So ... I found out how to do this after hours of working at Googling ... in fact, it should be much easier to find the answer, but, nevertheless, here:
1) Download the following module for your system (32 bit out of 64 bit): https://www.apachehaus.net/modules/mod_authnz_sspi/
2) Paste the file into the folder with your files. /apache/modules/
3) Edit the following configuration files:
3.1) php/php.ini: uncomment the extension=php_ldap.dllline.
3.2) apache/conf/httpd.ini: add the following to the end of the LoadModules section:
LoadModule authn_core_module modules/mod_authn_core.so
LoadModule authz_core_module modules/mod_authz_core.so
LoadModule authnz_sspi_module modules/mod_authnz_sspi.so
3.3) Find the tag <Directoryand remove the open and close tags along with your content. Then insert the following:
<Directory />
Options None
AllowOverride All
Order allow,deny
Allow from all
AuthName intranet
AuthType SSPI
SSPIAuth On
SSPIAuthoritative On
SSPIOfferBasic On
SSPIOmitDomain On
Require valid-user
</Directory>
Apache . Windows <?php echo $_SERVER['PHP_AUTH_USER'] ?>