Port 3469: Pluribus — A name without a spec

What This Port Is

Port 3469 sits in the registered ports range (1024–49151). These ports are neither reserved for system services like the well-known ports below 1024, nor freely ephemeral like the dynamic ports above 49151. They are registered with IANA — the Internet Assigned Numbers Authority — meaning a company or developer submitted a claim and IANA recorded the association.

For port 3469, IANA recorded the name: pluribus.

The Pluribus Registration

The registration almost certainly refers to Pluribus Networks, a software-defined networking company that built the Netvisor ONE operating system for data center fabric switches. Their platform manages distributed cloud networking across large switch deployments. Arista Networks acquired Pluribus in 2022, and the technology continues under Arista's umbrella.¹

What the registration doesn't include: an RFC, a protocol specification, or any public documentation of what actually runs on port 3469. IANA records names, but it doesn't require published specs. The result is a port that's "registered" in name only — a label on a door with no explanation of what's inside.

This is more common than it sounds. Companies frequently register port numbers for internal or proprietary use. Without a published protocol spec, the registration is essentially a namespace reservation.

What Range This Port Belongs To

The registered ports range (1024–49151) was created to give applications a stable, identifiable home that wouldn't collide with core system services. Any application can use any port, but registering one tells other developers "this is ours — pick something else."²

The registration doesn't mean your machine is running Pluribus software if port 3469 is open. Something else could be using it. Registrations prevent naming conflicts, not actual port collisions.

What's Actually Listening on Your Machine

If you see port 3469 open on a system and want to know what's using it:

macOS / Linux:

sudo lsof -i :3469

Linux (alternative):

ss -tlnp | grep 3469

Windows:

netstat -aon | findstr :3469

The process name or PID in the output will tell you what's actually there. On most machines, this port will be closed entirely.

Why Unassigned-in-Practice Ports Matter

When a port has a name but no spec, it occupies an interesting middle ground. It's not dangerous by definition — most registered-but-undocumented ports are simply proprietary software doing proprietary things. But it's also not verifiable. You can't look up the protocol and confirm that what's running matches expected behavior.

This is why firewall hygiene matters: don't leave ports open because a name in a registry sounds familiar. Open ports are attack surface regardless of what IANA calls them.