It appears that the ACS will allow you to use external databases for authentication, like windows, LDAP, novell, etc.. Is it possibe to set this up so that vpn users can authenticate to these databases using their current passwords? Thanks
You need to configure ACS Server to communicate with your external database, i.e Microsoft Active Directory (as LDAP), and your VPN box, i.e Cisco VPN 3000 Concentrator.
Configuring ACS external user database/unknown user policy: