UNIX and Linux System Administration Handbook
Description
"As an author, editor, and publisher, I never paid much attention to the competition-except in a few cases. This is one of those cases. The UNIX System Administration Handbook is one of the few books we ever measured ourselves against."
-Tim O'Reilly, founder of O'Reilly Media
"This edition is for those whose systems live in the cloud or in virtualized data centers; those whose administrative work largely takes the form of automation and configuration source code; those who collaborate closely with developers, network engineers, compliance officers, and all the other worker bees who inhabit the modern hive."
-Paul Vixie, Internet Hall of Fame-recognized innovator and founder of ISC and Farsight Security
"This book is fun and functional as a desktop reference. If you use UNIX and Linux systems, you need this book in your short-reach library. It covers a bit of the systems' history but doesn't bloviate. It's just straight-forward information delivered in a colorful and memorable fashion."
-Jason A. Nunnelley
UNIX ® and Linux ® System Administration Handbook, Fifth Edition, is today's definitive guide to installing, configuring, and maintaining any UNIX or Linux system, including systems that supply core Internet and cloud infrastructure.
Updated for new distributions and cloud environments, this comprehensive guide covers best practices for every facet of system administration, including storage management, network design and administration, security, web hosting, automation, configuration management, performance analysis, virtualization, DNS, security, and the management of IT service organizations. The authors-world-class, hands-on technologists-offer indispensable new coverage of cloud platforms, the DevOps philosophy, continuous deployment, containerization, monitoring, and many other essential topics.
Whatever your role in running systems and networks built on UNIX or Linux, this conversational, well-written ¿guide will improve your efficiency and help solve your knottiest problems.
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Persons
Evi Nemeth pioneered the discipline of UNIX system administration. She taught and mentored computer science students at the University of Colorado Boulder, was visiting faculty member at Dartmouth College and UC San Diego, and helped bring Internet technology to the developing world through her work with the Internet Society and the United Nations.
Garth Snyder has worked at NeXT and Sun and holds a BS in Engineering from Swarthmore College and an MD and an MBA from the University of Rochester.
Trent R. Hein (@trenthein) is a serial entrepreneur who is passionate about practical cybersecurity and automation. Outside of technology, he loves hiking, skiing, fly fishing, camping, bluegrass, dogs, and the Oxford comma. Trent holds a BS in Computer Science from the University of Colorado.
Ben Whaley is the founder of WhaleTech, an independent consultancy. He was honored by Amazon as one of the first AWS Community Heroes. He obtained a B.S. in Computer Science from the University of Colorado at Boulder.
Dan Mackin's (@dan_mackin) long-standing passion for technology inspired him to get a BS in Electrical and Computer Engineering from the University of Colorado at Boulder. He applies Linux and other open source technologies not only in his day job, but also to automation, monitoring, and weather metrics collection projects at home. Dan loves spending time with his wife and dog, skiing, movies, sailing, and backcountry touring.
Content
Tribute to Evi xl
Preface xlii
Foreword xliv
Acknowledgments xlvi
Section One: Basic Administration 1
Chapter 1: Where to Start 3
Essential duties of a system administrator 4
Suggested background 7
Linux distributions 8
Example systems used in this book 9
Notation and typographical conventions 12
Units 13
Man pages and other on-line documentation 14
Other authoritative documentation 16
Other sources of information 18
Ways to find and install software 19
Where to host 25
Specialization and adjacent disciplines 26
Recommended reading28
Chapter 2: Booting and System Management Daemons 30
Boot process overview 30
System firmware 32
Boot loaders 35
GRUB: the GRand Unified Boot loader 35
The FreeBSD boot process 39
System management daemons .41
systemd in detail 44
FreeBSD init and startup scripts 57
Reboot and shutdown procedures 59
Stratagems for a nonbooting system 60
Chapter 3: Access Control and Rootly Powers 65
Standard UNIX access control 66
Management of the root account69
Extensions to the standard access control model 79
Modern access control 83
Recommended reading89
Chapter 4: Process Control 90
Components of a process 90
The life cycle of a process 93
ps: monitor processes 98
Interactive monitoring with top101
nice and renice: influence scheduling priority102
The /proc filesystem 104
strace and truss: trace signals and system calls 105
Runaway processes 107
Periodic processes109
Chapter 5: The Filesystem 120
Pathnames 122
Filesystem mounting and unmounting 122
Organization of the file tree125
File types 126
File attributes132
Access control lists 140
Chapter 6: Software Installation and Management 153
Operating system installation 154
Managing packages 162
Linux package management systems 164
High-level Linux package management systems 166
FreeBSD software management175
Software localization and configuration 178
Recommended reading 181
Chapter 7: Scripting and the Shell 182
Scripting philosophy 183
Shell basics 189
sh scripting 198
Regular expressions 209
Python programming 215
Ruby programming 223
Library and environment management for Python and Ruby 229
Revision control with Git 235
Recommended reading 241
Chapter 8: User Management 243
Account mechanics 244
The /etc/passwd file 245
The Linux /etc/shadow file250
FreeBSD's /etc/master.passwd and /etc/login.conf files 252
The /etc/group file 254
Manual steps for adding users 255
Scripts for adding users: useradd, adduser, and newusers 260
