Port 475 carries tcpnethaspsrv, a network licensing service created by Aladdin Knowledge Systems (now part of SafeNet/Gemalto) for their HASP (Hardware Against Software Piracy) system.12
What This Port Does
Every time a piece of software needs to verify a HASP license dongle over a network, that check flows through port 475. The service answers one question: "Does this user have permission to run this software?"
Instead of requiring a physical dongle plugged into every computer, tcpnethaspsrv allows a central license server to manage dongles for an entire organization. Client machines connect to port 475, ask if they are licensed, and get an answer back.
The Hardware Dongle Era
Before software licensing moved to activation codes and cloud verification, expensive professional software used hardware dongles—small devices you plugged into a parallel port or USB slot. No dongle, no software. Simple. Physical. Impossible to pirate by copying files.
But this created a problem: in networked environments with dozens of users, managing physical dongles was a nightmare. Port 475 solved this by letting one dongle serve many users over TCP/IP.
How It Works
The HASP system uses a proprietary protocol optimized for license verification:
- Client software starts and needs to verify its license
- It connects to the license server on port 475
- The server checks if a valid dongle is present
- The server responds: authorized or denied
- The software either runs or refuses to start
The protocol runs on both TCP and UDP, though TCP is the primary transport.3
The Strange Survival of Physical Licensing
Hardware dongles feel like ancient history, but port 475 reminds us they never fully disappeared. In industries where software costs tens of thousands of dollars per seat—CAD systems, engineering tools, scientific applications—physical license enforcement still makes sense.
Port 475 is the protocol that kept that world alive into the network era.
Unofficial Use: SCO Unixware
In a peculiar twist, SCO Unixware 7 installations sometimes run an HTTP server on port 475 for the scohelp service.1 This has nothing to do with HASP licensing—it is just a collision, two different systems claiming the same port number.
This is one of the strange realities of the port system: official assignments do not always match actual use.
Security Considerations
If you are not running HASP-licensed software, port 475 should not be open on your network. An unexpected service on this port could indicate:
- Misconfigured software
- A legacy SCO Unix system running help services
- Unauthorized license server software
Like all well-known ports below 1024, opening port 475 typically requires administrator privileges on Unix-like systems.
Checking What Is Listening
To see if anything is listening on port 475:
On Linux/Mac:
On Windows:
If you see a process on port 475 and you are not running HASP-licensed software, investigate what opened it.
Related Ports
Port 475 is part of the well-known port range (0-1023), assigned and maintained by IANA. Other licensing and authentication-related ports include:
- Port 27000-27009: FlexLM (Flexible License Manager), another common software licensing system
- Port 1947: Sentinel HASP License Manager (newer HASP versions)
- Port 2080: Aladdin eToken authentication services
Why This Port Matters
Port 475 represents a specific moment in software history: when copy protection moved from floppy disk tricks and parallel port dongles to networked license management. The protocol is proprietary, the hardware is obscure, but the question it answers is universal.
Every time you launch expensive software and it checks if you are licensed, something like port 475 is probably involved—asking the license server, waiting for an answer, deciding whether to let you in.
That quiet transaction, repeated thousands of times a day in engineering firms and design studios around the world, is what port 475 carries.
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