1.backup old source list
sudo cp /etc/apt/source.list /etc/apt/sourc.list_bk
2.modify source list
sudo gedit /etc/apt/source.list
choose a fast server according to your location
- deb http://centos.bitcomm.cn/ubuntu natty main restricted universe multiverse
- deb http://centos.bitcomm.cn/ubuntu natty-security main restricted universe multiverse
- deb http://centos.bitcomm.cn/ubuntu natty-updates main restricted universe multiverse
- deb http://centos.bitcomm.cn/ubuntu natty-backports main restricted universe multiverse
- deb http://centos.bitcomm.cn/ubuntu natty-proposed main restricted universe multiverse
- deb-src http://centos.bitcomm.cn/ubuntu natty main restricted universe multiverse
- deb-src http://centos.bitcomm.cn/ubuntu natty-security main restricted universe multiverse
- deb-src http://centos.bitcomm.cn/ubuntu natty-updates main restricted universe multiverse
- deb-src http://centos.bitcomm.cn/ubuntu natty-backports main restricted universe multiverse
- deb-src http://centos.bitcomm.cn/ubuntu natty-proposed main restricted universe multiverse
3.update new source list
sudo apt-get update
come from http://blog.chinaunix.net/uid-452173-id-3253206.html