更新debian的更新源，选择用中科大的源，对于教育网来说比较快。
编辑文件
sudo vim /etc/apt/sources.lst
添加源内容，把原来的注释，然后
sudo apt-get update
IPv4版
deb http://debian.ustc.edu.cn/debian lenny main contrib non-free
deb-src http://debian.ustc.edu.cn/debian lenny main contrib non-free
deb http://debian.ustc.edu.cn/debian-security lenny/updates main contrib non-free
deb-src http://debian.ustc.edu.cn/debian-security lenny/updates main contrib non-free
deb http://ftp.sjtu.edu.cn/debian lenny main contrib non-free
deb-src http://ftp.sjtu.edu.cn/debian lenny main contrib non-free
deb-src http://debian.ustc.edu.cn/debian lenny main contrib non-free
deb http://debian.ustc.edu.cn/debian-security lenny/updates main contrib non-free
deb-src http://debian.ustc.edu.cn/debian-security lenny/updates main contrib non-free
deb http://ftp.sjtu.edu.cn/debian lenny main contrib non-free
deb-src http://ftp.sjtu.edu.cn/debian lenny main contrib non-free
IPv6版
#Stable:
deb http://security.debian.org/ stable/updates main contrib non-free
deb http://debian6.ustc.edu.cn/debian stable main non-free contrib
deb http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
deb-src http://debian6.ustc.edu.cn/debian stable main non-free contrib
deb-src http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
#Testing:
deb http://security.debian.org/ testing/updates main contrib non-free
deb http://debian6.ustc.edu.cn/debian testing main non-free contrib
deb http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
deb-src http: testing main non//debian6.ustc.edu.cn/debian-free contrib
deb-src http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
#Unstable:
deb http://security.debian.org/ testing/updates main contrib non-free
deb http://debian6.ustc.edu.cn/debian unstable main non-free contrib
deb http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
deb-src http: unstable main non//debian6.ustc.edu.cn/debian-free contrib
deb-src http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
deb http://security.debian.org/ stable/updates main contrib non-free
deb http://debian6.ustc.edu.cn/debian stable main non-free contrib
deb http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
deb-src http://debian6.ustc.edu.cn/debian stable main non-free contrib
deb-src http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
#Testing:
deb http://security.debian.org/ testing/updates main contrib non-free
deb http://debian6.ustc.edu.cn/debian testing main non-free contrib
deb http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
deb-src http: testing main non//debian6.ustc.edu.cn/debian-free contrib
deb-src http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
#Unstable:
deb http://security.debian.org/ testing/updates main contrib non-free
deb http://debian6.ustc.edu.cn/debian unstable main non-free contrib
deb http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
deb-src http: unstable main non//debian6.ustc.edu.cn/debian-free contrib
deb-src http://debian6.ustc.edu.cn/debian proposed-updates main contrib non-free
@2011.8.28
最近update的时候老是出现
W: GPG error: http://debian.ustc.edu.cn stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 07DC563D1F41B907
W: You may want to run apt-get update to correct these problems
还有好几条类似的信息，搞得人很烦躁。google到解决方案如下
执行
sudo apt-get install debian-archive-keyring
更新key信息
sudo apt-key update
再次更新源信息
sudo apt-get update
依然有个缺少“07DC563D1F41B907” 信息未解决，参考 debian教育网的源设置 。
建立文件key0x07DC563D1F41B907.asc，内容如下
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: PGP Universal 2.0.3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=oDfT
-----END PGP PUBLIC KEY BLOCK-----
然后回到终端，cd 到该文件的目录下，并输入命令如下：
sudo apt-key add key0x07DC563D1F41B907.asc
sudo apt-get update
即可。