Fajar, Yes. We're using Linux ES 5.4. We're leasing a virtual server from a vendor. While Linux ES 5.4 is the Linux server it can provide. Actually, it helped us. As we need PPTP VPN dailup for our application, the PPTP VPN installation on 5.4 is very smooth. While we can't make it work on Linux ES 6.0/6.1. We got two freeradius versions available on 5.4, freeradius1 and freeradius2, and we selected freeradius2. Thanks for advise raddebug. So far, it doesn't work well for us. As your advise, we actually tried radmin. radmin> debug condition '(User-Name == 1)' radmin> radmin> show debug level 4 radmin> show debug condition (User-Name == 1) //"1" is the username. radmin> show debug file /var/log/radius/tom.log We tail -f /var/log/radius/tom.log. We found two issues. 1. The output from the radmin is diffirent from "Radius -X". While we consider radiusd -X output more helpful information. While radmin didn't. 2. We like to filter the debug information for user "1" only, while the radmin still output all users. Can you please help to advise what would be the reason? You mentioned ixc virtualization, do you have a web site link for this software? I googled it, but not found. As we leasing the virtual server, we failed to nest install VMWare on our server. So your virtual server may work. Hello, James, Thanks for your reply. As mentioned previously, we failed to install VMWare on our leased virtual box. The reason to want multiple radiusd is, we don't know the raddebug solution previouly. We planed run second freeradius for debug only. We also need multiple radiusd instant for some other reason. Alan, We tried to configure multiple instances, but failed. So we need a handy configuration guide. Thank you all. Tom Deng.