sudo vi /etc/apt/sources.list
deb http://kambing.ui.ac.id/ubuntu/ xenial main restricted universe multiverse
deb http://kambing.ui.ac.id/ubuntu/ xenial-updates main restricted universe multiverse
deb http://kambing.ui.ac.id/ubuntu/ xenial-security main restricted universe multiverse
deb http://kambing.ui.ac.id/ubuntu/ xenial-backports main restricted universe multiverse
deb http://kambing.ui.ac.id/ubuntu/ xenial-proposed main restricted universe multiverse