Port 987 is a ghost. It sits in the well-known port range (0-1023)—the ports reserved for fundamental Internet services—but it has no official assignment from IANA. No protocol owns it. No service claims it.
And yet, it has a history.
What the Well-Known Range Means
Ports 0-1023 are called well-known ports. These are reserved by the Internet Assigned Numbers Authority (IANA) for standardized services that every network understands. SSH lives at port 22. HTTP at 80. HTTPS at 443. These assignments are meant to be permanent, universal, and authoritative.1
Port 987 is in this range. But unlike its neighbors, it was never officially assigned to anything.
The NetInfo Era
In the early 2000s, Apple used port 987 for NetInfo—a hierarchical distributed database that Mac OS X Server used to manage directory services. NetInfo tracked user accounts, group permissions, email configurations, printers, and network resources. It was part of how Mac OS X kept track of who could do what.2
NetInfo used RPC (Remote Procedure Call) to communicate between systems, and port 987 was part of the range of ports that NetInfo services occupied. It wasn't the primary NetInfo port (that was 1033), but it was in the constellation of ports that NetInfo touched.
Then, in 2007, Apple released Mac OS X 10.5 (Leopard) and completely removed NetInfo from the operating system. It was replaced by Open Directory, which used different protocols and different ports. NetInfo disappeared. Port 987 was left behind.3
What Happened to the Port
Port 987 wasn't reassigned. It wasn't reclaimed by IANA for something else. It just... remained. A reserved space in the well-known range, no longer needed.
Some port databases still list it as "NetInfo" or "Mac OS X RPC-based services."4 Others list it as unassigned. Both are correct, depending on when you're looking. It was used. It isn't anymore.
Why Unassigned Ports Matter
There are hundreds of ports like this. Services that were created, used for a while, and then abandoned. Protocols that never caught on. Assignments that were made decades ago and then forgotten.
The well-known port range is supposed to be permanent. But technology isn't. Services evolve. Protocols get replaced. Companies abandon their implementations. And the ports they once used become artifacts—reserved space that no one needs anymore.
Port 987 is one of those artifacts. It's a reminder that even in the carefully managed world of IANA assignments, not everything lasts forever.
How to Check What's Listening on Port 987
If you want to see if anything is actually using port 987 on your system, you can check:
On Linux or macOS:
On Windows:
Most likely, you'll see nothing. The port is open. Empty. Waiting for a service that will never return.
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