CentOS进行yum操作时不能访问国外镜像的解决方案

1. 例如执行yum update，经常报错“Cound not resolve host: xxxxx”，一般都是yum源是使用的国外镜像，国内访问很不好。这时可以将源手动替换为国内的清华大学源，或者阿里云源之类的。

详细使用方法可以参考https://mirrors.tuna.tsinghua.edu.cn/help/centos/，镜像站使用帮助，选择自己的版本即可。

下面贴出CentOS 7版本下，清华源的配置

 # CentOS-Base.repo
 #
 # The mirror system uses the connecting IP address of the client and the
 # update status of each mirror to pick mirrors that are updated to and
 # geographically close to the client.  You should use this for CentOS updates
 # unless you are manually picking other mirrors.
 #
 # If the mirrorlist= does not work for you, as a fall back you can try the
 # remarked out baseurl= line instead.
 #
 #

 [base]
 name=CentOS-$releasever - Base
 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/
 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
 gpgcheck=
 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

 #released updates
 [updates]
 name=CentOS-$releasever - Updates
 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/
 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
 gpgcheck=
 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

 #additional packages that may be useful
 [extras]
 name=CentOS-$releasever - Extras
 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/
 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
 gpgcheck=
 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

 #additional packages that extend functionality of existing packages
 [centosplus]
 name=CentOS-$releasever - Plus
 baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$basearch/
 #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
 gpgcheck=
 enabled=
 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

PS 如果觉得命令行使用不方便，可以直接用SFTP连上之后进行文件编辑。

2. 另外内核升级时可能用到/etc/yum.repos.d/elrepo.repo文件，也同样可以将其修改为清华大学的源。

同样贴出清华大学elrepo.repo源配置

### Name: 清华大学开源镜像
### URL: https://mirrors.tuna.tsinghua.edu.cn/elrepo/

[elrepo]
name=ELRepo.org Community Enterprise Linux Repository - el7
baseurl=https://mirrors.tuna.tsinghua.edu.cn/elrepo/elrepo/el7/$basearch/
#mirrorlist=http://mirrors.elrepo.org/mirrors-elrepo.el7
enabled=
gpgcheck=
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-elrepo.org
protect=

[elrepo-testing]
name=ELRepo.org Community Enterprise Linux Testing Repository - el7
baseurl=https://mirrors.tuna.tsinghua.edu.cn/elrepo/testing/el7/$basearch/
#mirrorlist=http://mirrors.elrepo.org/mirrors-elrepo-testing.el7
enabled=
gpgcheck=
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-elrepo.org
protect=

[elrepo-kernel]
name=ELRepo.org Community Enterprise Linux Kernel Repository - el7
baseurl=https://mirrors.tuna.tsinghua.edu.cn/elrepo/kernel/el7/$basearch/
#mirrorlist=http://mirrors.elrepo.org/mirrors-elrepo-kernel.el7
enabled=
gpgcheck=
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-elrepo.org
protect=

[elrepo-extras]
name=ELRepo.org Community Enterprise Linux Extras Repository - el7
baseurl=https://mirrors.tuna.tsinghua.edu.cn/elrepo/extras/el7/$basearch/
#mirrorlist=http://mirrors.elrepo.org/mirrors-elrepo-extras.el7
enabled=
gpgcheck=
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-elrepo.org
protect=