A networking teacher once told us, "Computer networking is not a game of gentlemen".
In one of the corporate trainings, there was an excellent C instructor.
He typed complete programs on his terminal which was live on the
projector and explained the concepts very nicely. Something else caught
my attention. He was using a 7-character password (yes, I counted the
keystrokes) to login to the remote Linux machine and the default
password given to us for our Linux accounts also had 7-characters. I
tried to login with the default password into the instructor's account
and I succeeded. So, I got this funny idea. I don't remember what his ID
was, but let us assume it was
who | grep his_id and found that there were two
pts/40. I ran
tty and found that mine was
/dev/pts/40. So, the other one must be the instructor's.
echo -n " " > /dev/pts/7 and I found that the cursor
blinking on the screen moved ahead. I had successfully redirected a
space to his terminal when the instructor was looking at us. Before, he
turned back. I ran
echo -ne "\b" > /dev/pts/7. That was a
backspace which brought the cursor back to its original place.
Then I wrote a small script to automate this process and I redirected all sorts of funny messages on the screen when the instructor looked at us. I remember some of them.
- When will this session be over? Are you guys hungry?
- Do you know who is doing this?
- FATAL: Disk has crashed.
- Hey instructor! Don't turn back.
- Twinkle twinkle little star.
It took some time for my batchmates to figure out who was doing this. Most of them were hiding their faces and giggling. A couple of times, the instructor became suspicious about why the class was acting funny all of a sudden. He looked back. The lady beside me was so scared that she almost held my hand to pull it away from the keyboard. That could have been a disaster but I redirected the backspaces just in time and I escaped narrowly.
I deleted most of them with backspaces before the instructor turned back. However, I did not delete the FATAL warning. I wanted to see how he would react. When he looked back, he stared at the message, thought for a while and pressed the ENTER key a few times and carried on with the training.