The encryption of data is performed by the remote access protocol, PPP. You enable encryption by configuring each VPN device that was added and configured in RAS. This configuration is identical to configuring encryption for other RAS devices, such as a modem.
To enable encryption on a VPN device on the PPTP server
1. Click Start, point to Settings, and then click Control Panel.
2. Double-click Network in Control Panel.
3. Click the Services tab and select Remote Access Service.
4. Click Properties to display the Remote Access Setup dialog box (shown below).
5. Select a VPN device for which you want to enable encryption, and then click Network. The Network Configuration dialog box appears.
6. Select Require Microsoft encrypted authentication and Require data encryption. This configures RAS and PPP to enforce Windows NT-based authentication of all remote clients connecting to the PPTP server.
7. Click OK to return to the Remote Access Setup dialog box.
8. Click Continue.
9. Close Network, shut down, and then restart the computer.