This technique is out of date and should no longer be used. Please use a more up to date technique like SAML. For Elgg you can use https://github.com/ColdTrick/simplesaml
Users can login to your Elgg community using their local (Windows) credentials.
There are some requirements to you local workstation/domain if you want this to work corerctly. Please read the INSTALL.txt
To get the NTLM information we use the PHP NTLM library.