New Words & Expressions

　　firewall n. 防火墙 offensive adj. 无理的，攻击性的

　　hacker n. 黑客 filter v. 过滤，滤过，渗入

　　private 私有的，秘密地 packet n. 小包，信息包

　　employee n. 职员，雇工 telnet n. 远程登录

　　traffic n. 流量 proxy n. 代理

　　retrieve v, 检索 match n.比较，匹配，符合

　　customizable 可定制的 block n. 妨碍，阻碍 port n. 端口 bug n. 故障，(程序)错误

　　unsolicited adj.主动提供的 junk n.垃圾，无用数据

　　spam n. 垃圾邮件 counter v. 还击，驳回

　　session n. 会话 inundate v. 淹没

　　macro [计]宏指令，宏功能 viruse n. 病毒

　　Abbreviations

　　HTTP (Hypertext Transfer Protocol) 超文本传输协议

　　FTP (File Transfer Protocol) 文件传输协议

　　SMTP (Simple Mail Transfer Protocol) 简单邮件传送协议

　　ICMP (Internet Control Message Protocol) 网际控制报文协议

　　A small home network has many of the same security issues that a large corporate network does. You can use a firewall to protect your home network and family from offensive Web sites and potential hackers.

　　一个小型家庭网有着与大公司的网络相同的安全问题。防火墙可以保护你的家庭网和家庭免遭恶意网站和潜在黑客的攻击。

　　Basically, a firewall is a barrier to keep destructive forces away from your property. In fact, that’s why it’s called a firewall. Its job is similar to a physical firewall that keeps a fire from spreading from one area to the next.

　　实质上，防火墙就是一个屏障，保护私有财产不受破坏。事实上，这就是它被称为防火墙的原因。它的作用类似于一堵防止火灾从一处蔓延到另一处的实实在在的防火墙。

　　What it does

　　A firewall is simply a program or hardware device that filters the information coming through the Internet connection into your private network or computer system. If an incoming packet of information is flagged by the filters, it is not allowed through.

　　防火墙做什么

　　一个防火墙就是一个程序或者一台硬件设备，用于过滤通过Internet连接进入你的专用网或计算机系统中的信息。如果一个输入的信息包被过滤器做了标记，它就不允许通过。

　　Firewalls use one or more of three methods to control traffic flowing in and out of the network:

　　(1) Packet filtering: Packets (small chunks of data) are analyzed against a set of filters. Packets that make it through the filters are sent to the requesting system and all others are discarded.

　　(2) Proxy service: Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.

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