Port 327 exists in a strange category: it's important enough to be in the well-known ports range (0-1023), but has never been assigned to any service. It sits in a block of eight consecutive unassigned ports (325-332) that IANA has kept empty since the registry was created.1
What "Unassigned" Means
The Internet Assigned Numbers Authority (IANA) maintains a registry of port numbers divided into three ranges:2
- Well-Known Ports (0-1023): System ports requiring elevated privileges, assigned through IETF Review or IESG Approval
- Registered Ports (1024-49151): User ports assigned to specific services upon request
- Dynamic/Private Ports (49152-65535): Not assigned, available for temporary use
Port 327 falls in the first category—the range reserved for fundamental Internet services. But unlike its neighbors (port 25 carries email, port 443 carries HTTPS), port 327 carries nothing. It's unassigned.
Why Unassigned Ports Exist
Not every port number in the well-known range has an assignment. Gaps exist for several reasons:
Future protocols: IANA keeps ports available for services not yet invented. In 1983, nobody knew we'd need HTTPS (port 443, assigned in 1994). Unassigned ports are reserved capacity for needs we haven't felt yet.
Failed assignments: Sometimes a protocol gets assigned a port but never gains adoption. IANA can de-assign these ports, returning them to unassigned status. As recently as February 2025, ports 2 and 3 were de-assigned and moved to reserved status.2
Administrative spacing: Leaving gaps between assigned ports provides organizational clarity in the registry and room for related services to cluster together.
What Might Be Using Port 327
Just because IANA hasn't assigned port 327 to an official service doesn't mean nothing uses it. On your system, you might find:
Custom applications: Developers sometimes pick arbitrary port numbers for internal services. An unassigned port in the well-known range is technically available, though using it requires elevated privileges.
Malware: Attackers sometimes use obscure, unassigned ports for command-and-control channels, betting that network administrators won't notice unusual traffic on ports without well-known services.
Local testing: Developers testing network applications might temporarily bind to port 327 during development.
How to Check What's Using Port 327
On Linux or macOS:
On Windows:
If something is listening on port 327, these commands will show you what process owns it.
The Value of Empty Space
Port 327 represents something important: reserved capacity. The Internet's addressing system doesn't use every number immediately. Some ports remain unassigned not because they're forgotten, but because the system needs room to grow.
Every unassigned port is a door that might open someday. Port 327 sits waiting—part of the Internet's reserve of possibility.
Related Ports
- Ports 325-326: Also unassigned, part of the same block
- Ports 328-332: Unassigned, completing the eight-port gap
- Port 344: PDAP (Prospero Data Access Protocol), the next assigned port after this unassigned block
Frequently Asked Questions
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