原文：http://zqwt.012.blog.163.com/blog/static/12044684200911166349340/?suggestedreading
If you already know what SSH, Telnet and Rlogin are, you can safely skip on to the next section.
如果你想了解ssh,telnet,rlogin的话，你可以跳过下一节。
SSH, Telnet and Rlogin are three ways of doing the same thing: logging in to a multi-user computer from another computer, over a network.
ssh,telnet,rlogin是三种一样的东西：通过网络从一台计算机登录到一个多用户的计算机。
Multi-user operating systems, such as Unix and VMS, usually present a command-line interface to the user, much like the ‘Command Prompt’ or ‘MS-DOS Prompt’ in Windows. The system prints a prompt, and you type commands which the system will obey.
多用户的操作系统，例如unix和vms，通常一个命令行的用户界面，就像Windows里面的'命令提示符'和'MS-DOS提示符‘。这个系统打印的提示符，和你输入的命令系统将服从。
Using this type of interface, there is no need for you to be sitting at the same machine you are typing commands to. The commands, and responses, can be sent over a network, so you can sit at one computer and give commands to another one, or even to more than one.
用这类型的接口,你就不必坐在同样一台机器上输入你的命令，这命令，和反应，能通过网络发送，因此你可以坐在一台发送命令