Port 3360: KV Server — Registered, Unknown, Quiet

What Range This Port Belongs To

Port 3360 sits in the registered ports range (1024–49151). These ports are neither the famous well-known ports below 1024 nor the free-for-all ephemeral ports above 49151. They occupy the middle ground: ports that someone, at some point, formally requested from IANA for a specific service.

Registered ports require an application to IANA. A person or organization had to describe their protocol, submit paperwork, and receive the assignment. Port 3360 went through that process.

The IANA Assignment: KV Server

The IANA registry lists port 3360 as assigned to "KV Server" (service name: kv-server) on both TCP and UDP.¹

That's nearly everything that's publicly known about it.

"KV Server" almost certainly means key-value server — a service for storing and retrieving data by key, the architectural pattern behind systems like Redis and Memcached. But who built it, when, for what product, and whether it was ever deployed at any meaningful scale is lost. No RFC was published. No protocol documentation survives in any searchable form. No open-source implementation claims this port.

This happens more often than you'd expect. The IANA registry stretches back decades. Services were registered for software that shipped to a small number of customers, or was acquired and discontinued, or simply faded. The registration remains; the software doesn't.

In Practice

Port 3360 is quiet. Security scanners don't flag it as commonly exploited. Network monitoring tools don't recognize it as a known service. If you see traffic on port 3360, it's almost certainly one of three things:

• An internal application that chose this port arbitrarily
• Software that was explicitly built to use the original KV Server protocol (vanishingly rare)
• Something unexpected that warrants investigation

How to Check What's Listening

If port 3360 is open on a machine you're responsible for, find out what's using it:

On Linux or macOS:

# Show what process is listening on port 3360
ss -tlnp | grep 3360

# Alternative using lsof
lsof -i :3360

On Windows:

netstat -ano | findstr :3360

The output will include the process ID. Cross-reference that with your process list (ps aux on Linux, Task Manager on Windows) to identify the application.

If something is listening on 3360 and you don't recognize it, treat that as worth investigating. An unrecognized listener on any port is an unrecognized listener.

Why Unassigned-in-Practice Ports Matter

The registered port range has over 48,000 slots. Many are actively used by well-known software. Many others, like port 3360, are technically assigned but practically vacant.

This matters for two reasons.

First, it creates ambiguity. When a port has an IANA assignment, automated tools may assume they know what's running there. A security scanner that sees port 3360 open might tag it as "KV Server" and move on — even though the actual service listening there could be anything. The label provides false certainty.

Second, it illustrates how the port numbering system ages. IANA doesn't reclaim abandoned registrations. The registry is append-only, accumulating history. Port 3360 will be listed as "KV Server" in the official registry indefinitely, regardless of whether that software still exists anywhere on Earth.

The practical lesson: the IANA label tells you what a port was intended for. It doesn't tell you what's actually running there. For that, you check.