book

CentOS Bible

by Christopher Negus, Timothy Boronczyk

August 2009

Beginner

984 pages

26h 2m

English

Wiley

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About the Technical Editor
Who You AreThis Book's Learn-Through-Tasks ApproachWhat You NeedConventions Used in This BookHow This Book Is OrganizedPart I: Getting StartedPart II: Using CentOSPart III: AdministrationPart IV: NetworkingAbout the Companion Media
1.1.1.1.1. What You Get with CentOS1.1.2. Stepping Stone to Red Hat Enterprise Linux1.2. What Is Linux?1.3. Linux's Roots in UNIX1.4. Common Linux Features1.5. Primary Advantages of Linux1.6. Going Forward with CentOS1.6.1. Help from the CentOS Project1.6.2. Training and Certification1.6.3. Documentation1.7. Summary
2.1. Using the CentOS Live CD2.2. Quick Installation2.3. Detailed Installation Instructions2.3.1. Installing CentOS 52.3.1.1. Install or Upgrade?2.3.1.2. From DVD, Network, or Hard Disk?2.3.2. Choosing Computer Hardware2.3.3. Preparing for Installation Using the Live CD2.3.3.1. Display Hardware Information2.3.3.2. Test Your Hardware2.3.4. Beginning the Installation2.3.5. Running CentOS Firstboot2.3.6. Going Forward after Installation2.4. Special Installation Procedures2.4.1. Alternatives for Starting Installation2.4.1.1. Booting Installation from Hard Disk2.4.1.2. Booting Installation Using PXE2.4.2. Installing from Other Media2.4.2.1. Beginning Installation2.4.2.2. Setting up an HTTP, FTP, or NFS Install Server2.4.2.2.1. Configuring an Install Server Using Files2.4.2.2.2. Configuring an Install Server Using Disk Images2.4.2.2.3. NFS Server2.4.2.2.4. Web Server2.4.2.2.5. FTP Server2.4.2.2.6. Hard Disk Install2.4.3. Starting a VNC Install2.4.4. Performing a Kickstart Installation2.4.4.1. Creating the Kickstart File2.4.4.2. Installing the Kickstart File2.4.4.3. Booting a Kickstart Installation2.5. Special Installation Topics2.5.1. Setting up to Dual-Boot Linux and Windows2.5.1.1. Resizing Your Windows Partitions2.5.1.2. Using Windows Partitions from Linux2.5.2. Partitioning Your Disks2.5.2.1. Partitioning with Disk Setup during Installation2.5.2.1.1. Reasons for Partitioning2.5.2.1.2. Deleting, Adding, and Editing Partitions2.5.2.2. Partitioning with fdisk2.5.2.3. Tips for Creating Partitions2.5.3. Using the GRUB Boot Loader2.5.3.1. Temporarily Changing Boot Options2.5.3.2. Permanently Changing Boot Options2.5.3.3. Adding a New GRUB Boot Image2.6. Troubleshooting Installation2.7. Summary
3.1. Logging in to CentOS3.2. Getting Familiar with the Desktop3.2.1. Touring Your Desktop3.2.1.1. Step 1: Checking out Your Home Folder3.2.1.2. Step 2: Change Some Preferences3.2.1.3. Step 3: Configure Your Panels3.2.2. Tips for Configuring Your Desktop3.3. Using the GNOME Desktop3.3.1. Using the Metacity Window Manager3.3.2. Using the GNOME Panels3.3.2.1. Use the Applications and System Menus3.3.2.2. Adding an Applet3.3.2.3. Adding Another Panel3.3.2.4. Adding an Application Launcher3.3.2.5. Adding a Drawer3.3.2.6. Changing Panel Properties3.3.3. Using the Nautilus File Manager3.3.4. Changing GNOME Preferences3.3.5. Managing Removable Media3.3.6. Trying Other GNOME Applications3.3.6.1. Taking Notes with Tomboy3.3.6.2. Checking Your Network from GNOME3.3.7. Exiting GNOME3.4. Running 3D Accelerated Desktop Effects3.5. Switching Desktop Environments3.6. Using the KDE Desktop3.6.1. Starting with KDE3.6.2. KDE Desktop Basics3.6.2.1. Getting around the Desktop3.6.2.1.1. Using the Mouse3.6.2.1.2. Using Keystrokes3.6.3. Managing Files with the Konqueror File Manager3.6.3.1. Working with Files3.6.3.2. Searching for Files with kfind3.6.3.3. Creating New Files and Folders3.6.4. Using the Konqueror Browser Features3.6.5. Configuring Konqueror Options3.6.6. Managing Windows3.6.6.1. Using the Taskbar3.6.6.2. Moving Windows3.6.6.3. Resizing Windows3.6.6.4. Pinning Windows on Top or Bottom3.6.6.5. Using Virtual Desktops3.6.7. Configuring the Desktop3.6.8. Adding Widgets3.6.8.1. Adding Widgets to the Panel3.7. Using the Xfce Desktop Environment3.8. Troubleshooting Your Desktop3.8.1. GUI Doesn't Work at Startup3.8.2. Tuning Your Video Card and Monitor3.8.2.1. Running the Display Settings Window3.8.2.2. Understanding the xorg.conf File3.8.3. Configuring Video Cards for Gaming3.8.4. Getting More Information3.9. Summary
4.1. The Shell Interface4.1.1. Checking Your Login Session4.1.2. Checking Directories and Permissions4.1.3. Checking System Activity4.1.4. Exiting the Shell4.2. Understanding the Shell4.3. Using the Shell in Linux4.3.1. Locating Commands4.3.2. Rerunning Commands4.3.2.1. Command-Line Editing4.3.2.2. Command-Line Completion4.3.2.3. Command-Line Recall4.3.3. Connecting and Expanding Commands4.3.3.1. Piping Commands4.3.3.2. Sequential Commands4.3.3.3. Background Commands4.3.3.4. Expanding Commands4.3.3.5. Expanding Arithmetic Expressions4.3.3.6. Expanding Variables4.3.4. Using Shell Environment Variables4.3.4.1. Common Shell Environment Variables4.3.4.2. Setting Your Own Environment Variables4.3.5. Managing Background and Foreground Processes4.3.5.1. Starting Background Processes4.3.5.2. Moving Commands to the Foreground and Background4.3.6. Configuring Your Shell4.3.6.1. Setting Your Prompt4.3.6.2. Adding Environment Variables4.3.6.3. Adding Aliases4.4. Working with the Linux File System4.4.1. Creating Files and Directories4.4.1.1. Using Metacharacters and Operators4.4.1.2. Using File-Matching Metacharacters4.4.1.3. Using File Re-Direction Metacharacters4.4.1.4. Understanding File Permissions4.4.2. Moving, Copying, and Deleting Files4.5. Using the vi Text Editor4.5.1. Starting with Vi4.5.2. Moving around the File4.5.3. Searching for Text4.5.4. Using Numbers with Commands4.6. Summary

