Servers announcing themselves as `Sun_SSH_1.0' apparently cannot

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

diff --git a/doc/config.but b/doc/config.but
index c59881e..dcbce98 100644 (file)
--- a/doc/config.but
+++ b/doc/config.but
@@ -2662,6 +2662,24 @@ SSH2 public-key authentication will fail.
 
 This is an SSH2-specific bug.
 
+\S{config-ssh-bug-rekey} \q{Ignores key re-exchange completely}
+
+\cfg{winhelp-topic}{ssh.bugs.rekey2}
+
+Some very old SSH servers cannot cope with repeat key exchange at
+all, and will ignore attempts by the client to start one. Since
+PuTTY pauses the session while performing a repeat key exchange, the
+effect of this would be to cause the session to hang after an hour
+(unless you have your rekey timeout set differently; see
+\k{config-ssh-kex-rekey} for more about rekeys).
+
+If this bug is detected, PuTTY will never initiate a repeat key
+exchange. If this bug is enabled when talking to a correct server,
+the session should still function, but may be less secure than you
+would expect.
+
+This is an SSH2-specific bug.
+
 \H{config-file} Storing configuration in a file
 
 PuTTY does not currently support storing its configuration in a file