Port 725 is a well-known port that was officially assigned by IANA for NetInfo, a directory service that Apple used in Mac OS X Server and earlier NeXTSTEP systems.1 NetInfo was completely deprecated and removed from Mac OS X in version 10.5 (Leopard) in 2007.2
This port still appears in IANA's registry, but the service it was designed for no longer exists.
What NetInfo Was
NetInfo was a hierarchical distributed database that Mac OS X Server used to manage administrative data—user accounts, groups, email configurations, NFS mounts, printer settings, and network resources. It was based on Sun RPC (Remote Procedure Call) and ran in the well-known ports range (0-1023).3
If you were managing a Mac OS X Server network in the early 2000s, NetInfo was how you configured directory services. Clients connected using the native NetInfo protocol over RPC, or via LDAP for broader compatibility.
Why It Disappeared
Apple replaced NetInfo with Open Directory starting in Mac OS X Server 10.2, and by 10.5, NetInfo was gone entirely. Open Directory offered better standards compliance (LDAP, Kerberos) and could integrate with existing directory services like Active Directory.4
The transition was complete enough that Apple removed NetInfo Manager and all NetInfo binaries from the operating system. Port 725 became obsolete overnight.
What This Port Teaches Us
Port 725 is a reminder that the well-known ports range isn't static. Services get deprecated. Protocols evolve. Companies move on.
IANA still lists port 725 as assigned to NetInfo, but nobody is listening on it anymore—at least not for its original purpose. If you see traffic on port 725 today, it's either:
- Legacy systems that haven't been updated since before 2007
- Something using the port unofficially because it's rarely monitored
- Misconfigured software
Checking What's Listening
On macOS or Linux:
On Windows:
If something is listening on port 725 in 2026, you should probably investigate why.
The Well-Known Ports Range
Port 725 sits in the well-known ports range (0-1023), also called system ports. These require root or administrator privileges to bind to, and IANA assigns them through strict procedures defined in RFC 6335.5
Getting a well-known port assignment is difficult. It requires IETF Review or IESG Approval—basically, your protocol needs to be important enough that the Internet standards body thinks it deserves a reserved number.
NetInfo met that bar in the 1990s. By 2007, it didn't matter anymore.
Why Unassigned and Abandoned Ports Matter
The port number space is finite. There are only 65,535 ports (0-65535), and only 1,024 of those are in the privileged well-known range. When a service dies but keeps its port assignment, that number sits unused.
IANA doesn't eagerly reclaim abandoned ports, because:
- Legacy systems might still depend on them
- Documentation scattered across the Internet still references them
- Backwards compatibility matters more than efficiency in protocol design
Port 725 is officially assigned but practically dead. It's a fossil in the registry.
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