What Is VPN
In this section
The virtual private network (VPN) technology included in Windows Server 2003 helps enable cost-effective, secure remote access to private networks. VPN allows administrators to take advantage of the Internet to help provide the functionality and security of private WAN connections at a lower cost. In Windows Server 2003, VPN is enabled using the Routing and Remote Access service. VPN is part of a comprehensive network access solution that includes support for authentication and authorization services, and advanced network security technologies.
There are two main strategies that help provide secure connectivity between private networks and enabling network access for remote users.
Dial-up or leased line connections
A dial-up or leased line connection creates a physical connection to a port on a remote access server on a private network. However, using dial-up or leased lines to provide network access is expensive when compared to the cost of providing network access using a VPN connection.
VPN connections use either Point-to-Point Tunneling Protocol (PPTP) or Layer Two Tunneling Protocol/Internet Protocol security (L2TP/IPSec) over an intermediate network, such as the Internet. By using the Internet as a connection medium, VPN saves the cost of long-distance phone service and hardware costs associated with using dial-up or leased line connections. A VPN solution includes advanced security technologies such as data encryption, authentication, authorization, and Network Access Quarantine Control.
پروتکل های VPN
البته پروتکل امنیتی SSL نیز جزء پروتکل های مورد استفاده در VPN به شمار می آید، ولی به علت اینکه SSL بیشتر بر روی پروتکل های HTTP، LDAP، POP3، SMTP و... مورد استفاده قرار می گیرد، بحث در مورد آن را به فرتی دیگر موکول می کنیم.