Red Hat Enterprise Linux 4 System Administration Guide Red Hat Enterprise Linux 4: System Administration Guide Copyright © 2005 Red Hat, Inc. Red Hat, Inc. 1801 Varsity Drive Raleigh NC 27606-2072 USA Phone: +1 919 754 3700 Phone: 888 733 4281 Fax: +1 919 754 3701 PO Box 13588 Research Triangle Park NC 27709 USA rhel-sag(EN)-4-Print-RHI (2005-06-06T17:10U1) Copyright © 2005 by Red Hat, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, V1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder. Distribution of the work or derivative of the work in any standard (paper) book form for commercial purposes is prohibited unless prior permission is obtained from the copyright holder. Red Hat and the Red Hat "Shadow Man" logo are registered trademarks of Red Hat, Inc. in the United States and other countries. All other trademarks referenced herein are the property of their respective owners. The GPG fingerprint of the security@redhat.com key is: CA 20 86 86 2B D6 9D FC 65 F6 EC C4 21 91 80 CD DB 42 A6 0E Table of Contents Introduction i 1. Changes To This Manual i 2. Architecture-specific Information ii 3. Document Conventions ii 4. Activate Your Subscription v 4.1. Provide a Red Hat Login v 4.2. Provide Your Subscription Number v 4.3. Connect Your System vi 5. Using the Mouse vi 6. Copying and Pasting Text With X vi 7. More to Come vi 7.1. Send in Your Feedback vi I. Installation-Related Information i 1. Kickstart Installations 1 1.1. What are Kickstart Installations? 1 1.2. How Do You Perform a Kickstart Installation? 1 1.3. Creating the Kickstart File 1 1.4. Kickstart Options 2 1.5. Package Selection 18 1.6. Pre-installation Script 19 1.7. Post-installation Script 21 1.8. Making the Kickstart File Available 22 1.9. Making the Installation Tree Available 23 1.10. Starting a Kickstart Installation 24 2. Kickstart Configurator 27 2.1. Basic Configuration 27 2.2. Installation Method 28 2.3. Boot Loader Options 30 2.4. Partition Information 30 2.5. Network Configuration 33 2.6. Authentication 34 2.7. Firewall Configuration 35 2.8. Display Configuration 36 2.9. Package Selection 39 2.10. Pre-Installation Script 39 2.11. Post-Installation Script 40 2.12. Saving the File 42 3. PXE Network Installations 43 3.1. Setting up the Network Server 43 3.2. PXE Boot Configuration 43 3.3. Adding PXE Hosts 45 3.4. Starting the tftp Server 46 3.5. Configuring the DHCP Server 47 3.6. Adding a Custom Boot Message 47 3.7. Performing the PXE Installation 47 4. Diskless Environments 49 4.1. Start the tftp Server 49 4.2. Configuring the DHCP Server 49 4.3. Configuring the NFS Server 50 4.4. Finish Configuring the Diskless Environment 50 4.5. Adding Hosts 51 4.6. Booting the Hosts 51 5. Basic System Recovery 53 5.1. Common Problems 53 5.2. Booting into Rescue Mode 53 5.3. Booting into Single-User Mode 56 5.4. Booting into Emergency Mode 56 II. File Systems 57 6. The ext3 File System 59 6.1. Features of ext3 59 6.2. Creating an ext3 File System 59 6.3. Converting to an ext3 File System 60 6.4. Reverting to an ext2 File System 60 7. Logical Volume Manager (LVM) 63 7.1. What is LVM? 63 7.2. What is LVM2? 64 7.3. Additional Resources 64 8. LVM Configuration 65 8.1. Automatic Partitioning 65 8.2. Manual LVM Partitioning 66 9. Redundant Array of Independent Disks (RAID) 73 9.1. What is RAID? 73 9.2. Who Should Use RAID? 73 9.3. Hardware RAID versus Software RAID 73 9.4. RAID Levels and Linear Support 74 10. Software RAID Configuration 77 10.1. Creating the RAID Partitions 77 10.2. Creating the RAID Devices and Mount Points 80 11. Swap Space 85 11.1. What is Swap Space? 85 11.2. Adding Swap Space 85 11.3. Removing Swap Space 87 11.4. Moving Swap Space 88 12. Managing Disk Storage 89 12.1. Standard Partitions using parted 89 12.2. LVM Partition Management 94 13. Implementing Disk Quotas 97 13.1. Configuring Disk Quotas 97 13.2. Managing Disk Quotas 100 13.3. Additional Resources 102 14. Access Control Lists 103 14.1. Mounting File Systems 103 14.2. Setting Access ACLs 103 14.3. Setting Default ACLs 104 14.4. Retrieving ACLs 105 14.5. Archiving File Systems With ACLs 105 14.6. Compatibility with Older Systems 106 14.7. Additional Resources 106 III. Package Management 109 15. Package Management with RPM 111 15.1. RPM Design Goals 111 15.2. Using RPM 112 15.3. Checking a Package’s Signature 117 15.4. Impressing Your Friends with RPM 118 15.5. Additional Resources 120 16. Package Management Tool 121 16.1. Installing Packages 121 16.2. Removing Packages 123 17. Red Hat Network 125 IV. Network-Related Configuration 129 18. Network Configuration 131 18.1. Overview 132 18.2. Establishing an Ethernet Connection 132 18.3. Establishing an ISDN Connection 133 18.4. Establishing a Modem Connection 135 18.5. Establishing an xDSL Connection 136 18.6. Establishing a Token Ring Connection 138 18.7. Establishing a Wireless Connection 139 18.8. Managing DNS Settings 141 18.9. Managing Hosts 142 18.10. Working with Profiles 143 18.11. Device Aliases 145 18.12. Establishing an IPsec Connection 146 18.13. Saving and Restoring the Network Configuration 151 19. Basic Firewall Configuration 153 19.1. Security Level Configuration Tool 153 19.2. Activating the iptables Service 155 20. Controlling Access to Services 157 20.1. Runlevels 157 20.2. TCP Wrappers 158 20.3. Services Configuration Tool 159 20.4. ntsysv 160 20.5. chkconfig 161 20.6. Additional Resources 161 21. OpenSSH 163 21.1. Why Use OpenSSH? 