Whether you had to install a CentOS server in a DMZ-ed network with paranoic system firewall rules or simply you want to use your own created RPM local repository to run RPM installs and CentOS system updates via monitored Proxy you will have to configure yum to use a proxy.
There is a standard way to do it by adding a proxy directive to /etc/yum.conf as explained in CentOS official documetnation.
However for some reason:
proxy vars adding to /etc/yum.conf [main] section is not working on CentOS 6.5?
However there is a dirty patch by using the OS environment standard variable http_proxy
To make yum work via proxy in gnome-terminal run first:
or if proxy is protected by username / password run instead:
Afterwards yum will work via the proxy, i.e.:
yum update && yum upgrade
To make http_proxy exported system wide check my previous post – Set Proxy System-Wide
Hope this helps someone.