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