51工具盒子可以联网：yum 好用：
方法1 好用：
(2)添加软件源进行加速
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
(3)安装epel软件源
curl -o /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
方法2：修改yum源
-
安装wget & 安装epel第三方源
yum install -y wget
yum install epel-release
-
备份/etc/yum.repos.d/CentOS-Base.repo文件
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.back
-
下载阿里云的Centos-6.repo文件
CentOS 5
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo
CentOS 6
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
CentOS 7
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
- 重新加载yum
yum clean all
yum makecache fast
二、 yum 失效 wget 不能使用
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.back
将etc/yum.repos.d/CentOS-Base.repo 内容替换为以下内容：
替换为：
[base]
name=CentOS-$releasever - Base - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
[updates]
name=CentOS-$releasever - Updates - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
[extras]
name=CentOS-$releasever - Extras - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
[centosplus]
name=CentOS-$releasever - Plus - mirrors.aliyun.com
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7
清理缓存：
sudo yum clean all
sudo yum makecache
sudo yum update
