0引言近年来,随着信息技术的发展,信息安全也逐渐引起了人们的关注。怎样在网络之间建立一条专有的安全通道,实现内部网络与外部网络之间的安全通信,成为了目前很多单位关注的重要问题。当然,很多开设了计算机实训课程的学校也较为关注这一问题。当下我国的初高中学校都开设了计算机课程,职业类学校以及各个高校也普遍建设有专门的计算机室。但是学生们往往只能在校内进行实训。要想实现校外用户与校内网络实训室之间的 0 Introduction In recent years, with the development of information technology, information security has gradually attracted people’s attention. How to establish a proprietary secure channel between networks and realize secure communication between the internal network and the external network has become an important issue that many units are currently concerned about. Of course, many schools that have set up computer-based training courses are also more concerned about this issue. At present, our country’s high schools have set up computer courses, vocational schools and various colleges and universities have also generally built a special computer room. However, students often only practice in school. In order to achieve off-campus users and network training room between the network