diff --git a/doc/faq.but b/doc/faq.but index 4dd1166b..6fc174a8 100644 --- a/doc/faq.but +++ b/doc/faq.but @@ -423,6 +423,56 @@ You can ask PuTTY to delete all this data; see \k{faq-cleanup}. On Unix, PuTTY stores all of this data in a directory \cw{~/.putty} by default. +\S{faq-trust-sigils} Why do small PuTTY icons appear next to the login +prompts? + +As of PuTTY 0.71, some lines of text in the terminal window are marked +with a small copy of the PuTTY icon (as far as pixels allow). + +This is to show trustworthiness. When the PuTTY icon appears next to a +line of text, it indicates that that line of text was generated by +PuTTY itself, and not generated by the server and sent to PuTTY. + +Text that comes from the server does not have this icon, and we've +arranged that the server should not be able to fake it. (There's no +control sequence the server can send which will make PuTTY draw its +own icon, and if the server tries to move the cursor back up to a line +that \e{already} has an icon and overwrite the text, the icon will +disappear.) + +This lets you tell the difference between (for example) a legitimate +prompt in which PuTTY itself asks you for your private key passphrase, +and a fake prompt in which the server tries to send the identical text +to trick you into telling \e{it} your private key passphrase. + +\S{faq-plink-pause} Why has Plink started saying \q{Press Return to +begin session}? + +As of PuTTY 0.71, if you use Plink for an interactive SSH session, +then after the login phase has finished, it will present a final +interactive prompt saying \q{Access granted. Press Return to begin +session}. + +This is another defence against servers trying to mimic the real +authentication prompts after the session has started. When you pass +through that prompt, you know that everything after it is generated by +the server and not by Plink itself, so any request for your private +key passphrase should be treated with suspicion. + +In Plink, we can't use the defence described in \k{faq-trust-sigils}: +Plink is running \e{in} the terminal, so anything it can write into +the terminal, the server could write in the same way after the session +starts. And we can't just print a separator line without a pause, +because then the server could simply move the cursor back up to it and +overwrite it (probably with a brief flicker, but you might easily miss +that). The only robust defence anyone has come up with involves this +pause. + +If you trust your server not to be abusive, you can turn this off. It +will also not appear in various other circumstances where Plink can be +confident it isn't necessary. See \k{plink-option-antispoof} for +details. + \H{faq-howto} HOWTO questions \S{faq-login}{Question} What login name / password should I use?