X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/1d2a9c9caa60dc62a8f510957880cb7941af4c2b..1b56c05584652dba13d7f4f54e7ac2560dab92fe:/doc/faq.but diff --git a/doc/faq.but b/doc/faq.but index 38531386..2592e50c 100644 --- a/doc/faq.but +++ b/doc/faq.but @@ -1,4 +1,4 @@ -\versionid $Id: faq.but,v 1.22 2002/03/24 13:42:30 jacob Exp $ +\versionid $Id: faq.but,v 1.35 2002/09/14 10:24:27 jacob Exp $ \A{faq} PuTTY FAQ @@ -37,10 +37,9 @@ version 0.52. \S{faq-ssh2-keyfmt}{Question} Does PuTTY support reading OpenSSH or \cw{ssh.com} SSHv2 private key files? -Not at present. OpenSSH and \cw{ssh.com} have totally different -formats for private key files, and neither one is particularly -pleasant, so PuTTY has its own. We do plan to write a converter at -some stage. +Version 0.52 doesn't, but in the latest development snapshots +PuTTYgen can load and save both OpenSSH and \cw{ssh.com} private key +files. \S{faq-ssh1}{Question} Does PuTTY support SSH v1? @@ -194,7 +193,7 @@ We do not have ports for any other systems at the present time. If anyone told you we had a Unix port, or an iPaq port, or any other port of PuTTY, they were mistaken. We don't. -\S{faq-wince}{Question} Will there be a port to Windows CE? +\S{faq-wince}{Question} Will there be a port to Windows CE or PocketPC? Probably not in the particularly near future. Despite sharing large parts of the Windows API, in practice WinCE doesn't appear to be @@ -532,6 +531,36 @@ and you should report it (although it might be a bug in your SSH server instead); but it doesn't necessarily mean you've actually run out of memory. +\S{faq-outofmem2}{Question} When attempting a file transfer, either +PSCP or PSFTP says \q{Out of memory} and dies. + +This is almost always caused by your login scripts on the server +generating output. PSCP or PSFTP will receive that output when they +were expecting to see the start of a file transfer protocol, and +they will attempt to interpret the output as file-transfer protocol. +This will usually lead to an \q{out of memory} error for much the +same reasons as given in \k{faq-outofmem}. + +This is a setup problem in your account on your server, \e{not} a +PSCP/PSFTP bug. Your login scripts should \e{never} generate output +during non-interactive sessions; secure file transfer is not the +only form of remote access that will break if they do. + +On Unix, a simple fix is to ensure that all the parts of your login +script that might generate output are in \c{.profile} (if you use a +Bourne shell derivative) or \c{.login} (if you use a C shell). +Putting them in more general files such as \c{.bashrc} or \c{.cshrc} +is liable to lead to problems. + +\S{faq-psftp-slow} PSFTP transfers files much slower than PSCP. + +We believe this is because the SFTP and SSH2 protocols are less +efficient at bulk data transfer than SCP and SSH1, because every +block of data transferred requires an acknowledgment from the far +end. It would in theory be possible to queue several blocks of data +to get round this speed problem, but as yet we haven't done the +coding. If you really want this fixed, feel free to offer to help. + \S{faq-bce}{Question} When I run full-colour applications, I see areas of black space where colour ought to be. @@ -683,29 +712,51 @@ You should still read the page} on the PuTTY website (also provided as \k{feedback} in the manual), and follow the guidelines contained in that. -\S{faq-broken-openssh31}{Question} Since my SSH server was upgraded to -OpenSSH 3.1p1, I can no longer connect with PuTTY. +\S{faq-openssh-bad-openssl}{Question} Since my SSH server was upgraded +to OpenSSH 3.1p1/3.4p1, I can no longer connect with PuTTY. There is a known problem when OpenSSH has been built against an incorrect version of OpenSSL; the quick workaround is to configure PuTTY to use SSH protocol 2 and the Blowfish cipher. +For more details and OpenSSH patches, see +\W{http://bugzilla.mindrot.org/show_bug.cgi?id=138}{bug 138} in the +OpenSSH BTS. + This is not a PuTTY-specific problem; if you try to connect with -another client you'll likely have similar problems. +another client you'll likely have similar problems. (Although PuTTY's +default cipher differs from many other clients.) -Configurations known to be broken and symptoms: +\e{OpenSSH 3.1p1:} configurations known to be broken (and symptoms): \b SSH 2 with AES cipher (PuTTY says "Assertion failed! Expression: (len & 15) == 0" in sshaes.c, or "Out of memory", or crashes) +\b SSH 2 with 3DES (PuTTY says "Incorrect MAC received on packet") + \b SSH 1 with Blowfish (PuTTY says "Incorrect CRC received on packet") \b SSH 1 with 3DES -For more details and OpenSSH patches, see -\W{http://bugzilla.mindrot.org/show_bug.cgi?id=138}{bug 138} in the -OpenSSH BTS. +\e{OpenSSH 3.4p1:} as of 3.4p1, only the problem with SSH 1 and +Blowfish remains. Rebuild your server, apply the patch linked to from +bug 138 above, or use another cipher (e.g., 3DES) instead. + +\e{Other versions:} we occasionally get reports of the same symptom +and workarounds with older versions of OpenSSH, although it's not +clear the underlying cause is the same. + +\S{faq-ssh2key-ssh1conn}{Question} Why do I see "Couldn't load private +key from ..."? Why can PuTTYgen load my key but not PuTTY? + +It's likely that you've generated an SSH protocol 2 key with PuTTYgen, +but you're trying to use it in an SSH 1 connection. SSH1 and SSH2 keys +have different formats, and (at least in 0.52) PuTTY's reporting of a +key in the wrong format isn't optimal. + +To connect using SSH 2 to a server that supports both versions, you +need to change the configuration from the default (see \k{faq-ssh2}). \H{faq-secure} Security questions @@ -749,6 +800,16 @@ all. For this reason we now believe PuTTY's DSA implementation is probably OK. However, if you have the choice, we still recommend you use RSA instead. +\S{faq-virtuallock}{Question} Couldn't Pageant use +\cw{VirtualLock()} to stop private keys being written to disk? + +Unfortunately not. The \cw{VirtualLock()} function in the Windows +API doesn't do a proper job: it may prevent small pieces of a +process's memory from being paged to disk while the process is +running, but it doesn't stop the process's memory as a whole from +being swapped completely out to disk when the process is long-term +inactive. And Pageant spends most of its time inactive. + \H{faq-admin} Administrative questions \S{faq-domain}{Question} Would you like me to register you a nicer @@ -846,6 +907,15 @@ developers. If you want to be sure your donation is going towards something worthwhile, ask us first. If you don't like these terms, feel perfectly free not to donate. We don't mind. +\H{faq-misc} Miscellaneous questions + +\S{faq-openssh}{Question} Is PuTTY a port of OpenSSH, or based on +OpenSSH? + +No, it isn't. PuTTY is almost completely composed of code written +from scratch for PuTTY. The only code we share with OpenSSH is the +detector for SSH1 CRC compensation attacks, written by CORE SDI S.A. + \S{faq-sillyputty}{Question} Where can I buy silly putty? You're looking at the wrong web site; the only PuTTY we know about