163 21.2. Configuring an OpenSSH Server 163 21.3. Configuring an OpenSSH Client 163 21.4. Additional Resources 168 22. Network File System (NFS) 169 22.1. Why Use NFS? 169 22.2. Mounting NFS File Systems 169 22.3. Exporting NFS File Systems 171 22.4. Additional Resources 175 23. Samba 177 23.1. Why Use Samba? 177 23.2. Configuring a Samba Server 177 23.3. Connecting to a Samba Share 183 23.4. Additional Resources 185 24. Dynamic Host Configuration Protocol (DHCP) 187 24.1. Why Use DHCP? 187 24.2. Configuring a DHCP Server 187 24.3. Configuring a DHCP Client 192 24.4. Additional Resources 193 25. Apache HTTP Server Configuration 195 25.1. Basic Settings 195 25.2. Default Settings 197 25.3. Virtual Hosts Settings 202 25.4. Server Settings 205 25.5. Performance Tuning 207 25.6. Saving Your Settings 207 25.7. Additional Resources 208 26. Apache HTTP Secure Server Configuration 211 26.1. Introduction 211 26.2. An Overview of Security-Related Packages 211 26.3. An Overview of Certificates and Security 213 26.4. Using Pre-Existing Keys and Certificates 214 26.5. Types of Certificates 214 26.6. Generating a Key 215 26.7. Generating a Certificate Request to Send to a CA 217 26.8. Creating a Self-Signed Certificate 218 26.9. Testing The Certificate 219 26.10. Accessing The Server 220 26.11. Additional Resources 220 27. Authentication Configuration 223 27.1. User Information 223 27.2. Authentication 224 27.3. Command Line Version 226 V. System Configuration 229 28. Console Access 231 28.1. Disabling Shutdown Via [Ctrl]-[Alt]-[Del] 231 28.2. Disabling Console Program Access 231 28.3. Defining the Console 232 28.4. Making Files Accessible From the Console 232 28.5. Enabling Console Access for Other Applications 233 28.6. The floppy Group 234 29. Date and Time Configuration 235 29.1. Time and Date Properties 235 29.2. Network Time Protocol (NTP) Properties 236 29.3. Time Zone Configuration 236 30. Keyboard Configuration 239 31. Mouse Configuration 241 32. X Window System Configuration 243 32.1. Display Settings 243 32.2. Display Hardware Settings 243 32.3. Dual Head Display Settings 244 33. User and Group Configuration 247 33.1. Adding a New User 247 33.2. Modifying User Properties 248 33.3. Adding a New Group 249 33.4. Modifying Group Properties 249 33.5. Command Line Configuration 250 33.6. Explaining the Process 253 33.7. Additional Information 254 34. Printer Configuration 257 34.1. Adding a Local Printer 258 34.2. Adding an IPP Printer 259 34.3. Adding a Remote UNIX (LPD) Printer 260 34.4. Adding a Samba (SMB) Printer 261 34.5. Adding a Novell NetWare (NCP) Printer 262 34.6. Adding a JetDirect Printer 263 34.7. Selecting the Printer Model and Finishing 264 34.8. Printing a Test Page 265 34.9. Modifying Existing Printers 266 34.10. Saving the Configuration File 268 34.11. Command Line Configuration 268 34.12. Managing Print Jobs 270 34.13. Sharing a Printer 272 34.14. Additional Resources 274 35. Automated Tasks 275 35.1. Cron 275 35.2. At and Batch 277 35.3. Additional Resources 279 36. Log Files 281 36.1. Locating Log Files 281 36.2. Viewing Log Files 281 36.3. Adding a Log File 282 36.4. Examining Log Files 283 37. Manually Upgrading the Kernel 285 37.1. Overview of Kernel Packages 285 37.2. Preparing to Upgrade 286 37.3. Downloading the Upgraded Kernel 287 37.4. Performing the Upgrade 288 37.5. Verifying the Initial RAM Disk Image 288 37.6. Verifying the Boot Loader 289 38. Kernel Modules 293 38.1. Kernel Module Utilities 293 38.2. Persistent Module Loading 295 38.3. Additional Resources 295 39. Mail Transport Agent (MTA) Configuration 297 VI. System Monitoring 299 40. Gathering System Information 301 40.1. System Processes 301 40.2. Memory Usage 303 40.3. File Systems 304 40.4. Hardware 304 40.5. Additional Resources 305 41. OProfile 307 41.1. Overview of Tools 307 41.2. Configuring OProfile 308 41.3. Starting and Stopping OProfile 312 41.4. Saving Data 312 41.5. Analyzing the Data 312 41.6. Understanding /dev/oprofile/ 315 41.7. Example Usage 316 41.8. Graphical Interface 316 41.9. Additional Resources 318 Index 321 Colophon 333 Introduction Welcome to the Red Hat Enterprise Linux System Administration Guide. The Red Hat Enterprise Linux System Administration Guide contains information on how to customize your Red Hat Enterprise Linux system to fit your needs. If you are looking for a step-by-step, task- oriented guide for configuring and customizing your system, this is the manual for you. This manual discusses many intermediate topics such as the following: • Setting up a network interface card (NIC) • Performing a Kickstart installation • Configuring Samba shares • Managing your software with RPM • Determining information about your system • Upgrading your kernel This manual is divided into the following main categories: • Installation-Related Reference • File Systems Reference • Package Management • Network Configuration • System Configuration • System Monitoring This guide assumes you have a basic understanding of your Red Hat Enterprise Linux system. If you need help installing Red Hat Enterprise Linux, refer to the Red Hat Enterprise Linux Installation Guide. For more general information about system administration, refer to the Red Hat Enterprise Linux Introduction to System Administration. If you need more advanced documentation such as an overview of file systems, refer to the Red Hat Enterprise Linux Reference Guide. If you need security information, refer to the Red Hat Enterprise Linux Security Guide. 1. Changes To This Manual This manual has been reorganized for clarity and updated for the latest features of Red Hat Enterprise Linux 4. Some of the changes include: Updated Kernel Modules and Manually Updating the Kernel Chapters The Kernel Modules and the Upgrading the Kernel Manually chapters include updated information in regards to the 2.6 kernel. Special thanks to Arjan van de Ven for his hard work in helping to complete this chapter. An Updated Network File System (NFS) Chapter The Network File System (NFS) chapter has been revised and reorganized to include NFSv4. Special thanks to Steve Dickson for his hard work in helping to complete this chapter. ii Introduction An Updated OProfile Chapter The OProfile chapter has been revised and reorganized to include updated information in regards to the 2.6 kernel. Special thanks to Will Cohen for his hard work in helping to complete this chapter. An Updated X Window System Chapter The X Window System chapter has been revised to include information on the X11R6.8 release developed by the X.Org team. Before reading this guide, you should be familiar with the contents of the Red Hat Enterprise Linux Installation Guide concerning installation issues, the Red Hat Enterprise Linux Introduction to System Administration for basic administration concepts, the Red Hat Enterprise Linux System Administration Guide for general customization instructions, and the Red Hat Enterprise Linux Security Guide for security related instructions. This guide contains information about topics for advanced users. HTML, PDF, and RPM versions of the manuals are available on the Red Hat Enterprise Linux Docu- mentation CD and online at http://www.redhat.com/docs/. Note Although this manual reflects the most current information possible, read the Red Hat Enterprise Linux Release Notes for information that may not have been available prior to our documentation being finalized. The Release Notes can be found on the Red Hat Enterprise Linux CD #1, online at http://www.redhat.com/docs/, or in the /usr/share/doc/redhat-release-4<product>/ directory after installation, where <product> is AS, ES, WS, or Desktop. 2. Architecture-specific Information Unless otherwise noted, information contained in this manual applies only to the x86 processor and processors featuring the Intel® Extended Memory 64 Technology (Intel® EM64T) and AMD64 tech- nologies. For architecture-specific information, refer to the Red Hat Enterprise Linux Installation Guide for your respective architecture. 3. Document Conventions In this manual, certain words are represented in different fonts, typefaces, sizes, and weights. This highlighting is systematic; different words are represented in the same style to indicate their inclusion in a specific category. The types of words that are represented this way include the following: command Linux commands (and other operating system commands, when used) are represented this way. This style should indicate to you that you can type the word or phrase on the command line and press [Enter] to invoke a command. Sometimes a command contains words that would be displayed in a different style on their own (such as file names). In these cases, they are considered to be part of the command, so the entire phrase is displayed as a command. For example: Use the cat testfile command to view the contents of a file, named testfile, in the current working directory.