Port 3090: Registered, Abandoned

What Port 3090 Is

Port 3090 sits in the registered port range — the block between 1024 and 49151 that IANA manages for applications that need a consistent, recognized address. Unlike well-known ports (0–1023), registered ports don't require elevated privileges to bind. Any application can open one; the registration just signals intent.

Port 3090 was associated with two services: Rappore Session Services (RTSS) and Senforce Session Services (STSS).¹ Both Rappore and Senforce were enterprise mobility and network access control companies from the mid-2000s. Neither appears to be operating today. Their port claims remain in databases as artifacts — entries that document what someone intended, not what anyone is running.

Known Unofficial Uses

Rainbow Six Vegas used port 3090 (UDP) for multiplayer matchmaking and game sessions.¹ Ubisoft's tactical shooter franchise needed a designated port for online play, and 3090 was one of several ports players were told to forward on their routers. The game series has since moved on, but the port forwarding guides still circulate.

Outside of gaming forums and port database entries, port 3090 sees no widely documented active use.

What the Scanners See

The SANS Internet Storm Center tracks probing activity on port 3090.² Automated scanners do occasionally knock on it — opportunistic sweeps that hit thousands of ports looking for anything listening. This isn't specific interest in port 3090; it's the background noise that hits every port in the registered range. Nothing notable lives here, so nothing notable is found.

How to Check What's on This Port

If you see traffic on port 3090 and want to know what's listening:

Linux/macOS:

sudo ss -tlnp | grep 3090
sudo lsof -i :3090

Windows:

netstat -ano | findstr :3090

The process ID from either command can be matched to a running application in your task manager or process list.

Why This Port Matters Anyway

Port 3090's emptiness is itself informative. The registered range contains thousands of ports in the same state: claimed once, abandoned, now neither free nor occupied. They're not available for fresh official registration without a process, but they're also not doing anything.

This is the practical reality of the port number system. IANA maintains assignments, but it can't force anyone to keep using them. Companies fold, products are discontinued, protocols are superseded. The ports stay registered, the databases keep listing them, and the numbers become minor archaeological sites — evidence of software that once ran somewhere.

If you're developing an application and considering port 3090, the honest answer is: nothing is actively using it, but it's not a clean unregistered port either.