PuTTY has the ability to change its character set configuration in
response to commands from the server. Some programs send these
-commands unexpectedly or inconveniently. In particular, \I{BitchX} (an
+commands unexpectedly or inconveniently. In particular, \i{BitchX} (an
IRC client) seems to have a habit of reconfiguring the character set
to something other than the user intended.
During an interactive session, PuTTY receives a stream of 8-bit
bytes from the server, and in order to display them on the screen it
-needs to know what character set to interpret them in.
-
-There are a lot of character sets to choose from. The \q{Received
-data assumed to be in which character set} option lets you select
-one. By default PuTTY will attempt to choose a character set that is
-right for your \i{locale} as reported by Windows; if it gets it wrong,
-you can select a different one using this control.
+needs to know what character set to interpret them in. Similarly,
+PuTTY needs to know how to translate your keystrokes into the encoding
+the server expects. Unfortunately, there is no satisfactory
+mechanism for PuTTY and the server to communicate this information,
+so it must usually be manually configured.
+
+There are a lot of character sets to choose from. The \q{Remote
+character set} option lets you select one. By default PuTTY will
+attempt to choose a character set that is right for your \i{locale} as
+reported by Windows; if it gets it wrong, you can select a different
+one using this control.
A few notable character sets are:
line-drawing characters, you can select \q{\i{CP437}}.
\b PuTTY also supports \i{Unicode} mode, in which the data coming from
-the server is interpreted as being in the \i{UTF-8} encoding of Unicode.
-If you select \q{UTF-8} as a character set you can use this mode.
-Not all server-side applications will support it.
+the server is interpreted as being in the \i{UTF-8} encoding of Unicode,
+and keystrokes are sent UTF-8 encoded. If you select \q{UTF-8} as a
+character set you can use this mode. Not all server-side applications
+will support it.
If you need support for a numeric \i{code page} which is not listed in
the drop-down list, such as code page 866, then you can try entering
If you need to force PuTTY to use a particular protocol, you can
explicitly set this to \q{IPv4} or \q{IPv6}.
+\S{config-loghost} \I{logical host name}\q{Logical name of remote host}
+
+\cfg{winhelp-topic}{connection.loghost}
+
+This allows you to tell PuTTY that the host it will really end up
+connecting to is different from where it thinks it is making a
+network connection.
+
+You might use this, for instance, if you had set up an SSH port
+forwarding in one PuTTY session so that connections to some
+arbitrary port (say, \cw{localhost} port 10022) were forwarded to a
+second machine's SSH port (say, \cw{foovax} port 22), and then
+started a second PuTTY connecting to the forwarded port.
+
+In normal usage, the second PuTTY will access the host key cache
+under the host name and port it actually connected to (i.e.
+\cw{localhost} port 10022 in this example). Using the logical host
+name option, however, you can configure the second PuTTY to cache
+the host key under the name of the host \e{you} know that it's
+\e{really} going to end up talking to (here \c{foovax}).
+
+This can be useful if you expect to connect to the same actual
+server through many different channels (perhaps because your port
+forwarding arrangements keep changing): by consistently setting the
+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.
+
+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
+of the port you really connected to (since the typical scenario is
+like the above example: you connect to a silly real port number and
+your connection ends up forwarded to the normal port-22 SSH server
+of some other machine). To override this, you can append a port
+number to the logical host name, separated by a colon. E.g. entering
+\cq{foovax:2200} as the logical host name will cause the host key to
+be cached as if you had connected to port 2200 of \c{foovax}.
+
+If you provide a host name using this option, it is also displayed
+in other locations which contain the remote host name, such as the
+default window title and the default SSH password prompt. This
+reflects the fact that this is the host you're \e{really} connecting
+to, which is more important than the mere means you happen to be
+using to contact that host. (This applies even if you're using a
+protocol other than SSH.)
+
\H{config-data} The Data panel
The Data panel allows you to configure various pieces of data which
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}
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}
such as \q{Local ports accept connections from other hosts} only take
effect on new forwardings.
+If the connection you are forwarding over SSH is itself a second SSH
+connection made by another copy of PuTTY, you might find the
+\q{logical host name} configuration option useful to warn PuTTY of
+which host key it should be expecting. See \k{config-loghost} for
+details of this.
+
\S{config-ssh-portfwd-localhost} Controlling the visibility of
forwarded ports
projects / u / mdw / putty / blobdiff