I have installed Ubuntu Server 18.04. Configured ssh login without pass but with RSA key. Installaed docker and other minor programs.
Everything was going smoothly but, at some point, I started to notice that whenever I was trying to get admin privileges via sudo the password prompt seemed to not work properly. It was too fast. In details, everytime it appears a password prompt, in few millisecond, vanishes due a press enter-event-like. Of course I am not pressing enter and the keybard is working correctly.
After I reboot this is happening also at the login, so I am not able to log. Any idea of what is happening and how to solve?