Port 679 exists in a strange space. It sits in the well-known ports range (0-1023)—ports that IANA reserves for standardized services—but nobody ever filed the official paperwork to claim it.
What "Unassigned" Means
The well-known ports range is supposed to be the Internet's reserved seating. Ports 0-1023 are managed by IANA and assigned to specific protocols through formal RFCs. Port 22 is SSH. Port 80 is HTTP. Port 443 is HTTPS.
Port 679? Nothing. Officially.
But "unassigned" doesn't mean "unused." It means nobody went through the formal process of requesting IANA assignment. The port exists. Packets can flow through it. Software can listen on it. It just doesn't carry an official protocol.
Unofficial Uses
Despite having no IANA assignment, port 679 has been used by specific applications:1
Altera Quartus Prime: Intel's FPGA (Field-Programmable Gate Array) development software uses port 679 for daemon processes. Engineers programming custom silicon chips need these daemons to communicate between the design software and hardware programming tools. Someone at Altera picked port 679. It worked. They shipped it.
Apple NetInfo: Mac OS X (before it was macOS) used port 679 for NetInfo—a distributed database system that managed user accounts, network configurations, and system resources.2 NetInfo has been deprecated since Mac OS X 10.5 (2007), replaced by Open Directory. But for years, port 679 carried RPC (Remote Procedure Call) traffic on every Mac running the NetInfo service.
Neither use was ever standardized. Neither became an RFC. Both were just engineers solving problems with the tools available.
Why Unassigned Ports Matter
The well-known ports range has 1,024 slots. Many are assigned. Many are not. The unassigned ones serve several purposes:
Reserved space for future standards: IANA keeps ports available for protocols that don't exist yet. When someone invents a new standard protocol and needs a well-known port, there needs to be space.
Application-specific use: Companies can use unassigned ports for proprietary software without conflicting with standard protocols. Altera chose 679 knowing it wouldn't collide with SSH or DNS.
Testing and development: Developers building new network services need ports to experiment with. Unassigned ports provide that space.
The risk is collision. If two different applications both use port 679 on the same system, they'll conflict. The FPGA software's daemon and a NetInfo service can't both listen on port 679 simultaneously. First one to bind wins. Second one fails.
Checking What's Listening
If you want to see whether anything is using port 679 on your system:
On Linux or macOS:
On Windows:
If something appears, you'll see the process ID and name. If nothing appears, the port is available.
The Gap Between Standards and Practice
Port 679 represents the difference between how the Internet is supposed to work (formal standards, IANA assignments, RFCs) and how it actually works (engineers picking available ports and shipping software).
Most network traffic flows through assigned ports carrying standardized protocols. But scattered throughout the port range are these informal uses—ports that nobody officially claimed but that carry real traffic anyway.
The well-known range is supposed to be controlled. Port 679 shows that even in the most carefully managed part of the port system, actual practice diverges from official procedure.
Frequently Asked Questions About Port 679
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