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Old 11-03-2005, 03:48 PM   #1
Woodsman
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/etc/issue observations


Yesterday I was logging into Slackware from the console. I inadvertently typed an incorrect password. As expected the login failed and the screen reset. However, the screen did not correctly display the information from /etc/issue, but instead displayed the back slash characters (\r, \m, \n, etc.) Is this standard behavior or is this repairable? Otherwise my /etc/issue file displays properly.

After surfing the net trying to shed light on this problem, I noticed that many people update their /etc/issue and issue.net files with every boot. Why would people want to do this? Why not just create a static /etc/issue and /etc/issue.net and go on to other things?

In a related issue I noticed when I log out from the console that if I have not toggled consoles I can Page-Up and read the screen from my previous login session. My .bash_logout script contains a clear command but I can Page-Up anyway. From a security perspective this does not sound like a Good Thing. Any easy tricks to destroy the screen buffer when logging out?
 
Old 11-03-2005, 09:10 PM   #2
Dankles
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Re: /etc/issue observations

Quote:
Originally posted by Woodsman

In a related issue I noticed when I log out from the console that if I have not toggled consoles I can Page-Up and read the screen from my previous login session. My .bash_logout script contains a clear command but I can Page-Up anyway. From a security perspective this does not sound like a Good Thing. Any easy tricks to destroy the screen buffer when logging out?
I'm not sure about the '/etc/issue' problem, but about clearing your screen at logout, try 'tput reset'.
 
Old 11-04-2005, 07:31 PM   #3
Woodsman
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Quote:
but about clearing your screen at logout, try 'tput reset'
Thanks for the reply, but the suggestion did not work. You did, however, provide me just enough info that I could begin searching the web. I discovered approximately a dozen suggested solutions. I tried them all and every one of them failed to prevent me from using Page-Up to view the screen buffer history after logging out. The only trick that succeeded for me was manually toggling back and forth to a different console.

I did find some online discussions in some developer groups and apparently this problem is hardly trivial. Unless somebody corrects me, there really is no way to programmatically clear the screen history buffer when logging out. I sure would like a solution to this.

Sure would like to know why my login screen text from /etc/issue hoses when I enter an incorrect password too.
 
Old 11-04-2005, 07:35 PM   #4
keefaz
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You could always disable console framebuffer so you could not page up anymore
(vga=normal in lilo.conf, then run lilo to apply the change)
 
Old 11-05-2005, 10:52 AM   #5
Woodsman
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I tried several so-called solutions. There are a lot of people on the web who post information who never test what they prescribe, that's for sure! The only solution that worked for me is toggling consoles. And then I found that somebody wrote a short script that does exactly that:

# Clear the screen and the scrollback buffer when in a VT.
case "`tty`" in
/dev/tty[0-9]*)
CUR_CONSOLE=`fgconsole`
clear
chvt 63
chvt "$CUR_CONSOLE"
;;
esac

I placed the script in my .bash_logout. Works great.

Now, to hopefully discover why the text from my /etc/issue goes foobar when the screen refreshes after typing an incorrect password.
 
  


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