Port 3366: Creative Partner — A Name Without a Face

What Port 3366 Is

Port 3366 sits in the registered port range (1024-49151). These ports are assigned by IANA to specific services, which distinguishes them from the well-known ports (0-1023) that require root or administrator privileges to open, and from the ephemeral ports (49152-65535) that operating systems hand out temporarily for outgoing connections.

Being in the registered range means a service was supposed to claim this port and document what it does. Port 3366 did have a claimant: something called "Creative Partner" (service name: creativepartnr), registered for both TCP and UDP. ¹

That's where the documentation ends.

No RFC. No product that currently answers to that name. No community memory of what Creative Partner was or who built it. The name sits in port databases like an entry in a phone book for a number that's been disconnected.

What Actually Uses This Port

MySQL, Informally

Port 3366 occasionally appears as a secondary MySQL port. MySQL's default is 3306 — and administrators running multiple MySQL instances on the same machine, or trying to avoid the well-known default for security reasons, sometimes land on 3366 by choice or coincidence. ²

It is not an official MySQL port. MySQL itself uses 3306 for classic protocol and 33060 for X Protocol. Port 3366 is just close enough to 3306 that it's an easy pick when you need an alternative.

Security Scan Noise

The SANS Internet Storm Center tracks probe activity against port 3366. The threat level is low — this port attracts scanner noise rather than targeted attacks — but it appears in logs regularly enough to be worth knowing about. ³

How to Check What's Listening

If you see port 3366 active on a machine and want to know why:

Linux / macOS:

ss -tlnp | grep 3366
# or
lsof -i :3366

Windows:

netstat -ano | findstr :3366
# Then look up the PID:
tasklist | findstr <PID>

Nmap (from another machine):

nmap -sV -p 3366 <target-ip>

The -sV flag asks Nmap to probe the service and try to identify what's actually running, rather than just reporting the port as open.

Why Unassigned Ports Matter

The registered port range has 48,128 slots. Not all of them are filled. The ones that are filled aren't all actively used — some were claimed by products that never shipped, companies that folded, or protocols that never gained adoption.

These quiet ports matter for a few reasons:

Firewall policy. A port with no known legitimate service has no reason to be open on most systems. Seeing it open is a signal worth investigating.

Ad-hoc conventions. When developers need a port for internal tools, databases, or test servers, they reach for something in the registered range that isn't well-known. Those choices become informal conventions on that team's infrastructure — undocumented, but real.

Scanner targets. Automated scanners probe the entire registered range looking for misconfigured or exposed services. A quiet port that suddenly responds is worth noticing.

Port 3366 is a placeholder in the registry, a neighbor of a famous port, and mostly empty space. That's most of what the registered range actually is.