Port 2063: ICG Bridge — A registered ghost

Port 2063 sits in the registered port range (1024–49151) with an official name in the IANA registry: icg-bridge, described as "ICG Bridge Port." That's where the paper trail ends.

No RFC. No assignee contact. No documentation. No known software that uses it. Whatever "ICG Bridge" referred to, it didn't leave enough behind to reconstruct.

The Registered Port Range

Ports 1024 through 49151 are registered ports. The idea is simple: organizations apply to IANA, get a port number assigned to their service, and the registry records it for posterity. This prevents two unrelated services from colliding on the same number.

In practice, the registry has accumulated thousands of entries like port 2063: names registered long ago by companies or projects that changed, dissolved, or simply moved on. The registration persists; the service doesn't.

This isn't a flaw in the system. It's an artifact of how the Internet grew. IANA doesn't revoke registrations when a service goes dark, because what was once used might still be running somewhere on a network nobody checks anymore.

Is Anything Actually Using This Port?

Almost certainly not at scale. Port 2063 doesn't appear in any firewall rule templates, security scanner databases, or known malware profiles. If something is listening on this port on your system, it's almost certainly an application that chose the number for its own reasons — not because it's honoring an ICG Bridge registration.

To check what's listening on port 2063 on your system:

Linux / macOS:

ss -tlnp | grep 2063
# or
lsof -i :2063

Windows:

netstat -ano | findstr :2063

If you see something, the process ID will tell you what it is.

Why Ghost Registrations Exist

The IANA registry was designed for a world where every port had one service and every service had one port. Reality is messier. Companies registered ports speculatively. Projects registered ports and then never shipped. Acquisitions buried the institutional knowledge of what a registration was for.

Port 2063 is a small artifact of that history — a placeholder that outlasted whatever it was meant to hold.