Port 1185: Catchpole — When You Name a Port After Yourself

What Runs on Port 1185

Port 1185 is officially registered with IANA for the Catchpole protocol—a service for streaming objects, data structures, and commands over the network. It operates on both TCP and UDP.¹

Unlike the well-known ports (0-1023) reserved for fundamental Internet services, port 1185 sits in the registered port range (1024-49151). These are ports assigned to specific applications or services, but without the elevated privileges required by system ports.

The Story Behind the Name

In 2002, a developer named Christian Catchpole wanted to register a port for his project—a compact wire protocol for streaming objects and data structures. He asked IANA for a low port number "in the interest of claiming something memorable."²

He got port 1185. And he named it after himself.

Twenty years later, the original software is gone. But the port registration persists. Catchpole now uses it for a completely different project: autonomous marine robotics. The protocol still streams objects and commands, but now they're flowing to underwater robots instead of whatever existed in 2002.²

This is how registered ports work. The number becomes yours. The technology changes. The door remains.

How It Works

The Catchpole protocol was designed for efficient object streaming—sending data structures and commands over the network in a compact binary format. The details of the current implementation aren't publicly documented, but the principle remains consistent with the original 2002 design: stream objects efficiently, minimize overhead, transmit commands reliably.

For asynchronous communication with autonomous systems (like marine robots), this makes sense. You need to send navigation commands, receive sensor data, stream telemetry, and handle all of it without blocking operations. A compact wire protocol with clear object boundaries solves exactly that problem.

The Beauty of Registered Ports

Port 1185 demonstrates something important about how the Internet's port system works. When you register a port with IANA:

• You get a stable identifier — The port number doesn't change, even if your software does
• You can evolve the service — The original 2002 protocol is gone, but the port lives on
• The name persists — Twenty years later, it's still called "catchpole"
• Nobody else can claim it — It's yours, officially, in the global registry

This is different from the ephemeral ports (49152-65535) that your OS assigns randomly when you open a connection. Those disappear when the connection closes. Registered ports are permanent. They're yours.

Is Anyone Using This?

Probably not. Port 1185 is a registered port for a specific project by a specific developer. Unless you're working with Christian Catchpole's marine robotics systems, you're unlikely to encounter traffic on this port.

And that's fine. The registered port range (1024-49151) contains thousands of ports claimed by projects large and small. Some became widely used (MySQL on 3306, PostgreSQL on 5432). Others serve niche purposes. Some are abandoned entirely but remain registered.

Port 1185 is a working example of the latter category—still actively used, but for a specialized purpose.

Checking What's Listening

If you want to see if anything is actually listening on port 1185 on your system:

On Linux or macOS:

sudo lsof -i :1185
# or
sudo netstat -tuln | grep 1185

On Windows:

netstat -ano | findstr :1185

If you see output, something is using the port. If not, it's idle. For most people, it will be idle—unless you're building underwater robots.

What This Port Teaches Us

Port 1185 isn't important because of what it does. It's important because of what it represents: the Internet's registry is made of people.

Someone wanted to build something in 2002. They needed a port. They asked for a memorable number. They got 1185 and named it after themselves. The project evolved. The port remained. And now, decades later, it serves autonomous robots exploring the ocean floor.

That's the beauty of the registered port system. It's not just technical infrastructure. It's a record of who built what, when, and why. Every port has a story. Port 1185's story is that someone claimed their own piece of the Internet's namespace—and actually kept using it.

Related Ports

• Port 1186 — MySQL Cluster Manager (the neighbor, serving databases instead of robots)
• Ports 1024-49151 — The full registered port range where developers claim their space
• Ports 49152-65535 — Ephemeral ports, assigned randomly and released when done