Port 3725: NA-ER-TIP — A Registered Port with a Forgotten Name

What Range This Port Belongs To

Port 3725 sits in the registered ports range (1024–49151). IANA manages this range, assigning port numbers to services upon request. Unlike the well-known ports (0–1023), which are reserved for foundational protocols like HTTP and SSH, registered ports serve more specialized or commercial applications.

Registration doesn't mean the service is widely deployed. It means someone filed the paperwork.

The Official Assignment

IANA registered port 3725 in April 2003 for a service called NA-ER-TIP — the Netia NA-ER Port, operating over both TCP and UDP.¹

Netia appears to have been a networking equipment context. What NA-ER-TIP actually does, what protocol it speaks, and whether any devices still run it — the documentation has largely evaporated. It's a registration without a story.

What Actually Uses Port 3725

The more practically relevant use comes from Novell PlateSpin, a workload migration and disaster recovery product. PlateSpin uses port 3725 for file transfer operations during machine migrations and replications, specifically via two processes: OFXController.exe and OFXControllerExecution.exe.²

If you're running PlateSpin and see a file transfer stall with a connection error on port 3725, the common causes are:

• A firewall blocking the port between source and target machines
• Another process already occupying port 3725 on the target
• Windows resource limits (MaxUserPort registry setting) preventing the port from being allocated on older Windows Server 2003 systems

This is a case where an obscure registered service and an unofficial-but-real use occupy the same port number with no connection to each other.

How to Check What's Listening on Port 3725

On Linux or macOS:

ss -tlnp | grep 3725
# or
lsof -i :3725

On Windows:

netstat -ano | findstr :3725

The PID in the output can be cross-referenced in Task Manager to identify the owning process.

Why Unassigned and Obscure Ports Matter

Most port activity on any system is invisible to users. Services start, bind to ports, and wait. When something goes wrong — a migration stalls, a connection times out, a firewall silently drops packets — the port number is often the first clue.

Port 3725 is a small example of the gap between IANA's registry and operational reality. The registry says one thing; production systems do another. Knowing to check both is the difference between a quick diagnosis and hours of confusion.