Red Hat Certified Technician and Engineer by Ghori, Asghar -- Read -- Imperial Library of Trantor

Index

Preface Acknowledgments About the Author Conventions Used in this Book About RHCT and RHCE Exams About this Book 01. Overview of Linux

Linux Distributions from Red Hat System Structure Features Logging In and Out Logging In and Out via Commands Logging In and Out via Graphical Interface Common Linux Commands What is the Command Line? The ls Command and its Variations The pwd Command The cd Command The tty Command The who Command The w Command The whoami Command The logname Command The id Command The groups Command The uname Command The hostname Command The clear Command The date Command The hwclock Command The cal Command The uptime Command The which Command The whereis Command The wc Command The wall Command Online Help man Sections Searching by Keyword Displaying Short Description Summary

02. Files and Directories

File System Tree The Root File System (/) – Disk-Based The Boot File System (/boot) – Disk-Based The Variable File System (/var) – Disk-Based The UNIX System Resources File System (/usr) – Disk-Based The Temporary File System (/tmp) – Disk-Based The Optional File System (/opt) – Disk-Based The Home File System (/home) – Disk-Based The Devices File System (/dev) – Virtual The /net File System (/net) – Virtual The Media File System (/media) – Virtual The Miscellaneous File System (/misc) – Virtual The Process File System (/proc) – Virtual The System File System (/sys) – Virtual The SELinux File System (/selinux) – Virtual Absolute and Relative Paths Absolute Path Relative Path File Types Regular Files Directory Files Executable Files Symbolic Link Files Device Files Named Pipe Files Socket Files File and Directory Operations File and Directory Naming Convention Creating Files and Directories Listing Files and Directories Displaying File Contents Copying Files and Directories Moving and Renaming Files and Directories Removing Files and Directories Displaying File and Directory Statistics Summary of File and Directory Operations File and Directory Operations Using Nautilus File Manager Modifying File and Directory Control Attributes Pattern Matching Comparing File Contents Finding Files Finding Files Using the find Command Finding Files Using the locate Command Sorting File Contents Linking Files and Directories Soft Link Hard Link Summary

03. File and Directory Permissions

Determining Access Permissions Permission Classes Permission Types Permission Modes Changing Access Permissions Using Symbolic Notation Using Octal (or Absolute) Notation Using Nautilus File Manager Setting Default Permissions Calculating Default Permissions Changing File Ownership and Group Membership Special Permissions The setuid Bit The setgid Bit The Sticky Bit Summary

04. Text Editors and Processors

The vi (vim) Editor Modes of Operation Starting the vi Editor Inserting text Navigating within vi Deleting Text Undoing and Repeating Searching and Replacing Text Copying, Moving and Pasting Text Changing Text Importing Contents of Another File Customizing vi Edit Sessions Saving and Quitting vi Miscellaneous vi Commands The nano Editor The Text Processors The awk Processor The sed Processor Summary

05. The Shells

The Shell Available Shells BASH Shell Features Variables Setting, Unsetting and Viewing Variables Pre-Defined Environment Variables Command and Variable Substitution Input, Output and Error Redirection Tab Completion, Command Line Editing and Command History Alias Substitution Tilde Substitution Special Characters Masking Special Meaning of Some Special Characters Pipes and Filters Pipes The tee Filter The cut Filter The pr Filter The tr Filter Summary

06. Basic Shell Scripting

Creating Shell Scripts Displaying Basic System Information Executing a Script Debugging a Shell Script Using Local Variables Using Pre-Defined Environment Variables Setting New Environment Variables Parsing Command Output Using Command Line Arguments Shifting Command Line Arguments Writing an Interactive Script Summary

07. System Processes

Understanding Processes Viewing System Processes Listing a Specific Process Determining Processes by Ownership Process States Process Priority Listing Open Files Signals and Their Use Executing a Command Immune to Hangup Signals Summary

