http://mkeadle.org/index.php?p=31
Apache and NTLM
Here’s where the NTLM authentication comes in. Head over to the mod_ntlm homepage and grab a copy. Gentoo doesn’t currently have an ebuild for mod_ntlm, so I had to install by hand, but there may be RPMs floating around somewhere if that’s your game. In order for mod_ntlm to work, you’ll need to have the server running Apache joined to the domain. The process used in Squid + NTLM can be used for that.
The neat thing about mod_ntlm is how easy it is to setup once it’s installed. All mod_ntlm functionality is controlled through .htaccess files (link for Apache2). Here’s a copy of the mod_ntlm enabled .htaccess I’m using. Once in place, users will be auto-authed by NTLM and you’ll be able to grab their username from the REMOTE_USER environment variable.