Hands-on Guide to the Red Hat Exams

Damian Tommasino is currently a Linux system administrator at TradeCard and CEO of Modular Learning, Inc., an online IT training company. His current certifications include RHCE, RHCSA, MCSA, CCNA, CCENT, MCP, Security+, Network+, and A+. He has a popular blog called Security Nut (http://secnut.blogspot.com) that covers Red Hat, Linux, security, and more. Damian also spends time over at techexams.net helping out in the forums and conversing with friends.

Preface xvi

Introduction 3

Chapter 1 Installation 29

Starting the Installation 29

An Older Install with RHEL5 33

The Firstboot Process 37

Verifying the Installation 40

Summary 41

Review Questions 42

Answers to Review Questions 42

Chapter 2 System Initialization 47

The Boot Process 47

Working with GRUB 51

The Config File 52

The GRUB Command Line 54

Runlevels 55

Runlevel Utilities 56

Rescue and Recovery Runlevels 59

Service Management 59

The Upstart Conversion 64

Summary 66

Review Questions 66

Answers to Review Questions 67

Chapter 3 Disks and Partitioning 71

Basic Partitions 71

Creating a Partition 75

Making a Swap Partition 81

Deleting a Partition 83

Logical Volume Manager 85

Creating an LVM Partition 89

Adjusting the Size of LVM Partitions 93

Migrating Data 96

Deleting an LVM Partition 99

Setting Up RAID 101

Creating a RAID Array 102

What to Do When a Disk Fails 105

Deleting a RAID Array 108

Summary 109

Review Questions 109

Answers to Review Questions 109

Chapter 4 File Systems and Such 113

File System Setup 113

Creating a File System 114

Creating a Swap 116

Mounting a File System 119

Extra File System Commands 125

Encryption with LUKS 128

Creating Encrypted Partitions 129

Mounting LUKS at Boot 132

Managing File System Quotas 132

Setting Up Quotas 132

Enabling Quotas 134

Quota Usage Reports 137

File System Security 137

Setting Up ACLs 138

GnuPG 141

Using AutoFS 141

Summary 144

Review Questions 144

Answers to Review Questions 145

Chapter 5 Networking 149

Setting Up Networking 149

Static IP Addresses 151

Routing 155

Creating Static Routes 156

Troubleshooting Network Connections 156

Networking Utilities 157

Network Monitoring and Analysis 159

Advanced Networking 160

Ethernet Bonding 160

Client DNS Troubleshooting 161

Summary 164

Review Questions 165

Answers to Review Questions 165

Chapter 6 Package Management 169

Working with RPM 169

Installing and Removing Packages 170

Querying and Verifying Packages 172

Doing It Again with Yum 177

Installing and Removing Packages 178

Searching for Packages 182

Configuring Additional Repositories 183

Making Your Own RPM 184

Creating an RPM 185

Creating Your Own Repository 188

Adding Your Custom Packages 190

The Red Hat Network 190

Registering Your System 191

Summary 191

Review Questions 192

Answers to Review Questions 192

Chapter 7 User Administration 195

Users and Groups 195

Users 196

Passwords 199

The Password File 200

The Shadow File 201

Groups 204

The Group File 204

Switching Accounts 206

User Account Initialization 207

User-Specific Files 207

Global User Configuration 208

Group Collaboration 209

Network User Authentication 211

Summary 215

Review Questions 215

Answers to Review Questions 216

Chapter 8 Network Installs 221

Kickstart Server Setup 221

Firewall and SELinux Configuration 224

Mastering Kickstart Config Files 225

Post Install 227

Advanced Partitioning 227

Automating Kickstart 228

TFTP Server 229

PXE Boot 232

Firewall and SELinux Configuration 233

Other Network Installs 234

Summary 235

Review Questions 235

Answers to Review Questions 236

Chapter 9 System Logging, Monitoring, and Automation 239

Working with Syslog 239

The Config File 241

Log Rotation 243

Centralized Logging 244

Centralized Logging (The RHEL5 Way) 246

User Login Events 247

Monitoring System Performance 248

Automation with cron and at 252

Creating cron Jobs 254

Single Jobs with at 258

Summary 261

Review Questions 261

Answers to Review Questions 262

Chapter 10 The Kernel 265

Kernel Basics 265

Updating the Kernel 268

Tuning the Kernel with /proc/sys 272

Summary 274

Review Questions 275

Answers to Review Questions 275

Chapter 11 SELinux 277

Understanding SELinux 277

Configuring SELinux 279