08. System Administration and Hardware

System Administration Overview System Administrator Resources Personal Computer Architecture and Components Slot PC Card PCI and PCIe Interface Card Network Interface Card (NIC) Small Computer System Interface (SCSI) Card Fibre Channel (FC) Card Multi-I/O (MIO) Card Bus Processor/Core Hard Drive Serial Port Parallel Port Universal Serial Bus (USB) FireWire Advanced Configuration and Power Interface (ACPI) Hardware Management Hardware Abstraction Layer and Plug and Play Hardware Device Files Probing and Configuring Devices Managing Device Files Dynamically with udev Listing Device Information Major and Minor Numbres Viewing Hardware Diagnostic Messages Available Hardware and Partitions to Work with Summary

09. Installation

Available Installation Methods Installation Requirements System Requirements CPU Requirements Physical Memory Requirements Planning Installation Downloading RHEL Installing Using Local CD/DVD – Text Mode Creating Standard Partitions Creating Software RAID Partitions Creating LVM Partitions Remaining Installation Steps Installing Using Local CD/DVD – Graphical Mode Specifics Firstboot in Graphical Mode Installation Log Files Virtual Console Screens Summary

10. X Window System and Desktop Managers

Overview X Server Configuring X Server X Server Configuration File Probing Hardware and Rebuilding X Server Configuration File Additional X Configuration Files X Startup File X Font Server X Clients Configuring a Sample X Client Program Display and Desktop Managers GNOME Display and Desktop Managers KDE Display and Desktop Managers Configuring System-Wide Default Display Manager Configuring Per-User Default Desktop Configuring System-Wide Default Desktop Manager Running X Applications Remotely Summary

11. Software Package Management

Package Overview Packages and Packaging Package Naming Convention Package Dependency Package Database Package Repository Red Hat Network (RHN) RHN Benefits Registering with RHN Administering Software via RHN Package Administration Tools Managing Packages with rpm Listing Installed Packages Installing a Package Upgrading a Package Freshening a Package Overwriting a Package Querying a Package Removing a Package Extracting Files from a Package Verifying Package Signature Verifying Attributes of an Installed Package Managing Packages with yum YUM Repository Creating a YUM Repository YUM Configuration File Listing Packages Installing and Updating Packages Searching Packages Removing Packages Checking Availability of Updated Packages Synchronizing Package Headers Managing Packages with pirut Updating Packages with pup Building a Custom Package Summary

12. Users and Groups

Overview User Authentication – The /etc/passwd File User Authentication – The /etc/group File User Authentication – The /etc/shadow File User Authentication – The /etc/gshadow File Verifying Consistency of User Authentication Files Locking User Authentication Files Managing Password Shadowing Managing User Accounts and Password Aging Creating a User Account Setting and Modifying Password Aging Modifying a User Account Switching Users Doing as Superuser Deleting a User Account Displaying Successful User Login Attempts History Displaying Unsuccessful User Login Attempts History Displaying Failed Login Attempts Displaying Currently Logged In Users Displaying Recent User Logins Managing Group Accounts Creating a Group Account Modifying a Group Account Managing Groups with gpasswd Command Deleting a Group Account Default Login Parameters User Initialization Files System-wide Initialization Files Per-user Initialization Files Summary

13. Disk Partitioning

Disk Partitioning Using fdisk Creating a Partition Creating a Swap Partition Deleting a Partition Disk Partitioning Using parted Creating a Partition Creating a Swap Partition Deleting a Partition Disk Partitioning Using Software RAID RAID 0 (Concatenation) RAID 0 (Striping) RAID 1 (mirroring) RAID 5 (striping with parity) RAID 6 Creating a RAID Array Replacing a Failed Disk in a RAID Array Deleting a RAID Array Disk Partitioning Using Logical Volume Manager Physical Volume Volume Group Physical Extent Logical Volume Logical Extent Managing Disk Space Using LVM Overview of LVM Configurator Creating a Physical Volume Creating and Displaying a Volume Group Creating and Displaying a Logical Volume Extending a Volume Group Extending a Logical Volume Reducing a Logical Volume Renaming a Logical Volume Removing a Logical Volume Moving Physical Extents Reducing a Volume Group Removing a Volume Group Uninitializing a Physical Volume Summary

