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Practical Linux Topics

Book Description

Teaches you how to improve your hands­-on knowledge of Linux using challenging, real-world scenarios. Each chapter explores a topic that has been chosen specifically to demonstrate how to enhance your base Linux system, and resolve important issues. This book enables sysadmins, DevOps engineers, developers, and other technical professionals to make full use of Linux’s rocksteady foundation.

Explore specific topics in networking, e­mail, filesystems, encryption, system monitoring, security, servers, and more-- including systemd and GPG. Understand salient security concerns and how to mitigate them. Applicable to almost all Linux flavors--Debian, Red Hat, Ubuntu, Linux Mint, CentOS--Practical Linux Topics ?c?an be used to reference other Unix-­type systems with little modification.

Improve your practical know­-how and background knowledge on servers and workstations alike, increase your ability to troubleshoot and ultimately solve the daily challenges encountered by all professional Linux users. Empower your Linux skills by adding Practical Linux Topics to your library today.

Table of Contents

  1. Cover
  2. Title
  3. Copyright
  4. Dedication
  5. Contents at a Glance
  6. Contents
  7. About the Author
  8. About the Technical Reviewer
  9. Introduction
  10. Chapter 1 : Real-Time Network Statistics with Iftop
    1. Monitoring Network Connections with netstat
    2. Introducing iftop
    3. Installing iftop
    4. Controlling iftop from the Keyboard
    5. Adding Screen Filters
    6. Using Regular Expressions
    7. Listening for Network Traffic
    8. Changing Filters Can Take Time
    9. Configuring iftop Scenarios
    10. Using iftop on Busy Routers
    11. Summary
  11. Chapter 2 : Destroying Sensitive Data
    1. A Note on Random Data Overwrites and Degaussing
    2. Using the shred Utility
      1. Installing shred
      2. Getting Started with shred
    3. Using the dd Utility
    4. Using the wipe Utility
    5. Booting Off External Media
    6. DBAN
    7. Summary
  12. Chapter 3 : Supercharged systemd
    1. Master the Basics
      1. Start at Boot
    2. Understand Units and Targets
      1. Units
      2. Targets
    3. Explore the Analysis Tool
      1. Power Options
      2. Checking the Logs
    4. Mind the Syntax
      1. Init Scripts
      2. Migrating to Systemd
    5. Summary
  13. Chapter 4 : Zero Downtime Linux
    1. The Promise of Continuous Availability
    2. Live Patching the Kernel
    3. Ksplice’s Uptrack
    4. First Impressions
    5. KernelCare—Worth the Cost
    6. Try kPatch
    7. Not the End of Reboots
    8. Summary
  14. Chapter 5 : Get More with Wget
    1. Long- and Shorthand Support
    2. Logging Errors
    3. Automating Tasks
    4. Fulfilling Requests with Retries
    5. Showing Progress
    6. DNS Considerations
    7. Using Authentication
    8. Denying and Crafting Cookies
    9. Creating Directory Structures
    10. Precision
    11. Security
      1. Posting Data
      2. Ciphers
      3. Initialisms
      4. Proxies
      5. Mirroring
    12. Downloading Assets
    13. Persistent Config
    14. A Note on Criminal Activity
    15. Summary
  15. Chapter 6 : SECURING SSH with PAM
    1. A Note About Standards
    2. Configuring Your SSH Server
    3. Wrapping Your Connections
    4. Getting Started with Two-Step Authentication
    5. Installing the Required Packages
      1. Installing Google Authenticator On Android
    6. Testing SSH Access
    7. Summary
  16. Chapter 7 : Your Disks, Your Way
    1. Creating a Filesystem
    2. The mke2fs Options
    3. Handling Index Node Problems
    4. Dealing with Problematic Files
    5. Shorter File Names Are Better
    6. Formatting A Partition
    7. Formatting Option
    8. Using tune2fs
    9. Using fsck
    10. Summary
  17. Chapter 8 : No sFTP Doesn’t Mean No Encryption
    1. Using lftp
      1. Installation
      2. Getting Started
    2. Main Configuration Options
    3. The Default lftp Config File
    4. Adding Multiple Options to One Line
    5. Mirroring Directories
    6. Using Regular Expressions
      1. Troubleshooting Tips
    7. Summary
  18. Chapter 9 : Making the Most of the Screen Utility
    1. Screen Utility Basics
      1. Using the Screen Utility—A Simple Example
      2. Listing Sessions
    2. Some Useful Tips and Commands
      1. Attaching an Existing Session to Your Current Window
      2. Using Passwords
      3. Killing a Session
      4. Logging Your Session
      5. Saving Config Settings to Your Home Directory
      6. Running a Command in a Script
    3. Tricksy Telnet
    4. Summary
  19. Chapter 10 : Improve Security with SELinux
    1. Understanding Key Concepts
      1. Deny Everything, Everything
      2. Segregating Applications
      3. Some Key Characteristics
      4. Understanding Domains and How They Can Be Used
    2. Setting Up SELinux
      1. Installation On Existing Servers
      2. Packages Required for Install
      3. Changing Modes and Policies
      4. Activating SELinux
      5. Post-Install Tools
    3. Operating SELinux
      1. Current Status
      2. Contexts
      3. Administrating SELinux
      4. Making Context Changes Persistent
      5. Verifying Labels
      6. Daemons
    4. Troubleshooting
      1. Documentation
      2. Graphical User Interface Tools
      3. audit2allow
      4. Grub Bootloader
      5. Disabling SELinux
      6. AVCstat
      7. Sesearch
    5. Summary
  20. Chapter 11 : Nattier Networks
    1. Old School: Using ifconfig
    2. New School: Using ip
    3. Old versus New
      1. Jumbo Frames
      2. IPv4 and IPv6
      3. The route Command
    4. Summary
  21. Chapter 12 : Keeping Information Private with GPG
    1. GPG Is Open and Free
    2. Running GPG
      1. Config Files
      2. Random Data
      3. Encrypting a Message
      4. Decrypting a Message
      5. Caveats
      6. Using Digital Signatures
    3. Setting Up GPG in Google Chrome
    4. Summary
  22. Chapter 13 : Get Permission from Your Peers with Sudo
    1. Basics
    2. The Main Config
    3. Using GUIs
    4. Using Terminals
    5. Editing Config
    6. Bugs and Threats
    7. Taking Total Control
    8. Aliases Within Aliases
    9. Troubleshooting
    10. Summary
  23. Chapter 14 : Loop Disks and Wubi
    1. Why Use Wubi in the Enterprise?
    2. Windows 8 and Wubi
    3. Windows 7 and Wubi
      1. Installing Wubi
      2. Backing Up Wubi
    4. Loop Devices
    5. Wubi Tips
    6. Summary
  24. Appendix A: Hack, Break, Fix
    1. Exploring DVL
    2. What’s in the Box
    3. Vulnerable
    4. Summary
  25. Index