Enable Windows NTLM Pass-through Authentication in Linux-based Apache
Thank Science for SuSE Linux Enterprise 11; it's made this process relatively easy. SLES 10 SP2 was giving me a headache because of some Windows 2008 based Active Directory authentication issues but upgrading SLES 11 took care of all that.
First thing is first, setup samba to authenticate to AD. Next, install the OpenSuSE mod_auth_ntlm_winbind RPM.
rpm --install https://download.opensuse.org/distribution/11.0/repo/oss/suse/i586/apache2-mod_auth_ntlm_winbind-0.0.0.lorikeet_svn_682-135.1.i586.rpm
The wiki for this Apache 2 module can be found here. Next, we're going to instasll pam_smb, set the proper permissions on winbindd_privileged, add the module to apache and restart the web service.
yast -i pam_smb setfacl -m u:wwwrun:rx /var/lib/samba/winbindd_privileged a2enmod auth_ntlm_winbind rcapache2 restart
Finally, add something to the effect of this to your Apache config file:
AuthName "NTLM Authentication" NTLMAuth on NTLMAuthHelper "/usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp" NTLMBasicAuthoritative on AuthType NTLM require valid-user
Restart the service and you should be authenticating automatically. Don't forget to add the website to your browser's Intranet zone if needed.
Also, I read that, unfortunately, auth_ntlm_winbind, doesn't work over SSL but I'm going to try it anyway. In the event that it doesn't, I'll be exploring Kerberos authentication within Apache.