14. File Systems and Swap

File System Types Extended File Systems (ext2 and ext3) Managing File Systems Creating a File System Mounting a File System Labeling a File System Viewing Mounted File Systems Extending a File System Reducing a File System Unmounting a File System Mounting a File System at System Boot Removing a File System Access Control List (ACL) Listing ACL Information Changing ACL Information Default ACL Understanding Disk Quota Configuring and Managing Disk Quota Configuring Disk Quota Activating Quota Automatically at System Reboot Reporting on Quota Usage Disabling Disk Quota Repairing a Damaged File System Managing Other Types of File Systems Monitoring File System Space Utilization Using df Using du Using Disk Usage Analyzer Understanding Swap Swap Space and Demand Paging Device and File System Swap Primary and Secondary Swap Managing Swap Creating and Enabling a Device Swap Creating and Enabling a File System Swap Enabling Swap Space at System Boot Activating and Deactivating Swap Spaces Manually Removing a Swap Space Swap Best Practices Summary

15. Shutdown and Boot

Shutting Down Run Control Levels Checking Current and Previous Run Control Levels Changing Run Control Levels Booting into Specific Run Control Levels The Boot Process – In a Nutshell Booting – BIOS Initialization Phase Booting – GRUB Phase Boot Examples Understanding GRUB Configuration File Managing GRUB Booting – Kernel Initialization Phase Booting – First Boot (init) Phase Understanding /etc/inittab File Understanding Virtual Console Screens Starting System and Network Services System Boot Log File Managing Services Managing Service Start and Stop via Commands Managing Service Start and Stop via Menu-Driven Program Managing Service Start and Stop via Service Configurator Summary

16. Linux Kernel

Overview Checking and Understanding Kernel Version Understanding Kernel Directory Structure The /boot File System The /proc File System The /lib/modules Directory The /usr/src Directory Managing Modules and the Kernel Listing a Module Building and Installing a New Module Loading and Unloading a Module Adding a Module to Initial RAM Disk Updating the Kernel Upgrading the Kernel Patching the Kernel Modifying Kernel Parameters Building a New Kernel from Source Code Obtaining Kernel Source Code Installing Kernel Source Code Creating Configuration File Building a New Kernel Creating a Boot CD Summary

17. Backup, Restore and Compression

Basics of Backup Backup, Archive, Restore and Recovery Functions Types of Backup Levels of Backup What to Backup Sample Backup Schedule Restore Procedure for the Sample Backup Managing Backups and Restores Performing Backups Using dump/restore Using tar Using rsync Using cpio Using dd Using mkisofs / cdrecord Compression Tools Using zip and unzip Using gzip and gunzip Using bzip2 and bunzip Using Archive Manager Summary

18. Print Services

Understanding the Printing System Types of Printer Configuration CUPS Directory Hierarchy SELinux Requirements for CUPS Managing CUPS Start and Stop Configuring Printers Configuring a Local Printer via Command Configuring a Local Printer via Printer Configurator Configuring a Remote Printer via Command Configuring a Remote Printer via Printer Configurator Configuring a Network Printer via Printer Configurator Configuring a Printer Class Configuring a Printer Using Browser-Based Tool Administering Printers via Commands Setting Default Print Destination Enabling and Disabling a Printer Accepting and Rejecting Print Requests Checking Printer Status Removing a Printer Administering Printers via Printer Configurator and Browser-Based Tool Administering Print Requests Submitting a Print Request Listing a Print Request Moving a Print Request Removing a Print Request Administering a Printer or Printer Class Remotely Summary

19. Job Scheduling and System Logging

Understanding Job Scheduling SELinux Requirements for Cron Managing Scheduling Daemons Start and Stop Controlling User Access Cron Log File Job Scheduling Using at Scheduling an at Job Listing and Removing at Jobs Job Scheduling Using crontab Syntax of the User crontab File Scheduling a cron Job Listing and Removing cron Jobs What is anacron? System Logging SELinux Requirements for Logging Daemons The System Log Configuration File Maintaining and Managing Log Files The System Log File Summary