5.1. Getting and Installing Software Packages5.1.1. Downloading and Installing Applications with yum5.1.1.1. Configuring yum (/etc/yum.conf)5.1.1.2. Adding yum Repositories (/etc/yum.repos.d/)5.1.1.3. Running yum to Download and Install RPMs5.1.1.4. Using yum to Install Packages Locally5.1.1.5. Using yum for Listing Packages5.1.1.6. Using the yum-utils Package5.1.2. Getting CentOS Software Updates5.1.2.1. Getting Alerted to Available Updates5.1.2.2. Getting Manual Updates with yum5.2. Managing RPM Packages5.2.1. Using the Add/Remove Window5.2.2. Using the rpm Command5.2.2.1. Verifying rpm Package Integrity5.2.2.2. Installing with rpm5.2.2.3. Upgrading Packages with rpm5.2.2.4. Freshening Packages with rpm5.2.2.5. Removing Packages with rpm5.2.2.6. Querying Packages with rpm5.2.2.7. Verifying Installed Packages with rpm5.3. Using Software in Different Formats5.3.1. Understanding Software Package Names and Formats5.3.2. Understanding Different Archive Formats5.3.3. Building and Installing from Source Code5.3.3.1. Installing Software in SRPM Format5.3.3.2. Installing Software in tar.gz or tar.bz2 Formats5.4. Using CentOS to Run Applications5.4.1. Finding Common Desktop Applications in Linux5.4.2. Investigating Your Desktop5.4.3. Starting Applications from a Menu5.4.4. Starting Applications from a Run Application Window5.4.5. Starting Applications from a Terminal Window5.4.6. Running Remote X Applications5.4.6.1. Traditional Method to Run Remote X Applications5.4.6.2. Launching a Remote X Application5.4.6.3. Using SSH to Run Remote X Applications5.5. Running Microsoft Windows, DOS, and Macintosh Applications5.5.1. Running DOS Applications5.5.1.1. Using mtools5.5.1.2. Using DOSBox5.5.2. Running Microsoft Windows Applications in Linux5.5.2.1. Running Windows Applications in WINE5.5.2.2. Assigning Drive Letters5.5.2.3. Installing Applications in WINE5.5.2.4. Launching Applications5.5.2.5. Tuning and Configuring WINE5.5.2.6. Finding More Windows Applications for WINE5.6. Running Applications in Virtual Environments5.6.1. Running Applications Virtually with Xen5.6.1.1. Before Installing Xen5.6.1.2. Installing Xen5.6.1.3. Installing a Guest Operating System5.6.2. Running Applications Virtually with KVM and QEMU5.7. Summary
6.1. Desktop Publishing in Linux6.1.1. Using Text Editors and Notepads6.1.2. Using Word Processors6.1.2.1. Using OpenOffice.org6.1.2.2. Other Word Processors6.1.2.2.1. StarOffice6.1.2.2.2. TextMaker6.2. Using Traditional Linux Publishing Tools6.2.1. Creating Documents in Groff or LaTeX6.2.2. Text Processing with Groff6.2.2.1. Formatting and Printing Documents with Groff6.2.2.2. Creating a Man Page with Groff6.2.3. Text Processing with TeX/LaTeX6.2.3.1. Creating and Formatting a LaTeX Document6.2.4. Converting Documents6.2.5. Creating DocBook Documents6.2.6. Understanding SGML and XML6.2.6.1. Understanding DocBook6.2.6.2. Creating DocBook Documents6.2.6.3. Converting DocBook Documents6.3. Displaying PDF Files with Evince6.4. Doing Page Layout with Scribus6.5. Working with Graphics6.5.1. Manipulating Images with GIMP6.5.2. Taking Screen Captures6.5.3. Creating Vector Graphic Images with Inkscape6.6. Using Scanners Driven by SANE6.7. Web Publishing6.8. Summary
7.1. Understanding Multimedia and Legal Issues in Linux7.2. Extending Freedom to Codecs7.3. Listening to Music in Linux7.3.1. Configuring a Sound Card7.3.1.1. Sound Card Features7.3.1.2. Detecting Your Sound Card Driver7.3.1.3. Adjusting Sound Levels7.3.1.4. Setting Your Sound Card to Record7.3.2. Choosing Audio Players7.3.3. Automatically Playing CDs7.3.4. Playing and Managing Music with Rhythmbox7.3.5. Playing Music with XMMS Audio Player7.3.5.1. Using the Equalizer7.3.5.2. Using the Playlist Editor7.3.6. Using ogg123, mpg321, and play Command-Line Players7.3.7. Using MIDI Audio Players7.3.8. Converting Audio Files with SoX7.3.9. Extracting and Encoding Music7.3.9.1. Extracting Music CDs with Sound Juicer7.3.9.2. Extracting and Encoding Music CDs from Commands7.3.10. Creating Your Own Music CDs7.3.10.1. Creating Audio CDs with cdrecord7.3.10.2. Creating Audio and Data CDs with K3b7.3.10.2.1. Creating a New Audio