1 \define{versionidfaq} \versionid $Id$
5 This FAQ is published on the PuTTY web site, and also provided as an
6 appendix in the manual.
8 \H{faq-intro} Introduction
10 \S{faq-what}{Question} What is PuTTY?
12 PuTTY is a client program for the SSH, Telnet and Rlogin network
15 These protocols are all used to run a remote session on a computer,
16 over a network. PuTTY implements the client end of that session: the
17 end at which the session is displayed, rather than the end at which
20 In really simple terms: you run PuTTY on a Windows machine, and tell
21 it to connect to (for example) a Unix machine. PuTTY opens a window.
22 Then, anything you type into that window is sent straight to the
23 Unix machine, and everything the Unix machine sends back is
24 displayed in the window. So you can work on the Unix machine as if
25 you were sitting at its console, while actually sitting somewhere
28 \H{faq-support} Features supported in PuTTY
30 \I{supported features}In general, if you want to know if PuTTY supports
31 a particular feature, you should look for it on the
32 \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/}{PuTTY web site}.
36 \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html}{changes
37 page}, and see if you can find the feature on there. If a feature is
38 listed there, it's been implemented. If it's listed as a change made
39 \e{since} the latest version, it should be available in the
40 development snapshots, in which case testing will be very welcome.
43 \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/}{Wishlist
44 page}, and see if you can find the feature there. If it's on there,
45 and not in the \q{Recently fixed} section, it probably \e{hasn't} been
48 \S{faq-ssh2}{Question} Does PuTTY support SSH-2?
50 Yes. SSH-2 support has been available in PuTTY since version 0.50.
52 Public key authentication (both RSA and DSA) in SSH-2 is new in
55 \S{faq-ssh2-keyfmt}{Question} Does PuTTY support reading OpenSSH or
56 \cw{ssh.com} SSH-2 private key files?
58 PuTTY doesn't support this natively, but as of 0.53
59 PuTTYgen can convert both OpenSSH and \cw{ssh.com} private key
60 files into PuTTY's format.
62 \S{faq-ssh1}{Question} Does PuTTY support SSH-1?
64 Yes. SSH-1 support has always been available in PuTTY.
66 \S{faq-localecho}{Question} Does PuTTY support \i{local echo}?
68 Yes. Version 0.52 has proper support for local echo.
70 In version 0.51 and before, local echo could not be separated from
71 local line editing (where you type a line of text locally, and it is
72 not sent to the server until you press Return, so you have the
73 chance to edit it and correct mistakes \e{before} the server sees
74 it). New in version 0.52, local echo and local line editing are
75 separate options, and by default PuTTY will try to determine
76 automatically whether to enable them or not, based on which protocol
77 you have selected and also based on hints from the server. If you
78 have a problem with PuTTY's default choice, you can force each
79 option to be enabled or disabled as you choose. The controls are in
80 the Terminal panel, in the section marked \q{Line discipline
83 \S{faq-savedsettings}{Question} Does PuTTY support storing settings,
84 so I don't have to change them every time?
86 Yes, all of PuTTY's settings can be saved in named session profiles.
87 You can also change the default settings that are used for new sessions.
88 See \k{config-saving} in the documentation for how to do this.
90 \S{faq-disksettings}{Question} Does PuTTY support storing its
91 settings in a disk file?
93 Not at present, although \k{config-file} in the documentation gives
94 a method of achieving the same effect.
96 \S{faq-fullscreen}{Question} Does PuTTY support full-screen mode,
99 Yes; this is a new feature in version 0.52.
101 \S{faq-password-remember}{Question} Does PuTTY have the ability to
102 \i{remember my password} so I don't have to type it every time?
106 Remembering your password is a bad plan for obvious security
107 reasons: anyone who gains access to your machine while you're away
108 from your desk can find out the remembered password, and use it,
109 abuse it or change it.
111 In addition, it's not even \e{possible} for PuTTY to automatically
112 send your password in a Telnet session, because Telnet doesn't give
113 the client software any indication of which part of the login
114 process is the password prompt. PuTTY would have to guess, by
115 looking for words like \q{password} in the session data; and if your
116 login program is written in something other than English, this won't
119 In SSH, remembering your password would be possible in theory, but
120 there doesn't seem to be much point since SSH supports public key
121 authentication, which is more flexible and more secure. See
122 \k{pubkey} in the documentation for a full discussion of public key
125 \S{faq-hostkeys}{Question} Is there an option to turn off the
126 \I{verifying the host key}annoying host key prompts?
128 No, there isn't. And there won't be. Even if you write it yourself
129 and send us the patch, we won't accept it.
131 Those annoying host key prompts are the \e{whole point} of SSH.
132 Without them, all the cryptographic technology SSH uses to secure
133 your session is doing nothing more than making an attacker's job
134 slightly harder; instead of sitting between you and the server with
135 a packet sniffer, the attacker must actually subvert a router and
136 start modifying the packets going back and forth. But that's not all
137 that much harder than just sniffing; and without host key checking,
138 it will go completely undetected by client or server.
140 Host key checking is your guarantee that the encryption you put on
141 your data at the client end is the \e{same} encryption taken off the
142 data at the server end; it's your guarantee that it hasn't been
143 removed and replaced somewhere on the way. Host key checking makes
144 the attacker's job \e{astronomically} hard, compared to packet
145 sniffing, and even compared to subverting a router. Instead of
146 applying a little intelligence and keeping an eye on Bugtraq, the
147 attacker must now perform a brute-force attack against at least one
148 military-strength cipher. That insignificant host key prompt really
149 does make \e{that} much difference.
151 If you're having a specific problem with host key checking - perhaps
152 you want an automated batch job to make use of PSCP or Plink, and
153 the interactive host key prompt is hanging the batch process - then
154 the right way to fix it is to add the correct host key to the
155 Registry in advance. That way, you retain the \e{important} feature
156 of host key checking: the right key will be accepted and the wrong
157 ones will not. Adding an option to turn host key checking off
158 completely is the wrong solution and we will not do it.
160 If you have host keys available in the common \i\c{known_hosts} format,
161 we have a script called
162 \W{http://www.tartarus.org/~simon-anonsvn/viewcvs.cgi/putty/contrib/kh2reg.py?view=markup}\c{kh2reg.py}
163 to convert them to a Windows .REG file, which can be installed ahead of
164 time by double-clicking or using \c{REGEDIT}.
166 \S{faq-server}{Question} Will you write an SSH server for the PuTTY
167 suite, to go with the client?
