Add a bug-compatibility flag to disable the

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

diff --git a/doc/config.but b/doc/config.but
index 9842758..6d81248 100644 (file)
--- a/doc/config.but
+++ b/doc/config.but
@@ -3208,6 +3208,29 @@ send an over-sized packet.  If this bug is enabled when talking to a
 correct server, the session will work correctly, but download
 performance will be less than it could be.
 
 correct server, the session will work correctly, but download
 performance will be less than it could be.
 

+\S{config-ssh-bug-winadj} \q{Chokes on PuTTY's SSH-2 \cq{winadj} requests}
+
+\cfg{winhelp-topic}{ssh.bugs.winadj}
+
+PuTTY sometimes sends a special request to SSH servers in the middle
+of channel data, with the name \cw{winadj@putty.projects.tartarus.org}
+(see \k{sshnames-channel}). The purpose of this request is to measure
+the round-trip time to the server, which PuTTY uses to tune its flow
+control. The server does not actually have to \e{understand} the
+message; it is expected to send back a \cw{SSH_MSG_CHANNEL_FAILURE}
+message indicating that it didn't understand it. (All PuTTY needs for
+its timing calculations is \e{some} kind of response.)
+
+It has been known for some SSH servers to get confused by this message
+in one way or another \dash because it has a long name, or because
+they can't cope with unrecognised request names even to the extent of
+sending back the correct failure response, or because they handle it
+sensibly but fill up the server's log file with pointless spam, or
+whatever. PuTTY therefore supports this bug-compatibility flag: if it
+believes the server has this bug, it will never send its
+\cq{winadj@putty.projects.tartarus.org} request, and will make do
+without its timing data.
+

 \H{config-serial} The Serial panel
 
 The \i{Serial} panel allows you to configure options that only apply
 \H{config-serial} The Serial panel
 
 The \i{Serial} panel allows you to configure options that only apply