Port 3475: Genisar Comm Port — Registered, Dormant, Effectively Empty

What Port 3475 Is

Port 3475 sits in the registered ports range (1024–49151), the middle tier of the port number space. These ports are assigned by IANA to specific services and applications — not reserved like the well-known ports below 1024, but formally claimed rather than freely available.

Port 3475 carries a name in the registry: genisar-port, registered in April 2002 for Genisar Comm Port, a product of Genisar Interactive Technologies.¹

Who Was Genisar?

Genisar Interactive Technologies was an early-2000s company working in online collaboration — the kind of software that predated the Zoom era, trying to solve sales calls, training sessions, and remote support over the early commercial Internet. They registered port 3475 for their communication protocol and submitted it to IANA.

The company is gone. The IANA entry is not.

That's how port registrations work: there's no expiration, no reclamation process, no mechanism for IANA to ask "is anyone still using this?" A company registers a port, the company folds, and the registration persists indefinitely. Port 3475 is now a ghost listing — formally claimed, practically abandoned, sitting in the registered range like a reserved parking space for a business that closed twenty years ago.

Is Anyone Using It Now?

No documented software actively uses port 3475 today. It doesn't appear in security advisories, malware databases, or common firewall rule sets. If you see traffic on port 3475 in your environment, it's almost certainly custom application traffic, a misconfiguration, or worth investigating.

How to Check What's Listening

If port 3475 shows up on a machine you manage, you can identify what's using it:

On Linux/macOS:

# Show the process listening on port 3475
ss -tlnp | grep 3475

# Or with lsof
lsof -i :3475

On Windows:

# Show listening processes with their PIDs
netstat -ano | findstr :3475

# Then look up the PID
Get-Process -Id <PID>

With nmap (remote):

nmap -sV -p 3475 <target-ip>

Why Dormant Registrations Matter

The registered ports range was designed to prevent collisions — two applications claiming the same port and fighting over traffic. But registration without enforcement creates its own problem: ports that are claimed but unused for decades, unavailable to new software that might actually want them.

Port 3475 is one of hundreds of these dormant registrations scattered through the 1024–49151 range. They're not dangerous. They're just occupying space in a namespace that has no garbage collection.