I have been set firewall from first installing , all port have been blocked but only kerberos authentication is set. My connected Fedora Core 6 might be cracked, so My NOT CONNECTED Fedora Core 6 was not cracked. Mystery was happened. I have had never no Kerberos server. redhat Fedora Core 6 only can cracking , self cracking OS???? arataki at estate.ocn.ne.jp