CentOS (Community Enterprise Operating System) has been commonly used and totally free of charge as a Red Hat rebuild for many years. This is where Red Hat logos and branding are removed from the system and redistributed as "CentOS". This is not quite as bad as it may first seem. Red Hat uses the open source code and redistribution is totally within the remit of the GPL (GNU Public License) agreement. What you lose out on is support. So, you may well find CentOS more used within smaller business operations and academia (where external support is not as critical). Support for CentOS is available only through public forums. Of course, this means that there is no guaranteed service level available.

CentOS began its operation in 2004 and is now entering its second decade. The free of charge product it brings on the market replicates the same reliability and predictability of its Red Hat cousin. The relationship between Red Hat and CentOS was more formalized in January 2014. The governance panel at CentOS now includes Red Hat board members among their numbers.

CentOS does not release beta versions in the same way as Red Hat. This means that the latest version available from the CentOS stable is version 7.0. This will use the same kernel and version 3.10.0-123 as the RHEL 7.0 distribution. The close resemblance between CentOS and Red Hat often means that CentOS becomes a perfect study platform for those wishing to learn Red Hat and, perhaps, gain their certifications. This is certainly a very viable option and the same applies to studying this book. Although, we will be using RHEL 7.1 beta, if you want to use CentOS, this should be very similar and mostly compatible with CentOS 7.

As CentOS does not offer subscription support, this in turn affects the product life cycle. To obtain the entire 13 years of support that RHEL 7 offers, a RHEL customer will have to purchase extended support for the final 3 years coverage. This means that CentOS has repositories that will distribute updates for 10 years, resulting in the fact that CentOS 7 can continually be updated until June 2024. Not bad at all when you see it like this and all without financial cost.

You can download the latest version of CentOS without the need to create an account directly from http://centos.org/download/.

We can say that Fedora is the home version of Red Hat. Although we have marked this as a home version, Fedora ships in a server version and it's your choice as to how and where you use Fedora. The support for newer laptops and the latest hardware is going to be far greater. This then often makes it a target for home users and enthusiasts. The current version is Fedora 21 and uses almost all the very latest kernel with version 3.17.4-301.

The other advantage of using Fedora, even if not in a production format, is that you become familiar with technologies. These technologies will become enterprise-ready at some point. In this way, you will learn as the product is developed. For example, RHEL 7 is based around Fedora 19 and 20. If you have been an enthusiastic Fedora champion, you will already be familiar with GRUB2, BTRFS, docker, and systemd (all of which debut in RHEL 7).

Support for Fedora is community-driven with software updates available for about 13 months from the initial product launch. For example, Fedora 21 will be supported for 1 month after the release of Fedora 23. The release dates are about every 6 months, which gives us an approximate support life of 13 months. This is often why Fedora (and similar distributions to Fedora) do not make it to the enterprise category because of such a short update life cycle.

For learning and home use, this is truly a great distribution. You can choose to download the workstation, server, or cloud version at https://getfedora.org/.

From a popularity perspective, Fedora is certainly there. The numbers of hits to the Fedora download page over the past twelve months rates Fedora as being the fourth most popular distribution. To support this data and to take a look at where we read this from, you may visit http://www.distrowatch.com.

If you are installing from scratch, then we hope that you are able to determine what you are actually installing. If you can't, then we have some issues we need to resolve before the installation. Often though, you may be faced with a machine that is preinstalled or a lab machine that you may have access to. An obvious first step to any faultfinding task will be to determine the actual OS and patch level that we will work on. We will now look at the many ways that exist to determine the flavor of Linux that you will use.

/etc/redhat-release
/etc/centos-release
/etc/fedora-release

$ cat /etc/system-release

Red Hat Enterprise Linux Server release 7.1 Beta (Maipo)

$ cat /etc/issue

\S
Kernel \r on an \m

Red Hat Enterprise Linux Server 7.1 (Maipo)
Kernel 3.10.0-210.el7.x86_64 on an x86_64

$ sudo yum install redhat-lsb-core

$ lsb_release -a
LSB Version:    :core-4.1-amd64:core-4.1-noarch
Distributor ID: RedHatEnterpriseServer
Description:    Red Hat Enterprise Linux Server release 7.1 Beta (Maipo)
Release:        7.1
Codename:       Maipo

$ sudo yum install redhat-lsb

$ lsb_release -a
LSB Version:    :core-4.1-amd64:core-4.1-noarch:cxx-4.1-amd64:cxx-4.1-noarch:desktop-4.1-amd64:desktop-4.1-noarch:languages-4.1-amd64:languages-4.1-noarch:printing-4.1-amd64:printing-4.1-noarch
Distributor ID: Fedora
Description:    Fedora release 21 (Twenty One)
Release:        21
Codename:       TwentyOne

$ uname -r
3.10.0-210.el7.x86_64

By now, I am hoping that you have a better understanding of what you are going to need to follow through this book and how it will help you learn Red Hat Enterprise Linux 7 networking, be it on RHEL, CentOS, or Fedora. You will now be able to differentiate the benefits of each distribution and identify the version that you will work on.

In the next chapter, we will start looking at configuring networks on RHEL 7. Additionally, we will look at how to gain administrative rights using su or sudo and its benefits. This will be particularly useful for those new to Linux administration and those who are a little lost with running tasks as an administrator.