wintime: add a precautionary memset to zero.

[PuTTY.git] / doc / using.but

diff --git a/doc/using.but b/doc/using.but
index fc5859cf97b60269ac557959cb480f021da53d7d..dd8d4f0ccb064ad574c1258b965c529c0f1af78a 100644 (file)
--- a/doc/using.but
+++ b/doc/using.but
@@ -1000,3 +1000,43 @@ different logging modes, all available from the GUI too:
 \b \c{-sshrawlog} selects \q{SSH packets and raw data} logging mode.
 
 For more information on logging configuration, see \k{config-logging}.
+
+\S2{using-cmdline-proxycmd} \i\c{-proxycmd}: specify a local proxy
+command
+
+This option enables PuTTY's mode for running a \I{Local proxy}command
+on the local machine and using it as a proxy for the network
+connection. It expects a shell command string as an argument.
+
+See \k{config-proxy-type} for more information on this, and on other
+proxy settings. In particular, note that since the special sequences
+described there are understood in the argument string, literal
+backslashes must be doubled (if you want \c{\\} in your command, you
+must put \c{\\\\} on the command line).
+
+\S2{using-cmdline-restrict-acl} \i\c{-restrict-acl}: restrict the
+\i{Windows process ACL}
+
+This option (on Windows only) causes PuTTY (or another PuTTY tool) to
+try to lock down the operating system's access control on its own
+process. If this succeeds, it should present an extra obstacle to
+malware that has managed to run under the same user id as the PuTTY
+process, by preventing it from attaching to PuTTY using the same
+interfaces debuggers use and either reading sensitive information out
+of its memory or hijacking its network session.
+
+This option is not enabled by default, because this form of
+interaction between Windows programs has many legitimate uses,
+including accessibility software such as screen readers. Also, it
+cannot provide full security against this class of attack in any case,
+because PuTTY can only lock down its own ACL \e{after} it has started
+up, and malware could still get in if it attacks the process between
+startup and lockdown. So it trades away noticeable convenience, and
+delivers less real security than you might want. However, if you do
+want to make that tradeoff anyway, the option is available.
+
+A PuTTY process started with \c{-restrict-acl} will pass that on to
+any processes started with Duplicate Session, New Session etc.
+(However, if you're invoking PuTTY tools explicitly, for instance as a
+proxy command, you'll need to arrange to pass them the
+\c{-restrict-acl} option yourself, if that's what you want.)