I found that my machines access URLs that look like the following
when
they connect to RHN, but the part after the date doesn't seem to be
predictable, and i'm not sure what to put for the version string in the
middle.
http://xmlrpc.rhn.redhat.com/XMLRPC/$RHN/redhat-linux-i386-9/listPackages...
http://xmlrpc.rhn.redhat.com/XMLRPC/$RHN/redhat-linux-i386-7.3/listPackag...
The part after the date looks suspiciously like the time in 24 hr.
format, e.g. 151830 is 3:18:30pm
-- mads