David you are exactly right on the money.
We want to authenticate with DOMAIN\username against our federated AD. What is also a complication is that samaccountname is not the actual user name. In fact, there's really no field in this AD that has the username property directly for all users (since this AD has trusts with several other domains). As you say, I can bind with DOMAIN\username against our AD with JXPlorer or Softerra ldap browser or ldp.exe.
How do you think we should attack this? I'm thinking in BindAuthenticator, we really can't use that bindWithDn method. I'd rather stay within the framework of what springsec provides, because the URL security and security tags are really nice and easy for configuring the rest of security within the app.
Also, we dont need to do authorization with AD. We have Role and other user info available via an internal restful web service (I'm using RestTemplate to get roles based on the username, as I have my own authorities populator class).
So right now, I just need Spring Security to bind with "DOMAIN\username" and password against our ldap server (Active Directory). Plain and simple. Can't use anonymous login, and can't use a manager dn to do lookups.

