Long time ago I wrote a small program that would mimic the entry point of a DEC terminal server, slow baud rates screen refresh and all, and with the permission of the computer lab manager I installed it in a few PCs, next to the original dec VT terminals that were actually connected to the server.
It didn't save any passwords or such, just display some random funny non-sense message to the user after s/he inserted login and password and then loop back again to the login prompt with a failed error message.
Even with this obvious message that would warn an alert user for the suspicious terminal, we (my friends and the lab manager) got a few laughs when people coming to the lab and finding all the VT terminals taken would use the PCs to login and tried several (many!) times until giving up, at which point we would tell them the truth. Mind you, these were people comfortable with VT terminals and unix cli and somewhat computer savvy!
It didn't save any passwords or such, just display some random funny non-sense message to the user after s/he inserted login and password and then loop back again to the login prompt with a failed error message.
Even with this obvious message that would warn an alert user for the suspicious terminal, we (my friends and the lab manager) got a few laughs when people coming to the lab and finding all the VT terminals taken would use the PCs to login and tried several (many!) times until giving up, at which point we would tell them the truth. Mind you, these were people comfortable with VT terminals and unix cli and somewhat computer savvy!