Ubuntu14.04更新源
http://jingyan.baidu.com/article/7f41ecec1b7a2e593d095ce6.html
Ubuntu源
http://wiki.ubuntu.org.cn/%E6%BA%90%E5%88%97%E8%A1%A8
网易163更新服务器（广东广州电信/联通千兆双线接入），包含其他开源镜像：
deb http://mirrors.163.com/ubuntu/ vivid main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-security main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-updates main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-proposed main restricted universe multiverse deb http://mirrors.163.com/ubuntu/ vivid-backports main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-security main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-updates main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-proposed main restricted universe multiverse deb-src http://mirrors.163.com/ubuntu/ vivid-backports main restricted universe multiverse