Tham khảo tài liệu vpn overview , công nghệ thông tin, quản trị mạng phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | . In client-to-gateway and gateway-to-gateway situations, Windows 2000 provides a rich set of administrative policies that can be implemented to control user access through direct-dial, PPTP, and L2TP/IPSec connections. These access policies allow administrators to grant or deny access based upon a combination of user ID, time-of-day, protocol port, encryption level, and more. While available natively within a Windows 2000 Active Directory environment, these access policies can also be enforced on non-Windows 2000 environments through the use of RADIUS. For example, an existing Windows NT–based PPTP server can be configured to use a Windows 2000 Server to authenticate users through RADIUS. When used in this way, the Windows 2000 Server can be configured to enforce acce5ss policies and apply them to the Windows NT–based PPTP server. This is an example of how Windows 2000 can simplify and strengthen central administration during a transition to Windows 2000, and demonstrates one of the many benefits of using Windows 2000 for authentication in heterogeneous environments.