Port 834: NetInfo (legacy) — A ghost in the well-known range

Port 834 sits in the well-known port range (0-1023), but you won't find it actively assigned in the IANA registry. This port is a ghost—a reminder of technology that once mattered, then vanished.

What Port 834 Was

Port 834 was used by NetInfo, an RPC-based directory service that ran on Mac OS X systems through version 10.4 (Tiger). NetInfo managed network-wide configuration data: users, groups, computer settings, and other system information stored in a distributed database.¹

NetInfo came from NeXTSTEP (the operating system that became Mac OS X) and was part of Apple's infrastructure for years. If you ran Mac OS X before 2007, NetInfo was running on your machine.

What Happened to NetInfo

Apple killed it. Completely.

Starting with Mac OS X Leopard (10.5) in 2007, NetInfo was gone—not deprecated, not hidden for advanced users, but entirely removed.² Apple replaced it with Open Directory and moved local user data to standard property list files in /var/db/dslocal/.

The migration wasn't gradual. Apple had been reducing NetInfo's role since OS X 10.2, but Leopard was the clean break. The service disappeared, the tools were removed, and the database format became a historical footnote.

Port 834 remains in the well-known range, but nothing officially uses it anymore.

What This Port Means Now

Port 834 is unassigned according to IANA's official registry. No modern service should be using it. If you see traffic on port 834, it's either:

• A legacy Mac system running OS X 10.4 or earlier (increasingly rare)
• A misconfigured service that claimed an unused port number
• Something pretending to be legitimate

How to Check What's Listening on Port 834

On Linux or macOS, use these commands to see if anything is listening:

# Using lsof (shows process details)
sudo lsof -i :834

# Using netstat (shows listening ports)
sudo netstat -an | grep 834

# Using ss (modern replacement for netstat)
sudo ss -tulpn | grep 834

On Windows:

netstat -an | findstr "834"

If you find something listening on port 834 and you're not running a Mac from 2007, investigate. Unassigned well-known ports shouldn't be in use without good reason.

Why Unassigned Ports Matter

The well-known port range (0-1023) is reserved territory. These ports require root privileges to bind on Unix systems, which makes them harder to hijack. IANA carefully manages assignments in this range.

Port 834 being unassigned means two things:

1. It's available — A future protocol could legitimately claim this port through IANA's assignment process
2. It's suspicious — If you see it in use, it's worth investigating because no standard service should be there

Unassigned well-known ports are like empty storefronts in a busy district. Their emptiness is notable. When something moves in without permission, you notice.

The Legacy

NetInfo is gone, but port 834 remains in the registry as a historical marker. It's a reminder that network protocols and services come and go, but port numbers persist. The Internet's infrastructure carries ghosts—port numbers that once meant something, then stopped, but never quite disappeared.

If you're scanning ports or monitoring network traffic, port 834 is one of those numbers that tells a story. Nothing should be there. If something is, ask why.