- Squid 3.1.20-2.2 - Debian 7.2 - Windows Server 2012 - Windows 7 64bits (client) - Mozilla Firefox 24 32 bits In this environment,authentication is donevia Kerberos,withkeypadgenerated byktpass. My keypad: root@japura:/etc/squid3# klist -ekt squid.keytab Keytab name: FILE:squid.keytab KVNO Timestamp Principal ---- ------------------- ------------------------------------------------------ 3 31-12-1969 21:00:00 HTTP/squidsrv.example.com@xxxxxxxxxxx (des-cbc-crc) 3 31-12-1969 21:00:00 HTTP/squidsrv.example.com@xxxxxxxxxxx (des-cbc-md5) 3 31-12-1969 21:00:00 HTTP/squidsrv.example.com@xxxxxxxxxxx (arcfour-hmac) 3 31-12-1969 21:00:00 HTTP/squidsrv.example.com@xxxxxxxxxxx (aes256-cts-hmac-sha1-96) 3 31-12-1969 21:00:00 HTTP/squidsrv.example.com@xxxxxxxxxxx (aes128-cts-hmac-sha1-96) AuthenticationIEandChromegoes smoothly, not in Firefox, in cache.log i have: authenticateNegotiateHandleReply: Error validating user via Negotiate. Error returned 'BH gss_accept_sec_context() failed: An unsupported mechanism was requested. ' I tried to fill network.negotiate-auth.trusted-uris with example.com (my domain) in about:config but without success. I tried to generate the keytab with msktutil, no success. Could someone please help me? It's a Windows 7 bug, a Mozilla Firefox bug or a wrong keytab? Would be grateful to receive a light. Best Regards, Allan Carvalho