Introduce a new checkbox and command-line option to inhibit use of

Pageant for local authentication. (This is a `don't use Pageant for
authentication at session startup' button rather than a `pretend
Pageant doesn't exist' button: that is, agent forwarding is
independent of this option.)

[originally from svn r6572]

doc/config.but

@@ -2310,6 +2310,24 @@ unwanted username prompts, you could try checking this option.
 This option only affects SSH-2 connections. SSH-1 connections always
 require an authentication step.
 
+\S{config-ssh-tryagent} \q{Attempt authentication using Pageant}
+
+\cfg{winhelp-topic}{ssh.auth.pageant}
+
+If this option is enabled, then PuTTY will look for Pageant (the SSH
+private-key storage agent) and attempt to authenticate with any
+suitable public keys Pageant currently holds.
+
+This behaviour is almost always desirable, and is therefore enabled
+by default. In rare cases you might need to turn it off in order to
+force authentication by some non-public-key method such as
+passwords.
+
+This option can also be controlled using the \c{-noagent}
+command-line option. See \k{using-cmdline-agentauth}.
+
+See \k{pageant} for more information about Pageant in general.
+
 \S{config-ssh-tis} \q{Attempt \I{TIS authentication}TIS or
 \i{CryptoCard authentication}}
 

doc/pageant.but

@@ -42,6 +42,10 @@ automatically from Pageant, and use it to authenticate. You can now
 open as many PuTTY sessions as you like without having to type your
 passphrase again.
 
+(PuTTY can be configured not to try to use Pageant, but it will try
+by default. See \k{config-ssh-tryagent} and
+\k{using-cmdline-agentauth} for more information.)
+
 When you want to shut down Pageant, click the right button on the
 Pageant icon in the System tray, and select \q{Exit} from the menu.
 Closing the Pageant main window does \e{not} shut down Pageant.

doc/using.but

@@ -685,6 +685,22 @@ Note that the \c{-pw} option only works when you are using the SSH
 protocol. Due to fundamental limitations of Telnet and Rlogin, these
 protocols do not support automated password authentication.
 
+\S2{using-cmdline-agentauth} \i\c{-agent} and \i\c{-noagent}:
+control use of Pageant for authentication
+
+The \c{-agent} option turns on SSH authentication using Pageant, and
+\c{-noagent} turns it off. These options are only meaningful if you
+are using SSH.
+
+See \k{pageant} for general information on \i{Pageant}
+
+These options are equivalent to the agent authentication checkbox in
+the Auth panel of the PuTTY configuration box (see
+\k{config-ssh-tryagent}).
+
+These options are not available in the file transfer tools PSCP and
+PSFTP.
+
 \S2{using-cmdline-agent} \I{-A-upper}\c{-A} and \i\c{-a}: control \i{agent
 forwarding}