Port 410: DECLadebug — The Ghost of Alpha Debugging

Port 410 is officially assigned to DECLadebug Remote Debug Protocol for both TCP and UDP.¹ It's a well-known port (in the 0-1023 range reserved by IANA), but one you'll likely never encounter in practice. This port belongs to a vanished world.

What DECLadebug Was

Ladebug was Digital Equipment Corporation's symbolic source code debugger for their Alpha platform running Tru64 UNIX.² It debugged programs written in DEC C, C++, Ada, COBOL, Fortran 90, and Fortran 77.³ The advantage DECLadebug had over other remote debug protocols at the time was support for 64-bit debugging—a significant capability when Alpha processors were among the first to embrace 64-bit computing.⁴

The remote debug protocol on port 410 allowed developers to debug programs running on one Alpha system from another machine. You'd connect across the network, set breakpoints, inspect memory, step through code—all the things debuggers do, but remotely.

The Platform That Vanished

DEC's Alpha architecture and Tru64 UNIX represented serious engineering. Alpha processors were fast, the operating system was robust, and companies ran critical infrastructure on these machines. But Digital Equipment Corporation was acquired by Compaq in 1998, Compaq merged with Hewlett-Packard in 2002, and HP discontinued Tru64 UNIX support in 2012.⁵

The machines are gone. The operating system is discontinued. But port 410 remains in IANA's registry, assigned to Hewlett Packard, a vestige of code that no longer runs.

Why This Port Matters

Port 410 is a ghost port—officially assigned but functionally extinct. Yet it teaches something important: port assignments outlive the systems they were created for. The Internet's port registry is an archaeological record. Every number tells a story about what we built, what we needed, what we thought would last forever.

Well-known ports (0-1023) are assigned by IANA and require formal registration.⁶ Port 410 earned that designation when DEC's Alpha systems mattered, when debugging across enterprise networks was cutting-edge, when 64-bit computing was new.

Now it's a museum piece. If you scan port 410 on a modern network, you'll find nothing. No service listens there. No protocol speaks its language. Just silence where debuggers once connected.

Checking Port 410

To see if anything is actually listening on port 410:

Linux/macOS:

sudo lsof -i :410
sudo netstat -tulpn | grep :410

Windows:

netstat -ano | findstr :410

You'll almost certainly find nothing. But the port exists, reserved, waiting for Alpha systems that will never boot again.

The Honest Reality

Port 410 is assigned but unused. In theory, any service could claim it—IANA controls well-known ports, but enforcement is social convention, not technical restriction. In practice, no modern software bothers. The debugging protocol it was designed for died with the platform.

This is what happens to ports when their purpose vanishes. They become historical markers. Port 410: Here lies DECLadebug. It debugged code on machines that no longer exist. It solved problems in an architecture that's been discontinued. It mattered once.

Related Ports

Other debugging and remote development ports include:

• Port 2049: Network File System (NFS), often used for remote development environments
• Port 3689: DAAP (Digital Audio Access Protocol), another protocol from a different era
• Port 4000-4999: Various debugging and development tools claim ports in this range