1 \define{versionidconfig} \versionid $Id$
3 \C{config} Configuring PuTTY
5 This chapter describes all the \i{configuration options} in PuTTY.
7 PuTTY is configured using the control panel that comes up before you
8 start a session. Some options can also be changed in the middle of a
9 session, by selecting \q{Change Settings} from the window menu.
11 \H{config-session} The Session panel
13 The Session configuration panel contains the basic options you need
14 to specify in order to open a session at all, and also allows you to
15 save your settings to be reloaded later.
17 \S{config-hostname} The \i{host name} section
19 \cfg{winhelp-topic}{session.hostname}
21 The top box on the Session panel, labelled \q{Specify your
22 connection by host name}, contains the details that need to be
23 filled in before PuTTY can open a session at all.
25 \b The \q{Host Name} box is where you type the name, or the \i{IP
26 address}, of the server you want to connect to.
28 \b The \q{Connection type} radio buttons let you choose what type of
29 connection you want to make: a \I{raw TCP connections}raw
30 connection, a \i{Telnet} connection, an \i{Rlogin} connection, an
31 \i{SSH} connection, or a connection to a local \i{serial line}. (See
32 \k{which-one} for a summary of the differences between SSH, Telnet
33 and rlogin; see \k{using-rawprot} for an explanation of \q{raw}
34 connections; see \k{using-serial} for information about using a
37 \b The \q{Port} box lets you specify which \i{port number} on the
38 server to connect to. If you select Telnet, Rlogin, or SSH, this box
39 will be filled in automatically to the usual value, and you will
40 only need to change it if you have an unusual server. If you select
41 Raw mode, you will almost certainly need to fill in the \q{Port} box
44 If you select \q{Serial} from the \q{Connection type} radio buttons,
45 the \q{Host Name} and \q{Port} boxes are replaced by \q{Serial line}
46 and \q{Speed}; see \k{config-serial} for more details of these.
48 \S{config-saving} \ii{Loading and storing saved sessions}
50 \cfg{winhelp-topic}{session.saved}
52 The next part of the Session configuration panel allows you to save
53 your preferred PuTTY options so they will appear automatically the
54 next time you start PuTTY. It also allows you to create \e{saved
55 sessions}, which contain a full set of configuration options plus a
56 host name and protocol. A saved session contains all the information
57 PuTTY needs to start exactly the session you want.
59 \b To save your default settings: first set up the settings the way
60 you want them saved. Then come back to the Session panel. Select the
61 \q{\i{Default Settings}} entry in the saved sessions list, with a single
62 click. Then press the \q{Save} button.
65 Note that PuTTY does not allow you to save a host name into the
66 Default Settings entry. This ensures that when PuTTY is started up,
67 the host name box is always empty, so a user can always just type in
68 a host name and connect.
71 If there is a specific host you want to store the details of how to
72 connect to, you should create a saved session, which will be
73 separate from the Default Settings.
75 \b To save a session: first go through the rest of the configuration
76 box setting up all the options you want. Then come back to the
77 Session panel. Enter a name for the saved session in the \q{Saved
78 Sessions} input box. (The server name is often a good choice for a
79 saved session name.) Then press the \q{Save} button. Your saved
80 session name should now appear in the list box.
83 You can also save settings in mid-session, from the \q{Change Settings}
84 dialog. Settings changed since the start of the session will be saved
85 with their current values; as well as settings changed through the
86 dialog, this includes changes in window size, window title changes
87 sent by the server, and so on.
90 \b To reload a saved session: single-click to select the session
91 name in the list box, and then press the \q{Load} button. Your saved
92 settings should all appear in the configuration panel.
94 \b To modify a saved session: first load it as described above. Then
95 make the changes you want. Come back to the Session panel, and press
96 the \q{Save} button. The new settings will be saved over the top of
100 To save the new settings under a different name, you can enter the new
101 name in the \q{Saved Sessions} box, or single-click to select a
102 session name in the list box to overwrite that session. To save
103 \q{Default Settings}, you must single-click the name before saving.
106 \b To start a saved session immediately: double-click on the session
107 name in the list box.
109 \b To delete a saved session: single-click to select the session
110 name in the list box, and then press the \q{Delete} button.
112 Each saved session is independent of the Default Settings
113 configuration. If you change your preferences and update Default
114 Settings, you must also update every saved session separately.
116 Saved sessions are stored in the \i{Registry}, at the location
118 \c HKEY_CURRENT_USER\Software\SimonTatham\PuTTY\Sessions
120 If you need to store them in a file, you could try the method
121 described in \k{config-file}.
123 \S{config-closeonexit} \q{\ii{Close Window} on Exit}
125 \cfg{winhelp-topic}{session.coe}
127 Finally in the Session panel, there is an option labelled \q{Close
128 Window on Exit}. This controls whether the PuTTY \i{terminal window}
129 disappears as soon as the session inside it terminates. If you are
130 likely to want to copy and paste text out of the session after it
131 has terminated, or restart the session, you should arrange for this
134 \q{Close Window On Exit} has three settings. \q{Always} means always
135 close the window on exit; \q{Never} means never close on exit
136 (always leave the window open, but \I{inactive window}inactive). The
137 third setting, and the default one, is \q{Only on clean exit}. In this
138 mode, a session which terminates normally will cause its window to
139 close, but one which is aborted unexpectedly by network trouble or a
140 confusing message from the server will leave the window up.
142 \H{config-logging} The Logging panel
144 \cfg{winhelp-topic}{logging.main}
146 The Logging configuration panel allows you to save \i{log file}s of your
147 PuTTY sessions, for debugging, analysis or future reference.
149 The main option is a radio-button set that specifies whether PuTTY
150 will log anything at all. The options are:
152 \b \q{None}. This is the default option; in this mode PuTTY will not
153 create a log file at all.
155 \b \q{Printable output}. In this mode, a log file will be
156 created and written to, but only printable text will be saved into
157 it. The various terminal control codes that are typically sent down
158 an interactive session alongside the printable text will be omitted.
159 This might be a useful mode if you want to read a log file in a text
160 editor and hope to be able to make sense of it.
162 \b \q{All session output}. In this mode, \e{everything} sent by
163 the server into your terminal session is logged. If you view the log
164 file in a text editor, therefore, you may well find it full of
165 strange control characters. This is a particularly useful mode if
166 you are experiencing problems with PuTTY's terminal handling: you
167 can record everything that went to the terminal, so that someone
168 else can replay the session later in slow motion and watch to see
171 \b \I{SSH packet log}\q{SSH packets}. In this mode (which is only used
172 by SSH connections), the SSH message packets sent over the encrypted
173 connection are written to the log file (as well as \i{Event Log}
174 entries). You might need this to debug a network-level problem, or
175 more likely to send to the PuTTY authors as part of a bug report.
176 \e{BE WARNED} that if you log in using a password, the password can
177 appear in the log file; see \k{config-logssh} for options that may
178 help to remove sensitive material from the log file before you send it
181 \b \q{SSH packets and raw data}. In this mode, as well as the
182 decrypted packets (as in the previous mode), the \e{raw} (encrypted,
183 compressed, etc) packets are \e{also} logged. This could be useful to
184 diagnose corruption in transit. (The same caveats as the previous mode
187 \S{config-logfilename} \q{Log file name}
189 \cfg{winhelp-topic}{logging.filename}
191 In this edit box you enter the name of the file you want to log the
192 session to. The \q{Browse} button will let you look around your file
193 system to find the right place to put the file; or if you already
194 know exactly where you want it to go, you can just type a pathname
197 There are a few special features in this box. If you use the \c{&}
198 character in the file name box, PuTTY will insert details of the
199 current session in the name of the file it actually opens. The
200 precise replacements it will do are:
202 \b \c{&Y} will be replaced by the current year, as four digits.
204 \b \c{&M} will be replaced by the current month, as two digits.
206 \b \c{&D} will be replaced by the current day of the month, as two
209 \b \c{&T} will be replaced by the current time, as six digits
210 (HHMMSS) with no punctuation.
212 \b \c{&H} will be replaced by the host name you are connecting to.
214 For example, if you enter the host name
215 \c{c:\\puttylogs\\log-&h-&y&m&d-&t.dat}, you will end up with files looking
218 \c log-server1.example.com-20010528-110859.dat
219 \c log-unixbox.somewhere.org-20010611-221001.dat
221 \S{config-logfileexists} \q{What to do if the log file already exists}
223 \cfg{winhelp-topic}{logging.exists}
225 This control allows you to specify what PuTTY should do if it tries
226 to start writing to a log file and it finds the file already exists.
227 You might want to automatically destroy the existing log file and
228 start a new one with the same name. Alternatively, you might want to
229 open the existing log file and add data to the \e{end} of it.
230 Finally (the default option), you might not want to have any
231 automatic behaviour, but to ask the user every time the problem
234 \S{config-logflush} \I{log file, flushing}\q{Flush log file frequently}
236 \cfg{winhelp-topic}{logging.flush}
238 This option allows you to control how frequently logged data is
239 flushed to disc. By default, PuTTY will flush data as soon as it is
240 displayed, so that if you view the log file while a session is still
241 open, it will be up to date; and if the client system crashes, there's
242 a greater chance that the data will be preserved.
244 However, this can incur a performance penalty. If PuTTY is running
245 slowly with logging enabled, you could try unchecking this option. Be
246 warned that the log file may not always be up to date as a result
247 (although it will of course be flushed when it is closed, for instance
248 at the end of a session).
250 \S{config-logssh} Options specific to \i{SSH packet log}ging
252 These options only apply if SSH packet data is being logged.
254 The following options allow particularly sensitive portions of
255 unencrypted packets to be automatically left out of the log file.
256 They are only intended to deter casual nosiness; an attacker could
257 glean a lot of useful information from even these obfuscated logs
258 (e.g., length of password).
260 \S2{config-logssh-omitpw} \q{Omit known password fields}
262 \cfg{winhelp-topic}{logging.ssh.omitpassword}
264 When checked, decrypted password fields are removed from the log of
265 transmitted packets. (This includes any user responses to
266 challenge-response authentication methods such as
267 \q{keyboard-interactive}.) This does not include X11 authentication
268 data if using X11 forwarding.
270 Note that this will only omit data that PuTTY \e{knows} to be a
271 password. However, if you start another login session within your
272 PuTTY session, for instance, any password used will appear in the
273 clear in the packet log. The next option may be of use to protect
276 This option is enabled by default.
278 \S2{config-logssh-omitdata} \q{Omit session data}
280 \cfg{winhelp-topic}{logging.ssh.omitdata}
282 When checked, all decrypted \q{session data} is omitted; this is
283 defined as data in terminal sessions and in forwarded channels (TCP,
284 X11, and authentication agent). This will usually substantially reduce
285 the size of the resulting log file.
287 This option is disabled by default.
289 \H{config-terminal} The Terminal panel
291 The Terminal configuration panel allows you to control the behaviour
292 of PuTTY's \i{terminal emulation}.
294 \S{config-autowrap} \q{Auto wrap mode initially on}
296 \cfg{winhelp-topic}{terminal.autowrap}
298 \ii{Auto wrap mode} controls what happens when text printed in a PuTTY
299 window reaches the right-hand edge of the window.
301 With auto wrap mode on, if a long line of text reaches the
302 right-hand edge, it will wrap over on to the next line so you can
303 still see all the text. With auto wrap mode off, the cursor will
304 stay at the right-hand edge of the screen, and all the characters in
305 the line will be printed on top of each other.
307 If you are running a full-screen application and you occasionally
308 find the screen scrolling up when it looks as if it shouldn't, you
309 could try turning this option off.
311 Auto wrap mode can be turned on and off by \i{control sequence}s sent by
312 the server. This configuration option controls the \e{default}
313 state, which will be restored when you reset the terminal (see
314 \k{reset-terminal}). However, if you modify this option in
315 mid-session using \q{Change Settings}, it will take effect
318 \S{config-decom} \q{DEC Origin Mode initially on}
320 \cfg{winhelp-topic}{terminal.decom}
322 \i{DEC Origin Mode} is a minor option which controls how PuTTY
323 interprets cursor-position \i{control sequence}s sent by the server.
325 The server can send a control sequence that restricts the \i{scrolling
326 region} of the display. For example, in an editor, the server might
327 reserve a line at the top of the screen and a line at the bottom,
328 and might send a control sequence that causes scrolling operations
329 to affect only the remaining lines.
331 With DEC Origin Mode on, \i{cursor coordinates} are counted from the top
332 of the scrolling region. With it turned off, cursor coordinates are
333 counted from the top of the whole screen regardless of the scrolling
336 It is unlikely you would need to change this option, but if you find
337 a full-screen application is displaying pieces of text in what looks
338 like the wrong part of the screen, you could try turning DEC Origin
339 Mode on to see whether that helps.
341 DEC Origin Mode can be turned on and off by control sequences sent
342 by the server. This configuration option controls the \e{default}
343 state, which will be restored when you reset the terminal (see
344 \k{reset-terminal}). However, if you modify this option in
345 mid-session using \q{Change Settings}, it will take effect
348 \S{config-crlf} \q{Implicit CR in every LF}
350 \cfg{winhelp-topic}{terminal.lfhascr}
352 Most servers send two control characters, \i{CR} and \i{LF}, to start a
353 \i{new line} of the screen. The CR character makes the cursor return to the
354 left-hand side of the screen. The LF character makes the cursor move
355 one line down (and might make the screen scroll).
357 Some servers only send LF, and expect the terminal to move the
358 cursor over to the left automatically. If you come across a server
359 that does this, you will see a \I{stair-stepping}stepped effect on the
362 \c First line of text
366 If this happens to you, try enabling the \q{Implicit CR in every LF}
367 option, and things might go back to normal:
369 \c First line of text
373 \S{config-erase} \q{Use \i{background colour} to erase screen}
375 \cfg{winhelp-topic}{terminal.bce}
377 Not all terminals agree on what colour to turn the screen when the
378 server sends a \q{\i{clear screen}} sequence. Some terminals believe the
379 screen should always be cleared to the \e{default} background
380 colour. Others believe the screen should be cleared to whatever the
381 server has selected as a background colour.
383 There exist applications that expect both kinds of behaviour.
384 Therefore, PuTTY can be configured to do either.
386 With this option disabled, screen clearing is always done in the
387 default background colour. With this option enabled, it is done in
388 the \e{current} background colour.
390 Background-colour erase can be turned on and off by \i{control
391 sequences} sent by the server. This configuration option controls the
392 \e{default} state, which will be restored when you reset the
393 terminal (see \k{reset-terminal}). However, if you modify this
394 option in mid-session using \q{Change Settings}, it will take effect
397 \S{config-blink} \q{Enable \i{blinking text}}
399 \cfg{winhelp-topic}{terminal.blink}
401 The server can ask PuTTY to display text that blinks on and off.
402 This is very distracting, so PuTTY allows you to turn blinking text
405 When blinking text is disabled and the server attempts to make some
406 text blink, PuTTY will instead display the text with a \I{background
407 colour, bright}bolded background colour.
409 Blinking text can be turned on and off by \i{control sequence}s sent by
410 the server. This configuration option controls the \e{default}
411 state, which will be restored when you reset the terminal (see
412 \k{reset-terminal}). However, if you modify this option in
413 mid-session using \q{Change Settings}, it will take effect
416 \S{config-answerback} \q{\ii{Answerback} to ^E}
418 \cfg{winhelp-topic}{terminal.answerback}
420 This option controls what PuTTY will send back to the server if the
421 server sends it the ^E \i{enquiry character}. Normally it just sends
422 the string \q{PuTTY}.
