Port 3117: Unassigned — A Blank Page in the Registered Range

What Port 3117 Is

Port 3117 is unassigned. IANA lists no service name for it, and no protocol has staked a claim here in any meaningful way.

That's not unusual. The registered port range (1024–49151) contains over 48,000 ports, and thousands of them sit empty — placeholders in a numbering system designed to scale, waiting for a use that may never come.

The Range It Lives In

Port 3117 belongs to the registered ports range (1024–49151), also called user ports. This range sits between the well-known ports (0–1023), which are reserved for foundational protocols like HTTP, DNS, and SSH, and the ephemeral ports (49152–65535), which operating systems hand out dynamically for outbound connections.

Registered ports are where applications go to stake a claim. You request a number from IANA, you get it assigned, and your protocol lives there. Port 3117 has no such claim on record.

Any Observed Uses?

One loose association: Tom Clancy's Rainbow Six: Vegas sweeps a broad UDP range (3074–3174) for multiplayer game traffic.¹ Port 3117 falls inside that window by arithmetic — but this isn't an assignment. It's a range, like casting a wide net. The game doesn't specifically need 3117; it needs whatever port in that range the connection negotiates.

Beyond that, no documented use. If you're seeing traffic on port 3117, it's application-specific to whatever is running on your system.

How to Check What's Using It

If you see port 3117 active on a machine, these commands will tell you what process owns it:

macOS / Linux:

lsof -i :3117

Windows:

netstat -ano | findstr :3117

The process ID from either command can be looked up in your task manager or with ps aux | grep <pid> on Unix systems.

Why Unassigned Ports Matter

The port numbering system works because most of it is predictable. Port 443 is always HTTPS. Port 22 is always SSH. That predictability is what lets firewalls make fast decisions and administrators reason about network traffic at a glance.

Unassigned ports are the gaps in that map. They're not forbidden — any application can use any port — but they carry no official meaning. Traffic on an unassigned port is worth a second look, not because it's suspicious by definition, but because you have no reference point to compare it against.

Port 3117 is one of those gaps. Nothing officially lives here. If something is listening, you'll want to know what it is.