CD7.3.10.2.2. Copying a CD7.3.10.2.3. Burning an ISO Image to CD7.3.11. Creating CD Labels with cdlabelgen7.4. Viewing TV and Webcams7.4.1. Watching TV with Tvtime7.4.1.1. Getting a Supported TV Card7.4.1.2. Starting Tvtime7.4.1.3. Selecting Channels in Tvtime7.4.2. Videoconferencing and VOIP with Ekiga7.4.2.1. Getting a Supported Webcam7.4.2.2. Running Ekiga7.5. Playing Video7.5.1. Examining Laws Affecting Video and Linux7.5.2. Understanding Video Content Types7.5.3. Watching Video with Xine7.5.3.1. Using Xine7.5.3.2. Creating Playlists with Xine7.5.3.3. Xine Tips7.5.4. Using Totem Movie Player7.6. Using a Digital Camera7.6.1. Displaying Images in gThumb7.6.2. Using Your Camera as a Storage Device7.7. Summary
8.1. Overview of Internet Applications and Commands8.2. Browsing the Web8.2.1. Understanding Web Browsing8.2.1.1. Uniform Resource Locators8.2.1.2. Web Pages8.2.2. Browsing the Web with Firefox8.2.3. Setting Up Firefox8.2.3.1. Setting Navigator Preferences8.2.3.2. Extending Firefox8.2.3.2.1. Using Plug-Ins8.2.3.2.2. Getting Add-Ons8.2.3.3. Changing Firefox Themes8.2.3.4. Securing Firefox8.2.3.5. Tips for Using Firefox8.2.4. Using Text-Based Web Browsers8.3. Communicating with E-Mail8.3.1. E-Mail Basics8.3.2. Using Evolution E-Mail8.3.2.1. Setting Evolution Preferences8.3.2.2. Receiving, Composing, and Sending E-Mail8.3.3. Thunderbird Mail Client8.3.4. Text-Based Mail Programs8.3.4.1. Mail Readers and Managers8.3.4.1.1. Mutt Mail Reader8.3.4.1.2. Alpine Mail Reader8.3.4.1.3. Mail Reader8.4. Participating in Newsgroups8.5. Instant Messaging with Pidgin8.6. Sharing Files with BitTorrent8.7. Using Remote Login, Copy, and Execution8.7.1. Using Telnet for Remote Login8.7.2. Copying Files with FTP8.7.2.1. Using the ftp Command8.7.2.1.1. FTP Directory Commands8.7.2.1.2. FTP File Copying Commands8.7.2.1.3. FTP Exiting Commands8.7.2.2. Using the lftp Command8.7.2.3. Using the gFTP Window8.7.3. Getting Files with wget8.7.3.1. Downloading a Single File8.7.3.2. Downloading a File with Username and Password8.7.3.3. Downloading a Whole Web Site8.7.3.4. Continuing a Download8.7.4. Using ssh for Remote Login/Remote Execution8.7.5. Using scp for Remote File Copy8.7.6. Using the "r" Commands: rlogin, rcp, and rsh8.8. Summary
9.1. Using the root User Account9.2. Becoming the Super User (the su Command)9.3. Learning about Administrative GUI Tools, Commands, Configuration Files, and Log Files9.3.1. Using Graphical Administration Tools9.3.1.1. Server Settings9.3.1.2. System Tools9.3.2. Administrative Commands9.3.3. Administrative Configuration Files9.3.4. Administrative Log Files9.3.5. Using Other Administrative Logins9.3.5.1. Understanding Administrative Logins9.3.5.2. Using sudo for Assigning Administrative Privilege9.4. Administering Your Linux System9.5. Configuring Hardware9.5.1. Checking Your Hardware9.5.2. Managing Hardware with HAL9.5.3. Reconfiguring Hardware with kudzu9.5.4. Configuring Modules9.5.4.1. Listing Loaded Modules9.5.4.2. Loading Modules9.5.4.3. Removing Modules9.6. Managing File Systems and Disk Space9.6.1. Mounting File Systems9.6.1.1. Supported File Systems9.6.1.2. Using the fstab File to Define Mountable File Systems9.6.1.3. Using the mount Command to Mount File Systems9.6.1.3.1. Mounting Removable Media9.6.1.3.2. Mounting CD or DVD Images9.6.1.4. Using the umount Command to Unmount a File System9.6.2. Using the mkfs Command to Create a File System9.6.3. Adding a Hard Disk9.6.4. Using RAID Disks9.6.5. Checking System Space9.6.5.1. Checking Disk Space with Disk Usage Analyzer9.6.5.2. Displaying System Space with df9.6.5.3. Checking Disk Usage with du9.6.5.4. Finding Disk Consumption with find9.7. Monitoring System Performance9.7.1. Watch Computer Usage with System Monitor9.7.2. Monitoring CPU Usage with top9.7.3. Monitoring Power Usage on Laptop Computers9.7.3.1. Using acpi_listen to Monitor ACPI Events9.8. Using Security Enhanced Linux9.9. Understanding Security Enhanced Linux9.9.1. Types and Roles in SELinux9.9.2. Users in SELinux9.9.3. Policies in SELinux9.9.4. Tools in SELinux9.10. Using SELinux in CentOS9.10.1. SELinux9.10.2. Checking Whether SELinux Is On9.10.3. Checking SELinux Status9.11. Summary
