Updating rhel without subscription
You can provide your installation number when prompted during the Note: This documentation is provided by Red Hat®, Inc. The copyright holder has added the further requirement that Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder.The Cent OS project redistributes these original works (in their unmodified form) as a reference for Cent OS-5 because Cent OS-5 is built from publicly available, open source SRPMS.
You will have no access to their repositories or updates.The only difference between Redhat Enterprise Linux (RHEL) and Cent OS is the Redhat logos.Because Redhat Enterprise Linux is based on GNU GPL licensed code, they must freely distribute the source for their distribution.Red Hat support of this subsystem is usually dismal, unless you are lucky and get knowledgeable guy (I once did).In most case they search database and quite something from it, without even understanding what problem you are experiencing.* And you are confusing the old "desktop" Red Hat Linux with the current ENTERPRISE distro - Red Hat Enterprise Linux (RHEL.) The desktop distro is as always freely available and is called Fedora.
The last Red Hat desktop distro was 9 (Shrike) back in 2003. If you really want REDHAT then I would do as stated above and DL Cent OS, which I use without issues.
Other things are the same so it depends on what you need it for.
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Cent OS is REDHAT SRPMS complied with the removal of RH TM.