How to kick a logged user

Hi, I´ve been searching a while about how to kick a logged user or force terminate it´s session. It seems that this has been asked before on the list, but I didn´t find an answer different from "radius can´t do that". The only answer that I´ve found is that it´s required an external script for this. Section 4.3 of the Freeradius FAQ mentions a radkill program, but the link included is dead. And also says "try using SNMP". I haven´t also been able to find information on how to use SNMP for this, so I ask the list: Can anyone post a link to download radkill? Or Can anyone explain me how to do this with SNMP? Or perhaps, Can anyone post a procedure to kick a logged user? Thanks for your replies, Edo