10.1. Creating User Accounts10.1.1. Adding Users with useradd10.1.2. Adding Users with User Manager10.2. Setting User Defaults10.2.1. Supplying Initial Login Scripts10.2.2. Supplying Initial .bashrc and .bash_profile Files10.2.3. Supplying an Initial .tcshrc File10.2.4. Configuring System-Wide Shell Options10.2.4.1. Configuring System-Wide Bash Options10.2.4.2. Configuring System-Wide tcsh Options10.2.5. Setting System Profiles10.2.6. Adding User Accounts to Servers10.3. Creating Portable Desktops10.4. Providing Support to Users10.4.1. Creating a Technical Support Mailbox10.4.2. Resetting a User's Password10.5. Modifying Accounts10.5.1. Modifying User Accounts with usermod10.5.2. Modifying User Accounts with User Manager10.6. Deleting User Accounts10.6.1. Deleting User Accounts with userdel10.6.2. Deleting User Accounts with User Manager10.7. Checking Disk Quotas10.7.1. Using Quota to Check Disk Usage10.7.1.1. Editing the /etc/fstab File10.7.1.2. Creating Quota Files10.7.1.3. Creating a Quota Start-Up Script10.7.1.4. Turn on the Quota Start-up Script10.7.1.5. Creating Quota Rules10.7.1.6. Updating Quota Settings10.7.1.7. Checking Quotas10.7.2. Using du to Check Disk Use10.7.3. Removing Temp Files Automatically10.8. Sending Mail to All Users10.9. Summary
11.1. Understanding Shell Scripts11.1.1. Executing and Debugging Shell Scripts11.1.2. Understanding Shell Variables11.1.2.1. Special Shell Variables11.1.2.2. Parameter Expansion in Bash11.1.3. Performing Arithmetic in Shell Scripts11.1.4. Using Programming Constructs in Shell Scripts11.1.4.1. The if . . . then Statements11.1.4.2. The case Command11.1.4.3. The for . . . do Loop11.1.4.4. The while . . . do and until . . . do Loops11.1.5. Some Useful External Programs11.1.5.1. The General Regular Expression Parser (grep)11.1.5.2. Extract Sections from Lines of Text (cut)11.1.5.3. Translate or Delete Characters (tr)11.1.5.4. The Stream Editor (sed)11.1.6. Trying Some Simple Shell Scripts11.1.6.1. A Simple Telephone List11.1.6.2. A Simple Backup Script11.2. System Initialization11.2.1. Starting init11.2.2. The inittab File11.3. System Startup and Shutdown11.3.1. Starting Run-Level Scripts11.3.2. Understanding Run-Level Scripts11.3.3. Understanding What Start-Up Scripts Do11.3.4. Changing Run-Level Script Behavior11.3.5. Reorganizing or Removing Run-Level Scripts11.3.6. Adding Run-Level Scripts11.3.7. Managing xinetd Services11.3.8. Manipulating Run Levels11.3.8.1. Determining the Current Run Level11.3.8.2. Changing to a Shutdown Run Level11.4. Scheduling System Tasks11.4.1. Using at.allow and at.deny11.4.2. Specifying When Jobs Are Run11.4.3. Submitting Scheduled Jobs11.4.4. Viewing Scheduled Jobs11.4.5. Deleting Scheduled Jobs11.4.6. Using the batch Command11.4.7. Using the cron Facility11.4.7.1. Modifying Scheduled Tasks with crontab11.4.7.2. Understanding cron Files11.5. Summary
12.1. Making a Simple Backup Archive12.2. Doing a Simple Backup with rsync12.2.1. Backing Up Files Locally12.2.2. Backing Up Files Remotely12.3. Choosing Backup Tools12.4. Selecting a Backup Strategy12.4.1. Full Backup12.4.2. Incremental Backup12.4.3. Disk Mirroring12.4.4. Network Backup12.5. Selecting a Backup Medium12.5.1. Magnetic Tape12.5.2. Writable CD Drives12.5.2.1. Getting cdrecord for Writable CDs12.5.2.2. Writing to CDs12.5.3. Writable DVD Drives12.5.4. Writing CDs or DVDs with growisofs12.6. Backing Up to a Hard Drive12.7. Backing Up Files with dump12.7.1. Creating a Backup with dump12.7.2. Understanding Dump Levels12.8. Automating Backups with cron12.9. Restoring Backed-Up Files12.9.1. Restoring an Entire File System12.9.2. Recovering Individual Files12.10. Configuring Amanda for Network Backups12.10.1. Creating Amanda Directories12.10.2. Creating the amanda.conf file12.10.3. Creating a disklist File12.10.4. Adding Amanda Network Services12.10.4.1. On the Amanda Server12.10.4.2. On Each Amanda Client12.10.5. Performing an Amanda Backup12.11. Using the pax Archiving Tool12.12. Summary
