Service: cadkey-licman (Cadkey License Manager)
Protocol: TCP/UDP
Status: Registered with IANA
Port range: Registered Ports (1024-49151)
What This Port Does
Port 1399 carries communication between CADKEY software and its license manager. When an engineer launches CADKEY, the software contacts the license manager on port 1399 to verify they have a valid license. If the check succeeds, the software opens. If it fails, the user sees an error instead of their CAD workspace.
This is the invisible gatekeeper of professional design work—the moment between clicking the icon and being allowed to create.
The Software Behind the Port
CADKEY was groundbreaking when it launched in 1984. Created by Peter Smith and Livingston Davies through their company Micro Control Systems, it was one of the first 3D CAD programs that could run on a personal computer rather than requiring expensive workstations.1
Before CADKEY, 3D computer-aided design meant mainframes and specialist hardware. CADKEY brought that capability to DOS machines, winning Editor's Choice and CAD Product of the Year awards from PC Magazine in both 1986 and 1988.1
The software changed hands several times:
- 1996: Baystate Technologies acquired it
- 1999: Operating as CADKEY Corporation with enhanced solid modeling
- 2003: Kubotek Corporation of Japan acquired the technology
- Today: Continues as KeyCreator under Kubotek USA1
How License Managers Work
Port 1399 exists because software companies needed to control who could use their expensive CAD software. A license manager is a separate service that:
- Runs on a server (or sometimes locally)
- Tracks how many licenses the organization owns
- Checks out licenses to users when they launch the software
- Returns licenses to the pool when users close the program
This meant a company could buy 10 licenses and have 50 employees share them—as long as no more than 10 people used CADKEY simultaneously. The license manager on port 1399 enforced this limit.
The Registered Ports Range
Port 1399 sits in the registered ports range (1024-49151). These ports are registered with IANA for specific services but don't require administrative privileges to use, unlike well-known ports (0-1023).
Anyone can request to register a port in this range for their application. CADKEY's developers registered 1399 for their license manager and 1400 for a related service called cadkey-tablet.2
Security Considerations
License managers create interesting security scenarios:
Firewall rules matter. If port 1399 is blocked between a user's workstation and the license server, the software won't run—even if they have a valid license. Network administrators had to explicitly allow this traffic.
Exposure risk. A license server listening on port 1399 shouldn't be exposed to the public Internet. These services were designed for internal networks, not Internet-facing connections.
Old software, persistent ports. Even if an organization stopped using CADKEY decades ago, port 1399 might still be referenced in old firewall rules or documentation—archaeological evidence of software that once ran there.
Checking What's Listening
To see if anything is using port 1399 on your system:
Linux/macOS:
Windows:
If you find something listening on port 1399 and you're not running CADKEY or KeyCreator, investigate what it is. This port should be quiet unless you're actively using the associated CAD software.
Related Ports
- Port 1400 — cadkey-tablet (Cadkey Tablet Daemon): Another CADKEY-related service, likely for handling input from digitizing tablets used in CAD work
Why Old Software Ports Matter
Port 1399 represents a specific moment in computing history—when 3D design moved from expensive workstations to personal computers, and when software licensing became sophisticated enough to need dedicated network protocols.
The port might see less traffic today than it did in the 1990s, but it remains registered. Somewhere, a license server is still listening on port 1399, still answering the question: does this person have permission to design?
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