vi / etc / profile
http_proxy=http://172.20.188.193:3128/
https_proxy=https://172.20.188.193:3128/
export http_proxy
export https_proxy
Then refresh sorce / etc / profile
/etc/yum.conf
Configuration
http_proxy=http://172.20.188.193:3128/
https_proxy=https://172.20.188.193:3128/