Instale o pacote resolvconf :
apt-get install resolvconf
Edite seu /etc/resolvconf/resolv.conf.d/base adicionando a seguinte linha:
dns-nameservers 8.8.8.8
dns-nameservers 8.8.4.4
Edite o /etc/network/interfaces add:
dns-nameservers 8.8.8.8
dns-nameservers 8.8.4.4
Executar:
resolvconf -u
Reinicie a rede:
/etc/init.d/networking restart