有的网络环境限制了访问所有外国IP，连yum都成了问题，只能改成国内源使用，特此记录一下清华大学源，以便日后需要

cd /etc/yum.repos.d/

mv CentOS-Base.repo CentOS-Base.repo.bak

mv epel.repo epel.repo.bak(没有可忽略)

vim CentOS-Base.repo# 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=http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#released updates

[updates]

name=CentOS-$releasever - Updates

baseurl=http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

#additional packages that may be useful

[extras]

name=CentOS-$releasever - Extras

baseurl=http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/

gpgcheck=1

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=http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$basearch/

gpgcheck=1

enabled=0

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

vim epel.repo[epel]

name=Extra Packages for Enterprise Linux 7 - $basearch

baseurl=http://mirrors.tuna.tsinghua.edu.cn/epel/7/$basearch

#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch

failovermethod=priority

enabled=1

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

[epel-debuginfo]

name=Extra Packages for Enterprise Linux 7 - $basearch - Debug

baseurl=http://mirrors.tuna.tsinghua.edu.cn/epel/7/$basearch/debug

#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-debug-7&arch=$basearch

failovermethod=priority

enabled=0

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

gpgcheck=1

[epel-source]

name=Extra Packages for Enterprise Linux 7 - $basearch - Source

baseurl=http://mirrors.tuna.tsinghua.edu.cn/epel/7/SRPMS

#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-source-7&arch=$basearch

failovermethod=priority

enabled=0

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

gpgcheck=1

添加RPM-GPG-KEY-EPEL-7curl https://mirrors.tuna.tsinghua.edu.cn/epel/RPM-GPG-KEY-EPEL-7 > /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7

运行以下命令生成缓存

yum clean all

yum makecache