Acabei adicionando backy confiável e confiável em /etc/apt/sources.list
e, em seguida, adicionado principal, restrito, universo e multiverso para todos eles
deb http://security.ubuntu.com/ubuntu trusty-security main restricted multiverse universe
deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted multiverse universe
deb http://security.ubuntu.com/ubuntu trusty main restricted multiverse universe
deb-src http://security.ubuntu.com/ubuntu trusty main restricted multiverse universe
deb http://security.ubuntu.com/ubuntu trusty-updates main restricted multiverse universe
deb-src http://security.ubuntu.com/ubuntu trusty-updates main restricted multiverse universe
deb http://security.ubuntu.com/ubuntu trusty-backports main restricted multiverse universe
deb-src http://security.ubuntu.com/ubuntu trusty-backports main restricted multiverse universe