yum 源
https://www.cnblogs.com/renpingsheng/p/7845096.html
安装nginx php mysql
https://www.cnblogs.com/flywind/p/6019631.html
centos7 默认只开启22端口,自带iptables、firewalld两个过滤
systemctl stop firewalld
只下载不安装
yum install --downloadonly --downloaddir= <directory> <package-name>
# 示例如下
yum install --downloadonly --downloaddir=/root/mypackages/ httpd