root@third:~# useradd fred
root@third:~# passwd fred
New password: 
Retype new password: 
passwd: password updated successfully
root@third:~# usermod -aG sudo fred
root@third:~# groups fred
##</code><code>##

root@third:~# exit
logout
Connection to 143.110.153.42 closed.
$ ssh fred@143.110.153.42
fred@143.110.153.42: Permission denied (publickey).
$ 

##</code><code>##

root@third:/# which su
/usr/bin/su