I need to disconnect users

I need to disconnect users that in 1 month already have consumed 1gbyte of data. The NAS sends me the traffic of the network every 5 minutes. The question is: how to do that when I get the data that the user has already consumed the traffic that was assigned, the freeradius disconnect the user ?. I am using the RadiusDesk implementation, I have configured plans and they work, but the consumption check is when the user is going to log in only. -- ________________________________________________ Lic. Ariel García Reyes. GNU/Linux Registered User #357058