424 If you accidentally write the contents of a binary file to your
425 terminal, you will probably find that it contains more than one ^E
426 character, and as a result your next command line will probably read
427 \q{PuTTYPuTTYPuTTY...} as if you had typed the answerback string
428 multiple times at the keyboard. If you set the answerback string to
429 be empty, this problem should go away, but doing so might cause
432 Note that this is \e{not} the feature of PuTTY which the server will
433 typically use to determine your terminal type. That feature is the
434 \q{\ii{Terminal-type} string} in the Connection panel; see
435 \k{config-termtype} for details.
437 You can include control characters in the answerback string using
438 \c{^C} notation. (Use \c{^~} to get a literal \c{^}.)
440 \S{config-localecho} \q{\ii{Local echo}}
442 \cfg{winhelp-topic}{terminal.localecho}
444 With local echo disabled, characters you type into the PuTTY window
445 are not echoed in the window \e{by PuTTY}. They are simply sent to
446 the server. (The \e{server} might choose to \I{remote echo}echo them
447 back to you; this can't be controlled from the PuTTY control panel.)
449 Some types of session need local echo, and many do not. In its
450 default mode, PuTTY will automatically attempt to deduce whether or
451 not local echo is appropriate for the session you are working in. If
452 you find it has made the wrong decision, you can use this
453 configuration option to override its choice: you can force local
454 echo to be turned on, or force it to be turned off, instead of
455 relying on the automatic detection.
457 \S{config-localedit} \q{\ii{Local line editing}}
459 \cfg{winhelp-topic}{terminal.localedit}
461 Normally, every character you type into the PuTTY window is sent
462 immediately to the server the moment you type it.
464 If you enable local line editing, this changes. PuTTY will let you
465 edit a whole line at a time locally, and the line will only be sent
466 to the server when you press Return. If you make a mistake, you can
467 use the Backspace key to correct it before you press Return, and the
468 server will never see the mistake.
470 Since it is hard to edit a line locally without being able to see
471 it, local line editing is mostly used in conjunction with \i{local echo}
472 (\k{config-localecho}). This makes it ideal for use in raw mode
473 \#{FIXME} or when connecting to \i{MUD}s or \i{talker}s. (Although some more
474 advanced MUDs do occasionally turn local line editing on and turn
475 local echo off, in order to accept a password from the user.)
477 Some types of session need local line editing, and many do not. In
478 its default mode, PuTTY will automatically attempt to deduce whether
479 or not local line editing is appropriate for the session you are
480 working in. If you find it has made the wrong decision, you can use
481 this configuration option to override its choice: you can force
482 local line editing to be turned on, or force it to be turned off,
483 instead of relying on the automatic detection.
485 \S{config-printing} \ii{Remote-controlled printing}
487 \cfg{winhelp-topic}{terminal.printing}
489 A lot of VT100-compatible terminals support printing under control
490 of the remote server. PuTTY supports this feature as well, but it is
491 turned off by default.
493 To enable remote-controlled printing, choose a printer from the
494 \q{Printer to send ANSI printer output to} drop-down list box. This
495 should allow you to select from all the printers you have installed
496 drivers for on your computer. Alternatively, you can type the
497 network name of a networked printer (for example,
498 \c{\\\\printserver\\printer1}) even if you haven't already
499 installed a driver for it on your own machine.
501 When the remote server attempts to print some data, PuTTY will send
502 that data to the printer \e{raw} - without translating it,
503 attempting to format it, or doing anything else to it. It is up to
504 you to ensure your remote server knows what type of printer it is
507 Since PuTTY sends data to the printer raw, it cannot offer options
508 such as portrait versus landscape, print quality, or paper tray
509 selection. All these things would be done by your PC printer driver
510 (which PuTTY bypasses); if you need them done, you will have to find
511 a way to configure your remote server to do them.
513 To disable remote printing again, choose \q{None (printing
514 disabled)} from the printer selection list. This is the default
517 \H{config-keyboard} The Keyboard panel
519 The Keyboard configuration panel allows you to control the behaviour
520 of the \i{keyboard} in PuTTY. The correct state for many of these
521 settings depends on what the server to which PuTTY is connecting
522 expects. With a \i{Unix} server, this is likely to depend on the
523 \i\c{termcap} or \i\c{terminfo} entry it uses, which in turn is likely to
524 be controlled by the \q{\ii{Terminal-type} string} setting in the Connection
525 panel; see \k{config-termtype} for details. If none of the settings here
526 seems to help, you may find \k{faq-keyboard} to be useful.
528 \S{config-backspace} Changing the action of the \ii{Backspace key}
530 \cfg{winhelp-topic}{keyboard.backspace}
532 Some terminals believe that the Backspace key should send the same
533 thing to the server as \i{Control-H} (ASCII code 8). Other terminals
534 believe that the Backspace key should send ASCII code 127 (usually
535 known as \i{Control-?}) so that it can be distinguished from Control-H.
536 This option allows you to choose which code PuTTY generates when you
539 If you are connecting over SSH, PuTTY by default tells the server
540 the value of this option (see \k{config-ttymodes}), so you may find
541 that the Backspace key does the right thing either way. Similarly,
542 if you are connecting to a \i{Unix} system, you will probably find that
543 the Unix \i\c{stty} command lets you configure which the server
544 expects to see, so again you might not need to change which one PuTTY
545 generates. On other systems, the server's expectation might be fixed
546 and you might have no choice but to configure PuTTY.
548 If you do have the choice, we recommend configuring PuTTY to
549 generate Control-? and configuring the server to expect it, because
550 that allows applications such as \c{emacs} to use Control-H for
553 (Typing \i{Shift-Backspace} will cause PuTTY to send whichever code
554 isn't configured here as the default.)
556 \S{config-homeend} Changing the action of the \i{Home and End keys}
558 \cfg{winhelp-topic}{keyboard.homeend}
560 The Unix terminal emulator \i\c{rxvt} disagrees with the rest of the
561 world about what character sequences should be sent to the server by
562 the Home and End keys.
564 \i\c{xterm}, and other terminals, send \c{ESC [1~} for the Home key,
565 and \c{ESC [4~} for the End key. \c{rxvt} sends \c{ESC [H} for the
566 Home key and \c{ESC [Ow} for the End key.
568 If you find an application on which the Home and End keys aren't
569 working, you could try switching this option to see if it helps.
571 \S{config-funkeys} Changing the action of the \i{function keys} and
574 \cfg{winhelp-topic}{keyboard.funkeys}
576 This option affects the function keys (F1 to F12) and the top row of
579 \b In the default mode, labelled \c{ESC [n~}, the function keys
580 generate sequences like \c{ESC [11~}, \c{ESC [12~} and so on. This
581 matches the general behaviour of Digital's terminals.
583 \b In Linux mode, F6 to F12 behave just like the default mode, but
584 F1 to F5 generate \c{ESC [[A} through to \c{ESC [[E}. This mimics the
585 \i{Linux virtual console}.
587 \b In \I{xterm}Xterm R6 mode, F5 to F12 behave like the default mode, but F1
588 to F4 generate \c{ESC OP} through to \c{ESC OS}, which are the
589 sequences produced by the top row of the \e{keypad} on Digital's
592 \b In \i{VT400} mode, all the function keys behave like the default
593 mode, but the actual top row of the numeric keypad generates \c{ESC
594 OP} through to \c{ESC OS}.
596 \b In \i{VT100+} mode, the function keys generate \c{ESC OP} through to
599 \b In \i{SCO} mode, the function keys F1 to F12 generate \c{ESC [M}
600 through to \c{ESC [X}. Together with shift, they generate \c{ESC [Y}
601 through to \c{ESC [j}. With control they generate \c{ESC [k} through
602 to \c{ESC [v}, and with shift and control together they generate
603 \c{ESC [w} through to \c{ESC [\{}.
605 If you don't know what any of this means, you probably don't need to
608 \S{config-appcursor} Controlling \i{Application Cursor Keys} mode
610 \cfg{winhelp-topic}{keyboard.appcursor}
612 Application Cursor Keys mode is a way for the server to change the
613 control sequences sent by the arrow keys. In normal mode, the arrow
614 keys send \c{ESC [A} through to \c{ESC [D}. In application mode,
615 they send \c{ESC OA} through to \c{ESC OD}.
617 Application Cursor Keys mode can be turned on and off by the server,
618 depending on the application. PuTTY allows you to configure the
621 You can also disable application cursor keys mode completely, using
622 the \q{Features} configuration panel; see
623 \k{config-features-application}.
625 \S{config-appkeypad} Controlling \i{Application Keypad} mode
627 \cfg{winhelp-topic}{keyboard.appkeypad}
629 Application Keypad mode is a way for the server to change the
630 behaviour of the numeric keypad.
632 In normal mode, the keypad behaves like a normal Windows keypad:
633 with \i{NumLock} on, the number keys generate numbers, and with NumLock
634 off they act like the arrow keys and Home, End etc.
636 In application mode, all the keypad keys send special control
637 sequences, \e{including} Num Lock. Num Lock stops behaving like Num
638 Lock and becomes another function key.
640 Depending on which version of Windows you run, you may find the Num
641 Lock light still flashes on and off every time you press Num Lock,
642 even when application mode is active and Num Lock is acting like a
643 function key. This is unavoidable.
645 Application keypad mode can be turned on and off by the server,
646 depending on the application. PuTTY allows you to configure the
649 You can also disable application keypad mode completely, using the
650 \q{Features} configuration panel; see
651 \k{config-features-application}.
653 \S{config-nethack} Using \i{NetHack keypad mode}
655 \cfg{winhelp-topic}{keyboard.nethack}
657 PuTTY has a special mode for playing NetHack. You can enable it by
658 selecting \q{NetHack} in the \q{Initial state of numeric keypad}
661 In this mode, the numeric keypad keys 1-9 generate the NetHack
662 movement commands (\cw{hjklyubn}). The 5 key generates the \c{.}
663 command (do nothing).
665 In addition, pressing Shift or Ctrl with the keypad keys generate
666 the Shift- or Ctrl-keys you would expect (e.g. keypad-7 generates
667 \cq{y}, so Shift-keypad-7 generates \cq{Y} and Ctrl-keypad-7
668 generates Ctrl-Y); these commands tell NetHack to keep moving you in
669 the same direction until you encounter something interesting.
671 For some reason, this feature only works properly when \i{Num Lock} is
672 on. We don't know why.
674 \S{config-compose} Enabling a DEC-like \ii{Compose key}
676 \cfg{winhelp-topic}{keyboard.compose}
678 DEC terminals have a Compose key, which provides an easy-to-remember
679 way of typing \i{accented characters}. You press Compose and then type
680 two more characters. The two characters are \q{combined} to produce
681 an accented character. The choices of character are designed to be
682 easy to remember; for example, composing \q{e} and \q{`} produces
683 the \q{\u00e8{e-grave}} character.
685 If your keyboard has a Windows \i{Application key}, it acts as a Compose
686 key in PuTTY. Alternatively, if you enable the \q{\i{AltGr} acts as
687 Compose key} option, the AltGr key will become a Compose key.
689 \S{config-ctrlalt} \q{Control-Alt is different from \i{AltGr}}
691 \cfg{winhelp-topic}{keyboard.ctrlalt}
693 Some old keyboards do not have an AltGr key, which can make it
694 difficult to type some characters. PuTTY can be configured to treat
695 the key combination Ctrl + Left Alt the same way as the AltGr key.
697 By default, this checkbox is checked, and the key combination Ctrl +
698 Left Alt does something completely different. PuTTY's usual handling
699 of the left Alt key is to prefix the Escape (Control-\cw{[})
700 character to whatever character sequence the rest of the keypress
701 would generate. For example, Alt-A generates Escape followed by
702 \c{a}. So Alt-Ctrl-A would generate Escape, followed by Control-A.
704 If you uncheck this box, Ctrl-Alt will become a synonym for AltGr,
705 so you can use it to type extra graphic characters if your keyboard
708 (However, Ctrl-Alt will never act as a Compose key, regardless of the
709 setting of \q{AltGr acts as Compose key} described in
712 \H{config-bell} The Bell panel
714 The Bell panel controls the \i{terminal bell} feature: the server's
715 ability to cause PuTTY to beep at you.
717 In the default configuration, when the server sends the character
718 with ASCII code 7 (Control-G), PuTTY will play the \i{Windows Default
719 Beep} sound. This is not always what you want the terminal bell
720 feature to do; the Bell panel allows you to configure alternative
723 \S{config-bellstyle} \q{Set the style of bell}
725 \cfg{winhelp-topic}{bell.style}
727 This control allows you to select various different actions to occur
730 \b Selecting \q{None} \I{terminal bell, disabling}disables the bell
731 completely. In this mode, the server can send as many Control-G
732 characters as it likes and nothing at all will happen.
734 \b \q{Make default system alert sound} is the default setting. It
735 causes the Windows \q{Default Beep} sound to be played. To change
736 what this sound is, or to test it if nothing seems to be happening,
737 use the Sound configurer in the Windows Control Panel.
739 \b \q{\ii{Visual bell}} is a silent alternative to a beeping computer. In
740 this mode, when the server sends a Control-G, the whole PuTTY window
741 will flash white for a fraction of a second.
743 \b \q{Beep using the \i{PC speaker}} is self-explanatory.
745 \b \q{Play a custom \i{sound file}} allows you to specify a particular
746 sound file to be used by PuTTY alone, or even by a particular
747 individual PuTTY session. This allows you to distinguish your PuTTY
748 beeps from any other beeps on the system. If you select this option,
749 you will also need to enter the name of your sound file in the edit
750 control \q{Custom sound file to play as a bell}.
752 \S{config-belltaskbar} \q{\ii{Taskbar}/\I{window caption}caption
755 \cfg{winhelp-topic}{bell.taskbar}
757 This feature controls what happens to the PuTTY window's entry in
758 the Windows Taskbar if a bell occurs while the window does not have
761 In the default state (\q{Disabled}) nothing unusual happens.
763 If you select \q{Steady}, then when a bell occurs and the window is
764 not in focus, the window's Taskbar entry and its title bar will
765 change colour to let you know that PuTTY session is asking for your
766 attention. The change of colour will persist until you select the
767 window, so you can leave several PuTTY windows minimised in your
768 terminal, go away from your keyboard, and be sure not to have missed
769 any important beeps when you get back.
771 \q{Flashing} is even more eye-catching: the Taskbar entry will
772 continuously flash on and off until you select the window.
774 \S{config-bellovl} \q{Control the \i{bell overload} behaviour}
776 \cfg{winhelp-topic}{bell.overload}
778 A common user error in a terminal session is to accidentally run the
779 Unix command \c{cat} (or equivalent) on an inappropriate file type,
780 such as an executable, image file, or ZIP file. This produces a huge
781 stream of non-text characters sent to the terminal, which typically
782 includes a lot of bell characters. As a result of this the terminal
783 often doesn't stop beeping for ten minutes, and everybody else in
784 the office gets annoyed.
786 To try to avoid this behaviour, or any other cause of excessive
787 beeping, PuTTY includes a bell overload management feature. In the
788 default configuration, receiving more than five bell characters in a
789 two-second period will cause the overload feature to activate. Once
790 the overload feature is active, further bells will \I{terminal bell,
791 disabling} have no effect at all, so the rest of your binary file
792 will be sent to the screen in silence. After a period of five seconds
793 during which no further bells are received, the overload feature will
794 turn itself off again and bells will be re-enabled.
796 If you want this feature completely disabled, you can turn it off
797 using the checkbox \q{Bell is temporarily disabled when over-used}.
799 Alternatively, if you like the bell overload feature but don't agree
800 with the settings, you can configure the details: how many bells
801 constitute an overload, how short a time period they have to arrive
802 in to do so, and how much silent time is required before the
803 overload feature will deactivate itself.
805 Bell overload mode is always deactivated by any keypress in the
806 terminal. This means it can respond to large unexpected streams of
807 data, but does not interfere with ordinary command-line activities
808 that generate beeps (such as filename completion).
