## VPN Technology

Windows NT includes support for VPNs created with the Point-to-Point Tunneling Protocol (PPTP).

This allows you to create encrypted connections among Windows NT and Microsoft Windows®95 computers over dial-up or dedicated connections. The VPN connections are authenticated with PAP or CHAP and the connection itself is encrypted with RSA RC-4 or Data Encryption Standard (DES). With the Routing and Remote Access Service (RRAS) package, permanent server-to-server Point-to-Point Tunneling Protocol (PPTP) can be created allowing secure communication between two LANs separated by the Internet.

VPNs can also be used to encapsulate a local area network (LAN) protocol such as IPX/SPX or NetBEUI, allowing it to traverse the TCP/IP-based Internet. Microsoft uses RRAS to connect a number of remote offices with the Redmond campus using VPNs across the Internet.

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UNIX and Windows NT VPN integration

Traditional UNIX VPN solutions are SSH, Sun Microsystem’s SKIP or router-based (Layer 2 Forwarding or L2F). SKIP is supported on Sun's Solaris, Windows NT and Windows 95, allowing VPNs to be created among the different platforms. There is also a freely available SKIP port for Linux called enSKIP.

Router-based VPNs are one way to avoid platform compatibility problems since Windows NT or UNIX computers do not require any modification or additional software.

Microsoft Windows® NT 5 supports L2TP as well as PPTP.

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Last Updated: December 1, 1997