169 No. The only reason we might want to would be if we could easily
170 re-use existing code and significantly cut down the effort. We don't
171 believe this is the case; there just isn't enough common ground
172 between an SSH client and server to make it worthwhile.
174 If someone else wants to use bits of PuTTY in the process of writing
175 a Windows SSH server, they'd be perfectly welcome to of course, but
176 I really can't see it being a lot less effort for us to do that than
177 it would be for us to write a server from the ground up. We don't
178 have time, and we don't have motivation. The code is available if
179 anyone else wants to try it.
181 \S{faq-pscp-ascii}{Question} Can PSCP or PSFTP transfer files in
186 Until recently, this was a limitation of the file transfer protocols:
187 the SCP and SFTP protocols had no notion of transferring a file in
188 anything other than binary mode. (This is still true of SCP.)
190 The current draft protocol spec of SFTP proposes a means of
191 implementing ASCII transfer. At some point PSCP/PSFTP may implement
194 \H{faq-ports} Ports to other operating systems
196 The eventual goal is for PuTTY to be a multi-platform program, able
197 to run on at least Windows, Mac OS and Unix.
199 Porting will become easier once PuTTY has a generalised porting
200 layer, drawing a clear line between platform-dependent and
201 platform-independent code. The general intention was for this
202 porting layer to evolve naturally as part of the process of doing
203 the first port; a Unix port has now been released and the plan
204 seems to be working so far.
206 \S{faq-ports-general}{Question} What ports of PuTTY exist?
208 Currently, release versions of PuTTY tools only run on full Win32
209 systems and Unix. \q{Win32} includes Windows 95, 98, and ME, and it
210 includes Windows NT, Windows 2000 and Windows XP.
212 In the development code, a partial port to the Mac OS (see
213 \k{faq-mac-port}) is under way.
215 Currently PuTTY does \e{not} run on Windows CE (see \k{faq-wince}),
216 and it does not quite run on the Win32s environment under Windows
217 3.1 (see \k{faq-win31}).
219 We do not have release-quality ports for any other systems at the
220 present time. If anyone told you we had an EPOC port, or an iPaq port,
221 or any other port of PuTTY, they were mistaken. We don't.
223 There are some third-party ports to various platforms, mentioned
224 on the Links page of our website.
226 \S{faq-unix}{Question} \I{Unix version}Is there a port to Unix?
228 As of 0.54, there are Unix ports of most of the traditional PuTTY
229 tools, and also one entirely new application.
231 If you look at the source release, you should find a \c{unix}
232 subdirectory containing \c{Makefile.gtk}, which should build you Unix
233 ports of Plink, PuTTY itself, PuTTYgen, PSCP, PSFTP, and also
234 \i\c{pterm} - an \cw{xterm}-type program which supports the same
235 terminal emulation as PuTTY. We do not yet have a Unix port of
238 If you don't have \i{Gtk}, you should still be able to build the
241 Note that Unix PuTTY has mostly only been tested on Linux so far;
242 portability problems such as BSD-style ptys or different header file
243 requirements are expected.
245 \S{faq-unix-why}{Question} What's the point of the Unix port? Unix
248 All sorts of little things. \c{pterm} is directly useful to anyone
249 who prefers PuTTY's terminal emulation to \c{xterm}'s, which at
250 least some people do. Unix Plink has apparently found a niche among
251 people who find the complexity of OpenSSL makes OpenSSH hard to
252 install (and who don't mind Plink not having as many features). Some
253 users want to generate a large number of SSH keys on Unix and then
254 copy them all into PuTTY, and the Unix PuTTYgen should allow them to
255 automate that conversion process.
257 There were development advantages as well; porting PuTTY to Unix was
258 a valuable path-finding effort for other future ports, and also
259 allowed us to use the excellent Linux tool
260 \W{http://valgrind.kde.org/}{Valgrind} to help with debugging, which
261 has already improved PuTTY's stability on \e{all} platforms.
263 However, if you're a Unix user and you can see no reason to switch
264 from OpenSSH to PuTTY/Plink, then you're probably right. We don't
265 expect our Unix port to be the right thing for everybody.
267 \S{faq-wince}{Question} Will there be a port to Windows CE or PocketPC?
269 It's currently being worked on, but it's only in its early stages yet,
270 and certainly isn't yet useful. PuTTY on portable devices would
271 clearly be a useful thing, so in the long term I hope it can be
272 brought up to release quality.
274 There's also a third-party port at
275 \W{http://pocketputty.duxy.net/}\c{http://pocketputty.duxy.net/}.
277 \S{faq-win31}{Question} Is there a port to \i{Windows 3.1}?
279 PuTTY is a 32-bit application from the ground up, so it won't run on
280 Windows 3.1 as a native 16-bit program; and it would be \e{very}
281 hard to port it to do so, because of Windows 3.1's vile memory
282 allocation mechanisms.
284 However, it is possible in theory to compile the existing PuTTY
285 source in such a way that it will run under \i{Win32s} (an extension to
286 Windows 3.1 to let you run 32-bit programs). In order to do this
287 you'll need the right kind of C compiler - modern versions of Visual
288 C at least have stopped being backwards compatible to Win32s. Also,
289 the last time we tried this it didn't work very well.
291 If you're interested in running PuTTY under Windows 3.1, help and
292 testing in this area would be very welcome!
294 \S{faq-mac-port}{Question} Will there be a port to the \I{Mac OS}Mac?
296 There are several answers to this question:
298 \b The Unix/Gtk port is already fully working under Mac OS X as an X11
301 \b A native (Cocoa) Mac OS X port has been started. It's just about
302 usable, but is of nowhere near release quality yet, and is likely to
303 behave in unexpected ways. Currently it's unlikely to be completed
304 unless someone steps in to help.
306 \b A separate port to the classic Mac OS (pre-OSX) is also in
307 progress; it too is not ready yet.
309 \S{faq-epoc}{Question} Will there be a port to EPOC?
311 I hope so, but given that ports aren't really progressing very fast
312 even on systems the developers \e{do} already know how to program
313 for, it might be a long time before any of us get round to learning
314 a new system and doing the port for that.
316 However, some of the work has been done by other people, and a beta
317 port of PuTTY for the Nokia 9200 Communicator series is available
318 from \W{http://s2putty.sourceforge.net/}\cw{http://s2putty.sourceforge.net/}
320 \H{faq-embedding} Embedding PuTTY in other programs
322 \S{faq-dll}{Question} Is the SSH or Telnet code available as a DLL?
324 No, it isn't. It would take a reasonable amount of rewriting for
325 this to be possible, and since the PuTTY project itself doesn't
326 believe in DLLs (they make installation more error-prone) none of us
327 has taken the time to do it.
