VPN

VPN

As we mentioned previously, RAS can also be used to form secure VPN connections over an IP network. You can do this as long as you have IP connectivity established on your computer either through RAS or through a network adapter. Today some computers have IP connectivity established either through Digital Subscriber Line (DSL) or cable modems and do not use RAS serial devices to connect to the Internet. If you do not have IP connectivity established, you can use RasDial first to establish IP connectivity over a serial device, as we have already described. Once IP connectivity is established either through RAS or through a network adapter, you can use RasDial to establish a secure link to your remote network over the existing IP connection.

Using the RAS client to establish a VPN connection requires building a phonebook entry that contains the remote VPN server's IP address information on the remote network instead of telephone dialing information. In a phonebook RASENTRY structure you must set the szDeviceType field to the string “RASDT_Vpn”. Once this field is set, the szLocalPhoneNumber field can be used to specify either a DNS name or an IP address string of the remote VPN server instead of a phone number. After the phonebook entry is established, RasDial can be called using the phonebook entry to establish the VPN link.