never arrive. Empty seats at a table that's been set for decades.

Maybe someday a protocol will claim port 867. Maybe it will always be empty. Either way, it's a reminder that the Internet is still unfinished—still leaving room for what comes next.