We've configured the PIX515 v6.22 to authenticate user (Cisco VPN client v4.01)using Windows IAS accordingly to Cisco documentation. The issue is that the user authentication prompt does not appear. IPSec VPN can be established and access to internal resources is working though. The Radius server resides on the DMZ. The PIX is supporting both IPSec site-to-site and remote access setup. Can someone please drop me a clue?