13.1. Linux Security Checklist13.2. Using Password Protection13.2.1. Choosing Good Passwords13.2.2. Using a Shadow Password File13.2.2.1. Breaking Encrypted Passwords13.2.2.2. Checking for the shadow Password File13.3. Securing Linux with iptables Firewalls13.3.1. Using the Security Level Configuration Window13.3.2. Configuring an iptables Firewall13.3.2.1. Turning on iptables13.3.2.2. Creating iptables Firewall Rules13.3.2.2.1. EXAMPLE 1: Firewall for Shared Internet Connection (Plus Servers)13.3.2.2.2. EXAMPLE 2: Firewall for Shared Internet Connection (No Servers)13.3.2.2.3. EXAMPLE 3: Firewall for Single Linux System with Internet Connection13.3.2.3. Understanding iptables13.3.2.3.1. Allowing FTP and IRC Services through an iptables Firewall13.3.2.3.2. Using iptables to Do SNAT or IP Masquerading13.3.2.3.3. Using iptables as a Transparent Proxy13.3.2.3.4. Using iptables to Do Port Forwarding13.3.2.3.5. Using Logging with IP Tables13.3.2.4. Enhancing Your IP Tables Firewall13.4. Controlling Access to Services with TCP Wrappers13.5. Checking Log Files13.5.1. Replacing the sysklogd Package13.5.2. Understanding the rsyslogd Service13.5.2.1. Re-Directing Logs to a loghost with rsyslogd13.5.2.2. Understanding the Messages Log File13.5.3. Tracking Log Messages with logwatch13.6. Using the Secure Shell Package13.6.1. Starting the SSH Service13.6.2. Using the ssh, sftp, and scp commands13.6.3. Using SSH, SCP, and SFTP without Passwords13.7. Securing Linux Servers13.7.1. Understanding Attack Techniques13.7.2. Protecting against Denial-of-Service Attacks13.7.2.1. Mailbombing13.7.2.1.1. Blocking Mail with procmail13.7.2.1.2. Blocking Mail with sendmail13.7.2.2. Spam Relaying13.7.2.3. Smurf Amplification Attack13.7.3. Protecting against Distributed DOS Attacks13.7.4. Protecting against Intrusion Attacks13.7.4.1. Evaluating Access to Network Services13.7.4.2. Disabling Network Services13.7.5. Securing Servers with SELinux13.7.6. Protecting Web Servers with Certificates and Encryption13.7.6.1. Symmetric Cryptography13.7.6.2. Public-Key Cryptography13.7.6.3. Secure Sockets Layer13.7.6.3.1. Creating SSL Certificates13.7.6.3.2. Using Third-Party Certificate Signers13.7.6.3.3. Creating a Certificate Service Request13.7.6.3.4. Getting the CSR Signed13.7.6.3.5. Creating Self-Signed Certificates13.7.6.3.6. Restarting Your Web Server13.7.6.3.7. Troubleshooting Your Certificates13.8. Summary
14.1. Connecting to the Network with NetworkManager14.1.1. Connecting to a Wireless Network14.1.2. Connecting to a Wired Network14.1.3. Setting Up a Virtual Private Network Connection14.2. Understanding Local Area Networks14.2.1. Planning, Getting, and Setting Up LAN Hardware14.2.1.1. LAN Topologies14.2.1.2. LAN Equipment14.2.1.3. LAN Equipment Setup14.2.2. Configuring TCP/IP for Your LAN14.2.2.1. Identifying Other Computers (Hosts and DNS)14.3. Setting Up a Wireless LAN14.3.1. Understanding Wireless Networks14.3.2. Choosing Wireless Hardware14.3.2.1. Selecting Antennas14.3.2.1.1. Using Indoor Antennas14.3.2.1.2. Using Outdoor Antennas14.3.3. Getting Wireless Drivers14.3.4. Installing Wireless Linux Software14.3.5. Configuring the Wireless LAN14.3.5.1. Configuring the Wireless Interface14.3.5.2. Activating the Wireless Interfaces14.3.5.3. Checking Your Wireless Connection14.3.6. Testing Distances14.3.7. Setting Wireless Extensions14.4. Understanding Internet Protocol Addresses14.4.1. IP Address Classes14.4.2. Understanding Netmasks14.4.3. Classless Inter-Domain Routing14.4.4. Getting IP Addresses14.5. Troubleshooting Your LAN14.5.1. Did Linux Find Your Ethernet Driver at Boot Time?14.5.2. Can You Reach Another Computer on the LAN?14.5.3. Is Your Ethernet Connection Up?14.5.4. Troubleshooting a Wireless LAN14.5.4.1. Checking Wireless Settings14.5.4.2. Checking TCP/IP14.5.4.3. Adapting to Poor Reception14.5.4.4. Use Debugging Tools14.5.5. Watching LAN Traffic with Wireshark14.5.5.1. Starting Wireshark14.5.5.2. Capturing Ethernet Data14.5.5.3. Interpreting Captured Ethernet Data14.6. Summary
