--- /dev/null
+\define{versionidintro} \versionid $Id: intro.but 5593 2005-04-05 18:01:32Z jacob $\r
+\r
+\C{intro} Introduction to PuTTY\r
+\r
+PuTTY is a free SSH, Telnet and Rlogin client for 32-bit Windows\r
+systems.\r
+\r
+\H{you-what} What are SSH, Telnet and Rlogin?\r
+\r
+If you already know what SSH, Telnet and Rlogin are, you can safely\r
+skip on to the next section.\r
+\r
+SSH, Telnet and Rlogin are three ways of doing the same thing:\r
+logging in to a multi-user computer from another computer, over a\r
+network.\r
+\r
+Multi-user operating systems, such as Unix and VMS, usually present\r
+a \i{command-line interface} to the user, much like the \q{\i{Command\r
+Prompt}} or \q{\i{MS-DOS Prompt}} in Windows. The system prints a\r
+prompt, and you type commands which the system will obey.\r
+\r
+Using this type of interface, there is no need for you to be sitting\r
+at the same machine you are typing commands to. The commands, and\r
+responses, can be sent over a network, so you can sit at one\r
+computer and give commands to another one, or even to more than one.\r
+\r
+SSH, Telnet and Rlogin are \i\e{network protocols} that allow you to\r
+do this. On the computer you sit at, you run a \i\e{client}, which\r
+makes a network connection to the other computer (the \i\e{server}).\r
+The network connection carries your keystrokes and commands from the\r
+client to the server, and carries the server's responses back to\r
+you.\r
+\r
+These protocols can also be used for other types of keyboard-based\r
+interactive session. In particular, there are a lot of bulletin\r
+boards, \i{talker systems} and \i{MUDs} (Multi-User Dungeons) which support\r
+access using Telnet. There are even a few that support SSH.\r
+\r
+You might want to use SSH, Telnet or Rlogin if:\r
+\r
+\b you have an account on a Unix or VMS system which you want to be\r
+able to access from somewhere else\r
+\r
+\b your Internet Service Provider provides you with a login account\r
+on a \i{web server}. (This might also be known as a \i\e{shell account}.\r
+A \e{shell} is the program that runs on the server and interprets\r
+your commands for you.)\r
+\r
+\b you want to use a \i{bulletin board system}, talker or MUD which can\r
+be accessed using Telnet.\r
+\r
+You probably do \e{not} want to use SSH, Telnet or Rlogin if:\r
+\r
+\b you only use Windows. Windows computers have their own\r
+ways of networking between themselves, and unless you are doing\r
+something fairly unusual, you will not need to use any of these\r
+remote login protocols.\r
+\r
+\H{which-one} How do SSH, Telnet and Rlogin differ?\r
+\r
+This list summarises some of the \i{differences between SSH, Telnet\r
+and Rlogin}.\r
+\r
+\b SSH (which stands for \q{\i{secure shell}}) is a recently designed,\r
+high-security protocol. It uses strong cryptography to protect your\r
+connection against eavesdropping, hijacking and other attacks. Telnet\r
+and Rlogin are both older protocols offering minimal security.\r
+\r
+\b SSH and Rlogin both allow you to \I{passwordless login}log in to the\r
+server without having to type a password. (Rlogin's method of doing this is\r
+insecure, and can allow an attacker to access your account on the\r
+server. SSH's method is much more secure, and typically breaking the\r
+security requires the attacker to have gained access to your actual\r
+client machine.)\r
+\r
+\b SSH allows you to connect to the server and automatically send a\r
+command, so that the server will run that command and then\r
+disconnect. So you can use it in automated processing.\r
+\r
+The Internet is a hostile environment and security is everybody's\r
+responsibility. If you are connecting across the open Internet, then\r
+we recommend you use SSH. If the server you want to connect to\r
+doesn't support SSH, it might be worth trying to persuade the\r
+administrator to install it.\r
+\r
+If your client and server are both behind the same (good) firewall,\r
+it is more likely to be safe to use Telnet or Rlogin, but we still\r
+recommend you use SSH.\r
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