一，自定义yum源
mkdir -p /etc/yum.repos.d/repo_bak/
mv /etc/yum.repos.d/*.repo /etc/yum.repos.d/repo_bak/
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.myhuaweicloud.com/repo/CentOS-Base-7.repo
yum makecache
二，安装工具包
yum -y install net-tools lftp rsync psmisc vim bash-completion
三，优化系统服务
systemctl stop ntpd postfix
yum -y remove ntp postfix
四，修改时间服务器
vim /etc/chrony.conf
server ntp.myhuaweicloud.com iburst
systemctl enable chronyd
systemctl start chronyd