Port 877 once carried NetInfo, Apple's original directory services protocol for Mac OS X. NetInfo was deprecated in 2007 and replaced by Open Directory, leaving this well-known port largely unused.
What Port 877 Was Used For
Port 877 sits in the well-known ports range (0-1023), the space reserved by IANA for established system services. Historically, it was used by NetInfo—Apple's hierarchical distributed database system for storing administrative information on Mac OS X systems.1
NetInfo handled critical directory services data:
- User and group accounts
- Email configurations
- Network filesystem (NFS) settings
- Printer configurations
- Computer and resource information
The service communicated over port 877 using RPC (Remote Procedure Call) protocols, allowing Mac OS X systems to query and update directory information across a network.2
Why This Port Is Now Silent
NetInfo was completely removed from Mac OS X with version 10.5 (Leopard) in 2007. Apple replaced it with Open Directory, a more modern directory services system that has been part of Mac OS X Server since versions 10.1-10.2.3
This means port 877 is largely a ghost port today—once home to a specific service, now mostly silent. You might still encounter it on very old Mac OS X systems running versions prior to 10.5, but these are increasingly rare in 2026.
What the Well-Known Ports Range Means
Port 877 falls in the well-known ports range (0-1023), also called system ports. These ports:
- Are assigned by IANA for established network services
- Typically require administrative/root privileges to bind to
- Are meant for services that need to be consistently found at the same port number
The well-known range is like the ground floor of a building—the addresses everyone knows. Port 80 for HTTP. Port 443 for HTTPS. Port 877 for... well, nothing anymore, in most cases.
How to Check What's Listening on Port 877
If you want to see whether anything is actually using port 877 on your system:
On Linux or macOS:
On Windows:
Most modern systems will return nothing. The port is silent.
Why Unassigned and Deprecated Ports Matter
The port number space is finite—65,535 ports for TCP, 65,535 for UDP. When a service is deprecated but its port number remains in the registry, that number becomes frozen in history. It's not available for something new, but nothing old uses it anymore either.
Port 877 is a reminder that the Internet's infrastructure has archaeology. Layers of what came before, still encoded in the numbers. NetInfo served Apple users for years, handling the essential question of "who is allowed to do what?" on Mac OS X systems. Then it was replaced by something better, and the port fell silent.
The well-known ports range is full of these ghosts. Services that mattered deeply to someone, somewhere, for some period of time. Then they were replaced, deprecated, forgotten. The port number remains, but nothing answers anymore.
Frequently Asked Questions About Port 877
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