Hi Markus, I built a new Centos server at version 6.5 and redo all the configuration on the new server in the same way. Magic happened: everything is working now. Thank you very much for your help and guidance. -- View this message in context: http://squid-web-proxy-cache.1019090.n4.nabble.com/squid-proxy-kerberos-authentication-failure-Help-tp4663964p4664090.html Sent from the Squid - Users mailing list archive at Nabble.com.