329 Most of the code cleanup work would be a good thing to happen in
330 general, so if anyone feels like helping, we wouldn't say no.
332 \S{faq-vb}{Question} Is the SSH or Telnet code available as a Visual
335 No, it isn't. None of the PuTTY team uses Visual Basic, and none of
336 us has any particular need to make SSH connections from a Visual
337 Basic application. In addition, all the preliminary work to turn it
338 into a DLL would be necessary first; and furthermore, we don't even
339 know how to write VB components.
341 If someone offers to do some of this work for us, we might consider
342 it, but unless that happens I can't see VB integration being
343 anywhere other than the very bottom of our priority list.
345 \S{faq-ipc}{Question} How can I use PuTTY to make an SSH connection
346 from within another program?
348 Probably your best bet is to use Plink, the command-line connection
349 tool. If you can start Plink as a second Windows process, and
350 arrange for your primary process to be able to send data to the
351 Plink process, and receive data from it, through pipes, then you
352 should be able to make SSH connections from your program.
354 This is what CVS for Windows does, for example.
356 \H{faq-details} Details of PuTTY's operation
358 \S{faq-term}{Question} What \i{terminal type} does PuTTY use?
360 For most purposes, PuTTY can be considered to be an \cw{xterm}
363 PuTTY also supports some terminal \i{control sequences} not supported by
364 the real \cw{xterm}: notably the Linux console sequences that
365 reconfigure the colour palette, and the title bar control sequences
366 used by \i\cw{DECterm} (which are different from the \cw{xterm} ones;
367 PuTTY supports both).
369 By default, PuTTY announces its terminal type to the server as
370 \c{xterm}. If you have a problem with this, you can reconfigure it
371 to say something else; \c{vt220} might help if you have trouble.
373 \S{faq-settings}{Question} Where does PuTTY store its data?
375 On Windows, PuTTY stores most of its data (saved sessions, SSH host
376 keys) in the \i{Registry}. The precise location is
378 \c HKEY_CURRENT_USER\Software\SimonTatham\PuTTY
380 and within that area, saved sessions are stored under \c{Sessions}
381 while host keys are stored under \c{SshHostKeys}.
383 PuTTY also requires a random number seed file, to improve the
384 unpredictability of randomly chosen data needed as part of the SSH
385 cryptography. This is stored by default in a file called \i\c{PUTTY.RND}
386 in your Windows home directory (\c{%HOMEDRIVE%\\%HOMEPATH%}), or in
387 the actual Windows directory (such as \c{C:\\WINDOWS}) if the home
388 directory doesn't exist, for example if you're using Win95. If you
389 want to change the location of the random number seed file, you can
390 put your chosen pathname in the Registry, at
392 \c HKEY_CURRENT_USER\Software\SimonTatham\PuTTY\RandSeedFile
394 On Unix, PuTTY stores all of this data in a directory \cw{~/.putty}.
396 \H{faq-howto} HOWTO questions
398 \S{faq-commands}{Question} \I{commands on the server}What commands
399 can I type into my PuTTY terminal window?
401 This is not a question you should be asking \e{us}. You need to read
402 the manuals, or ask the administrator, of \e{the computer you have
405 PuTTY does not process the commands you type into it. It's only a
406 communications tool. It makes a connection to another computer; it
407 passes the commands you type to that other computer; and it passes
408 the other computer's responses back to you. Therefore, the precise
409 range of commands you can use will not depend on PuTTY, but on what
410 kind of computer you have connected to and what software is running
411 on it. The PuTTY team cannot help you with that.
413 (Think of PuTTY as being a bit like a telephone. If you phone
414 somebody up and you don't know what language to speak to make them
415 understand you, it isn't \e{the telephone company}'s job to find
416 that out for you. We just provide the means for you to get in touch;
417 making yourself understood is somebody else's problem.)
419 If you are unsure of where to start looking for the administrator of
420 your server, a good place to start might be to remember how you
421 found out the host name in the PuTTY configuration. If you were
422 given that host name by e-mail, for example, you could try asking
423 the person who sent you that e-mail. If your company's IT department
424 provided you with ready-made PuTTY saved sessions, then that IT
425 department can probably also tell you something about what commands
426 you can type during those sessions. But the PuTTY maintainer team
427 does not administer any server you are likely to be connecting to,
428 and cannot help you with questions of this type.
430 \S{faq-startmax}{Question} How can I make PuTTY start up \i{maximise}d?
432 Create a Windows shortcut to start PuTTY from, and set it as \q{Run
435 \S{faq-startsess}{Question} How can I create a \i{Windows shortcut} to
436 start a particular saved session directly?
438 To run a PuTTY session saved under the name \q{\cw{mysession}},
439 create a Windows shortcut that invokes PuTTY with a command line
442 \c \path\name\to\putty.exe -load "mysession"
444 (Note: prior to 0.53, the syntax was \c{@session}. This is now
445 deprecated and may be removed at some point.)
447 \S{faq-startssh}{Question} How can I start an SSH session straight
448 from the command line?
450 Use the command line \c{putty -ssh host.name}. Alternatively, create
451 a saved session that specifies the SSH protocol, and start the saved
452 session as shown in \k{faq-startsess}.
454 \S{faq-cutpaste}{Question} How do I \i{copy and paste} between PuTTY and
455 other Windows applications?
457 Copy and paste works similarly to the X Window System. You use the
458 left mouse button to select text in the PuTTY window. The act of
459 selection \e{automatically} copies the text to the clipboard: there
460 is no need to press Ctrl-Ins or Ctrl-C or anything else. In fact,
461 pressing Ctrl-C will send a Ctrl-C character to the other end of
462 your connection (just like it does the rest of the time), which may
463 have unpleasant effects. The \e{only} thing you need to do, to copy
464 text to the clipboard, is to select it.
466 To paste the clipboard contents into a PuTTY window, by default you
467 click the right mouse button. If you have a three-button mouse and
468 are used to X applications, you can configure pasting to be done by
469 the middle button instead, but this is not the default because most
470 Windows users don't have a middle button at all.
472 You can also paste by pressing Shift-Ins.
474 \S{faq-options}{Question} How do I use all PuTTY's features (public
475 keys, proxying, cipher selection, etc.) in PSCP, PSFTP and Plink?
477 Most major features (e.g., public keys, port forwarding) are available
478 through command line options. See the documentation.
480 Not all features are accessible from the command line yet, although
481 we'd like to fix this. In the meantime, you can use most of
482 PuTTY's features if you create a PuTTY saved session, and then use
483 the name of the saved session on the command line in place of a
484 hostname. This works for PSCP, PSFTP and Plink (but don't expect
485 port forwarding in the file transfer applications!).
