If your organization uses a proxy server as an intermediary for Internet access, specify the proxy settings in /etc/yum.conf. If the proxy server also requires authentication, you also need to specify the proxy_username, and proxy_password settings.
proxy=<proxy server url> proxy_username=<user> proxy_password=pass
If you use the yum plugin (yum-rhn-plugin) to access the ULN, specify the enableProxy and httpProxy settings in /etc/sysconfig/rhn/up2date. In addition, If the proxy server requires authentication, you also need to specify the enableProxyAuth, proxyUser, and proxyPassword settings as shown below.
enableProxy=1 httpProxy=<proxy server url> enableProxyAuth=1 proxyUser=<user> proxyPassword=<password>