Why Squid Basic LDAP Authentication Still Prompts for a Password

A Squid configuration can check passwords against Active Directory and still produce a login box. Nothing is necessarily broken. AD describes where the account lives; it does not tell you how the browser will prove who the user is.

In this line, the important word is basic:

auth_param basic realm Windows Logon

The words after realm label the authentication protection space. They do not request a Windows access token or switch the challenge to Negotiate. A Basic LDAP helper receives supplied credentials and checks them against the directory.

There are three separate decisions in a typical configuration: how Squid challenges the client, how a helper validates that response, and which authenticated users or groups an access rule permits. A successful LDAP group lookup addresses the last decision. It cannot supply the browser's missing credentials.

If the requirement is a quiet sign-in

Choose a browser-supported integrated authentication scheme and configure its server-side prerequisites. For Kerberos-based Negotiate, that includes the service identity and key material, as well as client policy allowing authentication to that proxy. Merely changing the helper executable under a Basic configuration will not perform that conversion.

Decide which outcome you need before replacing a working LDAP setup. Accepting the same username and password used for a workstation login is a reasonable Basic authentication requirement. Reusing the logged-in Windows identity without asking for that password is a different requirement, with different protocol and deployment work.