Port 1771 sits in the registered ports range (1024–49151). IANA lists it under a service called vaultbase, assigned to one Jose A. Sesin at sesin@vaultbase.com.1 That domain no longer resolves. The service left no documentation, no RFC, no apparent users. The registration remains.
This is not unusual.
The Registered Ports Range
The well-known ports (0–1023) are carefully guarded: HTTP at 80, HTTPS at 443, SSH at 22. Every assignment there is intentional and consequential.
The registered ports range is different. Any company or developer can file with IANA to claim a port number for their service. The process is lightweight. The commitment is not enforced. Over the decades, thousands of companies claimed ports for services that shipped, pivoted, or vanished — and the registrations outlasted the services.
Port 1771 is one of these. Registered. Abandoned. Sitting in the IANA list indefinitely.
Is This Port in Active Use?
Not for vaultbase — whatever that was.
If you see traffic on port 1771, it is almost certainly one of three things:
- Custom software: Internal applications frequently pick ports from the registered range precisely because they are unlikely to conflict with anything in active use.
- Dynamic reassignment: Operating systems sometimes pull from this range for ephemeral connections, though most OSes prefer ports above 49152 for that purpose.
- Scanning or probing: Port scanners sweep ranges indiscriminately. A hit on 1771 may just be noise.
What's Listening on This Port?
To check on your own system:
macOS / Linux:
Windows:
The process ID returned will tell you which application opened the port.
Why Unassigned (and Ghost) Ports Matter
The port number space — 65,535 entries — sounds vast. In practice, the registered range is crowded with exactly these ghost registrations. When a developer needs a port for a new service, they scan the list, find something "registered" but clearly dormant, and have a choice: file a new registration and wait, or just use it informally and hope for the best.
Most choose the latter. This is how the Internet actually works: part careful engineering, part squatters' rights.
Port 1771 is available in any practical sense. Vaultbase is gone. The number waits.
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