hi,
** Questions need help ** Q1. Is there any article or book can help me to configure about CoA?
there are several posts out there of people who have done things with their kit - it really is very unique to each NAS/requirement
Q2. Will FreeRADIUS send CoA-Request out when someone modify the priv-lvl in users? Or what is a good way for me to test and understand the behavior of CoA?
no. changes to users are not tracked in that way - if you restart freeradius to pull in the new values it wont know that something needs to be sent to the NAS. you need a lot of logic and backend stuff to do CoA - ideally this would be some kind of DB with action scripts if values should be changed....with ability to pull out the session ID etc etc. radclient is a good way to test behaviour alan