15.1. Understanding How the Internet Is Structured15.1.1. Internet Domains15.1.2. Hostnames and IP Addresses15.1.3. Routing15.1.4. Proxies15.2. Using Dial-Up Connections to the Internet15.2.1. Getting Information15.2.2. Setting Up Dial-Up PPP15.2.3. Creating a Dial-Up Connection with the Network Configuration Window15.2.4. Launching Your PPP Connection15.2.5. Launching Your PPP Connection on Demand15.2.6. Checking Your PPP Connection15.2.6.1. Checking That Your Modem Was Detected15.2.6.2. Checking That Your PPP Interface Is Working15.2.6.3. Checking the Default Route15.2.6.4. Checking That the Name Servers Are Set15.2.6.5. Checking the CHAP-Secrets or PAP-Secrets File15.2.6.6. Looking at the ifcfg File15.2.6.7. Running Debugging15.3. Connecting Your LAN to the Internet15.4. Setting Up Linux as a Router15.4.1. Configuring the Linux Router15.4.1.1. Selecting IP Addresses15.4.1.2. Enable Forwarding and Masquerading15.4.2. Configuring Network Clients15.5. Configuring a Virtual Private Network Connection15.5.1. Understanding IPsec15.5.2. Using IPsec Protocols15.5.3. Using IPsec in CentOS15.5.4. Configuring an OpenVPN Server15.5.4.1. Decisions before Configuring OpenVPN15.5.4.2. Create a Public Key Infrastructure15.5.4.3. Create OpenVPN Server Configuration15.5.4.4. Create OpenVPN Client Configuration15.6. Setting Up Linux as a Proxy Server15.6.1. Starting the Squid Daemon15.6.2. Using a Simple squid.conf File15.6.3. Modifying the Squid Configuration File15.6.3.1. Configuring Access Control in squid.conf15.6.3.2. Configuring Caching in squid.conf15.6.3.3. Configuring Port Numbers in squid.conf15.6.4. Debugging Squid15.6.4.1. Checking the squid.conf File15.6.4.2. Checking Squid Log Files15.6.4.3. Using the top Command15.7. Setting Up Proxy Clients15.7.1. Configuring Firefox to Use a Proxy15.7.2. Configuring Other Browsers to Use a Proxy15.8. Summary
16.1. Common UNIX Printing Service16.2. Setting Up Printers16.2.1. Using the Printer Configuration Window16.2.1.1. Configuring Local Printers16.2.1.1.1. Adding a Local Printer16.2.1.1.2. Editing a Local Printer16.2.1.2. Configuring Remote Printers16.2.1.2.1. Adding a Remote CUPS Printer16.2.1.2.2. Adding a Remote UNIX Printer16.2.1.2.3. Adding a Windows (SMB) Printer16.2.1.2.4. Adding a JetDirect Printer16.2.2. Using Web-Based CUPS Administration16.2.3. Configuring the CUPS Server (cupsd.conf)16.2.4. Configuring CUPS Printer Options16.3. Using Printing Commands16.3.1. Using lpr to Print16.3.2. Listing Status with lpc16.3.3. Removing Print Jobs with lprm16.4. Configuring Print Servers16.4.1. Configuring a Shared CUPS Printer16.4.2. Configuring a Shared Samba Printer16.4.2.1. Understanding smb.conf for Printing16.5. Summary
17.1. Goals of Setting Up a File Server17.2. Setting Up an NFS File Server17.2.1. Sharing NFS File Systems17.2.1.1. Using the NFS Server Configuration Window17.2.1.2. Configuring the /etc/exports File17.2.1.2.1. Hostnames in /etc/exports17.2.1.2.2. Access Options in /etc/exports17.2.1.2.3. User Mapping Options in /etc/exports17.2.1.3. Exporting the Shared File Systems17.2.1.4. Starting the nfsd Daemons17.2.2. Using NFS File Systems17.2.2.1. Manually Mounting an NFS File System17.2.2.2. Automatically Mounting an NFS File System17.2.2.2.1. Mounting noauto File Systems17.2.2.2.2. Using mount Options17.2.2.3. Using autofs to Mount NFS File Systems on Demand17.2.3. Unmounting NFS File Systems17.2.4. Other Cool Things to Do with NFS17.3. Setting Up a Samba File Server17.3.1. Getting and Installing Samba17.3.2. Configuring a Simple Samba Server17.3.3. Configuring Samba with SWAT17.3.3.1. Turning on SWAT17.3.3.2. Starting with SWAT17.3.3.3. Creating Global Samba Settings in SWAT17.3.3.3.1. Base Options17.3.3.3.2. Security Options17.3.3.3.3. Logging Options17.3.3.3.4. Printing Options17.3.3.3.5. Browse Options17.3.3.3.6. WINS Options17.3.3.4. Configuring Shared Directories with SWAT17.3.3.5. Checking Your Samba Setup with SWAT17.3.4. Working with Samba Files and Commands17.3.4.1. Editing the smb.conf File17.3.4.2. Adding Samba Users17.3.4.3. Starting the Samba Service17.3.4.4. Testing Your Samba Permissions17.3.4.5. Checking the Status of Shared Directories17.3.5. Setting Up Samba Clients17.3.5.1. Using Samba Shared Directories from Linux17.3.5.1.1. Using Samba from Nautilus17.3.5.1.2. Mounting Samba Directories in Linux17.3.6. Troubleshooting Your Samba Server17.3.6.1. Basic Networking in Place?17.3.6.2. Samba Service Running?17.3.6.3. Firewall Open?17.3.6.4. User Passwords Working?17.4. Summary
