Originally posted by slynch1
I tried the tty program but could not get any display back to the terminal window, any ideas why.
There is no way to read back what the other person is typing unless you are the root user and have installed software specifically for that purpose. (see watch command & snp device under FreeBSD, not sure what the Linux equivilant is)

To investigate this further type:

mesg n
ls -l `tty`
mesg y
ls -l `tty`

You'll notice that the group write bit is toggled with that command. at no point is group READ set which would be required to gain some sort of access to the users input, if its even possible.

This is nothing particularly amazing, the whole reason it works at all is so that sysadmins and users can perfom limited text messaging to each other through the shell (using write & talk commands), and can be disabled by using the mesg n command. (finger user would then say (messages off) in the listing)

To put it in more simple terms this is all one way communication. (even talk is one way really) Just like SMS messaging on your cell phone.


Something similar would allow you to get one shot at a console login, but would require you to write a short script to emulate the login and if you get that wrong then they could potentially gain access to your account.

Basically you would write a script that pretends to be a login screen, gets the login and then logs out. You could leave this running if your stupid enough, but it won't be at all useful over a network.

Side Note: This is why WinNT requires the strange CTRL+ALT+DELETE to LOGON. So any password grabbers etc. are exposed.