487 \S{faq-pscp}{Question} How do I use PSCP.EXE? When I double-click it
488 gives me a command prompt window which then closes instantly.
490 PSCP is a command-line application, not a GUI application. If you
491 run it without arguments, it will simply print a help message and
494 To use PSCP properly, run it from a Command Prompt window. See
495 \k{pscp} in the documentation for more details.
497 \S{faq-pscp-spaces}{Question} \I{spaces in filenames}How do I use
498 PSCP to copy a file whose name has spaces in?
500 If PSCP is using the traditional SCP protocol, this is confusing. If
501 you're specifying a file at the local end, you just use one set of
502 quotes as you would normally do:
504 \c pscp "local filename with spaces" user@host:
505 \c pscp user@host:myfile "local filename with spaces"
507 But if the filename you're specifying is on the \e{remote} side, you
508 have to use backslashes and two sets of quotes:
510 \c pscp user@host:"\"remote filename with spaces\"" local_filename
511 \c pscp local_filename user@host:"\"remote filename with spaces\""
513 Worse still, in a remote-to-local copy you have to specify the local
514 file name explicitly, otherwise PSCP will complain that they don't
515 match (unless you specified the \c{-unsafe} option). The following
516 command will give an error message:
518 \c c:\>pscp user@host:"\"oo er\"" .
519 \c warning: remote host tried to write to a file called 'oo er'
520 \c when we requested a file called '"oo er"'.
522 Instead, you need to specify the local file name in full:
524 \c c:\>pscp user@host:"\"oo er\"" "oo er"
526 If PSCP is using the newer SFTP protocol, none of this is a problem,
527 and all filenames with spaces in are specified using a single pair
528 of quotes in the obvious way:
530 \c pscp "local file" user@host:
531 \c pscp user@host:"remote file" .
533 \H{faq-trouble} Troubleshooting
535 \S{faq-incorrect-mac}{Question} Why do I see \q{Incorrect MAC
538 One possible cause of this that used to be common is a bug in old
539 SSH-2 servers distributed by \cw{ssh.com}. (This is not the only
540 possible cause; see \k{errors-crc} in the documentation.)
541 Version 2.3.0 and below of their SSH-2 server
542 constructs Message Authentication Codes in the wrong way, and
543 expects the client to construct them in the same wrong way. PuTTY
544 constructs the MACs correctly by default, and hence these old
545 servers will fail to work with it.
547 If you are using PuTTY version 0.52 or better, this should work
548 automatically: PuTTY should detect the buggy servers from their
549 version number announcement, and automatically start to construct
550 its MACs in the same incorrect manner as they do, so it will be able
553 If you are using PuTTY version 0.51 or below, you can enable the
554 workaround by going to the SSH panel and ticking the box labelled
555 \q{Imitate SSH2 MAC bug}. It's possible that you might have to do
556 this with 0.52 as well, if a buggy server exists that PuTTY doesn't
559 In this context MAC stands for \ii{Message Authentication Code}. It's a
560 cryptographic term, and it has nothing at all to do with Ethernet
561 MAC (Media Access Control) addresses.
563 \S{faq-pscp-protocol}{Question} Why do I see \q{Fatal: Protocol
564 error: Expected control record} in PSCP?
566 This happens because PSCP was expecting to see data from the server
567 that was part of the PSCP protocol exchange, and instead it saw data
568 that it couldn't make any sense of at all.
570 This almost always happens because the \i{startup scripts} in your
571 account on the server machine are generating output. This is
572 impossible for PSCP, or any other SCP client, to work around. You
573 should never use startup files (\c{.bashrc}, \c{.cshrc} and so on)
574 which generate output in non-interactive sessions.
576 This is not actually a PuTTY problem. If PSCP fails in this way,
577 then all other SCP clients are likely to fail in exactly the same
578 way. The problem is at the server end.
580 \S{faq-colours}{Question} I clicked on a colour in the \ii{Colours}
581 panel, and the colour didn't change in my terminal.
583 That isn't how you're supposed to use the Colours panel.
585 During the course of a session, PuTTY potentially uses \e{all} the
586 colours listed in the Colours panel. It's not a question of using
587 only one of them and you choosing which one; PuTTY will use them
588 \e{all}. The purpose of the Colours panel is to let you adjust the
589 appearance of all the colours. So to change the colour of the
590 cursor, for example, you would select \q{Cursor Colour}, press the
591 \q{Modify} button, and select a new colour from the dialog box that
592 appeared. Similarly, if you want your session to appear in green,
593 you should select \q{Default Foreground} and press \q{Modify}.
594 Clicking on \q{ANSI Green} won't turn your session green; it will
595 only allow you to adjust the \e{shade} of green used when PuTTY is
596 instructed by the server to display green text.
598 \S{faq-winsock2}{Question} Plink on \i{Windows 95} says it can't find
601 Plink requires the extended Windows network library, WinSock version
602 2. This is installed as standard on Windows 98 and above, and on
603 Windows NT, and even on later versions of Windows 95; but early
604 Win95 installations don't have it.
606 In order to use Plink on these systems, you will need to download
608 \W{http://www.microsoft.com/windows95/downloads/contents/wuadmintools/s_wunetworkingtools/w95sockets2/}{WinSock 2 upgrade}:
610 \c http://www.microsoft.com/windows95/downloads/contents/
611 \c wuadmintools/s_wunetworkingtools/w95sockets2/
613 \S{faq-outofmem}{Question} After trying to establish an SSH-2
614 connection, PuTTY says \q{\ii{Out of memory}} and dies.
616 If this happens just while the connection is starting up, this often
617 indicates that for some reason the client and server have failed to
618 establish a session encryption key. Somehow, they have performed
619 calculations that should have given each of them the same key, but
620 have ended up with different keys; so data encrypted by one and
621 decrypted by the other looks like random garbage.
623 This causes an \q{out of memory} error because the first encrypted
624 data PuTTY expects to see is the length of an SSH message. Normally
625 this will be something well under 100 bytes. If the decryption has
626 failed, PuTTY will see a completely random length in the region of
627 two \e{gigabytes}, and will try to allocate enough memory to store
628 this non-existent message. This will immediately lead to it thinking
629 it doesn't have enough memory, and panicking.
