Port 852 is unassigned. The Internet Assigned Numbers Authority (IANA) lists it as available for assignment, but no protocol or service has officially claimed it.1
This doesn't mean it's unused. It means nobody asked IANA for it.
What Range Does Port 852 Belong To?
Port 852 sits in the well-known port range (0-1023). These ports are controlled by IANA and require formal approval for assignment. You can't just decide to run your service on port 852 and expect the rest of the Internet to recognize it.
The well-known range exists to prevent chaos. If every developer picked random ports for their protocols, nothing would interoperate. Port 80 is HTTP because IANA said so. Port 443 is HTTPS for the same reason. Port 852 is waiting for someone to ask.
What This Port Range Means
Ports 0-1023 are privileged on Unix-like systems. Binding to them typically requires root or administrator access. This restriction exists because services on well-known ports are assumed to be legitimate—your operating system trusts that whatever is listening on port 22 is actually SSH, not malware pretending to be SSH.
Port 852 inherits this trust framework despite having no assigned service. If you run something on port 852, your system treats it as privileged. The protocol might not exist yet, but the infrastructure is ready.
Does Port 852 Have Unofficial Uses?
Some sources mention port 852 in connection with Mac OS X RPC-based services, particularly Apple's legacy NetInfo directory service.2 NetInfo was deprecated over 15 years ago and completely removed in Mac OS X 10.5, replaced by Open Directory.
But there's no clear evidence that port 852 was ever officially used by NetInfo. Apple's RPC services operated across a range of ports (600-1023), and port 852 may have occasionally appeared in that traffic. This is the nature of unassigned ports—they sometimes get used informally, locally, temporarily.
No major protocol claims port 852 today.
Why Unassigned Ports Matter
The Internet doesn't assign ports speculatively. IANA doesn't say "we think someone might need this port someday, so let's give it a name." Ports get assigned when someone builds a protocol and requests official recognition.
Unassigned ports like 852 represent capacity. They're the empty slots in the addressing system. The fact that thousands of ports remain unassigned isn't a waste—it's headroom. It means the Internet can grow new protocols without running out of addresses.
How to Check What's Listening on Port 852
Even though port 852 has no official assignment, something could be listening on it. Here's how to check:
On Linux or macOS:
On Windows:
Using netstat (cross-platform):
If nothing returns, port 852 is silent. If something appears, you've found a service using an unassigned port—either legitimately (internal tools, development servers) or maliciously (malware sometimes hides on obscure ports).
Should You Use Port 852?
For internal services, testing, or development? Sure. Nobody owns it.
For a public-facing protocol? No. If you're building something meant to interoperate across the Internet, request an official port assignment from IANA. Unassigned ports are fine for private use but terrible for standards.
The well-known range (0-1023) is also the wrong place for new services. Modern protocols typically request assignments in the registered port range (1024-49151), which is easier to obtain and doesn't require root privileges to bind.
Related Ports
Port 852 sits among other unassigned ports in the upper 800s:1
- Port 849 — Unassigned
- Port 850 — Unassigned
- Port 851 — Unassigned
- Port 853 — DNS over TLS (DNS-over-TLS)
Port 853 is the nearest neighbor with an actual assignment. The contrast is stark—853 carries encrypted DNS queries for privacy-conscious users worldwide, while 852 sits empty.
Frequently Asked Questions About Port 852
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