I have configured squid 3.0 with NTLM, and this configuration in squid.conf is: auth_param ntlm program /usr/local/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp auth_param ntlm children 30 auth_param ntlm max_challenge_lifetime 2 minutes auth_param basic program /usr/local/bin/ntlm_auth --helper-protocol=squid-2.5-basic auth_param basic children 5 auth_param basic realm Squid proxy-caching web server auth_param basic credentialsttl 2 hours When a test the ntlm auth, in the Explorer client with a user authenticate in Domain Controller Windows 2003, the explorer or firefox show popup of the basic auth. How to use the ntlm auth with an user of the domain group without auth basic? Sincerely, Leandro Ferrari