What Port 3296 Is
Port 3296 sits in the registered ports range (1024–49151). Despite being listed as unassigned in some sources, IANA's official registry assigns it to rib-slm — the RIB License Manager.
RIB Software builds project management and estimating tools for the construction industry: cost planning, BIM management, financial control, and more. Their license manager runs on this port to verify that users have valid software licenses — the same role that license managers play across engineering and design software (think FlexLM for CAD tools, or similar).
The port runs on both TCP and UDP.
Who Uses It
If you're running RIB Software products — CostX, CANDY, BuildSmart, or related tools — your license server may be listening on port 3296. It's niche, industry-specific, and almost entirely invisible to anyone outside construction technology.
What "Registered" Actually Means
Registered doesn't mean required. IANA's registry is a coordination mechanism, not a mandate. Any application can use any registered port — the registry just records who formally claimed it and why. In practice, port 3296 was registered so that RIB's license manager has a predictable, documented home on the network. Firewall rules can allow it, network documentation can reference it, and IT staff can know what they're looking at.
There are over 48,000 registered ports. Most of them, like this one, belong to specialized software used in specific industries. The port system only feels vast when you're looking at the famous ones. The rest are quiet infrastructure for quiet tools.
How to Check What's Using This Port
If port 3296 shows up on your machine or network and you want to know why:
On macOS or Linux:
On Windows:
Then match the process ID against Task Manager or ps aux to find the application.
If you're not running RIB Software and something is listening on 3296, it's worth investigating — any port can be used by any process, legitimate or otherwise.
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