A Research And Practice Of The Key Technologys Of VPN

As the communication activity through Internet becomes more frequent, more and more attacks are threating the security of the data transported. To solve the problem, many techniques to protect the data are invented. VPN(Virtual Private Network) is one of the available choice.In order to build a less expensive, more secure and more extendable VPN, the IMD technology is used. A simple VPN system named IMD-VPN(Intermediate Driver VPN) based on IPSec(Internet Protocol Security) is designed and implemented to build a secure tunnel between two secure gateways. The architecture of the system is designed and the flow of the system is described. A particular design of encapsulate/decapsulate module, encode/decode module and validate module is provided to describe the flow and functions of the system. Also, the main problems should be considered when implement the system are discussed.IMD-VPN system has a simple structure which is easy to understand. The VPN software is coded with IMD technology, which allow the structure of the data to be changed. At the same time, because the IMD works at a low level of the operation system, it can capture and deal with the packet directly. No packet can jump over or ignore the software. As a result, an additional secure assurance is gained.The result shows that, IMD-VPN can successfully capture and reencapsulate the packets to be sent at the client. Before packets are sent, they can be changed. The server can decapsulate the received packets and send it to the target computer. After these operations, the key function of VPN is implemented.