Php REMOTE_USER variable

apache-2.4mediawikiPHPsingle-sign-onubuntu-14.04

I am trying to setup mediawiki with SSO. I was able to set up authentification with domain, but I cannot setup SSO.
For some reason, $_SERVER['REMOTE_USER'] variable is not set.
I looked into some anwsers in SO, but has no luck solving my issue.
I have also configured basic apache auth, but still no luck with getting remote user.

apache.conf:

<Directory />
    Options FollowSymLinks
    AllowOverride None
    AuthType Basic
    AuthName "some_auth"
    AuthBasicProvider file
    AuthUserFile /path/to/file
    Satisfy Any
    Require valid-user
</Directory>

Best Answer

Ok, seems that Satisfy Any was the reason, that REMOTE_USER was absent.