Install samba and krb from yum, then run the following…
authconfig --disablecache \ --enablewinbind \ --enablewinbindauth \ --smbsecurity=ads \ --smbworkgroup=howard.local \ --smbrealm=HOWARD.LOCAL \ --enablewinbindusedefaultdomain \ --winbindtemplatehomedir=/home/%U \ --winbindtemplateshell=/bin/bash \ --enablekrb5 \ --krb5realm=HOWARD.LOCAL \ --enablekrb5kdcdns \ --enablekrb5realmdns \ --enablelocauthorize \ --enablemkhomedir \ --enablepamaccess \ --updateall net ads join -S ad.howard.local -U administrator net ads dns register -U administrator