1 Prepare for Red Hat Hands-on Certifications CERTIFICATION OBJECTIVES 1.01 The RHCSA and RHCE Exams 1.06 System Setup Options 1.02 Basic Hardware Requirements 1.07 Configure Default File Sharing Services 1.03 Get Red Hat Enterprise Linux ✓ Two-Minute Drill 1.04 Installation Requirements Q&A Self Test 1.05 Installation Options 2 Chapter 1: Prepare for Red Hat Hands-on Certifi cations he Red Hat exams are an advanced challenge. While this book covers the Red Hat Certified System Administrator (RHCSA) exam, it provides the foundation for those Twho want to earn the Red Hat Certified Engineer (RHCE) certification. Red Hat offers several courses to help prepare for these exams, as described in the front matter and in this chapter. The focus of this chapter is installation, to create a common version of Red Hat Enterprise Linux (RHEL) as a test bed for future chapters. It assumes and describes hardware required to implement Red Hat’s default virtual machine (VM) solution, the Kernel-based Virtual Machine (KVM). As rebuild distributions such as the Community Enterprise Operating System (CentOS) and Scientific Linux are essentially identical to RHEL, you should be able to use those solutions too. Just about the only difference between a rebuild and RHEL is the trademarks and the access to repositories, which will be described in Chapter 7. Those of you familiar with earlier versions of the Red Hat requirements may note the recent changes to the Red Hat exams. Red Hat no longer gives a RHCT exam. It has now been replaced with the RHCSA. While the RHCSA is in many ways similar to the RHCT, there are significant differences. Most RHCSA objectives were covered on the former RHCT exam. However, the RHCSA is certainly not easier than the RHCT; it is just now a prerequisite to the RHCE. The RHCSA also includes a number of requirements that were formerly part of the RHCE objectives. Nevertheless, Red Hat suggests that candidates for the RHCSA will have one to three years of experience with the bash shell, user administration, system monitoring, basic networking, software updates, and more. Details are described in the introduction to this book. If you’re new to Linux or Unix, this book may not be enough for you. It’s not possible to provide sufficient detail, at least in a way that can be understood by newcomers to Linux and other Unix-based operating systems. If after reading this book, you find gaps in your knowledge, please refer to one of the following guides: ■ by Wale Soyinka (McGraw-Hill, 2008), provides a detailed step-by-step guide to this operating system. The RHCSA and RHCE Exams 3 ■ by Michael Jang (Jones & Bartlett, 2010), gives you a detailed look at how you can secure your Linux system and networks in every possible way. ■ by Michael Jang (Course Technology PTR, 2009), covers the certification many Linux professionals qualify for prior to working on the RHCSA and RHCE. Before installing Red Hat Enterprise Linux (RHEL), you need the right hardware. You’ll need to have a physical system with a 64-bit CPU capable of hardware virtualization. Details are discussed in the chapter. As such, while the RHCSA and RHCE exams are by and large not hardware exams, some basic hardware knowledge is a fundamental requirement for any Linux administrator. As for the operating system itself, you can purchase a subscription to RHEL, or you can use one of the “rebuild” distributions where the distribution is built by third parties from source code publicly released by Red Hat. If you’re experienced with other Unix-type operating systems such as Solaris, AIX, or HP-UX, prepare to leave some defaults at the door. There are even significant differences between the Ubuntu and Red Hat distributions. When Red Hat developed its Linux distribution, the company made some choices that are not consistent with standard Unix practices. When I took Red Hat’s RH300 course, some students with these backgrounds had difficulties with the course and the RHCE exam. For the purpose of this book, I’ll be running most commands as the Linux administrative user, root. Logging in as the root user is normally discouraged unless you’re administering a computer. However, since the RHCSA and RHCE exams test your administrative skills, it’s appropriate to run commands in this book as the root user. But you’ll also need to know how to set up regular users with partial or full administrative privileges. 4 Chapter 1: Prepare for Red Hat Hands-on Certifi cations INSIDE THE EXAM A Virtual Host servers to share files are fairly simple. In fact, no changes are required to the default con- The RHCSA assumes that you know how to figuration files for these services. Some of the “configure a physical machine to host virtual related steps described in this chapter depend guests.” In other words, you need to be able to on skills presented in future chapters. prepare a system to house VMs where other The original release of the RHCSA instances of RHEL (or even other operating objectives was worded slightly differently: systems such as Microsoft Windows) can be “Deploy file sharing services with HTTP/ installed. FTP.” I believe this provides a significant clue As this is RHEL, this is based on the Red to Red Hat’s intent with these objectives. To Hat default VM system, KVM. As appropri- that end, you’ll examine how to set up these ate rebuild distributions such as CentOS and services as file servers, based on their default Scientific Linux use the same source code, configurations. they also