1 引言作为一个公共的网络,Internet是缺乏安全性的,因此对内部网而言,必须采取一定的措施,保证内部私有信息的安全。路由器工作在网络层,其主要工作是转发IP报文,它是内部网和Internet的衔接处,所有内部网络到Internet的报文都要流经路由器。尽管路由器非常灵活,并拥有高度的用户配置能力,但它们一般并不查看所传输的数据,也不提供认证远程用户,加密 1 Introduction As a public network, the Internet is a lack of security, so the internal network, we must take certain measures to ensure the security of internal private information. Router at the network layer, its main job is to forward IP packets, it is the convergence of the internal network and the Internet, all internal network to the Internet packets must flow through the router. Although routers are very flexible and have a high degree of user-configurability, they typically do not look at the data being transmitted, nor do they provide authenticated remote users, encryption