automatic behaviour, but to ask the user every time the problem
comes up.
+\S{config-logflush} \q{Flush log file frequently}
+
+\cfg{winhelp-topic}{logging.flush}
+
+This option allows you to control how frequently logged data is
+flushed to disc. By default, PuTTY will flush data as soon as it is
+displayed, so that if you view the log file while a session is still
+open, it will be up to date; and if the client system crashes, there's
+a greater chance that the data will be preserved.
+
+However, this can incur a performance penalty. If PuTTY is running
+slowly with logging enabled, you could try unchecking this option. Be
+warned that the log file may not always be up to date as a result
+(although it will of course be flushed when it is closed, for instance
+at the end of a session).
+
\S{config-logssh} Options specific to SSH packet logging
These options only apply if SSH packet data is being logged.
turn this option off and make PuTTY only use the default foreground
and background colours.
+\S{config-xtermcolour} \q{Allow terminal to use xterm 256-colour mode}
+
+\cfg{winhelp-topic}{colours.xterm256}
+
+This option is enabled by default. If it is disabled, PuTTY will
+ignore any control sequences sent by the server which use the
+extended 256-colour mode supported by recent versions of \cw{xterm}.
+
+If you have an application which is supposed to use 256-colour mode
+and it isn't working, you may find you need to tell your server that
+your terminal supports 256 colours. On Unix, you do this by ensuring
+that the setting of \cw{TERM} describes a 256-colour-capable
+terminal. You can check this using a command such as \c{infocmp}:
+
+\c $ infocmp | grep colors
+\c colors#256, cols#80, it#8, lines#24, pairs#256,
+\e bbbbbbbbbb
+
+If you do not see \cq{colors#256} in the output, you may need to
+change your terminal setting. On modern Linux machines, you could
+try \cq{xterm-256color}.
+
\S{config-boldcolour} \q{Bolded text is a different colour}
\cfg{winhelp-topic}{colours.bold}
\cfg{winhelp-topic}{connection.keepalive}
-If you find your sessions are closing unexpectedly (\q{Connection
-reset by peer}) after they have been idle for a while, you might
-want to try using this option.
+If you find your sessions are closing unexpectedly (most often with
+\q{Connection reset by peer}) after they have been idle for a while,
+you might want to try using this option.
Some network routers and firewalls need to keep track of all
connections through them. Usually, these firewalls will assume a
SSH 2} option; by default this is disabled and PuTTY will stick to
recommended ciphers.
+\H{config-ssh-kex} The Kex panel
+
+\# FIXME: This whole section is draft. Feel free to revise.
+
+The Kex panel (short for \q{key exchange}) allows you to configure
+options related to SSH-2 key exchange.
+
+Key exchange occurs at the start of an SSH connection (and
+occasionally thereafter); it establishes a shared secret that is used
+as the basis for all of SSH's security features. It is therefore very
+important for the security of the connection that the key exchange is
+secure.
+
+Key exchange is a cryptographically intensive process; if either the
+client or the server is a relatively slow machine, the slower methods
+may take several tens of seconds to complete.
+
+If connection startup is too slow, or the connection hangs
+periodically, you may want to try changing these settings.
+
+If you don't understand what any of this means, it's safe to leave
+these settings alone.
+
+This entire panel is only relevant to SSH protocol version 2; none of
+these settings affect SSH-1 at all.
+
+\S{config-ssh-kex-order} Key exchange algorithm selection
+
+\cfg{winhelp-topic}{ssh.kex.order}
+
+PuTTY supports a variety of SSH-2 key exchange methods, and allows you
+to choose which one you prefer to use; configuration is similar to
+cipher selection (see \k{config-ssh-encryption}).
+
+PuTTY currently supports the following varieties of Diffie-Hellman key
+exchange:
+
+\b \q{Group 14}: a well-known 2048-bit group.
+
+\b \q{Group 1}: a well-known 1024-bit group. This is less secure
+\#{FIXME better words} than group 14, but may be faster with slow
+client or server machines, and may be the only method supported by
+older server software.
+
+\b \q{Group exchange}: with this method, instead of using a fixed
+group, PuTTY requests that the server suggest a group to use for key
+exchange; the server can avoid groups known to be weak, and possibly
+invent new ones over time, without any changes required to PuTTY's
+configuration. We recommend use of this method, if possible.
+
+If the first algorithm PuTTY finds is below the \q{warn below here}
+line, you will see a warning box when you make the connection, similar
+to that for cipher selection (see \k{config-ssh-encryption}).
+
+\# [Repeat key exchange bumph when config is added:] If the session
+key negotiated at connection startup is used too much or for too long,
+it may become feasible to mount attacks against the SSH connection.
+Therefore, the SSH protocol specifies that a new key exchange should
+take place every so often.
+
+\# While this renegotiation is taking place, no data can pass through
+the SSH connection, so it may appear to \q{freeze}. (The occurrence of
+repeat key exchange is noted in the Event Log; see
+\k{using-eventlog}.) Usually the same algorithm is used as at the
+start of the connection, with a similar overhead.
+
+\# [When options are added to frob how often this happens, we should
+hardcode the values recommended by the drafts -- 1 hour, 1GB -- in
+this documentation, in case PuTTY's defaults are obscured by Default
+Settings etc. Assuming we think they're good advice, that is.]
+
\H{config-ssh-auth} The Auth panel
The Auth panel allows you to configure authentication options for
This is an SSH2-specific bug.
-\S{config-ssh-bug-dhgex} \q{Chokes on Diffie-Hellman group exchange}
-
-\cfg{winhelp-topic}{ssh.bugs.dhgex2}
-
-We have anecdotal evidence that some SSH servers claim to be able to
-perform Diffie-Hellman group exchange, but fail to actually do so
-when PuTTY tries to. If your SSH2 sessions spontaneously close
-immediately after opening the PuTTY window, it might be worth
-enabling the workaround for this bug to see if it helps.
-
-We have no hard evidence that any specific version of specific
-server software reliably demonstrates this bug. Therefore, PuTTY
-will never \e{assume} a server has this bug; if you want the
-workaround, you need to enable it manually.
-
-This is an SSH2-specific bug.
-
\S{config-ssh-bug-pksessid2} \q{Misuses the session ID in PK auth}
\cfg{winhelp-topic}{ssh.bugs.pksessid2}
projects / u / mdw / putty / blobdiff