这是一个Linux下的vpn软件源码，并可交叉编译移植到嵌入式平台上，很好的。-This is a Linux source code under the vpn software, and can be ported to an embedded platform, cross-compilation, the good.

1 Introduction industry is facing fierce global competition, companies need in order to survive, a variety of analysis and decision-making to occupy and control the market. To improve the competitiveness, many companies use the DCS, SCADA, PLC and ot