closing connection

hi. I'm a new user with freeradius. i'm using it to authenticate clients in a Wlan, it work great, but I need to disconnect a user that have finished his available broswing time.(i use a prepaid cards) how can i do? in the code there are some rows to deny the authentication if a guest consume his "daily time", how I can enebled it? is enabled by default? I saw in wiki.freeradius.org the radiusKick at ftp://ftp.nmo.net/pub/radkill/radkill-latest.tar.gz<ftp://ftp.nmo.net/pub/radkill/radkill-latest.tar.gz> but i cannot download it, and probably it is obsolete (written in 2000). can anybody help me? best regards.