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to be in a dictionary. Option C uses two common words, which is
arguably better than option A, but not by much. Option D uses two closely related words
separated by a single number, which is also a poor choice for a password.
13. A. Phishing involves sending bogus e-mail or setting up fake Web sites that lure unsuspecting
individuals into divulging sensitive financial or other information. Script kiddies are intruders
who use root kits. Spoofing involves pretending data is coming from one computer when it’s
coming from another. Ensnaring isn’t a type of attack.
14. C. The /etc/nologin file, if present, prevents logins from ordinary users; only root may
log in. You might set this file when performing maintenance and then forget to remove it,
thus explaining the symptoms in the question. The syslogd daemon mentioned in option A
records system messages and is unlikely to produce the specified symptoms. The login process
ordinarily runs as root and is normally SUID root, so options B and D are also incorrect.
15. B, C. SSH is most directly a replacement for Telnet, but SSH also includes file-transfer
features that enable it to replace FTP in many situations. SSH is not a direct replacement
for either SMTP or NFS.
16. A. The ssh_host_dsa_key file holds one of three critical private keys for SSH. The fact
that this key is readable (and writeable!) to the entire world is disturbing. In principle, a
miscreant who has acquired this file might be able to redirect traffic and masquerade as
your system, duping users into delivering passwords and other sensitive data.
518 Chapter 10 N Securing Your System
17. B. SSH protocol level 2 is more secure than protocol level 1; thus, option B (specifying accep-
tance of level 2 only) is the safest approach. Option A is the least safe approach because it
precludes the use of the safer level 2. Options C and D are exactly equivalent in practice; both
support both protocol levels.
18. A. Allowing only normal users to log in via SSH effectively requires two passwords for any
remote root maintenance, improving security. SSH encrypts all connections, so it’s unlikely
that the password, or commands issued during an SSH session, will be intercepted. (None-
theless, some administrators prefer not to take even this small risk.) SSH doesn’t store pass-
words in a file.
19. D. Option D provides the correct command to import fredkey.pub prior to use. The
inspect-gpg and import-gpg commands of options A and C are fictitious; and there is
no --readkey option to gpg, as option B suggests.
20. C. The usual method of sending encrypted messages with GPG entails the sender using the
recipient’s public key to encrypt the message. Thus, option C is correct. Option A would be
correct if your correspondent needed to send you an encrypted message, but the question
only specifies your sending the encrypted message. Options B and D both entail delivery of
private keys, which is inadvisable at best, because private keys in the wrong hands permit
the holder to impersonate the person who owns the keys.
	CompTIA Linux+ Study Guide
	Acknowledgments
	About the Author
	Contents ata a Glance
	Contents
	Table of Exercises
	Introduction
	The Exam Objectives
	Assessment Test
	Answers to Assessment Test
	Part I: The CompTIA Linux+ LX0-101 Exam
	Chapter 1: Exploring Linux Command-Line Tools
	Understanding Command-Line Basics
	Using Streams, Redirection, and Pipes
	Processing Text Using Filters
	Using Regular Expressions
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 2: Managing Software
	Package Concepts
	Using RPM
	Using Debian Packages
	Converting Between Package Formats
	Package Dependencies and Conflicts
	Managing Shared Libraries
	Managing Processes
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 3: Configuring Hardware
	Configuring the BIOS and Core Hardware
	Configuring Expansion Cards
	Configuring USB Devices
	Configuring Hard Disks
	Designing a Hard Disk Layout
	Creating Partitions and Filesystems
	Maintaining Filesystem Health
	Mounting and Unmounting Filesystems
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 4: Managing Files
	Managing Files
	Managing File Ownership
	Controlling Access to Files
	Managing Disk Quotas
	Locating Files
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 5: Booting Linux and Editing Files
	Installing Boot Loaders
	Understanding the Boot Process
	Dealing with Runlevels and the Initialization Process
	Editing Files with Vi
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Part II: The CompTIA Linux+ LX0-102 Exam
	Chapter 6: Configuring the X Window System, Localization, and Printing
	Configuring Basic X Features
	Configuring X Fonts
	Managing GUI Logins
	Using X for Remote Access
	X Accessibility
	Configuring Localization and Internationalization
	Configuring Printing
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 7: Administering the System
	Managing Users and Groups
	Tuning User and System Environments
	Using System Log Files
	Maintaining the System Time
	Running Jobs in the Future
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 8: Configuring Basic Networking
	Understanding TCP/IP Networking
	Understanding Network Addressing
	Configuring Linux for a Local Network
	Diagnosing Network Connections
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 9: Writing Scripts, Configuring E-mail, and Using Databases
	Managing the Shell Environment
	Writing Scripts
	Managing E‑mail
	Managing Data with SQL
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Chapter 10: Securing Your System
	Administering Network Security
	Administering Local Security
	Configuring SSH
	Using GPG
	Summary
	Exam Essentials
	Review Questions
	Answers to Review Questions
	Appendix: About the Companion CD
	What You’ll Find on the CD
	System Requirements
	Using the CD
	Troubleshooting
	Glossary
	Index