Redhat – RHEL Clones (Centos, Scientific, CERN) network installation on XenServer 6.2

Have a look at Cobbler - https://fedorahosted.org/cobbler/ - I use it in a PXE environment but it should work for you.

If you absolutely want to use yum security plugin, there is a way to do this, although a little elaborate. But once you have it setup, it's all automated.

The only requirement is that you will need to have at-least one subscription to RHN. Which is a good investment IMO, but lets stick to the point.

1. Once you have the subscription, you can use mrepo, or reposync, to setup an in house Yum repo, that mirrors CentOS repos. (or you could just use rsync).
2. Then use the script attached to this mailing list post, to periodically connect to your RHN subscription, to download security packages info. Now you have two options.
   1. Extract just the package names from the generated "updateinfo.xml" file. And use that information to "search" your servers for Rpms needing security or other updates, using puppet or cfengine, or ssh-in-a-for-loop. This is simpler, gives you everything you want, but you can't use yum security.
   2. The other option is to use the modifyrepo command as shown here, to inject updateinfo.xml into repomd.xml. Before doing this, you will have to modify the perl script to change the Rpm MD5 sums inside the xml, from the RHN to Centos sums. And you will have to make sure if CentOS repos actually have all Rpms mentioned in updateinfo.xml, as they are behind RHN sometimes. But that's fine, you can ignore the updates CentOS hasn't caught up with, as there is little you can do about it, short of building them from SRPMs.

With option 2, you can install yum security plugin on all clients, and it will work.

Edit: This also works for Redhat RHEL 5 and 6 machines. And is simpler than using a heavy weight solution like Spacewalk or Pulp.