RADIUSdesk has an option that allow for users to register through the captive portal login page.
The registered user has to belong the a realm and have a profile.
We will now create the profile.
Our profile will be very simple and just reply with the Tunnel-Password (PSK) which we will make *12345678*.
Navigate to RADIUS → Profiles. Click on Add.
We create one called CampusPSK-Student.
Keep the defaults (no limits imposed) and click Save.
You will see that the system created a Profile Component and associated it with the profile.
In our case its called SimpleAdd_59.
Edit the Profile Component called SimpleAdd_59 and add a Reply attribute of Tunnel-Password := 12345678.