Yum错误是RHN服务器停机或者在我的服务器上有问题。
yum update Loaded plugins: rhnplugin, security There was an error communicating with RHN. RHN support will be disabled. Error communicating with server. The message was: Error Message: RHN Proxy could not successfully connect its RHN parent. Please contact your system administrator. Error Class Code: 1000 Error Class Info: RHN Proxy error. Explanation: An error has occurred while processing your request. If this problem persists please enter a bug report at bugzilla.redhat.com. If you choose to submit the bug report, please be sure to include details of what you were trying to do when this error occurred and details on how to reproduce this problem. Excluding Packages in global exclude list Finished Skipping security plugin, no data Setting up Update Process No Packages marked for Update 错误正是它所说的：它不能连接到RHN服务器。 如果你粘贴/etc/sysconfig/rhn/up2date （就像在他的评论中提到的@packs），你可以使用URL来validation它是否已经启动。 例如，如果您正在使用镜像，则该镜像是 – closures – closures。
同时validation您的服务器是否具有互联网连接，并尝试运行服务器（和其他URL）的traceroute以确保它不是本地问题。