Port 3164: IMPRS — A Registered Port That Leads Nowhere

What Port 3164 Is

Port 3164 sits in the registered port range (1024–49151). These ports are assigned by IANA to specific services after someone submits a request. Unlike well-known ports (0–1023), registered ports don't require elevated privileges to use, and enforcement is largely by convention.

IANA's registry lists port 3164 as assigned to IMPRS on both TCP and UDP. The contact on file is Lars Bohn at Nokia.¹ That's where the trail ends. No RFC was published. No public documentation describes what IMPRS is, what it does, or whether it was ever deployed. The registration exists; the protocol is effectively invisible.

This happens more often than you'd expect. Someone inside a company registers a port for an internal protocol or a product that never shipped, and the registration sits in the registry indefinitely. The port isn't truly "open" — it's just claimed.

Is Anything Actually Using It?

Possibly, in narrow contexts. Port 3164 falls within the range (3074–3174 UDP) reportedly used by Rainbow Six Vegas for multiplayer matchmaking and game traffic.² That's an unofficial use — Ubisoft never registered that range, and the overlap with 3164 is coincidental.

Outside of gaming, there's no evidence of software commonly binding to 3164 in production environments. If you see traffic on this port, it's worth investigating.

How to Check What's Listening

To see if anything on your own machine is using port 3164:

Linux / macOS:

# Show which process is listening on port 3164
ss -tlnp | grep 3164
# or
lsof -i :3164

Windows:

netstat -ano | findstr :3164

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

To check from outside — whether a remote host has something listening on 3164:

nmap -p 3164 <host>

If nothing is listening, you'll get closed or filtered. If something is there, nmap will tell you the state and may identify the service.

Why Ghost Registrations Matter

The IANA registry is not a locked vault — it's a coordination system that works on trust and convention. When a port gets registered and then abandoned, it creates ambiguity. Any software that later chooses that port for an unofficial purpose has to work around the ghost claim.

More practically: firewall rules and security scanners often flag unexpected traffic on registered ports. If you see 3164 in your logs and don't know what it is, that's worth understanding. A registered port with no known service is a reasonable thing to investigate.

Summary