810 \H{config-features} The Features panel
812 PuTTY's \i{terminal emulation} is very highly featured, and can do a lot
813 of things under remote server control. Some of these features can
814 cause problems due to buggy or strangely configured server
817 The Features configuration panel allows you to disable some of
818 PuTTY's more advanced terminal features, in case they cause trouble.
820 \S{config-features-application} Disabling application keypad and cursor keys
822 \cfg{winhelp-topic}{features.application}
824 \I{Application Keypad}Application keypad mode (see
825 \k{config-appkeypad}) and \I{Application Cursor Keys}application
826 cursor keys mode (see \k{config-appcursor}) alter the behaviour of
827 the keypad and cursor keys. Some applications enable these modes but
828 then do not deal correctly with the modified keys. You can force
829 these modes to be permanently disabled no matter what the server
832 \S{config-features-mouse} Disabling \cw{xterm}-style \i{mouse reporting}
834 \cfg{winhelp-topic}{features.mouse}
836 PuTTY allows the server to send \i{control codes} that let it take over
837 the mouse and use it for purposes other than \i{copy and paste}.
838 Applications which use this feature include the text-mode web
839 browser \i\c{links}, the Usenet newsreader \i\c{trn} version 4, and the
840 file manager \i\c{mc} (Midnight Commander).
842 If you find this feature inconvenient, you can disable it using the
843 \q{Disable xterm-style mouse reporting} control. With this box
844 ticked, the mouse will \e{always} do copy and paste in the normal
847 Note that even if the application takes over the mouse, you can
848 still manage PuTTY's copy and paste by holding down the Shift key
849 while you select and paste, unless you have deliberately turned this
850 feature off (see \k{config-mouseshift}).
852 \S{config-features-resize} Disabling remote \i{terminal resizing}
854 \cfg{winhelp-topic}{features.resize}
856 PuTTY has the ability to change the terminal's size and position in
857 response to commands from the server. If you find PuTTY is doing
858 this unexpectedly or inconveniently, you can tell PuTTY not to
859 respond to those server commands.
861 \S{config-features-altscreen} Disabling switching to the \i{alternate screen}
863 \cfg{winhelp-topic}{features.altscreen}
865 Many terminals, including PuTTY, support an \q{alternate screen}.
866 This is the same size as the ordinary terminal screen, but separate.
867 Typically a screen-based program such as a text editor might switch
868 the terminal to the alternate screen before starting up. Then at the
869 end of the run, it switches back to the primary screen, and you see
870 the screen contents just as they were before starting the editor.
872 Some people prefer this not to happen. If you want your editor to
873 run in the same screen as the rest of your terminal activity, you
874 can disable the alternate screen feature completely.
876 \S{config-features-retitle} Disabling remote \i{window title} changing
878 \cfg{winhelp-topic}{features.retitle}
880 PuTTY has the ability to change the window title in response to
881 commands from the server. If you find PuTTY is doing this
882 unexpectedly or inconveniently, you can tell PuTTY not to respond to
883 those server commands.
885 \S{config-features-qtitle} Response to remote \i{window title} querying
887 \cfg{winhelp-topic}{features.qtitle}
889 PuTTY can optionally provide the xterm service of allowing server
890 applications to find out the local window title. This feature is
891 disabled by default, but you can turn it on if you really want it.
893 NOTE that this feature is a \e{potential \i{security hazard}}. If a
894 malicious application can write data to your terminal (for example,
895 if you merely \c{cat} a file owned by someone else on the server
896 machine), it can change your window title (unless you have disabled
897 this as mentioned in \k{config-features-retitle}) and then use this
898 service to have the new window title sent back to the server as if
899 typed at the keyboard. This allows an attacker to fake keypresses
900 and potentially cause your server-side applications to do things you
901 didn't want. Therefore this feature is disabled by default, and we
902 recommend you do not set it to \q{Window title} unless you \e{really}
903 know what you are doing.
905 There are three settings for this option:
909 \dd PuTTY makes no response whatsoever to the relevant escape
910 sequence. This may upset server-side software that is expecting some
915 \dd PuTTY makes a well-formed response, but leaves it blank. Thus,
916 server-side software that expects a response is kept happy, but an
917 attacker cannot influence the response string. This is probably the
918 setting you want if you have no better ideas.
922 \dd PuTTY responds with the actual window title. This is dangerous for
923 the reasons described above.
925 \S{config-features-dbackspace} Disabling \i{destructive backspace}
927 \cfg{winhelp-topic}{features.dbackspace}
929 Normally, when PuTTY receives character 127 (^?) from the server, it
930 will perform a \q{destructive backspace}: move the cursor one space
931 left and delete the character under it. This can apparently cause
932 problems in some applications, so PuTTY provides the ability to
933 configure character 127 to perform a normal backspace (without
934 deleting a character) instead.
936 \S{config-features-charset} Disabling remote \i{character set}
939 \cfg{winhelp-topic}{features.charset}
941 PuTTY has the ability to change its character set configuration in
942 response to commands from the server. Some programs send these
943 commands unexpectedly or inconveniently. In particular, \I{BitchX} (an
944 IRC client) seems to have a habit of reconfiguring the character set
945 to something other than the user intended.
947 If you find that accented characters are not showing up the way you
948 expect them to, particularly if you're running BitchX, you could try
949 disabling the remote character set configuration commands.
951 \S{config-features-shaping} Disabling \i{Arabic text shaping}
953 \cfg{winhelp-topic}{features.arabicshaping}
955 PuTTY supports shaping of Arabic text, which means that if your
956 server sends text written in the basic \i{Unicode} Arabic alphabet then
957 it will convert it to the correct display forms before printing it
960 If you are using full-screen software which was not expecting this
961 to happen (especially if you are not an Arabic speaker and you
962 unexpectedly find yourself dealing with Arabic text files in
963 applications which are not Arabic-aware), you might find that the
964 \i{display becomes corrupted}. By ticking this box, you can disable
965 Arabic text shaping so that PuTTY displays precisely the characters
966 it is told to display.
968 You may also find you need to disable bidirectional text display;
969 see \k{config-features-bidi}.
971 \S{config-features-bidi} Disabling \i{bidirectional text} display
973 \cfg{winhelp-topic}{features.bidi}
975 PuTTY supports bidirectional text display, which means that if your
976 server sends text written in a language which is usually displayed
977 from right to left (such as \i{Arabic} or \i{Hebrew}) then PuTTY will
978 automatically flip it round so that it is displayed in the right
979 direction on the screen.
981 If you are using full-screen software which was not expecting this
982 to happen (especially if you are not an Arabic speaker and you
983 unexpectedly find yourself dealing with Arabic text files in
984 applications which are not Arabic-aware), you might find that the
985 \i{display becomes corrupted}. By ticking this box, you can disable
986 bidirectional text display, so that PuTTY displays text from left to
987 right in all situations.
989 You may also find you need to disable Arabic text shaping;
990 see \k{config-features-shaping}.
992 \H{config-window} The Window panel
994 The Window configuration panel allows you to control aspects of the
997 \S{config-winsize} Setting the \I{window size}size of the PuTTY window
999 \cfg{winhelp-topic}{window.size}
1001 The \q{\ii{Rows}} and \q{\ii{Columns}} boxes let you set the PuTTY
1002 window to a precise size. Of course you can also \I{window resizing}drag
1003 the window to a new size while a session is running.
1005 \S{config-winsizelock} What to do when the window is resized
1007 \cfg{winhelp-topic}{window.resize}
1009 These options allow you to control what happens when the user tries
1010 to \I{window resizing}resize the PuTTY window using its window furniture.
1012 There are four options here:
1014 \b \q{Change the number of rows and columns}: the font size will not
1015 change. (This is the default.)
1017 \b \q{Change the size of the font}: the number of rows and columns in
1018 the terminal will stay the same, and the \i{font size} will change.
1020 \b \q{Change font size when maximised}: when the window is resized,
1021 the number of rows and columns will change, \e{except} when the window
1022 is \i{maximise}d (or restored), when the font size will change.
1024 \b \q{Forbid resizing completely}: the terminal will refuse to be
1027 \S{config-scrollback} Controlling \i{scrollback}
1029 \cfg{winhelp-topic}{window.scrollback}
1031 These options let you configure the way PuTTY keeps text after it
1032 scrolls off the top of the screen (see \k{using-scrollback}).
1034 The \q{Lines of scrollback} box lets you configure how many lines of
1035 text PuTTY keeps. The \q{Display scrollbar} options allow you to
1036 hide the \i{scrollbar} (although you can still view the scrollback using
1037 the keyboard as described in \k{using-scrollback}). You can separately
1038 configure whether the scrollbar is shown in \i{full-screen} mode and in
1041 If you are viewing part of the scrollback when the server sends more
1042 text to PuTTY, the screen will revert to showing the current
1043 terminal contents. You can disable this behaviour by turning off
1044 \q{Reset scrollback on display activity}. You can also make the
1045 screen revert when you press a key, by turning on \q{Reset
1046 scrollback on keypress}.
1048 \S{config-erasetoscrollback} \q{Push erased text into scrollback}
1050 \cfg{winhelp-topic}{window.erased}
1052 When this option is enabled, the contents of the terminal screen
1053 will be pushed into the scrollback when a server-side application
1054 clears the screen, so that your scrollback will contain a better
1055 record of what was on your screen in the past.
1057 If the application switches to the \i{alternate screen} (see
1058 \k{config-features-altscreen} for more about this), then the
1059 contents of the primary screen will be visible in the scrollback
1060 until the application switches back again.
1062 This option is enabled by default.
1064 \H{config-appearance} The Appearance panel
1066 The Appearance configuration panel allows you to control aspects of
1067 the appearance of \I{PuTTY window}PuTTY's window.
1069 \S{config-cursor} Controlling the appearance of the \i{cursor}
1071 \cfg{winhelp-topic}{appearance.cursor}
1073 The \q{Cursor appearance} option lets you configure the cursor to be
1074 a block, an underline, or a vertical line. A block cursor becomes an
1075 empty box when the window loses focus; an underline or a vertical
1076 line becomes dotted.
1078 The \q{\ii{Cursor blinks}} option makes the cursor blink on and off. This
1079 works in any of the cursor modes.
1081 \S{config-font} Controlling the \i{font} used in the terminal window
1083 \cfg{winhelp-topic}{appearance.font}
1085 This option allows you to choose what font, in what \I{font size}size,
1086 the PuTTY terminal window uses to display the text in the session. You
1087 will be offered a choice from all the fixed-width fonts installed on the
1088 system. (VT100-style terminal handling can only deal with fixed-width
1091 \S{config-mouseptr} \q{Hide \i{mouse pointer} when typing in window}
1093 \cfg{winhelp-topic}{appearance.hidemouse}
1095 If you enable this option, the mouse pointer will disappear if the
1096 PuTTY window is selected and you press a key. This way, it will not
1097 obscure any of the text in the window while you work in your
1098 session. As soon as you move the mouse, the pointer will reappear.
1100 This option is disabled by default, so the mouse pointer remains
1101 visible at all times.
1103 \S{config-winborder} Controlling the \i{window border}
1105 \cfg{winhelp-topic}{appearance.border}
1107 PuTTY allows you to configure the appearance of the window border to
1110 The checkbox marked \q{Sunken-edge border} changes the appearance of
1111 the window border to something more like a DOS box: the inside edge
1112 of the border is highlighted as if it sank down to meet the surface
1113 inside the window. This makes the border a little bit thicker as
1114 well. It's hard to describe well. Try it and see if you like it.
1116 You can also configure a completely blank gap between the text in
1117 the window and the border, using the \q{Gap between text and window
1118 edge} control. By default this is set at one pixel. You can reduce
1119 it to zero, or increase it further.
1121 \H{config-behaviour} The Behaviour panel
1123 The Behaviour configuration panel allows you to control aspects of
1124 the behaviour of \I{PuTTY window}PuTTY's window.
1126 \S{config-title} Controlling the \i{window title}
1128 \cfg{winhelp-topic}{appearance.title}
1130 The \q{Window title} edit box allows you to set the title of the
1131 PuTTY window. By default the window title will contain the \i{host name}
1132 followed by \q{PuTTY}, for example \c{server1.example.com - PuTTY}.
1133 If you want a different window title, this is where to set it.
1135 PuTTY allows the server to send \c{xterm} \i{control sequence}s which
1136 modify the title of the window in mid-session (unless this is disabled -
1137 see \k{config-features-retitle}); the title string set here
1138 is therefore only the \e{initial} window title.
1140 As well as the \e{window} title, there is also an \c{xterm}
1141 sequence to modify the \I{icon title}title of the window's \e{icon}.
1142 This makes sense in a windowing system where the window becomes an
1143 icon when minimised, such as Windows 3.1 or most X Window System
1144 setups; but in the Windows 95-like user interface it isn't as
1147 By default, PuTTY only uses the server-supplied \e{window} title, and
1148 ignores the icon title entirely. If for some reason you want to see
1149 both titles, check the box marked \q{Separate window and icon titles}.
1150 If you do this, PuTTY's window title and Taskbar \I{window caption}caption will
1151 change into the server-supplied icon title if you \i{minimise} the PuTTY
1152 window, and change back to the server-supplied window title if you
1153 restore it. (If the server has not bothered to supply a window or
1154 icon title, none of this will happen.)
1156 \S{config-warnonclose} \q{Warn before \i{closing window}}
1158 \cfg{winhelp-topic}{behaviour.closewarn}
1160 If you press the \i{Close button} in a PuTTY window that contains a
1161 running session, PuTTY will put up a warning window asking if you
1162 really meant to close the window. A window whose session has already
1163 terminated can always be closed without a warning.
1165 If you want to be able to close a window quickly, you can disable
1166 the \q{Warn before closing window} option.
1168 \S{config-altf4} \q{Window closes on \i{ALT-F4}}
1170 \cfg{winhelp-topic}{behaviour.altf4}
1172 By default, pressing ALT-F4 causes the \I{closing window}window to
1173 close (or a warning box to appear; see \k{config-warnonclose}). If you
1174 disable the \q{Window closes on ALT-F4} option, then pressing ALT-F4
1175 will simply send a key sequence to the server.
1177 \S{config-altspace} \q{\ii{System menu} appears on \i{ALT-Space}}
1179 \cfg{winhelp-topic}{behaviour.altspace}
1181 If this option is enabled, then pressing ALT-Space will bring up the
1182 PuTTY window's menu, like clicking on the top left corner. If it is
1183 disabled, then pressing ALT-Space will just send \c{ESC SPACE} to
1186 Some \i{accessibility} programs for Windows may need this option
1187 enabling to be able to control PuTTY's window successfully. For
1188 instance, \i{Dragon NaturallySpeaking} requires it both to open the
1189 system menu via voice, and to close, minimise, maximise and restore
1192 \S{config-altonly} \q{\ii{System menu} appears on \i{Alt} alone}
1194 \cfg{winhelp-topic}{behaviour.altonly}
1196 If this option is enabled, then pressing and releasing ALT will
1197 bring up the PuTTY window's menu, like clicking on the top left
1198 corner. If it is disabled, then pressing and releasing ALT will have
1201 \S{config-alwaysontop} \q{Ensure window is \i{always on top}}
1203 \cfg{winhelp-topic}{behaviour.alwaysontop}
1205 If this option is enabled, the PuTTY window will stay on top of all
1208 \S{config-fullscreen} \q{\ii{Full screen} on Alt-Enter}
1210 \cfg{winhelp-topic}{behaviour.altenter}
1212 If this option is enabled, then pressing Alt-Enter will cause the
1213 PuTTY window to become full-screen. Pressing Alt-Enter again will
1214 restore the previous window size.
