Red Hat Enterprise Linux
Red Hat Enterprise Linux is a commercial derivate of Fedora tailored to meet the requirements of enterprise customers. It is a commercial product from Red Hat which also sponsors Fedora as a community project. Fedora is upstream for Red Hat Enterprise Linux but there are several other derivative distributions available too.
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 complimentary repository containing small number of additional packages which are licensed from its partners under different licensing terms.
If the source is publicly available, can anyone rebuild the binaries and produce a similar product?
Absolutely. There are several such rebuilds and derivatives of Red Hat Enterprise Linux available. A partial list is available at wikipedia
What's the difference between rebuilds and Red Hat Enterprise Linux ?
Red Hat Enterprise Linux is commercially supported by Red Hat and it is a commercial product with a range of software and hardware certifications including third party ISV applications. In addition to that, Red Hat also offers other management features via a web service called Red Hat Network and associated products including Red Hat Proxy and Red Hat Network Satellite that is not available to such rebuilds. Also layered products such as Red Hat Application Stack and Red Hat Directory Server is only supported on top of Red Hat Enterprise Linux subscriptions.
What's the relationship between rebuilds and Red Hat?
There is no official relationship but it is a complimentary one where Red Hat has publicly expressed its support for such efforts since many of the users using such rebuilds become Red Hat customers when they move into production deployments requiring commercial backing and support.
What's the difference between Fedora and Red Hat Enterprise Linux?
Both Fedora and Red Hat Enterprise Linux (RHEL) are open source. Fedora is a community project and serves as the base platform on which RHEL is built. The cost of RHEL comes from the subscription, which provides assorted certifications and support for additional architectures, as well as 7 years of enterprise support. Red Hat also enhances its RHEL offerings with additional software and with certification programs.
More information on the release history and lineage is available from the following link:
When you purchase RHEL, you are also helping to support Fedora. Since Red Hat sponsors Fedora, what is good for Red Hat is usually good for Fedora. The major differences are:
- Support and associated services - Red Hat Enterprise Linux is a commercially supported product by Red Hat and provides service legal agremeents that is important for enterprise customers. This support involves both product assistance (hand holding) as well as priorization of bug fixes and feature requests, certified hardware and software among other things. Fedora is supported by a wide community of developers and users but it is not commercially supported by Red Hat. Red Hat does sponsor a large number of resources and funds to the Fedora project including engineering, marketing and other services.
- Lifecyle - New versions of Red Hat Enterprise Linux is released about every 18 months and supported for upto 7 years. New Fedora releases are available every six months and every release gets updates for about 13 months.
- Software Packages - Software packages in Red Hat Enterprise Linux is limited to about 2000. These are the ones enterprise customers demand and are supported by Red Hat. Fedora offers a wide range of software packages and the latest release has nearly 10000 packages available in the repository
- Software Updates - Post release updates of software in Red Hat Enterprise Linux is usually limited to backported security and bug fixes although enhancements are also offered usually via the major scheduled updates. Red Hat also aims to provide ABI compatibility within a release while this is not guaranteed by the Fedora Project. Fedora software packages and updates are close to upstream and includes new features routinely.
Red Hat also provides a (older) comparison between the two options on their website:
What about packages not part of Red Hat Enterprise Linux?
In order to focus Red Hat's efforts and limit support costs, only a selected subset of packages found in Fedora are included in the commercially supported product line. Fedora Project has a community of people maintaining add-on packages for Red Hat Enterprise Linux and compatible rebuilds. Refer to the ["EPEL"] sub project for more details.