Install the following packages :
$ apt-get install winbind samba
Join the domain :
$ net rpc join -u Administrator -S "server"
Fetch the correct (Windows) domain name :
$ wbinfo -u
If you see the list of users, it's ok. Verify if there is winbind entry in /etc/nsswitch.conf
Put it in the /etc/samba/smb.conf config file
You can use the following PAM resources files :
auth required pam_winbind.so
account required pam_winbind.so
auth required pam_securetty.so
auth required pam_nologin.so
auth sufficient pam_winbind.so