Port 1033: NetInfo — A Legacy Door That Closed

What Is Port 1033?

Port 1033 is in the registered port range (1024-49151), meaning IANA has officially assigned it to a specific service: NetInfo. ¹

But here's the thing: NetInfo is dead. It's been dead since 2007.

The Story of NetInfo

NetInfo was Apple's network directory service, inherited from NeXTSTEP when Steve Jobs' NeXT Computer merged with Apple. ² It did what you'd expect—stored information about users, groups, hosts, and network resources in a distributed database. On Mac OS X systems through Tiger (10.4), if you saw port 1033 open, NetInfo was listening there, ready to answer queries about who you were and what groups you belonged to.

It worked. But it was NeXT's way of solving a problem that the Unix world had moved past.

What Changed

In Mac OS X Leopard (10.5, released in 2007), Apple deprecated NetInfo completely and replaced it with Open Directory—Apple's implementation of LDAP, the industry-standard directory protocol. ³ On modern Macs, user and group information lives in dslocal, a flat-file structure at /var/db/dslocal/nodes/default/. No daemon listening on port 1033. No network queries flying across that port.

Port 1033 remains in the IANA registry as a historical artifact. It's assigned. It's documented. But on any Mac running Leopard or later—which is now 17 years old—nothing is listening there.

Why This Matters

Port 1033 is a small example of how the Internet's port registry contains legacy assignments. Not every assigned port is actively used. Some are:

• Legacy services (like NetInfo) that were replaced by better standards
• Deprecated on modern systems but still in the official registry
• Historical markers of how computing evolved

When you scan for open ports and see nothing on 1033, that's correct—it's supposed to be silent. NetInfo was the wrong solution to a solved problem, and Apple moved on.

Checking for Listeners

If you want to see what's actually listening on port 1033 on your system:

# macOS / Linux
sudo lsof -i :1033

# Linux (alternative)
sudo netstat -tlnp | grep 1033

# Or use the Network Utility app on older Macs

On modern systems, you won't find anything. On very old Macs (Tiger era), you might find netinfod.

The Unassigned Ports Around It

Ports in the registered range like 1033 can be:

• Assigned — Reserved for a specific service (like NetInfo here)
• Unassigned — Available but not yet claimed
• Reserved — Set aside but intentionally not assigned

The registry itself is honest: it lists what was assigned, when, and by whom. It doesn't erase history. Port 1033 is proof that sometimes the Internet's memory is long, even for things that no longer work.