What This Port Is
Port 272 (both TCP and UDP) is officially unassigned by IANA. It sits in the well-known ports range (0-1023), sometimes called System Ports, but has no assigned service or protocol.1
The entire range from port 272 to 279 remains unassigned—a cluster of unclaimed addresses in the most restricted part of the port numbering system.
The Well-Known Ports Range
Ports 0-1023 are called well-known ports because they were meant for foundational Internet services. These ports require special privileges to use on most operating systems. You cannot just bind to port 272 as a regular user—the system treats it as restricted space.
Getting a port assigned in this range requires IETF Review or IESG Approval—the highest level of scrutiny in the Internet standards process.2 Most of these ports were claimed decades ago during the Internet's early architecture.
What Lives Nearby
The ports around 272 tell the story of protocols that seemed important once:
- Port 271: pt-tls (IETF Network Endpoint Assessment Posture Transport Protocol over TLS)—assigned in 2012 for network security assessment
- Port 280: http-mgmt (HTTP management)—a variant of web protocols that never caught on
Port 272 sits between them, unclaimed.
Why Unassigned Ports Matter
Every unassigned port represents flexibility in the Internet's architecture. As new protocols emerge, these gaps provide official addresses without having to repurpose or reclaim old assignments.
But unassigned well-known ports are rare. Most numbers in this range were allocated when Internet protocols were being invented faster than they could be implemented. Many official assignments point to protocols that were never widely deployed or have long been obsolete.
Port 272's absence from the registry is notable precisely because it is unusual—a hole in a namespace that was mostly filled before most of us ever connected.
Checking What's Listening
Even though port 272 is unassigned, software can still use it. To check if anything on your system is listening on port 272:
Linux/macOS:
Windows:
If you see output, something is using this port locally—likely a development server, custom application, or service that chose an unassigned port to avoid conflicts.
The Architecture of Absence
The Internet's port numbering system is a shared coordinate system. Well-known ports are the origin point—the addresses everyone agrees to check first for foundational services.
Port 272 is a coordinate with no landmark. Not forgotten, not deprecated, simply never assigned. In a namespace where almost every number has a history, some numbers have only potential.
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