Port 667 sits in the well-known ports range (0-1023) with an official IANA assignment. On paper, it's reserved for "disclose"—a service for campaign contribution disclosures developed by SDR Technologies. In practice, it's essentially unused.
This is the reality of port assignments: some services get allocated a number and then fade into obscurity before they ever matter.
What Lives Here
According to IANA records, port 667 is assigned to:1
- Service name: disclose
- Description: campaign contribution disclosures - SDR Technologies
- Protocol: TCP/UDP
- Status: Officially assigned
The service was intended for secure data transmission related to campaign finance disclosures. It never gained widespread adoption.
The Well-Known Range
Port 667 falls in the well-known ports range (0-1023), which IANA reserves for system services and widely-used protocols. Getting a port in this range requires going through IANA's formal assignment process—usually involving an RFC or standardization effort.
Port 667 got that assignment. But assignment doesn't equal usage.
Compare this to its neighbor, port 666, which was assigned to MDQS (Multi-Device Queueing System) but became famous for something else entirely: the original Doom used it for multiplayer gaming.2 Port 666 at least has a story. Port 667 just has a registry entry.
What This Port Actually Carries
In most networks: nothing.
Security researchers occasionally flag port 667 in malware reports—not because the disclose service is exploited, but because unused ports make convenient channels for command-and-control traffic.3 When a port has an official assignment but no legitimate traffic, malicious software can use it without immediately raising alarms.
This is the irony of abandoned assignments: they become more useful to attackers than to the services they were meant to serve.
Checking What's Listening
If you want to see if anything is actually using port 667 on your system:
Linux/macOS:
Windows:
If you see something listening here, it's worth investigating. It won't be the disclose service—that ship sailed years ago. It's either custom software or something you should be suspicious of.
Why Unassigned (or Abandoned) Ports Matter
The port numbering system has 65,535 possible values. IANA manages the first 1,024 as "well-known" and another range (1024-49151) as "registered" ports. But not every assignment succeeds.
Some services die before they launch. Some protocols get replaced by better alternatives. Some assignments were made in the 1980s or 1990s for systems that no longer exist.
Port 667 is evidence that the registry is partly historical artifact—a record of what people intended to build, not just what actually got built.
The well-known range is supposed to be precious. Only 1,024 ports exist in this range, and once assigned, they're rarely reclaimed. Port 667 occupies one of those slots for a service almost nobody uses.
Meanwhile, modern protocols crowd into the higher ranges or repurpose HTTP/HTTPS because the well-known ports are all taken—sometimes by ghosts like this one.
The Lesson
Not every door gets opened just because it has a number on it. Port 667 has an official assignment, a formal name, and a place in the registry. What it doesn't have is traffic.
It's a reminder that infrastructure isn't just about allocation—it's about adoption. The Internet runs on the ports that actually get used, not the ones that merely exist in documentation.
Port 667: officially assigned, practically abandoned, occasionally borrowed by malware. A footnote in the history of protocols that never were.
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