Clarify when ldisc->term may be NULL.

[PuTTY.git] / doc / config.but

diff --git a/doc/config.but b/doc/config.but
index 5e8c775b88122288e7a2ab7c7dba9ef3ec947354..e83bf2f55edb79a6539cd8c791220bd7dd6a9082 100644 (file)
--- a/doc/config.but
+++ b/doc/config.but
@@ -1758,7 +1758,9 @@ logical host name, you can arrange that PuTTY will not keep asking
 you to reconfirm its host key. Conversely, if you expect to use the
 same local port number for port forwardings to lots of different
 servers, you probably didn't want any particular server's host key
-cached under that local port number.
+cached under that local port number. (For this latter case, you
+could also explicitly configure host keys in the relevant sessions;
+see \k{config-ssh-kex-manual-hostkeys}.)
 
 If you just enter a host name for this option, PuTTY will cache the
 SSH host key under the default SSH port for that host, irrespective
@@ -2266,16 +2268,27 @@ make the most of a low-\i{bandwidth} connection.
 
 \cfg{winhelp-topic}{ssh.protocol}
 
-This allows you to select whether you would like to use \i{SSH protocol
-version 1} or \I{SSH-2}version 2. \#{FIXME: say something about this elsewhere?}
+This allows you to select whether you would prefer to use \i{SSH protocol
+version 1} or \I{SSH-2}version 2, and whether to permit falling back
+to the other version.
 
-PuTTY will attempt to use protocol 1 if the server you connect to
-does not offer protocol 2, and vice versa.
+With the settings \q{1} and \q{2}, PuTTY will attempt to use protocol 1
+if the server you connect to does not offer protocol 2, and vice versa.
 
 If you select \q{1 only} or \q{2 only} here, PuTTY will only connect
 if the server you connect to offers the SSH protocol version you
 have specified.
 
+You should normally leave this at the default, \q{2 only}. The older
+SSH-1 protocol is no longer developed, has many known cryptographic
+weaknesses, and is generally not considered to be secure. If you
+permit use of SSH-1 by selecting \q{2} instead of \q{2 only}, an
+active attacker can force downgrade to SSH-1 even if the server
+you're connecting to supports SSH-2.
+
+PuTTY's protocol 1 implementation is provided mainly for
+compatibility, and is no longer being enhanced.
+
 \S{config-ssh-sharing} Sharing an SSH connection between PuTTY tools
 
 \cfg{winhelp-topic}{ssh.sharing}
@@ -2339,8 +2352,6 @@ special case is that PSCP and PSFTP will \e{never} act as upstreams.
 
 \H{config-ssh-kex} The Kex panel
 
-\# FIXME: This whole section is draft. Feel free to revise.
-
 The Kex panel (short for \q{\i{key exchange}}) allows you to configure
 options related to SSH-2 key exchange.
 
@@ -2486,6 +2497,11 @@ that situation, you will probably want to use the \cw{-hostkey}
 command-line option to configure the expected host key(s); see
 \k{using-cmdline-hostkey}.
 
+For situations where PuTTY's automated host key management simply
+picks the wrong host name to store a key under, you may want to
+consider setting a \q{logical host name} instead; see
+\k{config-loghost}.
+
 To configure manual host keys via the GUI, enter some text describing
 the host key into the edit box in the \q{Manually configure host keys
 for this connection} container, and press the \q{Add} button. The text
@@ -3013,7 +3029,9 @@ needed with \q{Dynamic}), enter a hostname and port number separated
 by a colon, in the \q{Destination} box. Connections received on the
 source port will be directed to this destination. For example, to
 connect to a POP-3 server, you might enter
-\c{popserver.example.com:110}.
+\c{popserver.example.com:110}. (If you need to enter a literal
+\i{IPv6 address}, enclose it in square brackets, for instance
+\cq{[::1]:2200}.)
 
 \b Click the \q{Add} button. Your forwarding details should appear
 in the list box.