New SSH bug flag, for 'can't handle SSH2_MSG_IGNORE'. Another user

[u/mdw/putty] / doc / config.but

diff --git a/doc/config.but b/doc/config.but
index 750f188..c36e818 100644 (file)
--- a/doc/config.but
+++ b/doc/config.but
@@ -1788,6 +1788,22 @@ it explicitly every time. (Some Telnet servers don't support this.)
 
 In this box you can type that user name.
 
+\S{config-username-from-env} \q{Use of system username}
+
+\cfg{winhelp-topic}{connection.usernamefromenv}
+
+When the previous box (\k{config-username}) is left blank, by default,
+PuTTY will prompt for a username at the time you make a connection.
+
+In some environments, such as large corporate networks with \i{single
+sign-on}, a more sensible default may be to use the name of the user
+logged in to the local operating system (if any). This control allows
+you to change the default behaviour.
+
+The current system username is displayed in the dialog as a
+convenience. It is not saved in the configuration; if a saved session
+is later used by a different user, that user's name will be used.
+
 \S{config-termtype} \q{\ii{Terminal-type} string}
 
 \cfg{winhelp-topic}{connection.termtype}
@@ -2728,6 +2744,27 @@ connections fail.
 PuTTY's default is \cw{MIT-MAGIC-COOKIE-1}. If you change it, you
 should be sure you know what you're doing.
 
+\S{config-ssh-xauthority} X authority file for local display
+
+\cfg{winhelp-topic}{ssh.tunnels.xauthority}
+
+If you are using X11 forwarding, the local X server to which your
+forwarded connections are eventually directed may itself require
+authorisation.
+
+Some Windows X servers do not require this: they do authorisation by
+simpler means, such as accepting any connection from the local
+machine but not from anywhere else. However, if your X server does
+require authorisation, then PuTTY needs to know what authorisation
+is required.
+
+One way in which this data might be made available is for the X
+server to store it somewhere in a file which has the same format
+as the Unix \c{.Xauthority} file. If this is how your Windows X
+server works, then you can tell PuTTY where to find this file by
+configuring this option. By default, PuTTY will not attempt to find
+any authorisation for your local display.
+
 \H{config-ssh-portfwd} \I{port forwarding}The Tunnels panel
 
 \cfg{winhelp-topic}{ssh.tunnels.portfwd}
@@ -2911,9 +2948,6 @@ enabled when talking to a correct server, the session will succeed,
 but keepalives will not work and the session might be more
 vulnerable to eavesdroppers than it could be.
 
-This is an SSH-1-specific bug. No known SSH-2 server fails to deal
-with SSH-2 ignore messages.
-
 \S{config-ssh-bug-plainpw1} \q{Refuses all SSH-1 \i{password camouflage}}
 
 \cfg{winhelp-topic}{ssh.bugs.plainpw1}
@@ -2955,6 +2989,23 @@ will be impossible.
 
 This is an SSH-1-specific bug.
 
+\S{config-ssh-bug-ignore2} \q{Chokes on SSH-2 \i{ignore message}s}
+
+\cfg{winhelp-topic}{ssh.bugs.ignore2}
+
+An ignore message (SSH_MSG_IGNORE) is a message in the SSH protocol
+which can be sent from the client to the server, or from the server
+to the client, at any time. Either side is required to ignore the
+message whenever it receives it. PuTTY uses ignore messages in SSH-2
+to confuse the encrypted data stream and make it harder to
+cryptanalyse. It also uses ignore messages for connection
+\i{keepalives} (see \k{config-keepalive}).
+
+If it believes the server to have this bug, PuTTY will stop using
+ignore messages. If this bug is enabled when talking to a correct
+server, the session will succeed, but keepalives will not work and
+the session might be less cryptographically secure than it could be.
+
 \S{config-ssh-bug-hmac2} \q{Miscomputes SSH-2 HMAC keys}
 
 \cfg{winhelp-topic}{ssh.bugs.hmac2}