Hi Alan, thanks for your reply. A captive portal is excatly what I'm trying to make, but our scenario is rather complicated. The user have to be taken from the portal to a mobile application to continue the authentication process which will need Internet access. That's why I need to temporarily allow the user's access. If I understood you right, I have to make the user to re-authenticate to let the NAS know the Expiration attribute has changed? If so, I think configuring the NAS to authenticate with freeRADIUS every 10 minutes, and making the initial expiration value to a little longer than 10 min will solve the problem. Am I right? And I'm terribly sorry if this post doesn't follow the thread I started previously, I don't know how to follow a thread when replying to a mailing list.