1. repo url http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os 2. vi /etc/yum.repos.d/CentOS-Base.repo baseurl modify 3. yum clean all http://www.unixmen.com/ifconfig-command-found-centos-7-minimal-installation-quick-tip-fix/ * proxy config vi /etc/yum.conf proxy=http s ://x.x.x.x:8080