ok nice, i kinda figured it out, as i'm planning to use some php to add users to the mysql database.
for instance i noticed that if i add
"testuser", "cleartest-password", ":=", "testpassword" in the radcheck table
i can perform a successful login on the captive portal.
problem is.. what if i also want to limit the usage to 1 hour per day? or eventually bandwidth? are these values also to be added to radcheck? they go in radreply?
an exhaustive list of the usable attributes would be also interesting, ok i know i'm going OT here, so maybe i should ask in the proper section of this board (if any) wiki only reports some of them, and they are not well described/explained on what they are suitable for.