1 \define{versionidgs} \versionid $Id$
3 \C{gs} Getting started with PuTTY
5 This chapter gives a quick guide to the simplest types of
6 interactive login session using PuTTY.
8 \H{gs-insecure} \ii{Starting a session}
10 When you start PuTTY, you will see a \i{dialog box}. This dialog box
11 allows you to control everything PuTTY can do. See \k{config} for
12 details of all the things you can control.
14 You don't usually need to change most of the configuration options.
15 To start the simplest kind of session, all you need to do is to
16 enter a few basic parameters.
18 In the \q{Host Name} box, enter the Internet \i{host name} of the server
19 you want to connect to. You should have been told this by the
20 provider of your login account.
22 Now select a login \i{protocol} to use, from the \q{Connection type}
23 buttons. For a login session, you should select \i{Telnet},
24 \i{Rlogin} or \i{SSH}. See \k{which-one} for a description of the
25 differences between the three protocols, and advice on which one to
26 use. The fourth protocol, \I{raw protocol}\e{Raw}, is not used for
27 interactive login sessions; you would usually use this for debugging
28 other Internet services (see \k{using-rawprot}). The fifth option,
29 \e{Serial}, is used for connecting to a local serial line, and works
30 somewhat differently: see \k{using-serial} for more information on
33 When you change the selected protocol, the number in the \q{Port}
34 box will change. This is normal: it happens because the various
35 login services are usually provided on different network ports by
36 the server machine. Most servers will use the standard port numbers,
37 so you will not need to change the port setting. If your server
38 provides login services on a non-standard port, your system
39 administrator should have told you which one. (For example, many
40 \i{MUDs} run Telnet service on a port other than 23.)
42 Once you have filled in the \q{Host Name}, \q{Protocol}, and
43 possibly \q{Port} settings, you are ready to connect. Press the
44 \q{Open} button at the bottom of the dialog box, and PuTTY will
45 begin trying to connect you to the server.
47 \H{gs-hostkey} \ii{Verifying the host key} (SSH only)
49 If you are not using the \i{SSH} protocol, you can skip this
52 If you are using SSH to connect to a server for the first time, you
53 will probably see a message looking something like this:
55 \c The server's host key is not cached in the registry. You
56 \c have no guarantee that the server is the computer you
58 \c The server's rsa2 key fingerprint is:
59 \c ssh-rsa 1024 7b:e5:6f:a7:f4:f9:81:62:5c:e3:1f:bf:8b:57:6c:5a
60 \c If you trust this host, hit Yes to add the key to
61 \c PuTTY's cache and carry on connecting.
62 \c If you want to carry on connecting just once, without
63 \c adding the key to the cache, hit No.
64 \c If you do not trust this host, hit Cancel to abandon the
67 This is a feature of the SSH protocol. It is designed to protect you
68 against a network attack known as \i\e{spoofing}: secretly
69 redirecting your connection to a different computer, so that you
70 send your password to the wrong machine. Using this technique, an
71 attacker would be able to learn the password that guards your login
72 account, and could then log in as if they were you and use the
73 account for their own purposes.
75 To prevent this attack, each server has a unique identifying code,
76 called a \e{host key}. These keys are created in a way that prevents
77 one server from forging another server's key. So if you connect to a
78 server and it sends you a different host key from the one you were
79 expecting, PuTTY can warn you that the server may have been switched
80 and that a spoofing attack might be in progress.
82 PuTTY records the host key for each server you connect to, in the
83 Windows \i{Registry}. Every time you connect to a server, it checks
84 that the host key presented by the server is the same host key as it
85 was the last time you connected. If it is not, you will see a
86 warning, and you will have the chance to abandon your connection
87 before you type any private information (such as a password) into
90 However, when you connect to a server you have not connected to
91 before, PuTTY has no way of telling whether the host key is the
92 right one or not. So it gives the warning shown above, and asks you
93 whether you want to \I{trusting host keys}trust this host key or
96 Whether or not to trust the host key is your choice. If you are
97 connecting within a company network, you might feel that all the
98 network users are on the same side and spoofing attacks are
99 unlikely, so you might choose to trust the key without checking it.
100 If you are connecting across a hostile network (such as the
101 Internet), you should check with your system administrator, perhaps
102 by telephone or in person. (Some modern servers have more than one
103 host key. If the system administrator sends you more than one
104 \I{host key fingerprint}fingerprint, you should make sure the one
105 PuTTY shows you is on the list, but it doesn't matter which one it is.)
107 \# FIXME: this is all very fine but of course in practice the world
108 doesn't work that way. Ask the team if they have any good ideas for
109 changes to this section!
111 \H{gs-login} \ii{Logging in}
113 After you have connected, and perhaps verified the server's host
114 key, you will be asked to log in, probably using a \i{username} and
115 a \i{password}. Your system administrator should have provided you
116 with these. Enter the username and the password, and the server
117 should grant you access and begin your session. If you have
118 \I{mistyping a password}mistyped your password, most servers will
119 give you several chances to get it right.
121 If you are using SSH, be careful not to type your username wrongly,
122 because you will not have a chance to correct it after you press
123 Return; many SSH servers do not permit you to make two login attempts
124 using \i{different usernames}. If you type your username wrongly, you
125 must close PuTTY and start again.
127 If your password is refused but you are sure you have typed it
128 correctly, check that Caps Lock is not enabled. Many login servers,
129 particularly Unix computers, treat upper case and lower case as
130 different when checking your password; so if Caps Lock is on, your
131 password will probably be refused.
133 \H{gs-session} After logging in
135 After you log in to the server, what happens next is up to the
136 server! Most servers will print some sort of login message and then
137 present a \i{prompt}, at which you can type
138 \I{commands on the server}commands which the
139 server will carry out. Some servers will offer you on-line help;
140 others might not. If you are in doubt about what to do next, consult
141 your system administrator.
143 \H{gs-logout} \ii{Logging out}
145 When you have finished your session, you should log out by typing
146 the server's own logout command. This might vary between servers; if
147 in doubt, try \c{logout} or \c{exit}, or consult a manual or your
148 system administrator. When the server processes your logout command,
149 the PuTTY window should close itself automatically.
151 You \e{can} close a PuTTY session using the \i{Close button} in the
152 window border, but this might confuse the server - a bit like
153 hanging up a telephone unexpectedly in the middle of a conversation.
154 We recommend you do not do this unless the server has stopped
155 responding to you and you cannot close the window any other way.
projects / u / mdw / putty / blob