It depends on networkmanger , If you are using other networking interface , change command accordingly. Change PASSWD string to your password. If you don't mind script asking your password every time it's run remove "sudo - c passwd |" this part.
It provides to change DNS from following services go ahead add more and share too :)
1:Restore To Defaults 2:Untelly DNS 3:Tunlr DNS 4:Google DNS 5:Open DNS
Instructions:
1)If you are on Ubuntu based distors , change /etc/rc.d to /etc/init.d No need to change anything on arch based distros. 2) sudo chmod 777 DNS_changer.sh 3) ./DNS_changer.sh