What Port 3317 Is
Port 3317 sits in the registered port range (1024–49151), the middle tier of the port number space. Well-known ports (0–1023) are reserved for foundational protocols like HTTP, SSH, and DNS. Dynamic/ephemeral ports (49152–65535) are assigned on the fly by operating systems for outbound connections. Registered ports are the middle ground: companies and developers can claim them for specific applications by filing with IANA.
Port 3317 was claimed. The IANA registry lists it as "VSAI PORT," assigned to Rieko Asai at isl.mei.co.jp — the Information Systems Laboratory of Matsushita Electric Industrial, the company now known as Panasonic.1
That's where the trail ends.
The Registration That Explains Nothing
VSAI is not a public protocol. No RFC defines it. No official documentation describes it. The Matsushita email domain in the registration no longer resolves to anything useful, and no public source explains what VSAI stands for — Video Systems Application Interface, Virtual Something Application Interface, or something else entirely. Whatever it was, it appears to have been an internal Matsushita project that never shipped publicly or was superseded before anyone outside the company had reason to document it.
This happens more than you'd expect. The registered port range contains hundreds of ports registered in the 1990s for products that never shipped, protocols that were replaced, or internal tools that stayed internal. The registration persists; the purpose evaporates.
Unofficial Uses
Port 3317 has been associated with Attunity Replicate (now Qlik Replicate), a commercial database replication tool used for change data capture and moving data between databases and data warehouses.2 This is an unofficial use — Attunity did not register port 3317 with IANA — and your specific Qlik Replicate deployment may use a different port depending on configuration.
If you see port 3317 open on a machine, it's more likely to be Qlik Replicate or another application that chose this port than anything related to whatever VSAI was.
What's Actually Listening on This Port
To check what process has port 3317 open on your system:
macOS / Linux:
Windows:
The output will show the process ID (PID). Cross-reference it with your process list to find the application.
If nothing is listening, the port is idle — which is normal. Most ports are quiet most of the time.
Why Unassigned (and Ghost-Assigned) Ports Matter
The port number system is a finite namespace. There are 65,535 ports, and they have to serve every protocol ever invented or yet to be invented. IANA manages the registered range to prevent collisions — two different applications shouldn't independently decide they both live on port 3317.
When a registration becomes a ghost like this one, it creates mild friction: the port is technically "taken" but not usefully occupied. Applications that want to use this range have to work around it or accept the ambiguity. It's a small inefficiency baked into the history of the Internet — the archaeology of abandoned projects, visible in a registry that never forgets.
Frequently Asked Questions
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