1216 The full-screen feature is also available from the \ii{System menu}, even
1217 when it is configured not to be available on the Alt-Enter key. See
1218 \k{using-fullscreen}.
1220 \H{config-translation} The Translation panel
1222 The Translation configuration panel allows you to control the
1223 translation between the \i{character set} understood by the server and
1224 the character set understood by PuTTY.
1226 \S{config-charset} Controlling character set translation
1228 \cfg{winhelp-topic}{translation.codepage}
1230 During an interactive session, PuTTY receives a stream of 8-bit
1231 bytes from the server, and in order to display them on the screen it
1232 needs to know what character set to interpret them in.
1234 There are a lot of character sets to choose from. The \q{Received
1235 data assumed to be in which character set} option lets you select
1236 one. By default PuTTY will attempt to choose a character set that is
1237 right for your \i{locale} as reported by Windows; if it gets it wrong,
1238 you can select a different one using this control.
1240 A few notable character sets are:
1242 \b The \i{ISO-8859} series are all standard character sets that include
1243 various accented characters appropriate for different sets of
1246 \b The \i{Win125x} series are defined by Microsoft, for similar
1247 purposes. In particular Win1252 is almost equivalent to ISO-8859-1,
1248 but contains a few extra characters such as matched quotes and the
1251 \b If you want the old IBM PC character set with block graphics and
1252 line-drawing characters, you can select \q{\i{CP437}}.
1254 \b PuTTY also supports \i{Unicode} mode, in which the data coming from
1255 the server is interpreted as being in the \i{UTF-8} encoding of Unicode.
1256 If you select \q{UTF-8} as a character set you can use this mode.
1257 Not all server-side applications will support it.
1259 If you need support for a numeric \i{code page} which is not listed in
1260 the drop-down list, such as code page 866, then you can try entering
1261 its name manually (\c{\i{CP866}} for example) in the list box. If the
1262 underlying version of Windows has the appropriate translation table
1263 installed, PuTTY will use it.
1265 \S{config-cjk-ambig-wide} \q{Treat \i{CJK} ambiguous characters as wide}
1267 \cfg{winhelp-topic}{translation.cjkambigwide}
1269 There are \I{East Asian Ambiguous characters}some Unicode characters
1270 whose \I{character width}width is not well-defined. In most contexts, such
1271 characters should be treated as single-width for the purposes of \I{wrapping,
1272 terminal}wrapping and so on; however, in some CJK contexts, they are better
1273 treated as double-width for historical reasons, and some server-side
1274 applications may expect them to be displayed as such. Setting this option
1275 will cause PuTTY to take the double-width interpretation.
1277 If you use legacy CJK applications, and you find your lines are
1278 wrapping in the wrong places, or you are having other display
1279 problems, you might want to play with this setting.
1281 This option only has any effect in \i{UTF-8} mode (see \k{config-charset}).
1283 \S{config-cyr} \q{\i{Caps Lock} acts as \i{Cyrillic} switch}
1285 \cfg{winhelp-topic}{translation.cyrillic}
1287 This feature allows you to switch between a US/UK keyboard layout
1288 and a Cyrillic keyboard layout by using the Caps Lock key, if you
1289 need to type (for example) \i{Russian} and English side by side in the
1292 Currently this feature is not expected to work properly if your
1293 native keyboard layout is not US or UK.
1295 \S{config-linedraw} Controlling display of \i{line-drawing characters}
1297 \cfg{winhelp-topic}{translation.linedraw}
1299 VT100-series terminals allow the server to send \i{control sequence}s that
1300 shift temporarily into a separate character set for drawing simple
1301 lines and boxes. However, there are a variety of ways in which PuTTY
1302 can attempt to find appropriate characters, and the right one to use
1303 depends on the locally configured \i{font}. In general you should probably
1304 try lots of options until you find one that your particular font
1307 \b \q{Use Unicode line drawing code points} tries to use the box
1308 characters that are present in \i{Unicode}. For good Unicode-supporting
1309 fonts this is probably the most reliable and functional option.
1311 \b \q{Poor man's line drawing} assumes that the font \e{cannot}
1312 generate the line and box characters at all, so it will use the
1313 \c{+}, \c{-} and \c{|} characters to draw approximations to boxes.
1314 You should use this option if none of the other options works.
1316 \b \q{Font has XWindows encoding} is for use with fonts that have a
1317 special encoding, where the lowest 32 character positions (below the
1318 ASCII printable range) contain the line-drawing characters. This is
1319 unlikely to be the case with any standard Windows font; it will
1320 probably only apply to custom-built fonts or fonts that have been
1321 automatically converted from the X Window System.
1323 \b \q{Use font in both ANSI and OEM modes} tries to use the same
1324 font in two different character sets, to obtain a wider range of
1325 characters. This doesn't always work; some fonts claim to be a
1326 different size depending on which character set you try to use.
1328 \b \q{Use font in OEM mode only} is more reliable than that, but can
1329 miss out other characters from the main character set.
1331 \S{config-linedrawpaste} Controlling \i{copy and paste} of line drawing
1334 \cfg{winhelp-topic}{selection.linedraw}
1336 By default, when you copy and paste a piece of the PuTTY screen that
1337 contains VT100 line and box drawing characters, PuTTY will paste
1338 them in the form they appear on the screen: either \i{Unicode} line
1339 drawing code points, or the \q{poor man's} line-drawing characters
1340 \c{+}, \c{-} and \c{|}. The checkbox \q{Copy and paste VT100 line
1341 drawing chars as lqqqk} disables this feature, so line-drawing
1342 characters will be pasted as the \i{ASCII} characters that were printed
1343 to produce them. This will typically mean they come out mostly as
1344 \c{q} and \c{x}, with a scattering of \c{jklmntuvw} at the corners.
1345 This might be useful if you were trying to recreate the same box
1346 layout in another program, for example.
1348 Note that this option only applies to line-drawing characters which
1349 \e{were} printed by using the VT100 mechanism. Line-drawing
1350 characters that were received as Unicode code points will paste as
1353 \H{config-selection} The Selection panel
1355 The Selection panel allows you to control the way \i{copy and paste}
1356 work in the PuTTY window.
1358 \S{config-rtfpaste} Pasting in \i{Rich Text Format}
1360 \cfg{winhelp-topic}{selection.rtf}
1362 If you enable \q{Paste to clipboard in RTF as well as plain text},
1363 PuTTY will write formatting information to the clipboard as well as
1364 the actual text you copy. The effect of this is
1365 that if you paste into (say) a word processor, the text will appear
1366 in the word processor in the same \i{font}, \i{colour}, and style
1367 (e.g. bold, underline) PuTTY was using to display it.
1369 This option can easily be inconvenient, so by default it is
1372 \S{config-mouse} Changing the actions of the mouse buttons
1374 \cfg{winhelp-topic}{selection.buttons}
1376 PuTTY's copy and paste mechanism is by default modelled on the Unix
1377 \c{xterm} application. The X Window System uses a three-button mouse,
1378 and the convention is that the \i{left button} \I{selecting text}selects,
1379 the \i{right button} extends an existing selection, and the
1380 \i{middle button} pastes.
1382 Windows often only has two mouse buttons, so in PuTTY's default
1383 configuration (\q{Compromise}), the \e{right} button pastes, and the
1384 \e{middle} button (if you have one) \I{adjusting a selection}extends
1387 If you have a \i{three-button mouse} and you are already used to the
1388 \c{xterm} arrangement, you can select it using the \q{Action of
1389 mouse buttons} control.
1391 Alternatively, with the \q{Windows} option selected, the middle
1392 button extends, and the right button brings up a \i{context menu} (on
1393 which one of the options is \q{Paste}). (This context menu is always
1394 available by holding down Ctrl and right-clicking, regardless of the
1395 setting of this option.)
1397 \S{config-mouseshift} \q{Shift overrides application's use of mouse}
1399 \cfg{winhelp-topic}{selection.shiftdrag}
1401 PuTTY allows the server to send \i{control codes} that let it
1402 \I{mouse reporting}take over the mouse and use it for purposes other
1403 than \i{copy and paste}.
1404 Applications which use this feature include the text-mode web
1405 browser \c{links}, the Usenet newsreader \c{trn} version 4, and the
1406 file manager \c{mc} (Midnight Commander).
1408 When running one of these applications, pressing the mouse buttons
1409 no longer performs copy and paste. If you do need to copy and paste,
1410 you can still do so if you hold down Shift while you do your mouse
1413 However, it is possible in theory for applications to even detect
1414 and make use of Shift + mouse clicks. We don't know of any
1415 applications that do this, but in case someone ever writes one,
1416 unchecking the \q{Shift overrides application's use of mouse}
1417 checkbox will cause Shift + mouse clicks to go to the server as well
1418 (so that mouse-driven copy and paste will be completely disabled).
1420 If you want to prevent the application from taking over the mouse at
1421 all, you can do this using the Features control panel; see
1422 \k{config-features-mouse}.
1424 \S{config-rectselect} Default selection mode
1426 \cfg{winhelp-topic}{selection.rect}
1428 As described in \k{using-selection}, PuTTY has two modes of
1429 selecting text to be copied to the clipboard. In the default mode
1430 (\q{Normal}), dragging the mouse from point A to point B selects to
1431 the end of the line containing A, all the lines in between, and from
1432 the very beginning of the line containing B. In the other mode
1433 (\q{Rectangular block}), dragging the mouse between two points
1434 defines a rectangle, and everything within that rectangle is copied.
1436 Normally, you have to hold down Alt while dragging the mouse to
1437 select a rectangular block. Using the \q{Default selection mode}
1438 control, you can set \i{rectangular selection} as the default, and then
1439 you have to hold down Alt to get the \e{normal} behaviour.
1441 \S{config-charclasses} Configuring \i{word-by-word selection}
1443 \cfg{winhelp-topic}{selection.charclasses}
1445 PuTTY will select a word at a time in the terminal window if you
1446 \i{double-click} to begin the drag. This panel allows you to control
1447 precisely what is considered to be a word.
1449 Each character is given a \e{class}, which is a small number
1450 (typically 0, 1 or 2). PuTTY considers a single word to be any
1451 number of adjacent characters in the same class. So by modifying the
1452 assignment of characters to classes, you can modify the word-by-word
1453 selection behaviour.
1455 In the default configuration, the \i{character classes} are:
1457 \b Class 0 contains \i{white space} and control characters.
1459 \b Class 1 contains most \i{punctuation}.
1461 \b Class 2 contains letters, numbers and a few pieces of punctuation
1462 (the double quote, minus sign, period, forward slash and
1465 So, for example, if you assign the \c{@} symbol into character class
1466 2, you will be able to select an e-mail address with just a double
1469 In order to adjust these assignments, you start by selecting a group
1470 of characters in the list box. Then enter a class number in the edit
1471 box below, and press the \q{Set} button.
1473 This mechanism currently only covers ASCII characters, because it
1474 isn't feasible to expand the list to cover the whole of Unicode.
1476 Character class definitions can be modified by \i{control sequence}s
1477 sent by the server. This configuration option controls the
1478 \e{default} state, which will be restored when you reset the
1479 terminal (see \k{reset-terminal}). However, if you modify this
1480 option in mid-session using \q{Change Settings}, it will take effect
1483 \H{config-colours} The Colours panel
1485 The Colours panel allows you to control PuTTY's use of \i{colour}.
1487 \S{config-ansicolour} \q{Allow terminal to specify \i{ANSI colours}}
1489 \cfg{winhelp-topic}{colours.ansi}
1491 This option is enabled by default. If it is disabled, PuTTY will
1492 ignore any \i{control sequence}s sent by the server to request coloured
1495 If you have a particularly garish application, you might want to
1496 turn this option off and make PuTTY only use the default foreground
1497 and background colours.
1499 \S{config-xtermcolour} \q{Allow terminal to use xterm \i{256-colour mode}}
1501 \cfg{winhelp-topic}{colours.xterm256}
1503 This option is enabled by default. If it is disabled, PuTTY will
1504 ignore any control sequences sent by the server which use the
1505 extended 256-colour mode supported by recent versions of \cw{xterm}.
1507 If you have an application which is supposed to use 256-colour mode
1508 and it isn't working, you may find you need to tell your server that
1509 your terminal supports 256 colours. On Unix, you do this by ensuring
1510 that the setting of \i\cw{TERM} describes a 256-colour-capable
1511 terminal. You can check this using a command such as \c{infocmp}:
1513 \c $ infocmp | grep colors
1514 \c colors#256, cols#80, it#8, lines#24, pairs#256,
1517 If you do not see \cq{colors#256} in the output, you may need to
1518 change your terminal setting. On modern Linux machines, you could
1519 try \cq{xterm-256color}.
1521 \S{config-boldcolour} \q{Bolded text is a different colour}
1523 \cfg{winhelp-topic}{colours.bold}
1525 When the server sends a \i{control sequence} indicating that some text
1526 should be displayed in \i{bold}, PuTTY can handle this two ways. It can
1527 either change the \i{font} for a bold version, or use the same font in a
1528 brighter colour. This control lets you choose which.
1530 By default the box is checked, so non-bold text is displayed in
1531 light grey and bold text is displayed in bright white (and similarly
1532 in other colours). If you uncheck the box, bold and non-bold text
1533 will be displayed in the same colour, and instead the font will
1534 change to indicate the difference.
1536 \S{config-logpalette} \q{Attempt to use \i{logical palettes}}
1538 \cfg{winhelp-topic}{colours.logpal}
1540 Logical palettes are a mechanism by which a Windows application
1541 running on an \i{8-bit colour} display can select precisely the colours
1542 it wants instead of going with the Windows standard defaults.
1544 If you are not getting the colours you ask for on an 8-bit display,
1545 you can try enabling this option. However, be warned that it's never
1548 \S{config-syscolour} \q{Use \i{system colours}}
1550 \cfg{winhelp-topic}{colours.system}
1552 Enabling this option will cause PuTTY to ignore the configured colours
1553 for \I{default background}\I{default foreground}\q{Default
1554 Background/Foreground} and \I{cursor colour}\q{Cursor Colour/Text} (see
1555 \k{config-colourcfg}), instead going with the system-wide defaults.
1557 Note that non-bold and \i{bold text} will be the same colour if this
1558 option is enabled. You might want to change to indicating bold text
1559 by font changes (see \k{config-boldcolour}).
1561 \S{config-colourcfg} Adjusting the colours in the \i{terminal window}
1563 \cfg{winhelp-topic}{colours.config}
1565 The main colour control allows you to specify exactly what colours
1566 things should be displayed in. To modify one of the PuTTY colours,
1567 use the list box to select which colour you want to modify. The \i{RGB
1568 values} for that colour will appear on the right-hand side of the
1569 list box. Now, if you press the \q{Modify} button, you will be
1570 presented with a colour selector, in which you can choose a new
1571 colour to go in place of the old one. (You may also edit the RGB
1572 values directly in the edit boxes, if you wish; each value is an
1573 integer from 0 to 255.)
1575 PuTTY allows you to set the \i{cursor colour}, the \i{default foreground}
1576 and \I{default background}background, and the precise shades of all the
1577 \I{ANSI colours}ANSI configurable colours (black, red, green, yellow, blue,
1578 magenta, cyan, and white). You can also modify the precise shades used for
1579 the \i{bold} versions of these colours; these are used to display bold text
1580 if you have selected \q{Bolded text is a different colour}, and can also be
1581 used if the server asks specifically to use them. (Note that \q{Default
1582 Bold Background} is \e{not} the background colour used for bold text;
1583 it is only used if the server specifically asks for a bold
1586 \H{config-connection} The Connection panel
1588 The Connection panel allows you to configure options that apply to
1589 more than one type of \i{connection}.
