Port 879 has no job. It sits in the well-known port range but has never been assigned to any protocol.
What Range This Port Belongs To
Port 879 is in the well-known port range (0-1023). This range is controlled by the Internet Assigned Numbers Authority (IANA), and ports here are supposed to be assigned only to standardized protocols—things like HTTP on port 80 or SSH on port 22.1
But port 879 is unassigned. According to IANA records, the range 874-885 has no official assignments.2
This isn't unusual. Even in the well-known range, there are gaps—numbers held in reserve for protocols that might be standardized in the future.
What Unassigned Means
When a port is unassigned:
- No standard protocol uses it — There's no RFC defining what should run here
- It can still be used — Applications can listen on port 879, they just shouldn't expect it to mean anything specific
- It's available for assignment — If someone develops a new protocol and goes through the IANA process, port 879 could be assigned to it
Unassigned doesn't mean forbidden. It means unclaimed.
Why Unassigned Ports Matter
The existence of unassigned ports in the well-known range is actually important:
Room for future protocols — New network protocols are still being developed. When they're standardized, they need port numbers. Unassigned ports are the gaps where those future protocols will live.
Controlled allocation — IANA doesn't assign ports frivolously. Just because a port is unassigned doesn't mean anyone can claim it. You need a formal standards process (usually an RFC) to get a well-known port assigned.
Historical artifact — Some unassigned ports used to have assignments that were later deprecated. Others were simply never claimed. The gaps tell a story about which protocols succeeded and which were never built.
How to Check What's Using Port 879
If you see port 879 open on your system, something is listening there—but it's not a standard service.
On Linux or macOS:
or
On Windows:
This will show you the process ID and program name. Since port 879 has no standard assignment, you'll need to investigate what application opened it and whether that's expected.
Security Considerations
Unassigned ports have no inherent security risk—they're just numbers. But if you find port 879 open and you don't know why:
- Check what's listening — Use the commands above to identify the process
- Verify it's legitimate — Make sure the application is one you installed and trust
- Close it if unnecessary — If nothing should be listening, investigate further
An open port is a question: "What's listening, and should it be?"
Related Ports
- Port 874-885 — The entire range containing port 879 is currently unassigned2
- Well-known ports (0-1023) — The controlled range where port 879 lives
- Registered ports (1024-49151) — Ports that can be registered for specific applications without formal standardization
Frequently Asked Questions About Port 879
Была ли эта страница полезной?