Port 1547: Laplink — When Moving Files Meant Cables

Port 1547 is officially registered with IANA for Laplink, file transfer software that first appeared in 1983.¹²

What Laplink Does

Laplink was created to solve a problem that seems almost quaint now: how do you move files between two computers sitting right next to each other?

In the early 1980s, there were no USB drives. No local area networks in homes or small offices. No cloud storage. If you wanted to copy files from one PC to another, you needed special software and a special cable.

Laplink provided both. It used either:

• A parallel port cable (the "LapLink cable")
• A serial port null modem cable
• Later, USB connections

The software ran on both machines, established a connection over port 1547, and let you transfer files. Simple. Essential for its time.³

The Registered Port

Port 1547 is a registered port (range 1024-49151). These ports are assigned by IANA to specific services upon request. The registration for port 1547 shows:

• Service: laplink
• Port: 1547 (TCP and UDP)
• Contact: Michael Crawford at Traveling Software⁴

This means that technically, port 1547 belongs to Laplink. Any software using this port should be related to the Laplink protocol or have permission.

Does Anyone Still Use This?

Probably not much. Laplink still exists as a company and still makes remote access software, but the parallel port file transfer era is long gone. Parallel ports themselves are extinct on modern computers.

That said, registered ports don't expire. Port 1547 sits in the registry, waiting for software from 1983 that might still be running somewhere on a vintage machine.

Some sources mention Oracle Database Listener using port 1547 in certain configurations, though this would be an unofficial use of a port registered to someone else.⁵

Why This Port Matters

Port 1547 is a time capsule. It exists because someone in the 1980s recognized that computers needed to talk to each other, even before networking was common.

The problem Laplink solved—moving files between machines—is still fundamental. We just do it over Wi-Fi now, or through cloud sync, or via USB drives that hold more data than an entire computer from 1983.

But the port remains, registered and official, a marker of when file transfer felt like magic.

How to Check What's Using Port 1547

To see if anything is listening on port 1547 on your system:

On Linux/macOS:

sudo lsof -i :1547
# or
sudo netstat -tulpn | grep 1547

On Windows:

netstat -ano | findstr :1547

If you see something listening, it's probably not Laplink. More likely it's custom software or a service that chose this port arbitrarily. Unless you're running a very, very old system.

Related Ports

• Port 1548-1550: Also in the registered range, assigned to various legacy protocols
• Port 20-21: FTP, another file transfer protocol from the early Internet era
• Port 22: SSH with SCP/SFTP, the modern secure way to transfer files