CentOS更换vault源

每隔一段时间，CentOS就会对老版本的系统结束支持，对应的yum源也失效了，CentOS 5.x在2017年3月31日结束支持，导致使用yum安装和更新程序的时候出现404错误。在CentOS官方有一个http://vault.centos.org/包含所有发行的CentOS版本，因此需要将yum源修改为centos-vault的源，这里以CentOS 5.x为例进行讲解。

将 /etc/yum.repos.d/CentOS-Base.repo 文件中所有的源主机地址修改为http://vault.centos.org，并且将$releasever替换为当前系统所使用的CentOS版本，可以使用5.x最后的版本5.11。注意，需要将所有其他备用的主机都删除，内容如下：

[base]
name=CentOS-6.9 - Base - vault.centos.org
failovermethod=priority
baseurl=http://vault.centos.org/6.9/os/$basearch/
gpgcheck=0
 
#released updates 
[updates]
name=CentOS-6.9 - Updates - vault.centos.org
failovermethod=priority
baseurl=http://vault.centos.org/6.9/updates/$basearch/
gpgcheck=0
 
#additional packages that may be useful
[extras]
name=CentOS-6.9 - Extras - vault.centos.org
failovermethod=priority
baseurl=http://vault.centos.org/6.9/extras/$basearch/
gpgcheck=0
 
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-6.9 - Plus - vault.centos.org
failovermethod=priority
baseurl=http://vault.centos.org/6.9/centosplus/$basearch/
gpgcheck=0
enabled=0
 
#contrib - packages by Centos Users
[contrib]
name=CentOS-6.9 - Contrib - vault.centos.org
failovermethod=priority
baseurl=http://vault.centos.org/6.9/contrib/$basearch/
gpgcheck=0
enabled=0

[base]
name=CentOS-6.9 - Base - vault.centos.org
failovermethod=priority
baseurl=https://vault.centos.org/6.9/os/$basearch/
gpgcheck=0
 
#released updates 
[updates]
name=CentOS-6.9 - Updates - vault.centos.org
failovermethod=priority
baseurl=https://vault.centos.org/6.9/updates/$basearch/
gpgcheck=0
 
#additional packages that may be useful
[extras]
name=CentOS-6.9 - Extras - vault.centos.org
failovermethod=priority
baseurl=https://vault.centos.org/6.9/extras/$basearch/
gpgcheck=0
 
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-6.9 - Plus - vault.centos.org
failovermethod=priority
baseurl=https://vault.centos.org/6.9/centosplus/$basearch/
gpgcheck=0
enabled=0
 
#contrib - packages by Centos Users
[contrib]
name=CentOS-6.9 - Contrib - vault.centos.org
failovermethod=priority
baseurl=https://vault.centos.org/6.9/contrib/$basearch/
gpgcheck=0
enabled=0