18.1. Introducing SMTP and Sendmail18.2. Installing and Running Sendmail18.2.1. Starting Sendmail18.2.2. Other Programs18.2.3. Logging Performed by Sendmail18.3. Configuring Sendmail18.3.1. Getting a Domain Name18.3.2. Configuring Basic Sendmail Settings (sendmail.mc)18.3.3. Defining Outgoing Mail Access18.3.4. Configuring Virtual Servers18.3.5. Configuring Virtual Users18.3.6. Adding User Accounts18.3.7. Starting Sendmail and Generating Database Files18.3.8. Re-Directing Mail18.3.8.1. The .forward File18.3.8.2. The Aliases File18.4. Introducing Postfix18.5. Stopping Spam with SpamAssassin18.5.1. Using SpamAssassin18.5.2. Setting Up SpamAssassin on Your Mail Server18.5.3. Setting E-Mail Readers to Filter Spam18.6. Getting Mail from the Server (POP3 or IMAPv4)18.6.1. Accessing Mailboxes in Linux18.6.2. Configuring IMAPv4 and POP3 with Dovecot18.7. Getting Mail from Your Browser with SquirrelMail18.8. Administering a Mailing List with Mailman18.9. Summary
19.1. Understanding FTP Servers19.1.1. Attributes of FTP Servers19.1.2. FTP User Types19.2. Using the Very Secure FTP Server19.2.1. Quick-Starting vsFTPd19.2.2. Configuring vsFTPd19.2.2.1. User Accounts19.2.2.2. Setting FTP Access19.2.2.2.1. Downloading Files19.2.2.2.2. Uploading (Writing) Files from Local Users19.2.2.2.3. Uploading (Writing) Files from Anonymous Users19.2.2.3. Adding Message Files19.2.2.4. Logging vsFTPd Activities19.2.2.5. Setting Time-Outs19.2.2.6. Navigating a vsFTPd Site19.2.2.7. Setting Up vsFTPd behind a Firewall19.3. Getting More Information about FTP Servers19.4. Summary
20.1. Introduction to Web Servers20.1.1. The Apache Web Server20.1.2. Other Web Servers Available for CentOS20.2. Quick-Starting the Apache Web Server20.3. Configuring the Apache Server20.3.1. Configuring the Web Server (httpd.conf)20.3.1.1. Setting the Global Environment20.3.1.1.1. Revealing Subcomponents20.3.1.1.2. Setting the Server Root Directory20.3.1.1.3. Storing the Server's PID File20.3.1.1.4. Configuring Time-Out Values20.3.1.2. Setting the Number of Server Processes20.3.1.3. Binding to Specific Addresses20.3.1.4. Selecting Modules in httpd.conf20.3.1.5. Including Module-Specific Configuration Files20.3.1.6. Choosing the Server's User and Group20.3.1.7. Setting the Main Server's Configuration20.3.1.7.1. Setting an E-Mail Address20.3.1.7.2. Setting the Server Name20.3.1.7.3. Setting Canonical Names20.3.1.7.4. Identifying HTTP Content Directories20.3.1.7.5. Setting Access Options and Overrides20.3.1.8. Identifying User Directories20.3.1.9. Setting Default Index Files for Directories20.3.1.9.1. Setting Directory-Access Control20.3.1.9.2. Setting MIME-Type Defaults20.3.1.9.3. Setting Hostname Lookups20.3.1.9.4. Configuring HTTP Logging20.3.1.9.5. Adding a Signature20.3.1.9.6. Aliasing Relocated Content20.3.1.9.7. Redirecting Requests for Old Content20.3.1.10. Defining Indexing20.3.1.11. Defining Encoding and Language20.3.1.12. Adding MIME Types and Handlers20.3.1.13. Defining Actions and Headers20.3.1.14. Customizing Error Responses20.3.1.15. Setting Responses to Browsers20.3.1.16. Enabling Proxy and Caching Services20.3.1.17. Configuring Virtual Hosting20.3.2. Configuring Modules and Related Services (/etc/httpd/conf.d/*.conf)20.4. Starting and Stopping the Server20.5. Monitoring Server Activities20.5.1. Displaying Server Information20.5.2. Displaying Server Status20.5.3. Further Security of Server-Info and Server-Status20.5.4. Logging Errors20.5.5. Logging Hits20.5.6. Analyzing Web-Server Traffic20.6. Summary
21.1. Understanding LDAP21.1.1. Defining Information in Schemas21.1.2. Structuring Your LDAP Directories21.2. Setting Up the OpenLDAP Server21.2.1. Installing OpenLDAP Packages21.2.2. Configuring the OpenLDAP Server (slapd.conf)21.2.3. Starting the OpenLDAP Service21.3. Setting Up the Address Book21.4. More Ways to Configure LDAP21.5. Accessing an LDAP Address Book from Thunderbird21.6. Summary