File Contexts 279

Service and Boolean Options 283

SELinux Troubleshooting 286

Policy Violations 286

Summary 287

Review Questions 287

Answers to Review Questions 288

Chapter 12 System Security 291

Security Through TCP Wrappers 291

Firewall Rules Using iptables 293

Configuring iptables 294

Troubleshooting Firewall Rules 299

Working with NAT 300

Pluggable Authentication Module 301

Securing Access 301

PAM Troubleshooting 303

Managing Password Policies 304

Summary 305

Review Questions 305

Answers to the Review Questions 306

Chapter 13 Remote Access 309

Secure SHell (SSH) 309

Configuring SSH 310

Firewall and SELinux Configuration 313

SSH Security 314

Troubleshooting SSH 315

SSH Security Revisited 315

Public/Private Keys 316

Port Forwarding 317

VNC Servers 318

Connecting Clients 320

Summary 321

Review Questions 321

Answers to Review Questions 321

Chapter 14 Web Services 325

The Apache Web Server 325

Installing Apache 325

Configuring the Web Server 326

Firewall and SELinux Configuration 329

Troubleshooting Apache 332

Apache Security 334

Host-Based Security 334

User-Based Security 336

Setting Up HTTPS 339

CGI Applications 341

Virtual Hosts 342

Squid Web Proxy 343

Installing Squid 344

Configuring the Proxy 344

Firewall and SELinux Configuration 345

Web Proxy Security 346

Summary 347

Review Questions 347

Answers to Review Questions 348

Chapter 15 NFS 351

Network File Systems 351

Installing an NFS Server 352

Configuring NFS 353

Firewall and SELinux Configuration 358

NFS Security 360

Troubleshooting NFS 361

Connecting Clients 364

Summary 366

Review Questions 366

Answers to Review Questions 366

Chapter 16 Samba 369

Samba 369

Configuring Samba 370

Samba Security 377

Samba Clients 377

Summary 379

Review Questions 380

Answers to Review Questions 380

Chapter 17 FTP 383

File Transfer Protocol 383

Installing an FTP Server 384

Configuring vsftp 384

Firewall and SELinux Configuration 386

FTP Security 388

Troubleshooting FTP 389

Summary 390

Review Questions 390

Answers to Review Questions 391

Chapter 18 DNS 393

Setting Up BIND 393

Firewall and SELinux Configuration 394

Configuring a DNS Server 396

Master Server 397

Slave Server 401

Caching-Only Server 404

Forwarding-Only Server 406

DNS Utilities and Troubleshooting 406

BIND Security 412

Summary 417

Review Questions 417

Answers to Review Questions 418

Chapter 19 Network Services 421

Xinetd: The Master Service 421

Dynamic Host Configuration Protocol 426

Installing a DHCP Server 426

Configuring the DHCP Server 427

Security Configuration 431

Troubleshooting DHCP 432

Network Time Protocol 433

Installing a Time Server 434

Configuring NTP 434

Firewall and SELinux Configuration 436

NTP Security 437

Troubleshooting NTP 438

Summary 439

Review Questions 439

Answers to Review Questions 439

Chapter 20 Email Services 443

Email Service Overview 443

SMTP with Postfix 443

Configuring Postfix 445

Firewall and SELinux Configuration 449

Postfix Security 450

Alias Mapping 451

Receiving Mail with Dovecot 452

Configuring Dovecot 452

Firewall and SELinux Configuration 453

Dovecot Security 454

Testing the Mail Server 456

Summary 458

Review Questions 459

Answers to Review Questions 459

Chapter 21 Troubleshooting 463

Boot Issues 463

I Lost My Root User Password 463

Password Change Not Available in Single-User Mode 464

The MBR Is Corrupt 464

The Partition or Root File System Can't Be Found 465

Troubleshooting File Systems 466

The System Complains About a File System Label 466

The Superblock Has Become Corrupt 466

Users Can't Create Files in Their Home Directories 467

Miscellaneous 468

I Can't Remote into My System 468

I Can't Access Service X 468

When I Start a Service, It Tells Me "Cannot Bind to Address" 469

I Get the Error Message "No Route to Host" 469

My Ping to Another Host Has Failed 470

Summary 470

Chapter 22 Virtualization with KVM 473

Working with Virtual Machines 473

Setting Up the Physical Host 473

Installing a Virtual Client 474

Managing a Virtual Client 477

Monitoring Virtual Resources 479

Summary 480

Review Questions 480

Answers to Review Questions 481

Lab Exam 1 483

Lab Exam 2 485

Index 486

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