631 If this happens to you, it is quite likely to still be a PuTTY bug
632 and you should report it (although it might be a bug in your SSH
633 server instead); but it doesn't necessarily mean you've actually run
636 \S{faq-outofmem2}{Question} When attempting a file transfer, either
637 PSCP or PSFTP says \q{\ii{Out of memory}} and dies.
639 This is almost always caused by your \i{login scripts} on the server
640 generating output. PSCP or PSFTP will receive that output when they
641 were expecting to see the start of a file transfer protocol, and
642 they will attempt to interpret the output as file-transfer protocol.
643 This will usually lead to an \q{out of memory} error for much the
644 same reasons as given in \k{faq-outofmem}.
646 This is a setup problem in your account on your server, \e{not} a
647 PSCP/PSFTP bug. Your login scripts should \e{never} generate output
648 during non-interactive sessions; secure file transfer is not the
649 only form of remote access that will break if they do.
651 On Unix, a simple fix is to ensure that all the parts of your login
652 script that might generate output are in \c{.profile} (if you use a
653 Bourne shell derivative) or \c{.login} (if you use a C shell).
654 Putting them in more general files such as \c{.bashrc} or \c{.cshrc}
655 is liable to lead to problems.
657 \S{faq-psftp-slow}{Question} PSFTP transfers files much slower than PSCP.
659 The throughput of PSFTP 0.54 should be much better than 0.53b and
660 prior; we've added code to the SFTP backend to queue several blocks
661 of data rather than waiting for an acknowledgement for each. (The
662 SCP backend did not suffer from this performance issue because SCP
663 is a much simpler protocol.)
665 \S{faq-bce}{Question} When I run full-colour applications, I see
666 areas of black space where colour ought to be, or vice versa.
668 You almost certainly need to change the \q{Use \i{background colour} to
669 erase screen} setting in the Terminal panel. If there is too much
670 black space (the commoner situation), you should enable it, while if
671 there is too much colour, you should disable it. (See \k{config-erase}.)
673 In old versions of PuTTY, this was disabled by default, and would not
674 take effect until you reset the terminal (see \k{faq-resetterm}).
675 Since 0.54, it is enabled by default, and changes take effect
678 \S{faq-resetterm}{Question} When I change some terminal settings,
681 Some of the terminal options (notably \ii{Auto Wrap} and
682 background-colour screen erase) actually represent the \e{default}
683 setting, rather than the currently active setting. The server can
684 send sequences that modify these options in mid-session, but when
685 the terminal is reset (by server action, or by you choosing \q{Reset
686 Terminal} from the System menu) the defaults are restored.
688 In versions 0.53b and prior, if you change one of these options in
689 the middle of a session, you will find that the change does not
690 immediately take effect. It will only take effect once you reset
693 In version 0.54, the behaviour has changed - changes to these
694 settings take effect immediately.
696 \S{faq-idleout}{Question} My PuTTY sessions unexpectedly close after
697 they are \I{idle connections}idle for a while.
699 Some types of \i{firewall}, and almost any router doing Network Address
700 Translation (\i{NAT}, also known as IP masquerading), will forget about
701 a connection through them if the connection does nothing for too
702 long. This will cause the connection to be rudely cut off when
705 You can try to combat this by telling PuTTY to send \e{keepalives}:
706 packets of data which have no effect on the actual session, but
707 which reassure the router or firewall that the network connection is
708 still active and worth remembering about.
710 Keepalives don't solve everything, unfortunately; although they
711 cause greater robustness against this sort of router, they can also
712 cause a \e{loss} of robustness against network dropouts. See
713 \k{config-keepalive} in the documentation for more discussion of
716 \S{faq-timeout}{Question} PuTTY's network connections time out too
717 quickly when \I{breaks in connectivity}network connectivity is
720 This is a Windows problem, not a PuTTY problem. The timeout value
721 can't be set on per application or per session basis. To increase
722 the TCP timeout globally, you need to tinker with the Registry.
724 On Windows 95, 98 or ME, the registry key you need to create or
727 \c HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\
728 \c MSTCP\MaxDataRetries
730 (it must be of type DWORD in Win95, or String in Win98/ME).
731 (See MS Knowledge Base article
732 \W{http://support.microsoft.com/default.aspx?scid=kb;en-us;158474}{158474}
733 for more information.)
735 On Windows NT, 2000, or XP, the registry key to create or change is
737 \c HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\
738 \c Parameters\TcpMaxDataRetransmissions
740 and it must be of type DWORD.
741 (See MS Knowledge Base articles
742 \W{http://support.microsoft.com/default.aspx?scid=kb;en-us;120642}{120642}
744 \W{http://support.microsoft.com/default.aspx?scid=kb;en-us;314053}{314053}
745 for more information.)
747 Set the key's value to something like 10. This will cause Windows to
748 try harder to keep connections alive instead of abandoning them.
750 \S{faq-puttyputty}{Question} When I \cw{cat} a binary file, I get
751 \q{PuTTYPuTTYPuTTY} on my command line.
755 This is designed behaviour; when PuTTY receives the character
756 Control-E from the remote server, it interprets it as a request to
757 identify itself, and so it sends back the string \q{\cw{PuTTY}} as
758 if that string had been entered at the keyboard. Control-E should
759 only be sent by programs that are prepared to deal with the
760 response. Writing a binary file to your terminal is likely to output
761 many Control-E characters, and cause this behaviour. Don't do it.
764 To mitigate the effects, you could configure the answerback string
765 to be empty (see \k{config-answerback}); but writing binary files to
766 your terminal is likely to cause various other unpleasant behaviour,
767 so this is only a small remedy.
769 \S{faq-wintitle}{Question} When I \cw{cat} a binary file, my \i{window
770 title} changes to a nonsense string.
774 It is designed behaviour that PuTTY should have the ability to
775 adjust the window title on instructions from the server. Normally
776 the control sequence that does this should only be sent
777 deliberately, by programs that know what they are doing and intend
778 to put meaningful text in the window title. Writing a binary file to
779 your terminal runs the risk of sending the same control sequence by
780 accident, and cause unexpected changes in the window title. Don't do
783 \S{faq-password-fails}{Question} My \i{keyboard} stops working once
784 PuTTY displays the \i{password prompt}.
786 No, it doesn't. PuTTY just doesn't display the password you type, so
787 that someone looking at your screen can't see what it is.
789 Unlike the Windows login prompts, PuTTY doesn't display the password
790 as a row of asterisks either. This is so that someone looking at
791 your screen can't even tell how \e{long} your password is, which
792 might be valuable information.
794 \S{faq-keyboard}{Question} One or more \I{keyboard}\i{function keys}
795 don't do what I expected in a server-side application.
