«Is Red Hat Enterprise Linux a open source product?
Yes. Binaries and updates are part of the commercial subscription from Red Hat to its customers. The complete source code in the form of source RPM's is available publicly at Red Hat's ftp mirror, which is above and beyond the requirements of any of the free and open source licenses. Red Hat also provides a complementary repository containing small number of additional packages which are licensed from its partners under different licensing terms.
Is it possible to use the publicly available source RPMs to rebuild the distribution?
Absolutely. All the SRPMS are under free and open source licenses that permit this. There are several such rebuilds and derivatives of Red Hat Enterprise Linux available. CentOS and Scientific Linux are popular ones. »
ftp://https://www.jeuxvideo.com//ftp.redhat.com/pub/redhat/linux/enterprise/
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Généralement, un programme libre payant l'est parce qu'il y a un support derrière et que c'est une manière de soutenir le projet.