利用多层网络连接提高公网Web服务器安全性

公网发布的Web服务器的安全性一直是众多校园网络管理者所关注的问题。传统安全防范措施如:密码安全、账号策略、系统补丁、防火墙功能等并不能从根本上解决问题。通过提出一种新的防范方法,即在结合传统防范措施上再利用多层网络连接,把需要在公网发布ASP.net网站的前台发布、后台发布、SQL数据库服务分离,把其分布到不同的服务器,服务器各自连接在不同网段的网络,最后把这三台服务组成一个小局域网互相连接起来,达到互相之间的操作和连接。这种方法与只使用传统防范方法相比较,Web服务器的安全性在一定程度上得到了更进一步的提高。

Policy driven and multi-agent based fault tolerance for Web services

This paper proposes a policy driven and multi-agent based model to enhance the fault tolerance and recovery capabilities of Web services in distributed environment. The evaluation function of fault specifications and the corresponding handling mechanisms of the services are both defined in policies, which are expressed in XML. During the implementation of the services,the occurrences of faults are monitored by the service monitor agent through the local knowledge on the faults. Such local knowledge is dynamically generated by the service policy agent through querying and parsing the service policies from the service policies repository. When the fault occurs, the service process agent will focus on the process of fault handling and service recovery, which will be directed with the actions defined in the policies upon the specific conditions. Such a policy driven and multi-agent based fault handling approach can address the issues of flexibility, automation and availability.

嵌入式远程视频监控系统的设计

针对目前的局域网视频监控传输系统,以嵌入式Linux操作系统为平台,应用用户数据包协议(UDP,User Datagram Protocol)穿越网络地址转换(NAT,Network Address Translation)技术,设计了远程视频监控系统。该系统由2部分组成:发送端和接收端,由于2者分别处于不同的内网中,无法直接通信,故采用UDP穿越NAT技术,搭建公网服务器以协助双方建立连接并传输视频。经测试,该方案可以较好地穿越NAT,并且在接收端电脑上能实时的显示视频图像。