20. Basic Networking

Network Types Network Topologies Bus Topology Star Topology Ring Topology Hybrid Topology Introduction to OSI Reference Model Layer 7: The Application Layer Layer 6: The Presentation Layer Layer 5: The Session Layer Layer 4: The Transport Layer Layer 3: The Network Layer Layer 2: The Data Link Layer Layer 1: The Physical Layer Summary of OSI Layers Encapsulation and De-encapsulation Peer-to-Peer Model Introduction to TCP/IP TCP/IP Layers Hardware Address Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Hostname IP Address IPv6 Address Network Classes Subnetting Subnet Mask IP Aliasing Summary

21. Network Interface Administration and Routing

Understanding Configuration Files and Commands Network Configuration Files and Scripts Network Interface Administration Commands Configuring Network Interfaces Configuring a Network Interface Configuring IP Aliasing Setting Network Interfaces to Activate at System Boot Activating and Deactivating Network Interfaces Manually Adding IP Addresses and Hostnames to the /etc/hosts File Configuring Network Interfaces via Network Configurator Configuring IP Aliasing via Network Configurator Managing Network Interface Attributes Routing Routing Concepts Routing Table Managing Routes Adding Default and Static Routes Deleting a Route Adding, Modifying and Deleting a Route via Network Configurator Network Connectivity Troubleshooting Using ping Using netstat Using traceroute and tracepath Using mtr Using tcpdump Summary

22. DNS and DHCP

Name Resolution Approaches DNS Concepts and Components DNS Name Space and Domains DNS Zones and Zone Files DNS Roles Understanding BIND Software Packages Understanding DNS Server Configuration and Zone Files Using acl Directive for Access Control Configuring DNS SELinux Requirements for DNS Configuring a Master DNS Server Using rndc to Control BIND Configuring a Slave DNS Server Configuring a Caching DNS Server Configuring a Forwarding DNS Server Configuring DNS via BIND Configurator Configuring a DNS Client Configuring a DNS Client via Network Configurator Verifying DNS Functionality Using dig Using host Using nslookup Dynamic Host Configuration Protocol (DHCP) Understanding DHCP Server Configuration File Configuring DHCP SELinux Requirements for DHCP Configuring a DHCP Server Configuring a DHCP Client Summary

23. NIS and LDAP

NIS Concepts and Components NIS Domain NIS Maps NIS Server NIS Client NIS Daemons NIS Startup and Configuration Files Configuring an NIS Client SELinux Requirements for NIS Client Configuring an NIS Client Using Commands Configuring an NIS Client via Authentication Configurator Managing NIS Client Testing NIS Client Functionality Modifying a User Password Displaying and Searching NIS Maps Manually Binding a Client to Another NIS Server Introduction to LDAP Features and Benefits of Using LDAP LDAP Client Configuration Files LDAP Terminology Directory Entry Attribute Matching Rule Object Class Schema LDAP Data Interchange Format (LDIF) Distinguished Name and Relative Distinguished Name LDAP Roles Configuring an LDAP Client Configuring an LDAP Client at the Command Prompt Configuring an LDAP Client Using Authentication Configurator Summary

24. Internet Services and Electronic Mail

The Internet Services Common Internet Services The xinetd Daemon, /etc/xinetd.conf File and /etc/xinetd.d Directory Enabling an xinetd-controlled Service Disabling an xinetd-controlled Service The services and rpc Files File Transfer Protocol (FTP) SELinux Requirements for FTP Understanding vsFTP Configuration File Controlling Who Can Use vsFTP Configuring a vsFTP Server Configuring a vsFTP Server for Anonymous Access Testing the Functionality The wget Utility Electronic Mail How Mail System Works Configuring Sendmail Sendmail Configuration Files Key Macros Mapping Virtual Addresses Configuring a sendmail Server Checking Mail Statistics Configuring Postfix Postfix Daemons Postfix Configuration Files Displaying and Modifying /etc/postfix/main.cf Configuring a Postfix Server Setting Default MTA Verifying Mail Server Functionality Updating /etc/aliases File for Sendmail and Postfix Configuring Dovecot Dovecot Configuration File Configuring a Non-Secure POP3 Dovecot Server Configuring a Secure IMAP Dovecot Server Verifying Dovecot Functionality Summary

