Port 3318: ssrip — A Name, No Protocol

What Is Port 3318?

Port 3318 sits in the registered ports range (1024–49151). These ports are assigned by IANA upon request — any individual or organization can submit a registration for a port they intend to use for a specific service. The registry exists to prevent collisions: two protocols shouldn't unknowingly claim the same port.

Port 3318 was registered under the service name ssrip — the Switch to Switch Routing Information Protocol — by someone named Baba Hidekazu. It is registered for both TCP and UDP.

The IANA entry describes it as: "Swith to Swith Routing Information Protocol."

That's not a quote error. That's what the official record says.

What Is ssrip?

Unknown. There is no RFC defining this protocol. There is no public documentation explaining how it works, what problem it solves, or who was meant to use it. The name implies a protocol for exchanging routing information between network switches — but that description fits many things and explains nothing specific.

It may have been a proprietary protocol for an internal system that never shipped. It may have been registered speculatively. Whatever the intention, the documentation never followed.

Does Anything Actually Use Port 3318?

One real-world overlap: Citrix NetScaler Gateway uses the port range 3224–3324 UDP for Framehawk, its protocol for delivering virtual desktops and applications over lossy networks. Port 3318 falls inside that range. If you see UDP traffic on 3318 in a Citrix environment, that's the likely explanation — not ssrip.¹

Outside of that context, if you see something listening on port 3318, it's almost certainly an application that chose the port arbitrarily, not one implementing ssrip.

How to Check What's Listening on Port 3318

On Linux or macOS:

# Show what process is listening on port 3318
ss -tlnp | grep 3318

# Or with lsof
lsof -i :3318

On Windows:

netstat -ano | findstr :3318

The process ID in the output can be looked up in Task Manager to identify what's actually there.

Why Ghost Registrations Happen

The registered ports range exists on the honor system. IANA reviews submissions, but there's no requirement to publish an RFC, no enforcement of deployment, and no mechanism to reclaim abandoned registrations. A port can sit in the registry indefinitely after its original purpose fades or never materializes.

Port 3318 is a small artifact of that system: a name, a typo, an assignee, and nothing else.