centos5已停止了维护，国内大部分的源也停止维护，找了很久都没有找到可用的源。最后才发现，centos早期的源都已经vault.centos.org网站下，国内的镜像源也都改成了centos-vault，不能直接使用centos目录下的源。

腾讯云源：

[base]
name=CentOS-5.8 - Base
#mirrorlist=http://mirrorlist.centos.org/?release=5.8&arch=$basearch&repo=os
baseurl=http://mirrors.cloud.tencent.com/centos-vault/5.8/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#released updates 
[updates]
name=CentOS-5.8 - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=5.8&arch=$basearch&repo=updates
baseurl=http://mirrors.cloud.tencent.com/centos-vault/5.8/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#additional packages that may be useful
[extras]
name=CentOS-5.8 - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=5.8&arch=$basearch&repo=extras
baseurl=http://mirrors.cloud.tencent.com/centos-vault/5.8/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-5.8 - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=5.8&arch=$basearch&repo=centosplus
baseurl=http://mirrors.cloud.tencent.com/centos-vault/5.8/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

#contrib - packages by Centos Users
[contrib]
name=CentOS-5.8 - Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=5.8&arch=$basearch&repo=contrib
baseurl=http://mirrors.cloud.tencent.com/centos-vault/5.8/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5