797 If you've already tried all the relevant options in the PuTTY
798 Keyboard panel, you may need to mail the PuTTY maintainers and ask.
800 It is \e{not} usually helpful just to tell us which application,
801 which server operating system, and which key isn't working; in order
802 to replicate the problem we would need to have a copy of every
803 operating system, and every application, that anyone has ever
806 PuTTY responds to function key presses by sending a sequence of
807 control characters to the server. If a function key isn't doing what
808 you expect, it's likely that the character sequence your application
809 is expecting to receive is not the same as the one PuTTY is sending.
810 Therefore what we really need to know is \e{what} sequence the
811 application is expecting.
813 The simplest way to investigate this is to find some other terminal
814 environment, in which that function key \e{does} work; and then
815 investigate what sequence the function key is sending in that
816 situation. One reasonably easy way to do this on a \i{Unix} system is to
817 type the command \i\c{cat}, and then press the function key. This is
818 likely to produce output of the form \c{^[[11~}. You can also do
819 this in PuTTY, to find out what sequence the function key is
820 producing in that. Then you can mail the PuTTY maintainers and tell
821 us \q{I wanted the F1 key to send \c{^[[11~}, but instead it's
822 sending \c{^[OP}, can this be done?}, or something similar.
824 You should still read the
825 \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/feedback.html}{Feedback
826 page} on the PuTTY website (also provided as \k{feedback} in the
827 manual), and follow the guidelines contained in that.
829 \S{faq-openssh-bad-openssl}{Question} Since my SSH server was upgraded
830 to \i{OpenSSH} 3.1p1/3.4p1, I can no longer connect with PuTTY.
832 There is a known problem when OpenSSH has been built against an
833 incorrect version of OpenSSL; the quick workaround is to configure
834 PuTTY to use SSH protocol 2 and the Blowfish cipher.
836 For more details and OpenSSH patches, see
837 \W{http://bugzilla.mindrot.org/show_bug.cgi?id=138}{bug 138} in the
840 This is not a PuTTY-specific problem; if you try to connect with
841 another client you'll likely have similar problems. (Although PuTTY's
842 default cipher differs from many other clients.)
844 \e{OpenSSH 3.1p1:} configurations known to be broken (and symptoms):
846 \b SSH-2 with AES cipher (PuTTY says \q{Assertion failed! Expression:
847 (len & 15) == 0} in \cw{sshaes.c}, or \q{Out of memory}, or crashes)
849 \b SSH-2 with 3DES (PuTTY says \q{Incorrect MAC received on packet})
851 \b SSH-1 with Blowfish (PuTTY says \q{Incorrect CRC received on
856 \e{OpenSSH 3.4p1:} as of 3.4p1, only the problem with SSH-1 and
857 Blowfish remains. Rebuild your server, apply the patch linked to from
858 bug 138 above, or use another cipher (e.g., 3DES) instead.
860 \e{Other versions:} we occasionally get reports of the same symptom
861 and workarounds with older versions of OpenSSH, although it's not
862 clear the underlying cause is the same.
864 \S{faq-ssh2key-ssh1conn}{Question} Why do I see \q{Couldn't load
865 private key from ...}? Why can PuTTYgen load my key but not PuTTY?
867 It's likely that you've generated an SSH protocol 2 key with PuTTYgen,
868 but you're trying to use it in an SSH-1 connection. SSH-1 and SSH-2 keys
869 have different formats, and (at least in 0.52) PuTTY's reporting of a
870 key in the wrong format isn't optimal.
872 To connect using SSH-2 to a server that supports both versions, you
873 need to change the configuration from the default (see \k{faq-ssh2}).
875 \S{faq-rh8-utf8}{Question} When I'm connected to a \i{Red Hat Linux} 8.0
876 system, some characters don't display properly.
878 A common complaint is that hyphens in man pages show up as a-acute.
880 With release 8.0, Red Hat appear to have made \i{UTF-8} the default
881 character set. There appears to be no way for terminal emulators such
882 as PuTTY to know this (as far as we know, the appropriate escape
883 sequence to switch into UTF-8 mode isn't sent).
885 A fix is to configure sessions to RH8 systems to use UTF-8
886 translation - see \k{config-charset} in the documentation. (Note that
887 if you use \q{Change Settings}, changes may not take place immediately
888 - see \k{faq-resetterm}.)
890 If you really want to change the character set used by the server, the
891 right place is \c{/etc/sysconfig/i18n}, but this shouldn't be
894 \S{faq-screen}{Question} Since I upgraded to PuTTY 0.54, the
895 scrollback has stopped working when I run \c{screen}.
897 PuTTY's terminal emulator has always had the policy that when the
898 \q{\i{alternate screen}} is in use, nothing is added to the scrollback.
899 This is because the usual sorts of programs which use the alternate
900 screen are things like text editors, which tend to scroll back and
901 forth in the same document a lot; so (a) they would fill up the
902 scrollback with a large amount of unhelpfully disordered text, and
903 (b) they contain their \e{own} method for the user to scroll back to
904 the bit they were interested in. We have generally found this policy
905 to do the Right Thing in almost all situations.
907 Unfortunately, \c{screen} is one exception: it uses the alternate
908 screen, but it's still usually helpful to have PuTTY's scrollback
909 continue working. The simplest solution is to go to the Features
910 control panel and tick \q{Disable switching to alternate terminal
911 screen}. (See \k{config-features-altscreen} for more details.)
912 Alternatively, you can tell \c{screen} itself not to use the
913 alternate screen: the
914 \W{http://www4.informatik.uni-erlangen.de/~jnweiger/screen-faq.html}{\c{screen}
915 FAQ} suggests adding the line \cq{termcapinfo xterm ti@:te@} to your
918 The reason why this only started to be a problem in 0.54 is because
919 \c{screen} typically uses an unusual control sequence to switch to
920 the alternate screen, and previous versions of PuTTY did not support
923 \S{faq-alternate-localhost}{Question} Since I upgraded \i{Windows XP}
924 to Service Pack 2, I can't use addresses like \cw{127.0.0.2}.
926 Some people who ask PuTTY to listen on \i{localhost} addresses other
927 than \cw{127.0.0.1} to forward services such as \i{SMB} and \i{Windows
928 Terminal Services} have found that doing so no longer works since
929 they upgraded to WinXP SP2.
931 This is apparently an issue with SP2 that is acknowledged by Microsoft
932 in MS Knowledge Base article
933 \W{http://support.microsoft.com/default.aspx?scid=kb;en-us;884020}{884020}.
934 The article links to a fix you can download.
936 (\e{However}, we've been told that SP2 \e{also} fixes the bug that
937 means you need to use non-\cw{127.0.0.1} addresses to forward
938 Terminal Services in the first place.)
940 \S{faq-missing-slash}{Question} PSFTP commands seem to be missing a
941 directory separator (slash).
