We have NTLMv2 authentication code in QtNetwork, but it is not auto tested.
The qt-test-server has a non working (and disabled) squid3 configuration for NTLM authentication.

• Probably needs the "proxy" user added to the "winbindd_priv" group
  The qt-test-server does not have NTLM support in the apache web server.
• mod_auth_ntlm_winbind looks like a good fit, but only available as a source package
• Probably needs the "www-data" user added to the "winbindd_priv" group

In both cases, we would want to authenticate against local username/password and not use an external domain controller
(most setup guides assume you want to do single signon using corporate credentials)