1591 \S{config-keepalive} Using \i{keepalives} to prevent disconnection
1593 \cfg{winhelp-topic}{connection.keepalive}
1595 If you find your sessions are closing unexpectedly (most often with
1596 \q{Connection reset by peer}) after they have been idle for a while,
1597 you might want to try using this option.
1599 Some network \i{routers} and \i{firewalls} need to keep track of all
1600 connections through them. Usually, these firewalls will assume a
1601 connection is dead if no data is transferred in either direction
1602 after a certain time interval. This can cause PuTTY sessions to be
1603 unexpectedly closed by the firewall if no traffic is seen in the
1604 session for some time.
1606 The keepalive option (\q{Seconds between keepalives}) allows you to
1607 configure PuTTY to send data through the session at regular
1608 intervals, in a way that does not disrupt the actual terminal
1609 session. If you find your firewall is cutting \i{idle connections} off,
1610 you can try entering a non-zero value in this field. The value is
1611 measured in seconds; so, for example, if your firewall cuts
1612 connections off after ten minutes then you might want to enter 300
1613 seconds (5 minutes) in the box.
1615 Note that keepalives are not always helpful. They help if you have a
1616 firewall which drops your connection after an idle period; but if
1617 the network between you and the server suffers from \i{breaks in
1618 connectivity} then keepalives can actually make things worse. If a
1619 session is idle, and connectivity is temporarily lost between the
1620 endpoints, but the connectivity is restored before either side tries
1621 to send anything, then there will be no problem - neither endpoint
1622 will notice that anything was wrong. However, if one side does send
1623 something during the break, it will repeatedly try to re-send, and
1624 eventually give up and abandon the connection. Then when
1625 connectivity is restored, the other side will find that the first
1626 side doesn't believe there is an open connection any more.
1627 Keepalives can make this sort of problem worse, because they
1628 increase the probability that PuTTY will attempt to send data during
1629 a break in connectivity. (Other types of periodic network activity
1630 can cause this behaviour; in particular, SSH-2 re-keys can have
1631 this effect. See \k{config-ssh-kex-rekey}.)
1633 Therefore, you might find that keepalives help
1634 connection loss, or you might find they make it worse, depending on
1635 what \e{kind} of network problems you have between you and the
1638 Keepalives are only supported in Telnet and SSH; the Rlogin and Raw
1639 protocols offer no way of implementing them. (For an alternative, see
1640 \k{config-tcp-keepalives}.)
1642 Note that if you are using \i{SSH-1} and the server has a bug that makes
1643 it unable to deal with SSH-1 ignore messages (see
1644 \k{config-ssh-bug-ignore1}), enabling keepalives will have no effect.
1646 \S{config-nodelay} \q{Disable \i{Nagle's algorithm}}
1648 \cfg{winhelp-topic}{connection.nodelay}
1650 Nagle's algorithm is a detail of TCP/IP implementations that tries
1651 to minimise the number of small data packets sent down a network
1652 connection. With Nagle's algorithm enabled, PuTTY's \i{bandwidth} usage
1653 will be slightly more efficient; with it disabled, you may find you
1654 get a faster response to your keystrokes when connecting to some
1657 The Nagle algorithm is disabled by default for \i{interactive connections}.
1659 \S{config-tcp-keepalives} \q{Enable \i{TCP keepalives}}
1661 \cfg{winhelp-topic}{connection.tcpkeepalive}
1663 \e{NOTE:} TCP keepalives should not be confused with the
1664 application-level keepalives described in \k{config-keepalive}. If in
1665 doubt, you probably want application-level keepalives; TCP keepalives
1666 are provided for completeness.
1668 The idea of TCP keepalives is similar to application-level keepalives,
1669 and the same caveats apply. The main differences are:
1671 \b TCP keepalives are available on \e{all} connection types, including
1674 \b The interval between TCP keepalives is usually much longer,
1675 typically two hours; this is set by the operating system, and cannot
1676 be configured within PuTTY.
1678 \b If the operating system does not receive a response to a keepalive,
1679 it may send out more in quick succession and terminate the connection
1680 if no response is received.
1682 TCP keepalives may be more useful for ensuring that \i{half-open connections}
1683 are terminated than for keeping a connection alive.
1685 TCP keepalives are disabled by default.
1687 \S{config-address-family} \I{Internet protocol version}\q{Internet protocol}
1689 \cfg{winhelp-topic}{connection.ipversion}
1691 This option allows the user to select between the old and new
1692 Internet protocols and addressing schemes (\i{IPv4} and \i{IPv6}). The
1693 default setting is \q{Auto}, which means PuTTY will do something
1694 sensible and try to guess which protocol you wanted. (If you specify
1695 a literal \i{Internet address}, it will use whichever protocol that
1696 address implies. If you provide a \i{hostname}, it will see what kinds
1697 of address exist for that hostname; it will use IPv6 if there is an
1698 IPv6 address available, and fall back to IPv4 if not.)
1700 If you need to force PuTTY to use a particular protocol, you can
1701 explicitly set this to \q{IPv4} or \q{IPv6}.
1703 \H{config-data} The Data panel
1705 The Data panel allows you to configure various pieces of data which
1706 can be sent to the server to affect your connection at the far end.
1708 Each option on this panel applies to more than one protocol.
1709 Options which apply to only one protocol appear on that protocol's
1710 configuration panels.
1712 \S{config-username} \q{\ii{Auto-login username}}
1714 \cfg{winhelp-topic}{connection.username}
1716 All three of the SSH, Telnet and Rlogin protocols allow you to
1717 specify what user name you want to log in as, without having to type
1718 it explicitly every time. (Some Telnet servers don't support this.)
1720 In this box you can type that user name.
1722 \S{config-termtype} \q{\ii{Terminal-type} string}
1724 \cfg{winhelp-topic}{connection.termtype}
1726 Most servers you might connect to with PuTTY are designed to be
1727 connected to from lots of different types of terminal. In order to
1728 send the right \i{control sequence}s to each one, the server will need
1729 to know what type of terminal it is dealing with. Therefore, each of
1730 the SSH, Telnet and Rlogin protocols allow a text string to be sent
1731 down the connection describing the terminal. On a \i{Unix} server,
1732 this selects an entry from the \i\c{termcap} or \i\c{terminfo} database
1733 that tells applications what \i{control sequences} to send to the
1734 terminal, and what character sequences to expect the \i{keyboard}
1737 PuTTY attempts to emulate the Unix \i\c{xterm} program, and by default
1738 it reflects this by sending \c{xterm} as a terminal-type string. If
1739 you find this is not doing what you want - perhaps the remote
1740 system reports \q{Unknown terminal type} - you could try setting
1741 this to something different, such as \i\c{vt220}.
1743 If you're not sure whether a problem is due to the terminal type
1744 setting or not, you probably need to consult the manual for your
1745 application or your server.
1747 \S{config-termspeed} \q{\ii{Terminal speed}s}
1749 \cfg{winhelp-topic}{connection.termspeed}
1751 The Telnet, Rlogin, and SSH protocols allow the client to specify
1752 terminal speeds to the server.
1754 This parameter does \e{not} affect the actual speed of the connection,
1755 which is always \q{as fast as possible}; it is just a hint that is
1756 sometimes used by server software to modify its behaviour. For
1757 instance, if a slow speed is indicated, the server may switch to a
1758 less \i{bandwidth}-hungry display mode.
1760 The value is usually meaningless in a network environment, but
1761 PuTTY lets you configure it, in case you find the server is reacting
1762 badly to the default value.
1764 The format is a pair of numbers separated by a comma, for instance,
1765 \c{38400,38400}. The first number represents the output speed
1766 (\e{from} the server) in bits per second, and the second is the input
1767 speed (\e{to} the server). (Only the first is used in the Rlogin
1770 This option has no effect on Raw connections.
1772 \S{config-environ} Setting \i{environment variables} on the server
1774 \cfg{winhelp-topic}{telnet.environ}
1776 The Telnet protocol provides a means for the client to pass
1777 environment variables to the server. Many Telnet servers have
1778 stopped supporting this feature due to security flaws, but PuTTY
1779 still supports it for the benefit of any servers which have found
1780 other ways around the security problems than just disabling the
1783 Version 2 of the SSH protocol also provides a similar mechanism,
1784 which is easier to implement without security flaws. Newer \i{SSH-2}
1785 servers are more likely to support it than older ones.
1787 This configuration data is not used in the SSH-1, rlogin or raw
1790 To add an environment variable to the list transmitted down the
1791 connection, you enter the variable name in the \q{Variable} box,
1792 enter its value in the \q{Value} box, and press the \q{Add} button.
1793 To remove one from the list, select it in the list box and press
1796 \H{config-proxy} The Proxy panel
1798 \cfg{winhelp-topic}{proxy.main}
1800 The \ii{Proxy} panel allows you to configure PuTTY to use various types
1801 of proxy in order to make its network connections. The settings in
1802 this panel affect the primary network connection forming your PuTTY
1803 session, and also any extra connections made as a result of SSH \i{port
1804 forwarding} (see \k{using-port-forwarding}).
1806 \S{config-proxy-type} Setting the proxy type
1808 \cfg{winhelp-topic}{proxy.type}
1810 The \q{Proxy type} radio buttons allow you to configure what type of
1811 proxy you want PuTTY to use for its network connections. The default
1812 setting is \q{None}; in this mode no proxy is used for any
1815 \b Selecting \I{HTTP proxy}\q{HTTP} allows you to proxy your connections
1816 through a web server supporting the HTTP \cw{CONNECT} command, as documented
1817 in \W{http://www.ietf.org/rfc/rfc2817.txt}{RFC 2817}.
1819 \b Selecting \q{SOCKS 4} or \q{SOCKS 5} allows you to proxy your
1820 connections through a \i{SOCKS server}.
1822 \b Many firewalls implement a less formal type of proxy in which a
1823 user can make a Telnet connection directly to the firewall machine
1824 and enter a command such as \c{connect myhost.com 22} to connect
1825 through to an external host. Selecting \I{Telnet proxy}\q{Telnet}
1826 allows you to tell PuTTY to use this type of proxy.
1828 \b Selecting \I{Local proxy}\q{Local} allows you to specify an arbitrary
1829 command on the local machine to act as a proxy. When the session is
1830 started, instead of creating a TCP connection, PuTTY runs the command
1831 (specified in \k{config-proxy-command}), and uses its standard input and
1835 This could be used, for instance, to talk to some kind of network proxy
1836 that PuTTY does not natively support; or you could tunnel a connection
1837 over something other than TCP/IP entirely.
1839 If you want your local proxy command to make a secondary SSH
1840 connection to a proxy host and then tunnel the primary connection
1841 over that, you might well want the \c{-nc} command-line option in
1842 Plink. See \k{using-cmdline-ncmode} for more information.
1845 \S{config-proxy-exclude} Excluding parts of the network from proxying
1847 \cfg{winhelp-topic}{proxy.exclude}
1849 Typically you will only need to use a proxy to connect to non-local
1850 parts of your network; for example, your proxy might be required for
1851 connections outside your company's internal network. In the
1852 \q{Exclude Hosts/IPs} box you can enter ranges of IP addresses, or
1853 ranges of DNS names, for which PuTTY will avoid using the proxy and
1854 make a direct connection instead.
1856 The \q{Exclude Hosts/IPs} box may contain more than one exclusion
1857 range, separated by commas. Each range can be an IP address or a DNS
1858 name, with a \c{*} character allowing wildcards. For example:
1862 This excludes any host with a name ending in \c{.example.com} from
1867 This excludes any host with an IP address starting with 192.168.88
1870 \c 192.168.88.*,*.example.com
1872 This excludes both of the above ranges at once.
1874 Connections to the local host (the host name \i\c{localhost}, and any
1875 \i{loopback IP address}) are never proxied, even if the proxy exclude
1876 list does not explicitly contain them. It is very unlikely that this
1877 behaviour would ever cause problems, but if it does you can change
1878 it by enabling \q{Consider proxying local host connections}.
1880 Note that if you are doing \I{proxy DNS}DNS at the proxy (see
1881 \k{config-proxy-dns}), you should make sure that your proxy
1882 exclusion settings do not depend on knowing the IP address of a
1883 host. If the name is passed on to the proxy without PuTTY looking it
1884 up, it will never know the IP address and cannot check it against
1887 \S{config-proxy-dns} \I{proxy DNS}\ii{Name resolution} when using a proxy
1889 \cfg{winhelp-topic}{proxy.dns}
1891 If you are using a proxy to access a private network, it can make a
1892 difference whether \i{DNS} name resolution is performed by PuTTY itself
1893 (on the client machine) or performed by the proxy.
1895 The \q{Do DNS name lookup at proxy end} configuration option allows
1896 you to control this. If you set it to \q{No}, PuTTY will always do
1897 its own DNS, and will always pass an IP address to the proxy. If you
1898 set it to \q{Yes}, PuTTY will always pass host names straight to the
1899 proxy without trying to look them up first.
1901 If you set this option to \q{Auto} (the default), PuTTY will do
1902 something it considers appropriate for each type of proxy. Telnet,
1903 HTTP, and SOCKS5 proxies will have host names passed straight to
1904 them; SOCKS4 proxies will not.
1906 Note that if you are doing DNS at the proxy, you should make sure
1907 that your proxy exclusion settings (see \k{config-proxy-exclude}) do
1908 not depend on knowing the IP address of a host. If the name is
1909 passed on to the proxy without PuTTY looking it up, it will never
1910 know the IP address and cannot check it against your list.
1912 The original SOCKS 4 protocol does not support proxy-side DNS. There
1913 is a protocol extension (SOCKS 4A) which does support it, but not
1914 all SOCKS 4 servers provide this extension. If you enable proxy DNS
1915 and your SOCKS 4 server cannot deal with it, this might be why.
1917 \S{config-proxy-auth} \I{proxy username}Username and \I{proxy password}password
1919 \cfg{winhelp-topic}{proxy.auth}
1921 If your proxy requires \I{proxy authentication}authentication, you can
1922 enter a username and a password in the \q{Username} and \q{Password} boxes.
1924 \I{security hazard}Note that if you save your session, the proxy
1925 password will be saved in plain text, so anyone who can access your PuTTY
1926 configuration data will be able to discover it.
1928 Authentication is not fully supported for all forms of proxy:
1930 \b Username and password authentication is supported for HTTP
1931 proxies and SOCKS 5 proxies.
1935 \b With SOCKS 5, authentication is via \i{CHAP} if the proxy
1936 supports it (this is not supported in \i{PuTTYtel}); otherwise the
1937 password is sent to the proxy in \I{plaintext password}plain text.
1939 \b With HTTP proxying, the only currently supported authentication
1940 method is \I{HTTP basic}\q{basic}, where the password is sent to the proxy
1941 in \I{plaintext password}plain text.
1945 \b SOCKS 4 can use the \q{Username} field, but does not support
1948 \b You can specify a way to include a username and password in the
1949 Telnet/Local proxy command (see \k{config-proxy-command}).
1951 \S{config-proxy-command} Specifying the Telnet or Local proxy command
1953 \cfg{winhelp-topic}{proxy.command}
1955 If you are using the \i{Telnet proxy} type, the usual command required
1956 by the firewall's Telnet server is \c{connect}, followed by a host
1957 name and a port number. If your proxy needs a different command,
1958 you can enter an alternative here.
1960 If you are using the \i{Local proxy} type, the local command to run
1963 In this string, you can use \c{\\n} to represent a new-line, \c{\\r}
1964 to represent a carriage return, \c{\\t} to represent a tab
1965 character, and \c{\\x} followed by two hex digits to represent any
1966 other character. \c{\\\\} is used to encode the \c{\\} character
1969 Also, the special strings \c{%host} and \c{%port} will be replaced
1970 by the host name and port number you want to connect to. The strings
1971 \c{%user} and \c{%pass} will be replaced by the proxy username and
1972 password you specify. The strings \c{%proxyhost} and \c{%proxyport}
1973 will be replaced by the host details specified on the \e{Proxy} panel,
1974 if any (this is most likely to be useful for the Local proxy type).
