What Port 945 Was Used For
Port 945 (both TCP and UDP) was documented as being used by ipcserver, a Mac OS X RPC (Remote Procedure Call) service that supported NetInfo.12 NetInfo was Apple's proprietary directory service—the system that stored and distributed user accounts, passwords, network configuration, and other critical system information across Mac networks.
When you logged into a Mac running OS X Tiger or earlier, when the system looked up your username and password, when networked Macs shared configuration data—NetInfo was handling those requests, often communicating through services like ipcserver on port 945.
Current Status: Officially Unassigned
Despite its documented use on Apple systems, port 945 appears as Unassigned in the official IANA Service Name and Transport Protocol Port Number Registry.3 This means it was never formally registered with IANA, even during its active use.
Port 945 falls in the System Ports range (0-1023), which are assigned by IANA for well-known services. The fact that it remains unassigned today reflects NetInfo's obsolescence—there's no service actively claiming this port anymore.
The Death of NetInfo
NetInfo was never popular with system administrators. It was proprietary, complex, and incompatible with the LDAP-based directory services that had become the industry standard. Apple began migrating away from NetInfo in Mac OS X Server 10.2 Jaguar (2002) when they introduced Open Directory, their LDAP-based alternative.4
NetInfo was completely removed in Mac OS X 10.5 Leopard (2007). Every Mac running Leopard or later uses Open Directory and standard directory service protocols. Local accounts are now stored in XML property list files rather than NetInfo's database.5
The services that once used port 945—including ipcserver—disappeared along with NetInfo.
Why This Port Matters
Port 945 is a reminder that ports aren't permanent. Services get deprecated. Protocols become obsolete. Infrastructure that once powered millions of computers can vanish completely within a decade.
If you see port 945 active on a modern network, it's either:
- An extremely old Mac running OS X 10.4 Tiger or earlier (unlikely in 2026)
- A service unofficially reusing an abandoned port number
- Something worth investigating
How to Check What's Listening on Port 945
On macOS or Linux:
On Windows:
If nothing returns, the port isn't in use. If something does, you've found either a very old system or something unexpected.
Related Ports
- Port 111 — Portmapper/rpcbind, the service that helps RPC programs find each other
- Port 600-1023 — The range where Mac OS X RPC-based services operated6
- Port 389 — LDAP, the standard directory service protocol that replaced NetInfo
Frequently Asked Questions About Port 945
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