22.1. Using the Dynamic Host Configuration Protocol22.2. Setting Up a DHCP Server22.2.1. Opening Your Firewall and SELinux for DHCP22.2.2. Configuring the /etc/dhcpd.conf File22.2.2.1. Expanding the dhcpd.conf File22.2.2.2. Adding Options22.2.3. Starting the DHCP Server22.3. Setting Up a DHCP Client22.4. Summary
23.1. Finding MySQL Packages23.2. Configuring the MySQL Server23.2.1. Using MySQL User/Group Accounts23.2.2. Adding Administrative Users23.2.3. Setting MySQL Options23.2.3.1. Creating the my.cnf Configuration File23.2.3.2. Choosing Options23.2.3.3. Checking Options23.2.4. Using Sample my.cnf Files23.3. Starting the MySQL Server23.4. Checking That MySQL Server Is Working23.5. Working with MySQL Databases23.5.1. Starting the mysql Command23.5.2. Creating a Database with MySQL23.5.3. Adding Data to a MySQL Database Table23.5.3.1. Manually Entering Data23.5.3.2. Loading Data from a File23.6. Understanding MySQL Tables23.7. Displaying MySQL Databases23.7.1. Displaying All or Selected Records23.7.2. Displaying Selected Columns23.7.3. Sorting Data23.8. Making Changes to Tables and Records23.8.1. Altering the Structure of MySQL Tables23.8.2. Updating and Deleting MySQL Records23.9. Adding and Removing User Access23.9.1. Adding Users and Granting Access23.9.2. Revoking Access23.10. Backing Up Databases23.11. Checking and Fixing Databases23.12. Summary
24.1. Determining Goals for Your Server24.1.1. Using a Hosting Service24.2. Connecting a Public Server24.2.1. Choosing an ISP24.2.1.1. Checking Terms of Service24.2.1.2. Getting Static IP Addresses24.2.1.3. Choosing a Connection Speed24.2.2. Getting a Domain Name24.2.2.1. Checking Domain Name Availability24.2.2.2. Reserving a Domain Name24.3. Configuring Your Public Server24.3.1. Configuring Networking24.3.2. Configuring Servers24.3.3. Managing Security24.3.3.1. Opening Your Firewall24.3.3.2. Enabling SELinux24.3.3.3. Checking Logs and System Files24.3.3.4. Keeping Up with Updates24.4. Setting Up a Domain Name System Server24.4.1. Understanding DNS24.4.1.1. Understanding Authoritative Zones24.4.1.2. Understanding DNS Risks24.4.1.3. Understanding BIND24.4.2. DNS Name Server Example24.4.3. Quick-Starting a DNS Server24.4.3.1. Identifying Your DNS Servers24.4.3.2. Creating DNS Configuration Files (named.conf and var/named)24.4.3.2.1. Editing named.conf24.4.3.2.2. Setting Up the Zone Files (Inside)24.4.3.2.3. Setting Up the Zone Files (Outside)24.4.3.2.4. Setting Up the Zone Files (Reverse Lookup)24.4.3.3. Starting the named (DNS) Daemon24.4.4. Checking That DNS Is Working24.5. Getting More Information about BIND24.6. Summary
A.1. System RequirementsA.1.1.A.1.1.1. For Linux or Windows SystemsA.2. Using the Installation DVDA.3. Using the CentOS Live CDA.4. What's on the MediaA.4.1. Operating System and ApplicationsA.5. Source CodeA.6. TroubleshootingA.6.1. Customer Care

Content preview from CentOS Bible

Chapter 4. Using Linux Commands

This chapter presents a view of Linux from the shell. The shell is a command-line interpreter that lets you access some of the most critical Linux tools. The shell is powerful, complex, and almost completely unintuitive.

Although at first it isn't obvious how to use the shell, with the right help you can quickly learn many of the most important shell features. In CentOS, bash is the shell command interpreter used by default, and therefore, the one used for most of the examples in this chapter. Other shells, such as csh, ksh, sh, and others, are also available and are therefore also noted in this chapter.

This chapter is your guide to working with the Linux system commands, processes, and file system from the shell. It describes the shell environment and helps you tailor it to your needs. It also describes how to use and move around the file system.

The Shell Interface

Throughout this book, there are procedures that require you to use a shell to run commands. How you first get to a shell depends on whether your computer is configured to have a graphical user interface (GUI) or not. A desktop system, by its nature, starts with a GUI. Server systems often are run entirely from the command line. Here are ways of reaching a shell, depending on whether you have a desktop GUI running or not: