System Setings Wide Proxy RHEL 6

nano /etc/profile.d/proxy.sh

export http_proxy=http://host.name:port/
export ftp_proxy=http://host.name:port/
export HTTP_PROXY=http://host.name:port/
export FTP_PROXY=http://host.name:port/
export no_proxy=.localdomain.com

save

source /etc/profile.d/proxy.sh

now try yum update, or whatever. except ping (icmp)