[CentOS] Whereis yum-rhn-plugin package?

Hi all,

  I need to setup a repo server to allocate updates for RHEL3, RHEL4, RHEL5 and 
CentOS5. Apart of mrrepo tool, I see that I can use reposync from yum-utils 
package and yum-rhn-plugin package to setup a mirror update server. But I can't 
to find yum-rhn-plugin under centos5 repo. Where is it?? Or I need to use 
package released from upstream vendor??


Thanks
-- 
CL Martinez
carlopmart {at} gmail {d0t} com