n.防火壁；隔火墙
The proxy firewall maintain context more easily than the packet filter firewall. 代理防火墙比包过滤器防火墙易于保持更多的上下文
The firewall sit between the power phone system internal network and the public data network. 防火墙位于强力电话系统内部网络与公共数据网络之间。
The packet filter rout provide the same functionality as the packet filter firewall describe in section2.1.1. 包过滤路由器与包过滤防火墙具有同一功能，如2。1。1部分所述。
Inside of the firewall the only permit destination for traffic from the interior or exterior route is the bastion host. 在防火墙内部，对于来自内外部路由器的通信量来说，唯一允许到达的目的地是bastion主机。