1975 To get a literal \c{%} sign, enter \c{%%}.
1977 If a Telnet proxy server prompts for a username and password
1978 before commands can be sent, you can use a command such as:
1980 \c %user\n%pass\nconnect %host %port\n
1982 This will send your username and password as the first two lines to
1983 the proxy, followed by a command to connect to the desired host and
1984 port. Note that if you do not include the \c{%user} or \c{%pass}
1985 tokens in the Telnet command, then the \q{Username} and \q{Password}
1986 configuration fields will be ignored.
1988 \H{config-telnet} The \i{Telnet} panel
1990 The Telnet panel allows you to configure options that only apply to
1993 \S{config-oldenviron} \q{Handling of OLD_ENVIRON ambiguity}
1995 \cfg{winhelp-topic}{telnet.oldenviron}
1997 The original Telnet mechanism for passing \i{environment variables} was
1998 badly specified. At the time the standard (RFC 1408) was written,
1999 BSD telnet implementations were already supporting the feature, and
2000 the intention of the standard was to describe the behaviour the BSD
2001 implementations were already using.
2003 Sadly there was a typing error in the standard when it was issued,
2004 and two vital function codes were specified the wrong way round. BSD
2005 implementations did not change, and the standard was not corrected.
2006 Therefore, it's possible you might find either \i{BSD} or \i{RFC}-compliant
2007 implementations out there. This switch allows you to choose which
2008 one PuTTY claims to be.
2010 The problem was solved by issuing a second standard, defining a new
2011 Telnet mechanism called \i\cw{NEW_ENVIRON}, which behaved exactly like
2012 the original \i\cw{OLD_ENVIRON} but was not encumbered by existing
2013 implementations. Most Telnet servers now support this, and it's
2014 unambiguous. This feature should only be needed if you have trouble
2015 passing environment variables to quite an old server.
2017 \S{config-ptelnet} Passive and active \i{Telnet negotiation} modes
2019 \cfg{winhelp-topic}{telnet.passive}
2021 In a Telnet connection, there are two types of data passed between
2022 the client and the server: actual text, and \e{negotiations} about
2023 which Telnet extra features to use.
2025 PuTTY can use two different strategies for negotiation:
2027 \b In \I{active Telnet negotiation}\e{active} mode, PuTTY starts to send
2028 negotiations as soon as the connection is opened.
2030 \b In \I{passive Telnet negotiation}\e{passive} mode, PuTTY will wait to
2031 negotiate until it sees a negotiation from the server.
2033 The obvious disadvantage of passive mode is that if the server is
2034 also operating in a passive mode, then negotiation will never begin
2035 at all. For this reason PuTTY defaults to active mode.
2037 However, sometimes passive mode is required in order to successfully
2038 get through certain types of firewall and \i{Telnet proxy} server. If
2039 you have confusing trouble with a \i{firewall}, you could try enabling
2040 passive mode to see if it helps.
2042 \S{config-telnetkey} \q{Keyboard sends \i{Telnet special commands}}
2044 \cfg{winhelp-topic}{telnet.specialkeys}
2046 If this box is checked, several key sequences will have their normal
2049 \b the Backspace key on the keyboard will send the \I{Erase Character,
2050 Telnet special command}Telnet special backspace code;
2052 \b Control-C will send the Telnet special \I{Interrupt Process, Telnet
2053 special command}Interrupt Process code;
2055 \b Control-Z will send the Telnet special \I{Suspend Process, Telnet
2056 special command}Suspend Process code.
2058 You probably shouldn't enable this
2059 unless you know what you're doing.
2061 \S{config-telnetnl} \q{Return key sends \i{Telnet New Line} instead of ^M}
2063 \cfg{winhelp-topic}{telnet.newline}
2065 Unlike most other remote login protocols, the Telnet protocol has a
2066 special \q{\i{new line}} code that is not the same as the usual line
2067 endings of Control-M or Control-J. By default, PuTTY sends the
2068 Telnet New Line code when you press Return, instead of sending
2069 Control-M as it does in most other protocols.
2071 Most Unix-style Telnet servers don't mind whether they receive
2072 Telnet New Line or Control-M; some servers do expect New Line, and
2073 some servers prefer to see ^M. If you are seeing surprising
2074 behaviour when you press Return in a Telnet session, you might try
2075 turning this option off to see if it helps.
2077 \H{config-rlogin} The Rlogin panel
2079 The \i{Rlogin} panel allows you to configure options that only apply to
2082 \S{config-rlogin-localuser} \I{local username in Rlogin}\q{Local username}
2084 \cfg{winhelp-topic}{rlogin.localuser}
2086 Rlogin allows an automated (password-free) form of login by means of
2087 a file called \i\c{.rhosts} on the server. You put a line in your
2088 \c{.rhosts} file saying something like \c{jbloggs@pc1.example.com},
2089 and then when you make an Rlogin connection the client transmits the
2090 username of the user running the Rlogin client. The server checks
2091 the username and hostname against \c{.rhosts}, and if they match it
2092 \I{passwordless login}does not ask for a password.
2094 This only works because Unix systems contain a safeguard to stop a
2095 user from pretending to be another user in an Rlogin connection.
2096 Rlogin connections have to come from \I{privileged port}port numbers below
2097 1024, and Unix systems prohibit this to unprivileged processes; so when the
2098 server sees a connection from a low-numbered port, it assumes the
2099 client end of the connection is held by a privileged (and therefore
2100 trusted) process, so it believes the claim of who the user is.
2102 Windows does not have this restriction: \e{any} user can initiate an
2103 outgoing connection from a low-numbered port. Hence, the Rlogin
2104 \c{.rhosts} mechanism is completely useless for securely
2105 distinguishing several different users on a Windows machine. If you
2106 have a \c{.rhosts} entry pointing at a Windows PC, you should assume
2107 that \e{anyone} using that PC can \i{spoof} your username in
2108 an Rlogin connection and access your account on the server.
2110 The \q{Local username} control allows you to specify what user name
2111 PuTTY should claim you have, in case it doesn't match your \i{Windows
2112 user name} (or in case you didn't bother to set up a Windows user
2115 \H{config-ssh} The SSH panel
2117 The \i{SSH} panel allows you to configure options that only apply to
2120 \S{config-command} Executing a specific command on the server
2122 \cfg{winhelp-topic}{ssh.command}
2124 In SSH, you don't have to run a general shell session on the server.
2125 Instead, you can choose to run a single specific command (such as a
2126 mail user agent, for example). If you want to do this, enter the
2127 command in the \q{\ii{Remote command}} box.
2129 Note that most servers will close the session after executing the
2132 \S{config-ssh-noshell} \q{Don't start a \I{remote shell}shell or
2133 \I{remote command}command at all}
2135 \cfg{winhelp-topic}{ssh.noshell}
2137 If you tick this box, PuTTY will not attempt to run a shell or
2138 command after connecting to the remote server. You might want to use
2139 this option if you are only using the SSH connection for \i{port
2140 forwarding}, and your user account on the server does not have the
2141 ability to run a shell.
2143 This feature is only available in \i{SSH protocol version 2} (since the
2144 version 1 protocol assumes you will always want to run a shell).
2146 This feature can also be enabled using the \c{-N} command-line
2147 option; see \k{using-cmdline-noshell}.
2149 If you use this feature in Plink, you will not be able to terminate
2150 the Plink process by any graceful means; the only way to kill it
2151 will be by pressing Control-C or sending a kill signal from another
2154 \S{config-ssh-comp} \q{Enable \i{compression}}
2156 \cfg{winhelp-topic}{ssh.compress}
2158 This enables data compression in the SSH connection: data sent by
2159 the server is compressed before sending, and decompressed at the
2160 client end. Likewise, data sent by PuTTY to the server is compressed
2161 first and the server decompresses it at the other end. This can help
2162 make the most of a low-\i{bandwidth} connection.
2164 \S{config-ssh-prot} \q{Preferred \i{SSH protocol version}}
2166 \cfg{winhelp-topic}{ssh.protocol}
2168 This allows you to select whether you would like to use \i{SSH protocol
2169 version 1} or \I{SSH-2}version 2. \#{FIXME: say something about this elsewhere?}
2171 PuTTY will attempt to use protocol 1 if the server you connect to
2172 does not offer protocol 2, and vice versa.
2174 If you select \q{1 only} or \q{2 only} here, PuTTY will only connect
2175 if the server you connect to offers the SSH protocol version you
2178 \S{config-ssh-encryption} \ii{Encryption} algorithm selection
2180 \cfg{winhelp-topic}{ssh.ciphers}
2182 PuTTY supports a variety of different \i{encryption algorithm}s, and
2183 allows you to choose which one you prefer to use. You can do this by
2184 dragging the algorithms up and down in the list box (or moving them
2185 using the Up and Down buttons) to specify a preference order. When
2186 you make an SSH connection, PuTTY will search down the list from the
2187 top until it finds an algorithm supported by the server, and then
2190 PuTTY currently supports the following algorithms:
2192 \b \i{AES} (Rijndael) - 256, 192, or 128-bit SDCTR or CBC (SSH-2 only)
2194 \b \i{Arcfour} (RC4) - 256 or 128-bit stream cipher (SSH-2 only)
2196 \b \i{Blowfish} - 256-bit SDCTR (SSH-2 only) or 128-bit CBC
2198 \b \ii{Triple-DES} - 168-bit SDCTR (SSH-2 only) or CBC
2200 \b \ii{Single-DES} - 56-bit CBC (see below for SSH-2)
2202 If the algorithm PuTTY finds is below the \q{warn below here} line,
2203 you will see a warning box when you make the connection:
2205 \c The first cipher supported by the server
2206 \c is single-DES, which is below the configured
2207 \c warning threshold.
2208 \c Do you want to continue with this connection?
2210 This warns you that the first available encryption is not a very
2211 secure one. Typically you would put the \q{warn below here} line
2212 between the encryptions you consider secure and the ones you
2213 consider substandard. By default, PuTTY supplies a preference order
2214 intended to reflect a reasonable preference in terms of security and
2217 In SSH-2, the encryption algorithm is negotiated independently for
2218 each direction of the connection, although PuTTY does not support
2219 separate configuration of the preference orders. As a result you may
2220 get two warnings similar to the one above, possibly with different
2223 Single-DES is not recommended in the SSH-2 protocol
2224 standards, but one or two server implementations do support it.
2225 PuTTY can use single-DES to interoperate with
2226 these servers if you enable the \q{Enable legacy use of single-DES in
2227 SSH-2} option; by default this is disabled and PuTTY will stick to
2228 recommended ciphers.
2230 \H{config-ssh-kex} The Kex panel
2232 \# FIXME: This whole section is draft. Feel free to revise.
2234 The Kex panel (short for \q{\i{key exchange}}) allows you to configure
2235 options related to SSH-2 key exchange.
2237 Key exchange occurs at the start of an SSH connection (and
2238 occasionally thereafter); it establishes a \i{shared secret} that is used
2239 as the basis for all of SSH's security features. It is therefore very
2240 important for the security of the connection that the key exchange is
2243 Key exchange is a cryptographically intensive process; if either the
2244 client or the server is a relatively slow machine, the slower methods
2245 may take several tens of seconds to complete.
2247 If connection startup is too slow, or the connection hangs
2248 periodically, you may want to try changing these settings.
2250 If you don't understand what any of this means, it's safe to leave
2251 these settings alone.
2253 This entire panel is only relevant to SSH protocol version 2; none of
2254 these settings affect SSH-1 at all.
2256 \S{config-ssh-kex-order} \ii{Key exchange algorithm} selection
2258 \cfg{winhelp-topic}{ssh.kex.order}
2260 PuTTY supports a variety of SSH-2 key exchange methods, and allows you
2261 to choose which one you prefer to use; configuration is similar to
2262 cipher selection (see \k{config-ssh-encryption}).
2264 PuTTY currently supports the following varieties of \i{Diffie-Hellman key
2267 \b \q{Group 14}: a well-known 2048-bit group.
2269 \b \q{Group 1}: a well-known 1024-bit group. This is less secure
2270 \#{FIXME better words} than group 14, but may be faster with slow
2271 client or server machines, and may be the only method supported by
2272 older server software.
2274 \b \q{\ii{Group exchange}}: with this method, instead of using a fixed
2275 group, PuTTY requests that the server suggest a group to use for key
2276 exchange; the server can avoid groups known to be weak, and possibly
2277 invent new ones over time, without any changes required to PuTTY's
2278 configuration. We recommend use of this method, if possible.
2280 If the first algorithm PuTTY finds is below the \q{warn below here}
2281 line, you will see a warning box when you make the connection, similar
2282 to that for cipher selection (see \k{config-ssh-encryption}).
2284 \S{config-ssh-kex-rekey} \ii{Repeat key exchange}
2286 \cfg{winhelp-topic}{ssh.kex.repeat}
2288 If the session key negotiated at connection startup is used too much
2289 or for too long, it may become feasible to mount attacks against the
2290 SSH connection. Therefore, the SSH-2 protocol specifies that a new key
2291 exchange should take place every so often; this can be initiated by
2292 either the client or the server.
2294 While this renegotiation is taking place, no data can pass through
2295 the SSH connection, so it may appear to \q{freeze}. (The occurrence of
2296 repeat key exchange is noted in the Event Log; see
2297 \k{using-eventlog}.) Usually the same algorithm is used as at the
2298 start of the connection, with a similar overhead.
2300 These options control how often PuTTY will initiate a repeat key
2301 exchange (\q{rekey}). You can also force a key exchange at any time
2302 from the Special Commands menu (see \k{using-specials}).
2304 \# FIXME: do we have any additions to the SSH-2 specs' advice on
2305 these values? Do we want to enforce any limits?
2307 \b \q{Max minutes before rekey} specifies the amount of time that is
2308 allowed to elapse before a rekey is initiated. If this is set to zero,
2309 PuTTY will not rekey due to elapsed time. The SSH-2 protocol
2310 specification recommends a timeout of at most 60 minutes.
2312 You might have a need to disable time-based rekeys completely for the same
2313 reasons that \i{keepalives} aren't always helpful. If you anticipate
2314 suffering a network dropout of several hours in the middle of an SSH
2315 connection, but were not actually planning to send \e{data} down
2316 that connection during those hours, then an attempted rekey in the
2317 middle of the dropout will probably cause the connection to be
2318 abandoned, whereas if rekeys are disabled then the connection should
2319 in principle survive (in the absence of interfering \i{firewalls}). See
2320 \k{config-keepalive} for more discussion of these issues; for these
2321 purposes, rekeys have much the same properties as keepalives.
2322 (Except that rekeys have cryptographic value in themselves, so you
2323 should bear that in mind when deciding whether to turn them off.)
2324 Note, however, the the SSH \e{server} can still initiate rekeys.
2326 \b \q{Max data before rekey} specifies the amount of data (in bytes)
2327 that is permitted to flow in either direction before a rekey is
2328 initiated. If this is set to zero, PuTTY will not rekey due to
2329 transferred data. The SSH-2 protocol specification recommends a limit
2330 of at most 1 gigabyte.
2334 As well as specifying a value in bytes, the following shorthand can be
2337 \b \cq{1k} specifies 1 kilobyte (1024 bytes).
2339 \b \cq{1M} specifies 1 megabyte (1024 kilobytes).
2341 \b \cq{1G} specifies 1 gigabyte (1024 megabytes).
