System administration tools
vlock - A program which locks one or more virtual consoles
The vlock program locks one or more sessions on the console. Vlock
can lock the current terminal (local or remote) or the entire virtual
console system, which completely disables all console access. The
vlock program unlocks when either the password of the user who started
vlock or the root password is typed.
Install vlock if you need to disable access to one console or to all