NTLM Authentication against Apache
From SifWiki
oucmonrelle This article doesn't yet tell you how to setup NTLM Auth, for that, try this: http://mkeadle.org/index.php?p=13
If you're getting this error:
send_ntlm_challenge: no conn. handle...trouble communicating with PDC/BDC? returning internal server error
Firstly, set up your DNS! Make sure your Primary Domain Controller IP address both reverse and forward resolves. It's not good enough that you have an entry in /etc/hosts or that the normal DNS server in /etc/resolv.conf can resolve the address, you *must* also make sure that PDC will forward/reverse resolve too.
Secondly, make sure that you've defined the Authentication in Apache as follows, don't try to use the dotted IP address instead, it won't work:
AuthType NTLM NTLMAuth on NTLMAuthoritative on NTLMBasicAuth off NTLMBasicRealm SIFTAH NTLMDomain SIFTAH.NET NTLMServer PDC.SIFTAH.NET #NTLMBackup BDC.SIFTAH.NET Require valid-user
In my example above I don't have a BDC (Backup Domain Controller) specified, hence it's commented out.
There are a number of versions of the mod_ntlm module floating about the net, they will compile against Apache 2.0.55 with a bit of twiddling, I had limited progress with the mod_ntlm from SourceForge and so I used this version of the module, which seems to include a couple of bug fixes: http://modntlm.jamiekerwick.co.uk/

