The embodiment of the invention provides a virtual
private network implementation method and a
client device. The virtual
private network implementation method provided by the invention comprises the following steps that: a NDIS ((
Network Driver Interface Specification) interlayer driver captures a message transmitted to an
intranet server by an application program, and according to a
process identification PID corresponding to the message, judges whether to allow a process corresponding to the message to use the SSL VPN; if so, the NDIS interlayer driver establishes a new message, sets a destination address of the new message as native address of the
client device, sets a destination port number of the new message as a port number for a
client to receive the message, modifies a source
IP address of the original message to be a
virtual IP address, takes the original message as load of the new message, and submits the new message to a NDIS network card driver; and the NDIS network card driver transmits the new message to the client, and the client transmits the new message to the
intranet server. The embodiment of the invention realizes a virtual
private network based on
process control, and starting speed of the client is fast.