locking a console keyboard

[Thierry ITTY]

Hello

I have some red hat linux servers in various locations where people come
and go. They stay with a display and a keyboard, (no mouse, graphics, and
so on), waiting for a login. Sometimes people (usually young kids) type
garbage on the keyboard, maybe hoping something to happen.
I wondered how I could lock the keyboard with some magic sequence. 
So the official admin would have to type this sequence to unlock the
keyboard, then enter his login, and this would avoid pages of garbage on
the display

Is there some tool or a patch to getty to do this ?

TIA