We're trying to validate LDAP authentication from Linux against our AD global catalog servers. I'm seeing lots of LDAP query tools, but what I need is a free/open source application that can use LDAP to query AD to authenticate... something as simple as entering the hostname/IP of our AD/global catalog server and the port, then passing an AD username/password to it to validate logon capability. Anyone know of any software/apps that can do this? I don't want to get into configuring Samba for LDAP or trying to authenticate my actual Linux server again AD... I just want an application that uses LDAP for authentication.

I believe that you will also need Kerberos.

No, no kerberos required. AD provides and LDAP interfaces so a bind is a bind...

As for the specifics here, what application is this? I don't understand how you'd want this application to work. The authentication is just a small part of an end application, not the entire app. Unless that app is just ldapsearch which will let you do a bind of course.