Hello,
I set up an LDAP authentication server (SAMBA 4). I did a test on "System: Access: Tester" and the connection works fine.
The LDAP server is used with SAMBA4 AD. In Windows 10 clients all users/groups can connect.
I configured the proxy web service to connect with LDAP authentication server, but when I open a internet browser (Chrome, Firefox) do not make the connection. The internet browser show a dialog box to authenticate with proxy server.
I put any valid user and your respective password, but don't work. See atached image.
(http://ap.imagensbrasil.org/images/2017/03/28/opnsense_proxy_ldap.jpg)
Regards,
Marcelo Costa
Porto Alegre - Brazil