Change MAC Address

[Enrypase]

Hi all :D
I have a problem when I change the MAC address. (I use backbox in a virtual machine)
I did these commands:

Sudo su
Password
ifconfig enp0s3 down
macchanger -r enp0s3 (it gives me a new MAC address)
ip link set enp0s3 address NEW MAC ADDRESS
ifconfig enp0s3 up
service network-manager restart

Then I tried to go on firefox, but it doesn't work.
What did I fail?

Sorry for my English.
Help please.

[ostendali]

if you restart the network manager that will reset your mac addr, it is an obvious and expected behavior.