Port 740 has no official service assignment from IANA. It sits in the well-known port range—the most prestigious addresses in the Internet's numbering system—yet remains unclaimed.
What Range This Port Belongs To
Port 740 is part of the well-known ports (0-1023), also called system ports. These numbers are controlled by IANA and typically require IETF Review or IESG Approval for assignment.1
This is the range where you find the Internet's core protocols: HTTP at 80, HTTPS at 443, SSH at 22. Being unassigned in this range means port 740 was reserved but never officially allocated to a specific protocol.
Observed Unofficial Uses
While port 740 has no official assignment, it has been observed in the wild:
Mac OS X RPC Services: Port 740 has been documented as part of the RPC-based services range (600-1023) used by older Mac OS X systems, including NetInfo—Apple's directory service that was deprecated in Mac OS X 10.5.23
NetInfo is long gone, replaced by Open Directory. But the port number remains, sitting unused in most networks, occasionally repurposed for whatever local service needs it.
Why Unassigned Ports Matter
Unassigned ports aren't accidents. They represent:
Reserved capacity: IANA doesn't assign well-known ports casually. The numbers below 1024 are finite and valuable. Port 740 might be reserved for a future protocol that requires this specific address space.
Historical artifacts: Some unassigned ports were once allocated to protocols that never gained adoption or have since been deprecated. The assignment was withdrawn, leaving the port number free again.
Local flexibility: Networks use unassigned ports for internal services without risking conflicts with standard protocols. If you see traffic on port 740, it's something specific to that network—not a universal Internet service.
How to Check What's Listening
To see if anything is using port 740 on your system:
On Linux or Mac:
On Windows:
If nothing appears, the port is unused. If you see a process, it's something running locally—not a standard Internet service.
The Nature of Gaps
The well-known port range is full of these gaps. Numbers that were reserved decades ago. Protocols that never materialized. Services that came and went before most of today's Internet existed.
Port 740 is one of them. Not abandoned—just waiting. Available for whatever needs it next, whether that's an official IANA assignment or just another local RPC service that needs a place to listen.
Frequently Asked Questions About Port 740
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