25. Network Time Protocol

NTP Concepts and Components Time Source Stratum Levels NTP Roles Configuring NTP SELinux Requirements for NTP Configuring NTP Server and Peer Configuring an NTP Client Configuring an NTP Client Using Date/Time Configurator Managing NTP Updating System Clock Manually Querying NTP Servers Tracing Roots of an NTP Server Summary

26. NFS and AutoFS

Understanding Network File System (NFS) Benefits NFS Statelessness NFS Versions NFS Security NFS Daemons, Commands, Configuration Files and Scripts How NFS Works? SELinux Requirements for NFS Configuring NFS Configuring an NFS Server Configuring an NFS Server Using NFS Configurator Configuring an NFS Client Managing NFS Viewing Exported and Mounted Resources Unmounting a Resource Unexporting a Resource Monitoring NFS Activities Understanding AutoFS Features and Benefits How AutoFS Works? AutoFS Configuration File Managing AutoFS Start and Stop The AutoFS Maps Defining the Master Map Defining the Special Map Defining a Direct Map Defining an Indirect Map Mounting User Home Directories Summary

27. Samba

Understanding Samba Features of Samba SELinux Requirements for Samba Samba Daemons, Commands, Configuration Files and Scripts Understanding Samba Software Packages Configuring Samba for File Sharing Configuring a Samba Server Using Commands Configuring a Samba Server via Samba Server Configurator Configuring a Samba Server via Samba Web Administration Tool Accessing a Samba Share on Another RHEL System Accessing a Samba Share on Windows Accessing a Windows Share on RHEL Unmounting a Share Summary

28. Network Installation

Configuring Network Installation Servers Configuring an NFS Installation Server Configuring an FTP Installation Server Configuring an HTTP Installation Server Installing RHEL Using Network Installation Servers Methods of Booting a Client Preparing a Bootable CD Preparing a Bootable USB Drive Installing RHEL Using Installation CD, Bootable CD or USB Drive Installing RHEL via Kickstart Making Installation Files / Images Available Creating Kickstart Configuration File Copying Kickstart Configuration to a CD, USB or Network Drive Beginning the Installation Process Network (PXE) Boot / Network Install Summary

29. Web and Caching Proxy Servers

The Apache Web Server Apache Features Key Apache Files The httpd.conf File Apache Log Files Apache Web Server Security Overview Security at the Firewall Level Security at the SELinux Level SELinux File Security Context Security in the httpd.conf File Configuring an Apache Web Server The Apache Virtual Host Configuring a Non-Secure Virtual Host Configuring a Secure Virtual Host Overview of the HTTP Configurator Squid Web Caching Proxy Server Squid Daemon, and Startup and Configuration Files SELinux Requirements for Squid Configuring a Squid Server for Proxy Services Summary

30. System and Network Security

The OpenSSH Service Private and Public Encryption Keys How SSH Encryption Takes Place Without Private/Public Keys How SSH Authentication Takes Place With Private/Public Keys Commands and Daemon, Configuration and Log Files Configuring an OpenSSH Server Accessing an OpenSSH Server Using User Password Configuring Key-Based and Passwordless Authentication Executing a Command Remotely Using ssh Transferring Files Using scp Transferring Files Using sftp Accessing an OpenSSH Server from a Windows System Pluggable Authentication Modules (PAM) TCP Wrappers Netfilter, Firewall and IPTables Understanding IPTables Configuration File Modifying IPTables Rules at the Command Prompt Managing IPTables Start and Stop Modifying IPTables Rules Using Security Level Configurator Network Address Translation Configuring IP Masquerading Security Enhanced Linux SELinux Configuration File SELinux Security Contexts Checking Current Activation Mode Modifying the Activation Mode Checking the Status of SELinux Modifying Security Contexts Configuring SELinux via SELinux Configurator Viewing Alerts with SELinux Troubleshooter Browser Common System Hardening Tasks Summary

31. System, Network and Security Troubleshooting

Appendix A: RHCT Exam Practice Exercises Appendix B: RHCE Exam Practice Exercises Appendix C: Summary of Commands Appendix D: Summary of Files Appendix E: Summary of System Daemons Bibliography Glossary Index

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