A virtual private network (VPN) is a technology that creates an encrypted connection over a less secure network. The benefit of using a VPN is that it ensures the appropriate level of security to the connected systems when the underlying network infrastructure alone cannot provide it. The justification for using a VPN instead of a private network usually boils down to cost and feasibility: It is either not feasible to have a private network (e.g., for a traveling sales rep) or it is too costly to do so. The most common types of VPNs are remote-access VPNs and site-to-site VPNs.
Name some VPN technologies supported by Windows 2000
Microsoft Windows 2000-based virtual private networking (VPN) supports Internet-industry standards technology to provide customers with an open interoperable VPN solution. Microsoft is committed to IETF (Internet Engineering Task Force) standards-track-based technology such as Internet Protocol Security (IPSec) and Layer 2 Tunneling Protocol (L2TP) as well as Point-to-Point Tunneling Protocol (PPTP)a proven published informational RFC that is supported in multiple interoperable third-party products.
PPTP provides simple-to-use, lower-cost VPN security. Unlike IPSec technology, PPTP is compatible with Network Address Translators (NAT) and supports both multi-protocol and multicast environments. It also combines standard user password authentication with strong encryption without requiring the complexity and expense of public key infrastructure (PKI).
IPSec provides advanced security for VPN but was not designed to address critical remote access requirements such as User Authentication and Address Assignment. In addition, it does not support multi-protocol or multicast (including some routing protocols). It is applicable primarily to IP-only, unicast-only situations.
L2TP in combination with IPSec is the only standards-track technology that addresses these remote access VPN requirements while leveraging IPSec for encryption. L2TP currently retains the same IETF standards-track status as IPSec.
Third-party IPSec-only implementations that do not use L2TP with IPSec are using non-standard proprietary technologies that can lock customers into closed solutions.
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