Virtual Tunneling Through the Internet

If users are connected to the Internet, and their intranet is connected to the Internet, you should be able to connect everyone in a virtual network. But using the Internet in this way to link hosts to corporate intranets is not sufficiently secure.

One solution is to use a protocol tunnel by generating a stream of packets that you want to send between the remote host and the corporate intranet, encrypting them, and treating the encrypted set of packets as data to be t ransmitted by a separate TCP/IP connection. When those packets (which actually contain the encrypted packets) arrive at their destination across t he Internet, the receiving host decrypts them and handles them appropriately. Memphis will come with Point-to-Point Tunneling Protocol (PPTP), which you need for this type of security.

Protocol tunneling isn't new: Windows NT implemented PPTP last year. Other tunneling products include AltaVista's Tunnel 96 software, and many firewall vendors include tunneling options in their offerings. The big news is that PPTP's inclusion in Windows brings a widely deployed IP tunneling standard to the general user.

PPTP works by establishing a virtual adapter on the Windows client through the dial-up networking control panel. PPTP appears as a new modem type (the Virtual Private Networking Adapter), and the dial-up network wizard walks the user through the setup. When tunneling is enabled, a new IP default route is established and th e "real" IP traffic is routed through the tunnel. When the tunnel is on, no other Internet hosts are visible, but once the tunnel is disconnected, the default route is removed and systems can be seen again.

Microsoft decided in May to release PPTP independently instead of waiting to bundle it with Memphis. You can download PPTP at http://www.microsoft.com .