Design And Implementation Of VPN For Medium-sized And Small Enterprises

Along with the unceasing deepening of the application of Internet in the enterprise realm, VPN (Virtual Private Network), as a low-priced and safe network scheme, gets more and more attention by medium-sized and small enterprises. However, they have their own characteristics. Unlike those large business enterprises, which afford to a large deal of equipments to build their own VPN, they need many cheaper and more effective approaches.For satisfying the demand of the medium-sized and small enterprises in the homeland, various typical protocol of VPN has been compared in this paper. And a lower-priced scheme, which fits the medium-sized and small enterprises, has been chosen.Being directly and closely connected with the system kernel, the realization of IPSec VPN is quite different in the source unopened Windows operating system from that in the source opened system. Considering the applied environment in the medium-sized and small domestic enterprises and the filter of network data, IPSec has been made into a NDIS Intermediate Driver, which is inserted between the network layer and the data-link layer in this paper. This method can make the data encrypted in the data-link layer, and it can carry out the IPSec. The paper elaborates the design thought, structure and the work principles. Ultimately, it has realized the kernel mold of IPSec using C and established a simple IPSec VPN channel in LAN.At last, the paper sums up the fields that project is adapted to and puts forward the main direction of the further study work and some problems needed to be resolved further.