Fixing Authentication is requried to set the network proxy used for download packages
Non-root users
Step 1: Launch a Terminal Console and type
# gnome-session-properties
Step 2: Uncheck PackageKit Update Applet .
Root User
Step 1: Disabled /etc/yum/pluginconf.d
# vim /etc/yum/pluginconf.d/refresh-packagekit.conf
[main]
enabled=0