Port 3116: MCTET Gateway — A Name Without a Story

What This Port Is

Port 3116 sits in the registered port range (1024–49151), the middle tier of the port numbering system. Ports here are assigned by IANA to specific services upon request — they're not grabbed first-come-first-served like the ephemeral ports above 49151, but they're also not the tightly controlled well-known ports below 1024 that require root/admin privileges to bind.

IANA records port 3116 as assigned to MCTET Gateway (service name: mctet-gateway), registered around 2005 by someone at BMC Software, the IT management software company. The same registrant claimed three ports in a row:

Three-tier architecture. Master, gateway, Java service. Someone had a plan.

What MCTET Is

Unknown, and honestly: barely findable.

No RFC was filed. No public specification exists. BMC Software has never publicly documented a protocol called MCTET. The registration exists in the IANA registry, the service name exists in port databases, and that's approximately where the trail ends.

It was likely an internal BMC system — possibly related to enterprise job scheduling or IT automation, which is BMC's core business — that either never shipped in a form requiring public port access, or was retired before the Internet had enough memory to record it.

Unofficial Uses

One unofficial use is incidental rather than intentional: port 3116 falls within the UDP range 3074–3174 that Tom Clancy's Rainbow Six: Vegas used for multiplayer traffic.¹ If you were hosting a Rainbow Six Vegas server and your router forwarded that entire UDP range, packets passed through 3116 without anyone naming them that. It wasn't chosen — it was just in the way.

Beyond that, no malware campaigns, no application communities, and no services have staked a claim here.

How to Check What's Listening

If you're seeing traffic on port 3116 and want to know why:

macOS / Linux:

sudo lsof -i :3116
sudo ss -tulnp | grep 3116

Windows:

netstat -ano | findstr :3116

Cross-reference any PID that appears against your running process list. Unexpected listeners on obscure registered ports sometimes indicate misconfigured software or, less often, something that shouldn't be there.

Why Ghost Registrations Exist

The IANA registry is not curated aggressively. Ports get registered when a company or developer submits a request. They don't always get unregistered when the project dies, pivots, or ships on different ports entirely.

Port 3116 is a fossil. The registration is real. The intent behind it existed. The protocol itself didn't survive into a form anyone can inspect today. That happens more than the clean port number tables suggest — behind every unassigned-looking port is sometimes just an assignment that time forgot.