Ubuntu su authentication failed

After Ubuntu is installed, the root user is locked by default and cannot log on or "Su" to the root user. Some people say this is a bad practice, especially for servers. I think this is more secure for desktop users. But for servers, you can set it to "allow Su to root, but not allow root users to log on directly ". For the convenience of development, this method is adopted on the desktop and server.

Allow Su to root

It is very simple. The following is the setting method:

Me @ tipfoo :~ $ Sudo passwd

Password: <--- enter the password of the user during installation

Enter new Unix Password: <--- New Root User Password

Retype new Unix Password: <--- repeat the New Root User Password

Passwd: the password is successfully updated.