Hello On Centos 6 I want used squid (version 3.1.4) with Kerberos authentication so only AD Windows 2003 authenticated users can surfing. Well I perform the steps (explained at link http://wiki.squid-cache.org/ConfigExamples/Authenticate/Kerberos) but when users tried to surfing the IE require user and password and didn't surfing. Why? Can you help me. **** MORE INFO **** I did the following steps: Install and configure samba modify krb5.conf net ads join -U DOMAIN\administrator kinit administrator@DOMAIN export KRB5_KTNAME=FILE:/etc/squid/HTTP.keytab net ads keytab CREATE -U DOMAIN\administrator net ads keytab ADD HTTP -U DOMAIN\administrator unset KRB5_KTNAME chgrp squid /etc/squid/HTTP.keytab chmod g+r /etc/squid/HTTP.keytab modify squid startup file with : KRB5_KTNAME=/etc/squid/HTTP.keytab export KRB5_KTNAME below squid.conf file: .... auth_param negotiate program /usr/lib/squid/squid_kerb_auth auth_param negotiate children 10 auth_param negotiate keep_alive on acl auth proxy_auth REQUIRED ... http_access deny !auth http_access allow auth http_access deny all .... With command : /usr/lib/squid/squid_kerb_auth_test proxyserver The token was displayed.