To restrict users from accessing the system using Centriy free can be easily managed by using the following files
1. You have to manually create the the files accordingly and place it at /etc/centifydc. Next you have to line 273 and uncomment the line
..... pam.allow.users: file:/etc/centrifydc/users.allow .....
If you are blocking by groups, you can likewise uncomment the
..... pam.allow.groups: file:/etc/centrifydc/groups.allow .....
2. Flush and Reload Centrify-Free
# adflush # adreload
3. Add users you wish to have access into the system into /etc/centrifydc/users.allow