Look up what a TCP or UDP port is used for

Look up the registered service for a TCP or UDP port number.

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ToolPort Number Lookup
Input
Output
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Preview

How it works

The numeric port is checked against the IANA registry with transport protocol kept separate, then the registered service and assignment status are shown. Registry data describes allocation, not whether a host is listening.

  • IANA covers ports 0 through 65535.
  • TCP and UDP assignments remain distinct even for the same number.

Worked example

Port 443
Looked up by number
Input
											443
Output
												Port: 443
Protocol: TCP
Service: HTTPS
Description: HTTP over TLS, encrypted web traffic
Assignment: Well-known (system) port

When to use this

Firewall reviews, packet analysis, and internal service documentation look up ports.

Edge cases

  • Port 0 is reserved rather than a normal endpoint.
  • A registered service may not be running on a particular host.
  • TCP 53 and UDP 53 are separate entries.

References