What Port 730 Does
Port 730 is officially assigned to NetInfo, a Remote Procedure Call (RPC)-based directory service originally developed by NeXT Computer. NetInfo was a distributed network configuration database that stored system-wide configuration information—users, groups, network settings—in a binary database instead of traditional Unix text files.
Both TCP and UDP protocols can operate on port 730, though modern systems no longer use this service.
The Service No Longer Runs
NetInfo was completely deprecated in Mac OS X Leopard (10.5), released in 2007. No current operating system uses port 730 for NetInfo. If you see traffic on this port today, it's either legacy equipment that hasn't been updated in nearly two decades, or something else entirely that shouldn't be using a well-known port assigned to a dead service.
The NeXT Legacy
NetInfo was introduced in NeXTSTEP version 0.9 and immediately caused controversy.1 It replaced both the traditional Unix system configuration files (like /etc/passwd and /etc/hosts) and Sun Microsystems' Network Information Service (NIS, formerly Yellow Pages).
This was bold. Instead of scattered text files, everything lived in one hierarchical database. User accounts, network settings, mounted volumes—all accessible through a unified directory service. When Apple acquired NeXT in 1997, NetInfo came along and became the native directory service for Mac OS X.2
The Problem With Replacing Everything
NetInfo worked beautifully when it worked. But when it broke, it broke spectacularly.
Starting in NeXTSTEP version 2, DNS queries went through NetInfo. If you disabled NetInfo to use traditional Unix configuration files, you also disabled DNS support.3 Your computer couldn't resolve domain names anymore. A misbehaving NetInfo server could lock you out of the network entirely—no web browsing, no email, nothing. NeXT computers became somewhat notorious for this fragility.
The deeper issue: NetInfo was proprietary. It was unique to NeXT systems (though NeXT later licensed it to an Australian company called Xedoc for other Unix systems). This made integration with standard directory services difficult. The rest of the Unix world was moving toward LDAP (Lightweight Directory Access Protocol), an open standard.
The Slow Sunset
Apple recognized the problem. In Mac OS X Server 10.2 Jaguar (2002), they introduced Open Directory, which combined NetInfo with LDAP support.4 Initially, Open Directory was just a network-visible NetInfo domain paired with an Authentication Manager service.
Over the next several years, Apple gradually replaced NetInfo's functionality with LDAP-based services. Mac OS X Tiger (10.4) was the last version to fully support NetInfo.5 With Leopard (10.5) in 2007, NetInfo was completely removed and replaced by dslocal—a local directory node that uses standard property list files in /var/db/dslocal/.
Port 730 remained assigned to NetInfo in the IANA registry, but the service itself was gone.
What This Port Represents
Port 730 is a well-known port (0-1023), meaning it was assigned by IANA for a system-level service. Well-known ports are supposed to be stable, permanent assignments for fundamental Internet services.
But the Internet outlives individual implementations. NetInfo existed for roughly two decades—1988 to 2007—and then vanished. The port assignment remains, a fossil in the registry. It's a reminder that even ambitious, well-engineered systems can be replaced by open standards.
The truth is this: proprietary solutions rarely survive contact with the broader ecosystem. NetInfo tried to be better than Unix configuration files, and in some ways it was. But it couldn't be better than an open protocol that every other system could interoperate with.
Security Considerations
If you detect traffic on port 730 on a modern network:
- Check the source. Is this actually an ancient Mac OS X Tiger system (or earlier) still running?
- Verify legitimacy. NetInfo shouldn't exist in production environments anymore. If something is using this port, it's either extremely outdated infrastructure or potentially malicious software masquerading as a defunct service.
- Block if unused. Since no current systems should be using NetInfo, blocking port 730 at the firewall is reasonable for most networks.
How to Check What's Listening
On Unix-like systems:
On Windows:
If you find something listening on port 730, investigate immediately. It shouldn't be there.
Related Ports
NetInfo actually used multiple ports:
- Port 1033: NetInfo-local, for local NetInfo communication
- Port 1849: Used by later Apple directory services for communication between Open Directory and AppleTalk
All of these ports are now historical curiosities.
Frequently Asked Questions About Port 730
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