To build secure connections over the Internet, you must have a Windows NT 4.0 PPTP-enabled server. PPTP is a tunneling protocol that makes it possible to set up secure connections over the Internet. With PPTP, you can support two different types of tunneling, voluntary and compulsory. Voluntary tunneling is initiated by the client computer. It does not require support from an ISP, nor does it require support in network devices, such as bridges or routers. Compulsory tunneling is initiated by a PPTP-enabled server that resides on the ISP network. As a result, it requires support on edge Network Access Servers or routers, but does not require support on clients or intermediate devices. The following diagram illustrates the difference between voluntary and compulsory tunneling.
Voluntary tunneling requires a PPTP-enabled client. Currently, PPTP-enabled clients are available from Microsoft for Microsoft Windows 95 or Windows NT operating systems, and from third-parties for Macintosh and Microsoft Windows 3.1 operating systems. If your system supports a variety of platforms for which there are no PPTP clients available (such as UNIX), then you should select an ISP that implements compulsory tunneling.
Note
Compulsory tunneling requires a PPTP-enabled Network Access Server (NAS) or router.
Regardless of which type of tunneling you implement, you must have a PPTP-enabled server. If you are a corporation, you should set up a dedicated PPTP-enabled server on your corporate network. Use the following steps to set up a PPTP server.
Important
PPTP supports multiple network protocols, such as IP, IPX, and NetBEUI. In order for two computers to establish a tunnel over the Internet, both computers must be using the same network protocol.