943 Some people have reported the following incorrect behaviour with
948 \c Remote directory is /dir1/dir2
949 \c psftp> get filename.ext
951 \c /dir1/dir2filename.ext: no such file or directory
953 This is not a bug in PSFTP. There is a known bug in some versions of
955 (\W{http://bugzilla.mindrot.org/show_bug.cgi?id=697}{bug 697}) that
956 causes these symptoms; it appears to have been introduced around
957 3.7.x. It manifests only on certain platforms (AIX is what has been
960 There is a patch for OpenSSH attached to that bug; it's also fixed in
961 recent versions of portable OpenSSH (from around 3.8).
963 \S{faq-connaborted}{Question} Do you want to hear about \q{Software
964 caused connection abort}?
966 In the documentation for PuTTY 0.53 and 0.53b, we mentioned that we'd
967 like to hear about any occurrences of this error. Since the release
968 of PuTTY 0.54, however, we've been convinced that this error doesn't
969 indicate that PuTTY's doing anything wrong, and we don't need to hear
970 about further occurrences. See \k{errors-connaborted} for our current
971 documentation of this error.
973 \S{faq-rekey}{Question} My SSH-2 session \I{locking up, SSH-2
974 sessions}locks up for a few seconds every so often.
976 Recent versions of PuTTY automatically initiate \i{repeat key
977 exchange} once per hour, to improve session security. If your client
978 or server machine is slow, you may experience this as a delay of
979 anything up to thirty seconds or so.
981 These \I{delays, in SSH-2 sessions}delays are inconvenient, but they
982 are there for your protection. If they really cause you a problem,
983 you can choose to turn off periodic rekeying using the \q{Kex}
984 configuration panel (see \k{config-ssh-kex}), but be aware that you
985 will be sacrificing security for this. (Falling back to SSH-1 would
986 also remove the delays, but would lose a \e{lot} more security
987 still. We do not recommend it.)
989 \S{faq-xpwontrun}{Question} PuTTY fails to start up. Windows claims that
990 \q{the application configuration is incorrect}.
992 This is caused by a bug in certain versions of \i{Windows XP} which is
993 triggered by PuTTY 0.58. It can be avoided by installing
994 Service Pack 2, by using a different version of PuTTY, or by installing
995 a special \i{manifest file} alongside the PuTTY executable.
997 \W{http://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/xp-wont-run}{\q{xp-wont-run}}
998 entry in PuTTY's wishlist has more details.
1000 \H{faq-secure} Security questions
1002 \S{faq-publicpc}{Question} Is it safe for me to download PuTTY and
1003 use it on a public PC?
1005 It depends on whether you trust that PC. If you don't trust the
1006 public PC, don't use PuTTY on it, and don't use any other software
1007 you plan to type passwords into either. It might be watching your
1008 keystrokes, or it might tamper with the PuTTY binary you download.
1009 There is \e{no} program safe enough that you can run it on an
1010 actively malicious PC and get away with typing passwords into it.
1012 If you do trust the PC, then it's probably OK to use PuTTY on it
1013 (but if you don't trust the network, then the PuTTY download might
1014 be tampered with, so it would be better to carry PuTTY with you on a
1017 \S{faq-cleanup}{Question} What does PuTTY leave on a system? How can
1018 I \i{clean up} after it?
1020 PuTTY will leave some Registry entries, and a random seed file, on
1021 the PC (see \k{faq-settings}). If you are using PuTTY on a public
1022 PC, or somebody else's PC, you might want to clean these up when you
1023 leave. You can do that automatically, by running the command
1024 \c{putty -cleanup}. (Note that this only removes settings for
1025 the currently logged-in user on \i{multi-user systems}.)
1027 If PuTTY was installed from the installer package, it will also
1028 appear in \q{Add/Remove Programs}. Older versions of the uninstaller
1029 do not remove the above-mentioned registry entries and file.
1031 \S{faq-dsa}{Question} How come PuTTY now supports \i{DSA}, when the
1032 website used to say how insecure it was?
1034 DSA has a major weakness \e{if badly implemented}: it relies on a
1035 random number generator to far too great an extent. If the random
1036 number generator produces a number an attacker can predict, the DSA
1037 private key is exposed - meaning that the attacker can log in as you
1038 on all systems that accept that key.
1040 The PuTTY policy changed because the developers were informed of
1041 ways to implement DSA which do not suffer nearly as badly from this
1042 weakness, and indeed which don't need to rely on random numbers at
1043 all. For this reason we now believe PuTTY's DSA implementation is
1044 probably OK. However, if you have the choice, we still recommend you
1047 \S{faq-virtuallock}{Question} Couldn't Pageant use
1048 \cw{VirtualLock()} to stop private keys being written to disk?
1050 Unfortunately not. The \cw{VirtualLock()} function in the Windows
1051 API doesn't do a proper job: it may prevent small pieces of a
1052 process's memory from being paged to disk while the process is
1053 running, but it doesn't stop the process's memory as a whole from
1054 being swapped completely out to disk when the process is long-term
1055 inactive. And Pageant spends most of its time inactive.
1057 \H{faq-admin} Administrative questions
1059 \S{faq-domain}{Question} Would you like me to register you a nicer
1062 No, thank you. Even if you can find one (most of them seem to have
1063 been registered already, by people who didn't ask whether we
1064 actually wanted it before they applied), we're happy with the PuTTY
1065 web site being exactly where it is. It's not hard to find (just type
1066 \q{putty} into \W{http://www.google.com/}{google.com} and we're the
1067 first link returned), and we don't believe the administrative hassle
1068 of moving the site would be worth the benefit.
1070 In addition, if we \e{did} want a custom domain name, we would want
1071 to run it ourselves, so we knew for certain that it would continue
1072 to point where we wanted it, and wouldn't suddenly change or do
1073 strange things. Having it registered for us by a third party who we
1074 don't even know is not the best way to achieve this.
