Port 3380: SNS Channels — Registered, Forgotten

What Port 3380 Is

Port 3380 sits in the registered ports range (1024–49151). These ports require formal IANA registration — unlike the well-known ports below 1024, which are tightly controlled, or the ephemeral ports above 49151, which are freely assigned by the operating system for outbound connections.

IANA's registry lists port 3380 as assigned to a service called SNS Channels (sns-channels), registered by a contact at firstfloor.com.¹ Both TCP and UDP are reserved. That's where the trail ends.

The Ghost Registration

First Floor was a software company. The domain no longer resolves to anything active. There is no public documentation for what "SNS Channels" was, no RFC, no open-source implementation, no forum posts asking for help with it. Whatever protocol was planned for this port never became real — or became real only inside one company's internal systems and then disappeared with it.

This happens more than you'd expect. The IANA registry is full of registrations from companies that no longer exist, services that were never deployed publicly, and protocols that died in private beta. The number is reserved forever; the service is gone.

In practice, port 3380 behaves like an unassigned port. Nothing well-known listens here. Nothing well-known connects here.

If You See Traffic on Port 3380

If something on your network is listening on or connecting to port 3380, it's almost certainly one of:

• A custom or internal application that chose this port because it appeared unoccupied
• Malware (obscure port numbers appeal to attackers precisely because they attract less scrutiny)
• A misconfigured service

Worth investigating either way.

How to Check What's Listening

On Linux or macOS:

# Show what process is listening on port 3380
ss -tlnp | grep 3380

# Or with lsof
lsof -i :3380

On Windows:

netstat -ano | findstr :3380

The output will show the process ID (PID). Cross-reference with Task Manager or ps aux to identify the process.

Why Ghost Registrations Matter

The registered port range was designed to prevent collisions — if your application registers a port with IANA, other applications are expected to avoid it. In practice, enforcement is nonexistent. A ghost registration like SNS Channels blocks no one; applications use whatever port they want regardless of IANA's list.

This is why the port number space is messier than the clean system it was designed to be. Real-world port usage is determined by convention and market adoption, not registry entries.