I have the following configured for authentication in my squid 3.1.1 server: auth_param negotiate program /usr/lib/squid3/squid_kerb_auth auth_param negotiate children 10 auth_param negotiate keep_alive on auth_param basic program /usr/lib/squid3/pam_auth auth_param basic children 3 auth_param basic realm Squid proxy-caching web server auth_param basic credentialsttl 2 hours auth_param basic casesensitive off Which works just fine in my all-linux-and-firefox-and-chromium network. Every now and then though a Windows (7) user comes into the network and for whatever reason proxy authentication doesn't work on those nodes. My guess is that windows is trying to do Negotiate authentication but squid is not able to understand what it's sending. Am I close? Any solutions? Cheers, b.