The following commands doest work directly in the latest version of the Ubuntu server. You need to install them manually .
ifconfig, ifup, ifdown
just type the command as shown in the image below
1 ] Installing ifconfig command.
just type :--> sudo apt install net-tools.
2] Installing ifup, ifdown command.
Just type :--> sudo apt install ifupdown
3] Installing traceroute command.
Just type :--> sudo apt install traceroute
