What Port 3328 Is
Port 3328 is registered in the IANA port registry under the name egptlm — the Eaglepoint License Manager. It operates on both TCP and UDP, and was used by Eagle Point Software's floating network license system to let clients check out software licenses from a central server.
If you see traffic on this port today, it's almost certainly a legacy installation of Eagle Point CAD software — or something unrelated using the port informally.
The Registered Port Range
Port 3328 sits in the registered ports range (1024–49151). This range works differently from the well-known ports (0–1023):
- Well-known ports (0–1023) require IANA assignment and OS-level privileges to bind
- Registered ports (1024–49151) are assigned by IANA on request but don't require special privileges to use
- Any application can bind to a registered port without root access
The registered range is where most application-layer software lives: databases, game servers, enterprise tools, and yes — CAD software license managers.
The Software Behind It
Eagle Point Software Corporation was founded in 1983 in Dubuque, Iowa. For decades, they built civil engineering and landscape design software — most notably the LANDCADD series — as add-ons to AutoCAD, MicroStation, and IntelliCAD.
Network license managers like egptlm were standard in the CAD industry throughout the 1990s and 2000s. Engineering firms bought floating licenses: a pool of seats shared across a network, with a license server tracking who had checked one out. Port 3328 was how Eagle Point's clients talked to that server.
Eagle Point eventually sold the LANDCADD rights to Keysoft Solutions and pivoted entirely to e-learning software (Pinnacle Series) for the AEC industry. The CAD products that needed port 3328 are largely gone. The port assignment in the IANA registry remains.1
What You'll Actually Find Here
In practice, port 3328 is quiet. You're unlikely to encounter it unless you're maintaining genuinely old civil engineering software infrastructure.
If you do see unexpected traffic on port 3328, it's worth investigating — unassigned or obscure registered ports sometimes get used informally by applications that assume the port is free.
How to Check What's Listening
On Linux or macOS:
On Windows:
The output will show the process ID (PID) bound to the port, which you can then look up to identify the application.
Why Unoccupied Registered Ports Matter
The registered port range contains thousands of ports assigned to software that's been discontinued, renamed, or forgotten. These assignments don't expire automatically — IANA doesn't reclaim ports just because the software stopped shipping.
This creates a practical reality: when you see traffic on an obscure registered port, it could be the assigned legacy application, an entirely different application that chose the port informally, or something you'd rather not have on your network. The port number alone doesn't tell you. The process inspection commands above tell you.
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