2345 Disabling data-based rekeys entirely is a bad idea. The \i{integrity},
2346 and to a lesser extent, \i{confidentiality} of the SSH-2 protocol depend
2347 in part on rekeys occuring before a 32-bit packet sequence number
2348 wraps around. Unlike time-based rekeys, data-based rekeys won't occur
2349 when the SSH connection is idle, so they shouldn't cause the same
2350 problems. The SSH-1 protocol, incidentally, has even weaker integrity
2351 protection than SSH-2 without rekeys.
2353 \H{config-ssh-auth} The Auth panel
2355 The Auth panel allows you to configure \i{authentication} options for
2358 \S{config-ssh-noauth} \q{Bypass authentication entirely}
2360 \cfg{winhelp-topic}{ssh.auth.bypass}
2362 In SSH-2, it is possible to establish a connection without using SSH's
2363 mechanisms to identify or authenticate oneself to the server. Some
2364 servers may prefer to handle authentication in the data channel, for
2365 instance, or may simply require no authentication whatsoever.
2367 By default, PuTTY assumes the server requires authentication (most
2368 do), and thus must provide a username. If you find you are getting
2369 unwanted username prompts, you could try checking this option.
2371 This option only affects SSH-2 connections. SSH-1 connections always
2372 require an authentication step.
2374 \S{config-ssh-tryagent} \q{Attempt authentication using Pageant}
2376 \cfg{winhelp-topic}{ssh.auth.pageant}
2378 If this option is enabled, then PuTTY will look for Pageant (the SSH
2379 private-key storage agent) and attempt to authenticate with any
2380 suitable public keys Pageant currently holds.
2382 This behaviour is almost always desirable, and is therefore enabled
2383 by default. In rare cases you might need to turn it off in order to
2384 force authentication by some non-public-key method such as
2387 This option can also be controlled using the \c{-noagent}
2388 command-line option. See \k{using-cmdline-agentauth}.
2390 See \k{pageant} for more information about Pageant in general.
2392 \S{config-ssh-tis} \q{Attempt \I{TIS authentication}TIS or
2393 \i{CryptoCard authentication}}
2395 \cfg{winhelp-topic}{ssh.auth.tis}
2397 TIS and CryptoCard authentication are (despite their names) generic
2398 forms of simple \I{challenge/response authentication}challenge/response
2399 authentication available in SSH protocol version 1 only. You might use
2400 them if you were using \i{S/Key} \i{one-time passwords}, for example,
2401 or if you had a physical \i{security token} that generated responses
2402 to authentication challenges.
2404 With this switch enabled, PuTTY will attempt these forms of
2405 authentication if the server is willing to try them. You will be
2406 presented with a challenge string (which will be different every
2407 time) and must supply the correct response in order to log in. If
2408 your server supports this, you should talk to your system
2409 administrator about precisely what form these challenges and
2412 \S{config-ssh-ki} \q{Attempt \i{keyboard-interactive authentication}}
2414 \cfg{winhelp-topic}{ssh.auth.ki}
2416 The SSH-2 equivalent of TIS authentication is called
2417 \q{keyboard-interactive}. It is a flexible authentication method
2418 using an arbitrary sequence of requests and responses; so it is not
2419 only useful for \I{challenge/response authentication}challenge/response
2420 mechanisms such as \i{S/Key}, but it can also be used for (for example)
2421 asking the user for a \I{password expiry}new password when the old one
2424 PuTTY leaves this option enabled by default, but supplies a switch
2425 to turn it off in case you should have trouble with it.
2427 \S{config-ssh-agentfwd} \q{Allow \i{agent forwarding}}
2429 \cfg{winhelp-topic}{ssh.auth.agentfwd}
2431 This option allows the SSH server to open forwarded connections back
2432 to your local copy of \i{Pageant}. If you are not running Pageant, this
2433 option will do nothing.
2435 See \k{pageant} for general information on Pageant, and
2436 \k{pageant-forward} for information on agent forwarding. Note that
2437 there is a security risk involved with enabling this option; see
2438 \k{pageant-security} for details.
2440 \S{config-ssh-changeuser} \q{Allow attempted \i{changes of username} in SSH-2}
2442 \cfg{winhelp-topic}{ssh.auth.changeuser}
2444 In the SSH-1 protocol, it is impossible to change username after
2445 failing to authenticate. So if you mis-type your username at the
2446 PuTTY \q{login as:} prompt, you will not be able to change it except
2447 by restarting PuTTY.
2449 The SSH-2 protocol \e{does} allow changes of username, in principle,
2450 but does not make it mandatory for SSH-2 servers to accept them. In
2451 particular, \i{OpenSSH} does not accept a change of username; once you
2452 have sent one username, it will reject attempts to try to
2453 authenticate as another user. (Depending on the version of OpenSSH,
2454 it may quietly return failure for all login attempts, or it may send
2457 For this reason, PuTTY will by default not prompt you for your
2458 username more than once, in case the server complains. If you know
2459 your server can cope with it, you can enable the \q{Allow attempted
2460 changes of username} option to modify PuTTY's behaviour.
2462 \S{config-ssh-privkey} \q{\ii{Private key} file for authentication}
2464 \cfg{winhelp-topic}{ssh.auth.privkey}
2466 This box is where you enter the name of your private key file if you
2467 are using \i{public key authentication}. See \k{pubkey} for information
2468 about public key authentication in SSH.
2470 This key must be in PuTTY's native format (\c{*.\i{PPK}}). If you have a
2471 private key in another format that you want to use with PuTTY, see
2472 \k{puttygen-conversions}.
2474 If a key file is specified here, and \i{Pageant} is running (see
2475 \k{pageant}), PuTTY will first try asking Pageant to authenticate with
2476 that key, and ignore any other keys Pageant may have. If that fails,
2477 PuTTY will ask for a passphrase as normal.
2479 \H{config-ssh-tty} The TTY panel
2481 The TTY panel lets you configure the remote pseudo-terminal.
2483 \S{config-ssh-pty} \I{pseudo-terminal allocation}\q{Don't allocate
2486 \cfg{winhelp-topic}{ssh.nopty}
2488 When connecting to a \i{Unix} system, most \I{interactive
2489 connections}interactive shell sessions are run in a \e{pseudo-terminal},
2490 which allows the Unix system to pretend it's talking to a real physical
2491 terminal device but allows the SSH server to catch all the data coming
2492 from that fake device and send it back to the client.
2494 Occasionally you might find you have a need to run a session \e{not}
2495 in a pseudo-terminal. In PuTTY, this is generally only useful for
2496 very specialist purposes; although in Plink (see \k{plink}) it is
2497 the usual way of working.
2499 \S{config-ttymodes} Sending \i{terminal modes}
2501 \cfg{winhelp-topic}{ssh.ttymodes}
2503 The SSH protocol allows the client to send \q{terminal modes} for
2504 the remote pseudo-terminal. These usually control the server's
2505 expectation of the local terminal's behaviour.
2507 If your server does not have sensible defaults for these modes, you
2508 may find that changing them here helps. If you don't understand any of
2509 this, it's safe to leave these settings alone.
2511 (None of these settings will have any effect if no pseudo-terminal
2512 is requested or allocated.)
2514 You can add or modify a mode by selecting it from the drop-down list,
2515 choosing whether it's set automatically or to a specific value with
2516 the radio buttons and edit box, and hitting \q{Add}. A mode (or
2517 several) can be removed from the list by selecting them and hitting
2518 \q{Remove}. The effect of the mode list is as follows:
2520 \b If a mode is not on the list, it will not be specified to the
2521 server under any circumstances.
2523 \b If a mode is on the list:
2527 \b If the \q{Auto} option is selected, the PuTTY tools will decide
2528 whether to specify that mode to the server, and if so, will send
2533 PuTTY proper will send modes that it has an opinion on (currently only
2534 the code for the Backspace key, \cw{ERASE}). Plink on Unix
2535 will propagate appropriate modes from the local terminal, if any.
2539 \b If a value is specified, it will be sent to the server under all
2540 circumstances. The precise syntax of the value box depends on the
2545 By default, all of the available modes are listed as \q{Auto},
2546 which should do the right thing in most circumstances.
2548 The precise effect of each setting, if any, is up to the server. Their
2549 names come from \i{POSIX} and other Unix systems, and they are most
2550 likely to have a useful effect on such systems. (These are the same
2551 settings that can usually be changed using the \i\c{stty} command once
2552 logged in to such servers.)
2554 Some notable modes are described below; for fuller explanations, see
2555 your server documentation.
2557 \b \I{ERASE special character}\cw{ERASE} is the character that when typed
2558 by the user will delete one space to the left. When set to \q{Auto}
2559 (the default setting), this follows the setting of the local Backspace
2560 key in PuTTY (see \k{config-backspace}).
2563 This and other \i{special character}s are specified using \c{^C} notation
2564 for Ctrl-C, and so on. Use \c{^<27>} or \c{^<0x1B>} to specify a
2565 character numerically, and \c{^~} to get a literal \c{^}. Other
2566 non-control characters are denoted by themselves. Leaving the box
2567 entirely blank indicates that \e{no} character should be assigned to
2568 the specified function, although this may not be supported by all
2572 \b \I{QUIT special character}\cw{QUIT} is a special character that
2573 usually forcefully ends the current process on the server
2574 (\cw{SIGQUIT}). On many servers its default setting is Ctrl-backslash
2575 (\c{^\\}), which is easy to accidentally invoke on many keyboards. If
2576 this is getting in your way, you may want to change it to another
2577 character or turn it off entirely.
2579 \b Boolean modes such as \cw{ECHO} and \cw{ICANON} can be specified in
2580 PuTTY in a variety of ways, such as \cw{true}/\cw{false},
2581 \cw{yes}/\cw{no}, and \cw{0}/\cw{1}.
2583 \b Terminal speeds are configured elsewhere; see \k{config-termspeed}.
2585 \H{config-ssh-x11} The X11 panel
2587 \cfg{winhelp-topic}{ssh.tunnels.x11}
2589 The X11 panel allows you to configure \i{forwarding of X11} over an
2592 If your server lets you run X Window System applications, X11
2593 forwarding allows you to securely give those applications access to
2594 a local X display on your PC.
2596 To enable X11 forwarding, check the \q{Enable X11 forwarding} box.
2597 If your X display is somewhere unusual, you will need to enter its
2598 location in the \q{X display location} box; if this is left blank,
2599 PuTTY will try to find a sensible default in the environment, or use the
2600 primary local display (\c{:0}) if that fails.
2602 See \k{using-x-forwarding} for more information about X11
2605 \S{config-ssh-x11auth} Remote \i{X11 authentication}
2607 \cfg{winhelp-topic}{ssh.tunnels.x11auth}
2609 If you are using X11 forwarding, the virtual X server created on the
2610 SSH server machine will be protected by authorisation data. This
2611 data is invented, and checked, by PuTTY.
2613 The usual authorisation method used for this is called
2614 \i\cw{MIT-MAGIC-COOKIE-1}. This is a simple password-style protocol:
2615 the X client sends some cookie data to the server, and the server
2616 checks that it matches the real cookie. The cookie data is sent over
2617 an unencrypted X11 connection; so if you allow a client on a third
2618 machine to access the virtual X server, then the cookie will be sent
2621 PuTTY offers the alternative protocol \i\cw{XDM-AUTHORIZATION-1}. This
2622 is a cryptographically authenticated protocol: the data sent by the
2623 X client is different every time, and it depends on the IP address
2624 and port of the client's end of the connection and is also stamped
2625 with the current time. So an eavesdropper who captures an
2626 \cw{XDM-AUTHORIZATION-1} string cannot immediately re-use it for
2627 their own X connection.
2629 PuTTY's support for \cw{XDM-AUTHORIZATION-1} is a somewhat
2630 experimental feature, and may encounter several problems:
2632 \b Some X clients probably do not even support
2633 \cw{XDM-AUTHORIZATION-1}, so they will not know what to do with the
2634 data PuTTY has provided.
2636 \b This authentication mechanism will only work in SSH-2. In SSH-1,
2637 the SSH server does not tell the client the source address of
2638 a forwarded connection in a machine-readable format, so it's
2639 impossible to verify the \cw{XDM-AUTHORIZATION-1} data.
2641 \b You may find this feature causes problems with some SSH servers,
2642 which will not clean up \cw{XDM-AUTHORIZATION-1} data after a
2643 session, so that if you then connect to the same server using
2644 a client which only does \cw{MIT-MAGIC-COOKIE-1} and are allocated
2645 the same remote display number, you might find that out-of-date
2646 authentication data is still present on your server and your X
2649 PuTTY's default is \cw{MIT-MAGIC-COOKIE-1}. If you change it, you
2650 should be sure you know what you're doing.
2652 \H{config-ssh-portfwd} \I{port forwarding}The Tunnels panel
2654 \cfg{winhelp-topic}{ssh.tunnels.portfwd}
2656 The Tunnels panel allows you to configure tunnelling of arbitrary
2657 connection types through an SSH connection.
2659 Port forwarding allows you to tunnel other types of \i{network
2660 connection} down an SSH session. See \k{using-port-forwarding} for a
2661 general discussion of port forwarding and how it works.
2663 The port forwarding section in the Tunnels panel shows a list of all
2664 the port forwardings that PuTTY will try to set up when it connects
2665 to the server. By default no port forwardings are set up, so this
2668 To add a port forwarding:
2670 \b Set one of the \q{Local} or \q{Remote} radio buttons, depending
2671 on whether you want to \I{local port forwarding}forward a local port
2672 to a remote destination (\q{Local}) or \I{remote port forwarding}forward
2673 a remote port to a local destination (\q{Remote}). Alternatively,
2674 select \q{Dynamic} if you want PuTTY to \I{dynamic port forwarding}provide
2675 a local SOCKS 4/4A/5 proxy on a local port (note that this proxy only
2676 supports TCP connections; the SSH protocol does not support forwarding
2679 \b Enter a source \i{port number} into the \q{Source port} box. For
2680 local forwardings, PuTTY will listen on this port of your PC. For
2681 remote forwardings, your SSH server will listen on this port of the
2682 remote machine. Note that most servers will not allow you to listen
2683 on \I{privileged port}port numbers less than 1024.
2685 \b If you have selected \q{Local} or \q{Remote} (this step is not
2686 needed with \q{Dynamic}), enter a hostname and port number separated
2687 by a colon, in the \q{Destination} box. Connections received on the
2688 source port will be directed to this destination. For example, to
2689 connect to a POP-3 server, you might enter
2690 \c{popserver.example.com:110}.
2692 \b Click the \q{Add} button. Your forwarding details should appear
2695 To remove a port forwarding, simply select its details in the list
2696 box, and click the \q{Remove} button.
2698 In the \q{Source port} box, you can also optionally enter an \I{listen
2699 address}IP address to listen on, by specifying (for instance)
2701 See \k{using-port-forwarding} for more information on how this
2702 works and its restrictions.
2704 In place of port numbers, you can enter \i{service names}, if they are
2705 known to the local system. For instance, in the \q{Destination} box,
2706 you could enter \c{popserver.example.com:pop3}.
2708 You can \I{port forwarding, changing mid-session}modify the currently
2709 active set of port forwardings in mid-session using \q{Change
2710 Settings} (see \k{using-changesettings}). If you delete a local or
2711 dynamic port forwarding in mid-session, PuTTY will stop listening for
2712 connections on that port, so it can be re-used by another program. If
2713 you delete a remote port forwarding, note that:
2715 \b The SSH-1 protocol contains no mechanism for asking the server to
2716 stop listening on a remote port.
2718 \b The SSH-2 protocol does contain such a mechanism, but not all SSH
2719 servers support it. (In particular, \i{OpenSSH} does not support it in
2720 any version earlier than 3.9.)
