Port 2706 is registered with IANA under the service name ncdmirroring — NCD Mirroring — assigned on behalf of Network Computing Devices (NCD), a company that no longer exists.
The Registered Range
Port 2706 falls in the registered ports range (1024–49151). IANA maintains this range to prevent two organizations from accidentally building services that clash on the same port number. Companies and individuals can formally register a port for their protocol, and that assignment stays in the registry indefinitely — even after the company shuts down.
Who Was NCD?
Network Computing Devices was founded in Mountain View, California in 1987, one of the earliest makers of X terminals — thin clients that ran a display server locally but executed applications on a remote Unix host. Before the PC era had fully won, NCD's terminals let users run graphical workstation software without owning a workstation.
At its peak in 1994, NCD pulled in $160.9 million in revenue. By 2004, the thin client market had been eclipsed by cheap PCs and the company ceased operations. Its ThinSTAR product line was acquired by Neoware Systems in 2002.1
What NCD Mirroring Was
The specifics of the ncdmirroring protocol are not publicly documented in any surviving RFC or open specification. Based on NCD's product line, it was almost certainly a session or display mirroring capability built into NCDware — their terminal management software — allowing administrators to observe or duplicate a user's X terminal session. Screen sharing for a pre-web world.
The registration is attributed to Tim Stevenson in the IANA database.2
What This Port Is Now
Essentially dormant. No modern software registers itself on port 2706. You are unlikely to find anything listening here on a contemporary system.
If you do find something on port 2706, that warrants investigation — not because this port has a dangerous history, but because there's no legitimate reason modern software would be using it.
How to Check What's Listening
On Linux or macOS:
On Windows:
If something appears, the process ID will tell you what's running. On Linux, lsof will show the process name directly.
Why Dead Registrations Matter
The IANA port registry is a graveyard of discontinued products and forgotten companies. These registrations matter because they prevent accidental reuse — a new protocol built on 2706 would conflict with any NCD infrastructure still somehow running in some ancient data center somewhere.
Dead registrations are also a record. They tell you that someone, at some point, built something here. Port 2706 is a small monument to the era when thin clients were the future.
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