1076 \S{faq-webhosting}{Question} Would you like free web hosting for the
1079 We already have some, thanks.
1081 \S{faq-link}{Question} Would you link to my web site from the PuTTY
1084 Only if the content of your web page is of definite direct interest
1085 to PuTTY users. If your content is unrelated, or only tangentially
1086 related, to PuTTY, then the link would simply be advertising for
1089 One very nice effect of the Google ranking mechanism is that by and
1090 large, the most popular web sites get the highest rankings. This
1091 means that when an ordinary person does a search, the top item in
1092 the search is very likely to be a high-quality site or the site they
1093 actually wanted, rather than the site which paid the most money for
1096 The PuTTY web site is held in high esteem by Google, for precisely
1097 this reason: lots of people have linked to it simply because they
1098 like PuTTY, without us ever having to ask anyone to link to us. We
1099 feel that it would be an abuse of this esteem to use it to boost the
1100 ranking of random advertisers' web sites. If you want your web site
1101 to have a high Google ranking, we'd prefer that you achieve this the
1102 way we did - by being good enough at what you do that people will
1103 link to you simply because they like you.
1105 In particular, we aren't interested in trading links for money (see
1106 above), and we \e{certainly} aren't interested in trading links for
1107 other links (since we have no advertising on our web site, our
1108 Google ranking is not even directly worth anything to us). If we
1109 don't want to link to you for free, then we probably won't want to
1112 If you have software based on PuTTY, or specifically designed to
1113 interoperate with PuTTY, or in some other way of genuine interest to
1114 PuTTY users, then we will probably be happy to add a link to you on
1115 our Links page. And if you're running a mirror of the PuTTY web
1116 site, we're \e{definitely} interested.
1118 \S{faq-sourceforge}{Question} Why don't you move PuTTY to
1121 Partly, because we don't want to move the web site location (see
1124 Also, security reasons. PuTTY is a security product, and as such it
1125 is particularly important to guard the code and the web site against
1126 unauthorised modifications which might introduce subtle security
1127 flaws. Therefore, we prefer that the Subversion repository, web site and
1128 FTP site remain where they are, under the direct control of system
1129 administrators we know and trust personally, rather than being run
1130 by a large organisation full of people we've never met and which is
1131 known to have had breakins in the past.
1133 No offence to SourceForge; I think they do a wonderful job. But
1134 they're not ideal for everyone, and in particular they're not ideal
1137 \S{faq-mailinglist1}{Question} Why can't I subscribe to the
1138 putty-bugs mailing list?
1140 Because you're not a member of the PuTTY core development team. The
1141 putty-bugs mailing list is not a general newsgroup-like discussion
1142 forum; it's a contact address for the core developers, and an
1143 \e{internal} mailing list for us to discuss things among ourselves.
1144 If we opened it up for everybody to subscribe to, it would turn into
1145 something more like a newsgroup and we would be completely
1146 overwhelmed by the volume of traffic. It's hard enough to keep up
1147 with the list as it is.
1149 \S{faq-mailinglist2}{Question} If putty-bugs isn't a
1150 general-subscription mailing list, what is?
1152 There isn't one, that we know of.
1154 If someone else wants to set up a mailing list or other forum for
1155 PuTTY users to help each other with common problems, that would be
1156 fine with us, though the PuTTY team would almost certainly not have the
1157 time to read it. It's probably better to use one of the established
1158 newsgroups for this purpose (see \k{feedback-other-fora}).
1160 \S{faq-donations}{Question} How can I donate to PuTTY development?
1162 Please, \e{please} don't feel you have to. PuTTY is completely free
1163 software, and not shareware. We think it's very important that
1164 \e{everybody} who wants to use PuTTY should be able to, whether they
1165 have any money or not; so the last thing we would want is for a
1166 PuTTY user to feel guilty because they haven't paid us any money. If
1167 you want to keep your money, please do keep it. We wouldn't dream of
1170 Having said all that, if you still really \e{want} to give us money,
1171 we won't argue :-) The easiest way for us to accept donations is if
1172 you send money to \cw{<anakin@pobox.com>} using PayPal
1173 (\W{http://www.paypal.com/}\cw{www.paypal.com}). Alternatively, if
1174 you don't trust PayPal, you could donate through e-gold
1175 (\W{http://www.e-gold.com}\cw{www.e-gold.com}): deposit your
1176 donation in account number 174769, then send us e-mail to let us
1177 know you've done so (otherwise we might not notice for months!).
1179 Small donations (tens of dollars or tens of euros) will probably be
1180 spent on beer or curry, which helps motivate our volunteer team to
1181 continue doing this for the world. Larger donations will be spent on
1182 something that actually helps development, if we can find anything
1183 (perhaps new hardware, or a copy of Windows XP), but if we can't
1184 find anything then we'll just distribute the money among the
1185 developers. If you want to be sure your donation is going towards
1186 something worthwhile, ask us first. If you don't like these terms,
1187 feel perfectly free not to donate. We don't mind.
1189 \S{faq-permission}{Question} Can I have permission to put PuTTY on a
1190 cover disk / distribute it with other software / etc?
1192 Yes. You need not bother asking us explicitly for permission. You
1193 already have permission. Redistribution of the unmodified PuTTY
1194 binary in this way is entirely permitted by our licence (see
1195 \k{licence}), and you are welcome to do it as much as you like.
1197 If you are distributing PuTTY within your own organisation, or for
1198 use with your own product, then we recommend (but do not insist)
1199 that you offer your own first-line technical support, to answer
1200 questions directly relating to the interaction of PuTTY with your
1201 particular environment. If your users mail us directly, we won't be
1202 able to give them very much help about things specific to your own
1205 \H{faq-misc} Miscellaneous questions
1207 \S{faq-openssh}{Question} Is PuTTY a port of \i{OpenSSH}, or based on
1210 No, it isn't. PuTTY is almost completely composed of code written
1211 from scratch for PuTTY. The only code we share with OpenSSH is the
1212 detector for SSH-1 CRC compensation attacks, written by CORE SDI S.A.
1214 \S{faq-sillyputty}{Question} Where can I buy silly putty?
1216 You're looking at the wrong web site; the only PuTTY we know about
1217 here is the name of a computer program.
1219 If you want the kind of putty you can buy as an executive toy, the
1220 PuTTY team can personally recommend Thinking Putty, which you can
1221 buy from Crazy Aaron's Putty World, at
1222 \W{http://www.puttyworld.com}\cw{www.puttyworld.com}.
1224 \S{faq-meaning}{Question} What does \q{PuTTY} mean?
1226 It's the name of a popular SSH and Telnet client. Any other meaning
1227 is in the eye of the beholder. It's been rumoured that \q{PuTTY}
1228 is the antonym of \q{\cw{getty}}, or that it's the stuff that makes your
1229 Windows useful, or that it's a kind of plutonium Teletype. We
1230 couldn't possibly comment on such allegations.
1232 \S{faq-pronounce}{Question} How do I pronounce \q{PuTTY}?
1234 Exactly like the English word \q{putty}, which we pronounce
1235 /\u02C8{'}p\u028C{V}ti/.