2722 If you ask to delete a remote port forwarding and PuTTY cannot make
2723 the server actually stop listening on the port, it will instead just
2724 start refusing incoming connections on that port. Therefore,
2725 although the port cannot be reused by another program, you can at
2726 least be reasonably sure that server-side programs can no longer
2727 access the service at your end of the port forwarding.
2729 If you delete a forwarding, any existing connections established using
2730 that forwarding remain open. Similarly, changes to global settings
2731 such as \q{Local ports accept connections from other hosts} only take
2732 effect on new forwardings.
2734 \S{config-ssh-portfwd-localhost} Controlling the visibility of
2737 \cfg{winhelp-topic}{ssh.tunnels.portfwd.localhost}
2739 The source port for a forwarded connection usually does not accept
2740 connections from any machine except the \I{localhost}SSH client or
2741 server machine itself (for local and remote forwardings respectively).
2742 There are controls in the Tunnels panel to change this:
2744 \b The \q{Local ports accept connections from other hosts} option
2745 allows you to set up local-to-remote port forwardings in such a way
2746 that machines other than your client PC can connect to the forwarded
2747 port. (This also applies to dynamic SOCKS forwarding.)
2749 \b The \q{Remote ports do the same} option does the same thing for
2750 remote-to-local port forwardings (so that machines other than the
2751 SSH server machine can connect to the forwarded port.) Note that
2752 this feature is only available in the SSH-2 protocol, and not all
2753 SSH-2 servers support it (\i{OpenSSH} 3.0 does not, for example).
2755 \S{config-ssh-portfwd-address-family} Selecting \i{Internet protocol
2756 version} for forwarded ports
2758 \cfg{winhelp-topic}{ssh.tunnels.portfwd.ipversion}
2760 This switch allows you to select a specific Internet protocol (\i{IPv4}
2761 or \i{IPv6}) for the local end of a forwarded port. By default, it is
2762 set on \q{Auto}, which means that:
2764 \b for a local-to-remote port forwarding, PuTTY will listen for
2765 incoming connections in both IPv4 and (if available) IPv6
2767 \b for a remote-to-local port forwarding, PuTTY will choose a
2768 sensible protocol for the outgoing connection.
2770 Note that some operating systems may listen for incoming connections
2771 in IPv4 even if you specifically asked for IPv6, because their IPv4
2772 and IPv6 protocol stacks are linked together. Apparently \i{Linux} does
2773 this, and Windows does not. So if you're running PuTTY on Windows
2774 and you tick \q{IPv6} for a local or dynamic port forwarding, it
2775 will \e{only} be usable by connecting to it using IPv6; whereas if
2776 you do the same on Linux, you can also use it with IPv4. However,
2777 ticking \q{Auto} should always give you a port which you can connect
2778 to using either protocol.
2780 \H{config-ssh-bugs} \I{SSH server bugs}The Bugs panel
2782 Not all SSH servers work properly. Various existing servers have
2783 bugs in them, which can make it impossible for a client to talk to
2784 them unless it knows about the bug and works around it.
2786 Since most servers announce their software version number at the
2787 beginning of the SSH connection, PuTTY will attempt to detect which
2788 bugs it can expect to see in the server and automatically enable
2789 workarounds. However, sometimes it will make mistakes; if the server
2790 has been deliberately configured to conceal its version number, or
2791 if the server is a version which PuTTY's bug database does not know
2792 about, then PuTTY will not know what bugs to expect.
2794 The Bugs panel allows you to manually configure the bugs PuTTY
2795 expects to see in the server. Each bug can be configured in three
2798 \b \q{Off}: PuTTY will assume the server does not have the bug.
2800 \b \q{On}: PuTTY will assume the server \e{does} have the bug.
2802 \b \q{Auto}: PuTTY will use the server's version number announcement
2803 to try to guess whether or not the server has the bug.
2805 \S{config-ssh-bug-ignore1} \q{Chokes on SSH-1 \i{ignore message}s}
2807 \cfg{winhelp-topic}{ssh.bugs.ignore1}
2809 An ignore message (SSH_MSG_IGNORE) is a message in the SSH protocol
2810 which can be sent from the client to the server, or from the server
2811 to the client, at any time. Either side is required to ignore the
2812 message whenever it receives it. PuTTY uses ignore messages to
2813 \I{password camouflage}hide the password packet in SSH-1, so that
2814 a listener cannot tell the length of the user's password; it also
2815 uses ignore messages for connection \i{keepalives} (see
2816 \k{config-keepalive}).
2818 If this bug is detected, PuTTY will stop using ignore messages. This
2819 means that keepalives will stop working, and PuTTY will have to fall
2820 back to a secondary defence against SSH-1 password-length
2821 eavesdropping. See \k{config-ssh-bug-plainpw1}. If this bug is
2822 enabled when talking to a correct server, the session will succeed,
2823 but keepalives will not work and the session might be more
2824 vulnerable to eavesdroppers than it could be.
2826 This is an SSH-1-specific bug. No known SSH-2 server fails to deal
2827 with SSH-2 ignore messages.
2829 \S{config-ssh-bug-plainpw1} \q{Refuses all SSH-1 \i{password camouflage}}
2831 \cfg{winhelp-topic}{ssh.bugs.plainpw1}
2833 When talking to an SSH-1 server which cannot deal with ignore
2834 messages (see \k{config-ssh-bug-ignore1}), PuTTY will attempt to
2835 disguise the length of the user's password by sending additional
2836 padding \e{within} the password packet. This is technically a
2837 violation of the SSH-1 specification, and so PuTTY will only do it
2838 when it cannot use standards-compliant ignore messages as
2839 camouflage. In this sense, for a server to refuse to accept a padded
2840 password packet is not really a bug, but it does make life
2841 inconvenient if the server can also not handle ignore messages.
2843 If this \q{bug} is detected, PuTTY will assume that neither ignore
2844 messages nor padding are acceptable, and that it thus has no choice
2845 but to send the user's password with no form of camouflage, so that
2846 an eavesdropping user will be easily able to find out the exact length
2847 of the password. If this bug is enabled when talking to a correct
2848 server, the session will succeed, but will be more vulnerable to
2849 eavesdroppers than it could be.
2851 This is an SSH-1-specific bug. SSH-2 is secure against this type of
2854 \S{config-ssh-bug-rsa1} \q{Chokes on SSH-1 \i{RSA} authentication}
2856 \cfg{winhelp-topic}{ssh.bugs.rsa1}
2858 Some SSH-1 servers cannot deal with RSA authentication messages at
2859 all. If \i{Pageant} is running and contains any SSH-1 keys, PuTTY will
2860 normally automatically try RSA authentication before falling back to
2861 passwords, so these servers will crash when they see the RSA attempt.
2863 If this bug is detected, PuTTY will go straight to password
2864 authentication. If this bug is enabled when talking to a correct
2865 server, the session will succeed, but of course RSA authentication
2868 This is an SSH-1-specific bug.
2870 \S{config-ssh-bug-hmac2} \q{Miscomputes SSH-2 HMAC keys}
2872 \cfg{winhelp-topic}{ssh.bugs.hmac2}
2874 Versions 2.3.0 and below of the SSH server software from
2875 \cw{ssh.com} compute the keys for their \i{HMAC} \i{message authentication
2876 code}s incorrectly. A typical symptom of this problem is that PuTTY
2877 dies unexpectedly at the beginning of the session, saying
2878 \q{Incorrect MAC received on packet}.
2880 If this bug is detected, PuTTY will compute its HMAC keys in the
2881 same way as the buggy server, so that communication will still be
2882 possible. If this bug is enabled when talking to a correct server,
2883 communication will fail.
2885 This is an SSH-2-specific bug.
2887 \S{config-ssh-bug-derivekey2} \q{Miscomputes SSH-2 \i{encryption} keys}
2889 \cfg{winhelp-topic}{ssh.bugs.derivekey2}
2891 Versions below 2.0.11 of the SSH server software from \i\cw{ssh.com}
2892 compute the keys for the session encryption incorrectly. This
2893 problem can cause various error messages, such as \q{Incoming packet
2894 was garbled on decryption}, or possibly even \q{Out of memory}.
2896 If this bug is detected, PuTTY will compute its encryption keys in
2897 the same way as the buggy server, so that communication will still
2898 be possible. If this bug is enabled when talking to a correct
2899 server, communication will fail.
2901 This is an SSH-2-specific bug.
2903 \S{config-ssh-bug-sig} \q{Requires padding on SSH-2 \i{RSA} \i{signatures}}
2905 \cfg{winhelp-topic}{ssh.bugs.rsapad2}
2907 Versions below 3.3 of \i{OpenSSH} require SSH-2 RSA signatures to be
2908 padded with zero bytes to the same length as the RSA key modulus.
2909 The SSH-2 specification says that an unpadded signature MUST be
2910 accepted, so this is a bug. A typical symptom of this problem is
2911 that PuTTY mysteriously fails RSA authentication once in every few
2912 hundred attempts, and falls back to passwords.
2914 If this bug is detected, PuTTY will pad its signatures in the way
2915 OpenSSH expects. If this bug is enabled when talking to a correct
2916 server, it is likely that no damage will be done, since correct
2917 servers usually still accept padded signatures because they're used
2918 to talking to OpenSSH.
2920 This is an SSH-2-specific bug.
2922 \S{config-ssh-bug-pksessid2} \q{Misuses the \i{session ID} in SSH-2 PK auth}
2924 \cfg{winhelp-topic}{ssh.bugs.pksessid2}
2926 Versions below 2.3 of \i{OpenSSH} require SSH-2 \i{public-key authentication}
2927 to be done slightly differently: the data to be signed by the client
2928 contains the session ID formatted in a different way. If public-key
2929 authentication mysteriously does not work but the Event Log (see
2930 \k{using-eventlog}) thinks it has successfully sent a signature, it
2931 might be worth enabling the workaround for this bug to see if it
2934 If this bug is detected, PuTTY will sign data in the way OpenSSH
2935 expects. If this bug is enabled when talking to a correct server,
2936 SSH-2 public-key authentication will fail.
2938 This is an SSH-2-specific bug.
2940 \S{config-ssh-bug-rekey} \q{Handles SSH-2 key re-exchange badly}
2942 \cfg{winhelp-topic}{ssh.bugs.rekey2}
2944 Some SSH servers cannot cope with \i{repeat key exchange} at
2945 all, and will ignore attempts by the client to start one. Since
2946 PuTTY pauses the session while performing a repeat key exchange, the
2947 effect of this would be to cause the session to hang after an hour
2948 (unless you have your rekey timeout set differently; see
2949 \k{config-ssh-kex-rekey} for more about rekeys).
2950 Other, very old, SSH servers handle repeat key exchange even more
2951 badly, and disconnect upon receiving a repeat key exchange request.
2953 If this bug is detected, PuTTY will never initiate a repeat key
2954 exchange. If this bug is enabled when talking to a correct server,
2955 the session should still function, but may be less secure than you
2958 This is an SSH-2-specific bug.
2960 \H{config-serial} The Serial panel
2962 The \i{Serial} panel allows you to configure options that only apply
2963 when PuTTY is connecting to a local \I{serial port}\i{serial line}.
2965 \S{config-serial-line} Selecting a serial line to connect to
2967 \cfg{winhelp-topic}{serial.line}
2969 The \q{Serial line to connect to} box allows you to choose which
2970 serial line you want PuTTY to talk to, if your computer has more
2971 than one serial port.
2973 On Windows, the first serial line is called \cw{COM1}, and if there
2974 is a second it is called \cw{COM2}, and so on.
2976 This configuration setting is also visible on the Session panel,
2977 where it replaces the \q{Host Name} box (see \k{config-hostname}) if
2978 the connection type is set to \q{Serial}.
2980 \S{config-serial-speed} Selecting the speed of your serial line
2982 \cfg{winhelp-topic}{serial.speed}
2984 The \q{Speed} box allows you to choose the speed (or \q{baud rate})
2985 at which to talk to the serial line. Typical values might be 9600,
2986 19200, 38400 or 57600. Which one you need will depend on the device
2987 at the other end of the serial cable; consult the manual for that
2988 device if you are in doubt.
2990 This configuration setting is also visible on the Session panel,
2991 where it replaces the \q{Port} box (see \k{config-hostname}) if the
2992 connection type is set to \q{Serial}.
2994 \S{config-serial-databits} Selecting the number of data bits
2996 \cfg{winhelp-topic}{serial.databits}
2998 The \q{Data bits} box allows you to choose how many data bits are
2999 transmitted in each byte sent or received through the serial line.
3000 Typical values are 7 or 8.
3002 \S{config-serial-stopbits} Selecting the number of stop bits
3004 \cfg{winhelp-topic}{serial.stopbits}
3006 The \q{Stop bits} box allows you to choose how many stop bits are
3007 used in the serial line protocol. Typical values are 1, 1.5 or 2.
3009 \S{config-serial-parity} Selecting the serial parity checking scheme
3011 \cfg{winhelp-topic}{serial.parity}
3013 The \q{Parity} box allows you to choose what type of parity checking
3014 is used on the serial line. The settings are:
3016 \b \q{None}: no parity bit is sent at all.
3018 \b \q{Odd}: an extra parity bit is sent alongside each byte, and
3019 arranged so that the total number of 1 bits is odd.
3021 \b \q{Even}: an extra parity bit is sent alongside each byte, and
3022 arranged so that the total number of 1 bits is even.
3024 \b \q{Mark}: an extra parity bit is sent alongside each byte, and
3027 \b \q{Space}: an extra parity bit is sent alongside each byte, and
3030 \S{config-serial-flow} Selecting the serial flow control scheme
3032 \cfg{winhelp-topic}{serial.flow}
3034 The \q{Flow control} box allows you to choose what type of flow
3035 control checking is used on the serial line. The settings are:
3037 \b \q{None}: no flow control is done. Data may be lost if either
3038 side attempts to send faster than the serial line permits.
3040 \b \q{XON/XOFF}: flow control is done by sending XON and XOFF
3041 characters within the data stream.
3043 \b \q{RTS/CTS}: flow control is done using the RTS and CTS wires on
3046 \b \q{DSR/DTR}: flow control is done using the DSR and DTR wires on
3049 \H{config-file} \ii{Storing configuration in a file}
3051 PuTTY does not currently support storing its configuration in a file
3052 instead of the \i{Registry}. However, you can work around this with a
3053 couple of \i{batch file}s.
3055 You will need a file called (say) \c{PUTTY.BAT} which imports the
3056 contents of a file into the Registry, then runs PuTTY, exports the
3057 contents of the Registry back into the file, and deletes the
3058 Registry entries. This can all be done using the Regedit command
3059 line options, so it's all automatic. Here is what you need in
3063 \c regedit /s putty.reg
3064 \c regedit /s puttyrnd.reg
3065 \c start /w putty.exe
3066 \c regedit /ea new.reg HKEY_CURRENT_USER\Software\SimonTatham\PuTTY
3067 \c copy new.reg putty.reg
3069 \c regedit /s puttydel.reg
3071 This batch file needs two auxiliary files: \c{PUTTYRND.REG} which
3072 sets up an initial safe location for the \c{PUTTY.RND} random seed
3073 file, and \c{PUTTYDEL.REG} which destroys everything in the Registry
3074 once it's been successfully saved back to the file.
3076 Here is \c{PUTTYDEL.REG}:
3080 \c [-HKEY_CURRENT_USER\Software\SimonTatham\PuTTY]
3082 Here is an example \c{PUTTYRND.REG} file:
3086 \c [HKEY_CURRENT_USER\Software\SimonTatham\PuTTY]
3087 \c "RandSeedFile"="a:\\putty.rnd"
3089 You should replace \c{a:\\putty.rnd} with the location where you
3090 want to store your random number data. If the aim is to carry around
3091 PuTTY and its settings on one floppy, you probably want to store it