use KVM. In this chapter, not only will you install RHEL, but also you will install those packages that support KVM. Using Other Versions of Red Hat For the purpose of this chapter, you can Default File Sharing Configuration install RHEL 6 using a paid subscription or Services from a demonstration DVD. You can also use one of the rebuild distributions. However, RHCSAs are expected to know how to “Con- while RHEL 6 is based in part on the work figure a system to run a default configuration done on the Fedora Linux distribution, it’s HTTP server” and “Configure a system to run based in part on both the Fedora 12 and 13 a default configuration FTP server.” The de- releases. So it’s possible if you use Fedora 12 fault Red Hat solutions for these services are or 13, the configuration files may in some the Apache Web server and the very secure cases be quite different from RHEL 6. Later FTP (vsFTP) server. While these services can versions of Fedora are likely to have features be complex, the steps required to set up these not found in RHEL 6. The RHCSA and RHCE Exams 5 CERTIFICATION OBJECTIVE 1.01 The RHCSA and RHCE Exams Red Hat first started giving certification exams in 1999. Since that time, their exams have evolved. The former RHCT was a complete subset of the RHCE. Today, the RHCSA now covers topics separate from but closely related to the RHCE. In addition, Red Hat has focused the exams more on hands-on configuration. Multiple choice questions were removed from the exam in 2003. More recently, in 2009, they simplified the exam by removing the requirement to install Linux on a “bare-metal” system. (However, the changes implemented in 2011 suggest that you need to know how to install Linux over a network on a VM.) In addition, there is no longer a separate troubleshooting portion of the exam. For more information, see www.redhat.com/certification/faq. Red Hat provides “pre- available through the Red Hat web pages assessment” tests for Red Hat RHCSA for each course. Red Hat requires contact and RHCE Exam Prep courses. They information before providing those correspond to the RH134 and RH254 preassessment tests. courses, respectively. These tests are The Exam Experience Red Hat’s certification tests are hands-on exams. As such, they are respected throughout the industry as a sign of genuine practical knowledge. When you pass a Red Hat exam, you will stand head and shoulders above the candidate who has passed only a “standard” multiple-choice certification exam. When time starts, you’ll be faced with a live system. You’ll be given actual configuration problems associated with the items listed in the exam objectives for each certification, shown at www.redhat.com/certification/rhcsa/objectives/ and www.redhat.com/certification/rhce/objectives/. Naturally, this book is dedicated to helping you gain the skills described on those web pages. 6 Chapter 1: Prepare for Red Hat Hands-on Certifi cations While you won’t have Internet access during the exam, you will have access to online documentation such as man and info pages as well as documentation in the / usr/share/doc/ directories, assuming appropriate packages are installed. In addition, Red Hat provides the exam in electronic format. While the basic instructions may be in a local language such as English, the RHCSA and RHCE exams are available in 12 different languages: English, Simplified Chinese, Traditional Chinese, Dutch, French, Italian, Japanese, Korean, Portuguese, Russian, Spanish, and Turkish. Red Hat also has prep courses for both exams. The outline for those courses are available from www.redhat.com. While this book is not intended as a substitute for such courses, they are consistent with the outline of those courses. This book covers the objectives associated with each of these exams. Exam Watch This book’s the front matter for this book, in Table 2, coverage of the items listed in the RHCSA page (TBD). and RHCE exam objectives can be found The RHCSA Exam The RHCSA exam allows you to demonstrate your ability to configure live physical and virtual systems for networking, security, custom filesystems, package updates, user management, and more. In essence, the RHCSA exam covers those skills required to configure and administer a Linux workstation in the enterprise. The RHCSA exam (like the RHCE exam) lasts two hours. When you sit down to take the exam, you’ll have tasks to perform on a live RHEL system. Any changes that are made must survive a reboot. When you’ve completed the given tasks, the person grading the exam will see if the system is configured to meet the requirements. For example, if you’re told to “create, delete, and modify local user accounts,” it doesn’t matter if the associated configuration file has been modified with the vi editor or the graphical User Manager tool. As long as you don’t cheat, it’s the results that matter. The RHCSA and RHCE Exams 7 The RHCE Exam The RHCE exam tests your ability to configure live physical and virtual servers to configure network services such as Apache, vsFTP, the Network File System (NFS), Samba, the Postfix e-mail service, remote logging, and more. It also tests your ability to handle complex configuration options associated with Security Enhanced Linux (SELinux), firewalls, networking, and more. In essence, if you pass the RHCE exam, hiring managers will know that you’re qualified to help manage their enterprises of Linux systems. The RHCE exam also lasts two hours. When you sit down to take the exam, you’ll be