Port 3075 — The Registered Port Nobody Claimed

What Is Port 3075?

Port 3075 sits in the registered port range — the block of ports from 1024 to 49151 that IANA manages on behalf of software vendors and standards bodies. Unlike the well-known ports below 1024 (which carry HTTP, SSH, DNS, and the other foundations of the Internet), registered ports exist for specific applications that asked IANA to reserve a number.

IANA registered port 3075 for Orbix 2000 Locator, a service from IONA Technologies' Orbix product line — a CORBA (Common Object Request Broker Architecture) middleware platform from the late 1990s. CORBA was the distributed computing vision of its era: objects on different machines calling each other across a network, with a locator service helping them find each other. Orbix 2000 was one of its commercial implementations.

CORBA lost the future to web services, then REST, then gRPC. Orbix followed. The registration remains in the IANA registry as a quiet fossil.

Who Actually Uses It Now

The gaming community has informally adopted port 3075, particularly for titles running on or alongside the Xbox Live network:

• Call of Duty: World at War — used UDP 3075 for multiplayer matchmaking traffic¹
• Lost Planet: Extreme Condition — listed 3075 as part of its online play requirements
• Rainbow Six Vegas — used a range spanning 3074 through 3174, with 3075 included
• Blazing Angels Online — another title that documented this port

None of this is official. These games weren't coordinating with IANA or Orbix. They needed a port, picked one (or inherited it from a neighbor — port 3074 is the well-known Xbox Live port), and it spread by convention across titles and forum guides.

What Range This Port Belongs To

Registered ports: 1024–49151

This range is where applications live. IANA accepts registration requests, reviews them, and assigns numbers to avoid conflicts between software vendors. The assignments are voluntary — nothing technically stops software from using any port it wants, but the registry reduces chaos by giving vendors a place to declare their intentions.

Below 1024: well-known ports (HTTP, SSH, DNS — the Internet's foundations, require root privileges on Unix systems)

Above 49151: dynamic/ephemeral ports (assigned temporarily by operating systems for outgoing connections)

At 3075, you're firmly in registered territory — documented but not enforced.

Checking What's on This Port

If you see traffic on port 3075 on your own machine or network:

On Linux/macOS:

# See what process is listening on port 3075
ss -tlnp | grep 3075
# or
lsof -i :3075

On Windows:

netstat -ano | findstr :3075
# then look up the PID in Task Manager

From outside the machine:

nmap -p 3075 <target-ip>

If you're a gamer experiencing NAT issues with Xbox Live or older Call of Duty titles, forwarding both UDP and TCP on 3075 alongside 3074 is commonly cited as the fix.

Why Unassigned (and Dormant) Ports Matter

A port with a registered but defunct service is neither clean nor claimed. The registration discourages fresh official use, but the lack of active software means firewalls aren't watching for it, and conventions form in the gaps.

This is how port ecosystems drift. A technology gets registered, the technology dies, the number persists in documentation, game developers or sysadmins inherit it by proximity or habit, and eventually the port has an entirely different de facto identity than the one IANA intended.

Port 3075 is a minor example. The ecosystem has thousands of them.