given tasks to perform on a live RHEL system. As with the RHCSA, any changes that are made must survive a reboot. In any case, it doesn’t matter if you’ve configured the associated configuration file with the nano editor or a GUI tool. As long as you don’t cheat, it’s the results that matter. The topics in the Red Hat preparation courses in a few areas go beyond those listed in the Red Hat Exam Prep guide. While such topics are not currently part of the exam, they may be included in future versions of the Red Hat exams. If You’re Studying “Just” for the RHCSA Exam Red Hat has been known to make minor changes to the requirements on occasion. Future changes may be based on topics covered in the Red Hat RHCSA Rapid Track course, RH199. So if you’re not planning to take the RHCSA within the next few months, watch the outline for that course. It may in effect be a preview of where Red Hat wants to take the RHCSA exam in the future. Evolving Requirements Changes happen to the requirements for the Red Hat exams. You can see that in the differences between the RHCT and the RHCSA. You can see that in the changes to the exam format, where bare-metal installations are no longer required. In fact, that change happened over two years into the life of RHEL 5. Changes happened in the first month after RHEL 6 was released. So when you’re preparing for the RHCSA or RHCE exams, watch the associated exam objectives carefully. In addition, Red Hat announced its most recent format changes through the WordPress blog publishing site, at http://redhatcertification.wordpress.com/. 8 Chapter 1: Prepare for Red Hat Hands-on Certifi cations CERTIFICATION OBJECTIVE 1.02 Basic Hardware Requirements Now it’s time to explore in detail the hardware that Red Hat Enterprise Linux can handle. While some manufacturers now include their own Linux hardware drivers, most Linux hardware support comes from third parties, starting with the work of volunteers. Fortunately, there is a vast community of Linux users, many of whom produce drivers for Linux and distribute them freely on the Internet. If a certain piece of hardware is popular, you can be certain that Linux support for that piece of hardware will pop up somewhere on the Internet and will be incorporated into various Linux distributions, including Red Hat Enterprise Linux. Hardware Compatibility If you only have 32-bit systems available, be prepared to spend some money. KVM is the default VM solution for RHEL 6. Red Hat has configured it to operate only on 64-bit systems. Fortunately, most PCs and servers sold today are 64-bit systems. Even the lowly Intel i3 CPU can handle 64-bit operating systems. There are even 64-bit versions of the Intel Atom CPU common on netbook systems. Similar comparisons can be made for CPUs from Advanced Micro Devices. Be careful when purchasing a new computer to use with Linux. Though Linux has come a long way the last few years, and you should have little problem installing it on most modern servers or PCs, you shouldn’t assume Linux will install or run flawlessly on computer, especially if the system in question is a state-of-the-art laptop computer. (And you do need a 64-bit system to prepare for the Red Hat exams.) Laptops are often designed with proprietary configurations that work with Linux only after some reverse engineering. For example, when I installed RHEL 6 on a brand-name business laptop built in 2010, I had to do a bit of extra work to make the wireless adapter work with RHEL 6. The architecture of a server or PC defines the components that it uses as well as the way that they are connected. In other words, the architecture describes much more than just the CPU. It includes standards for other hardware such as the hard drive, the network card, the keyboard, the graphics adapter, and more. All software is written for a specific computer architecture. Basic Hardware Requirements 9 Even when a manufacturer creates a device for a CPU platform, it may not work with Linux. Therefore, it’s important to know the basic architecture of a computer. But strictly speaking, if you want hardware compatible with and supported by Red Hat, consult the hardware compatibility list at http://hardware.redhat.com/hcl/. Exam Watch While it is objectives directly addresses hardware. important to know how Linux interacts However, to practice for the exams, you do with your hardware, the Red Hat exams need to install RHEL 6. And to confi gure a are not hardware exams. With the possible system for KVM, which requires hardware- exception of the Internet Small Computer assisted virtualization, you need a system Systems Interface (iSCSI) targets in the with 64-bit CPUs and related hardware. RHCE objectives, no part of the exam Architectures While RHEL 6 has been built for a variety of architectures, you can focus on the Intel/AMD 64-bit or x86_64 architecture for the RHCSA and RHCE exams. As of this writing, these exams are offered only on computers with such CPUs, so you need not worry about special architecture-specific issues such as specialty bootloaders or 64-bit module directories. Nevertheless, customized Red Hat distributions are available for a variety of platforms. You can install RHEL 6 on systems with a wide variety of CPUs. But remember, to test a system for the required KVM virtualization solution, you’ll need a 64-bit system. Red Hat supports four basic different CPU architectures: ■ x86 (32-bit) ■ Intel/AMD64 (x86_64) ■ IBM Power Architecture (64-bit) ■ IBM System Z Architecture