Safe removal of a user's account and files264
User login lockout265
Risk reduction with PAM 266
Centralized account management 266
Chapter 9: Cloud Computing 270
The cloud in context 271
Cloud platform choices 273
Cloud service fundamentals 276
Clouds: VPS quick start by platform283
Cost control 291
Recommended Reading 293
Chapter 10: Logging 294
Log locations296
The systemd journal 299
Syslog 302
Kernel and boot-time logging 318
Management and rotation of log files 319
Management of logs at scale 321
Logging policies 323
Chapter 11: Drivers and the Kernel 325
Kernel chores for system administrators 326
Kernel version numbering 327
Devices and their drivers 328
Linux kernel configuration339
FreeBSD kernel configuration 344
Loadable kernel modules 346
Booting 348
Booting alternate kernels in the cloud 355
Kernel errors356
Recommended reading 359
Chapter 12: Printing 360
CUPS printing 361
CUPS server administration 365
Troubleshooting tips 369
Recommended reading 371
Section Two: Networking 373
Chapter 13: TCP/IP Networking 375
TCP/IP and its relationship to the Internet 375
Networking basics 378
Packet addressing384
IP addresses: the gory details 387
Routing 398
IPv4 ARP and IPv6 neighbor discovery 401
DHCP: the Dynamic Host Configuration Protocol402
Security issues 406
Basic network configuration 410
Linux networking417
FreeBSD networking 425
Network troubleshooting 428
Network monitoring 437
Firewalls and NAT 440
Cloud networking448
Recommended reading 457
Chapter 14: Physical Networking 459
Ethernet: the Swiss Army knife of networking460
Wireless: Ethernet for nomads 469
SDN: software-defined networking 473
Network testing and debugging474
Building wiring 475
Network design issues476
Management issues 478
Recommended vendors 479
Recommended reading 480
Chapter 15: IP Routing 481
Packet forwarding: a closer look482
Routing daemons and routing protocols 485
Protocols on parade 488
Routing protocol multicast coordination490
Routing strategy selection criteria 490
Routing daemons492
Cisco routers494
Recommended reading 496
Chapter 16: DNS: The Domain Name System 498
DNS architecture 499
DNS for lookups 500
The DNS namespace 502
How DNS works 503
The DNS database512
The BIND software 525
Split DNS and the view statement 541
BIND configuration examples 543
Zone file updating547
DNS security issues 551
BIND debugging 568
Recommended reading 576
Chapter 17: Single Sign-On 578
Core SSO elements 579
LDAP: "lightweight" directory services 580
Using directory services for login 586
Alternative approaches594
Recommended reading 595
Chapter 18: Electronic Mail 596
Mail system architecture 597
Anatomy of a mail message600
The SMTP protocol 603
Spam and malware 605
Message privacy and encryption 607
Mail aliases 608
Email configuration 612
sendmail 613
Exim 640
Postfix 658
Recommended reading 672
Chapter 19: Web Hosting 674
HTTP: the Hypertext Transfer Protocol 674
Web software basics 682
Web hosting in the cloud 694
Apache httpd696
NGINX 704
HAProxy 710
Recommended reading 714
Section Three: Storage 715
Chapter 20: Storage 717
I just want to add a disk! 718
Storage hardware 721
Storage hardware interfaces 730
Attachment and low-level management of drives 733
The software side of storage: peeling the onion 739
Disk partitioning 742
Logical volume management 747
RAID: redundant arrays of inexpensive disks 753
Filesystems 762
Traditional filesystems: UFS, ext4, and XFS 763
Next-generation filesystems: ZFS and Btrfs 772
ZFS: all your storage problems solved 773
Btrfs: "ZFS lite" for Linux 783
Data backup strategy 788
Recommended reading 790
Chapter 21: The Network File System 791
Meet network file services 791
The NFS approach794
Server-side NFS 801
Client-side NFS 807
Identity mapping for NFS version 4 810
nfsstat: dump NFS statistics 811
Dedicated NFS file servers 812
Automatic mounting 812
Recommended reading 818
Chapter 22: SMB 819
Samba: SMB server for UNIX 820
Installing and configuring Samba 821
Mounting SMB file shares 825
Browsing SMB file shares 826
Ensuring Samba security 826
Debugging Samba827
Recommended reading 829
Section Four: Operations 831
Chapter 23: Configuration Management 833
Configuration management in a nutshell834
Dangers of configuration management 834
Elements of configuration management 835
Popular CM systems compared 841
Introduction to Ansible 852
Introduction to Salt 871
Ansible and Salt compared 893
Best practices895
Recommended reading 899
Chapter 24: Virtualization 900
Virtual vernacular901
Virtualization with Linux 905
FreeBSD bhyve 910
VMware910
VirtualBox 911
Packer 911
Vagrant 913
Recommended reading 914
Chapter 25: Containers 915
Background and core concepts 916
Docker: the open source container engine 919
Containers in practice937
Container clustering and management 942
Recommended reading 948
Chapter 26: Continuous Integration and Delivery 949
CI/CD essentials 951
Pipelines 955
Jenkins: the open source automation server 961
CI/CD in practice964
Containers and CI/CD978
Recommended reading 980
Chapter 27: Security 981
Elements of security 983
How security is compromised 983
Basic security measures 987
Passwords and user accounts 992
Security power tools 996
Cryptography primer1005
SSH, the Secure SHell1016
Firewalls 1027
Virtual private networks (VPNs) 1030
Certifications and standards 1031
Sources of security information 1034
When your site has been attacked 1037
Recommended reading 1038
Chapter 28: Monitoring 1040
An overview of monitoring 1041
The monitoring culture 1044
The monitoring platforms1045
Data collection 1051
Network monitoring 1055
Systems monitoring 1056
Application monitoring 1059
Security monitoring 1061
SNMP: the Simple Network Management Protocol 1063
Tips and tricks for monitoring1068
Recommended reading 1069
Chapter 29: Performance Analysis 1070
Performance tuning philosophy 1071
Ways to improve performance 1073
Factors that affect performance 1074
Stolen CPU cycles 1075
Analysis of performance problems 1076
System performance checkup 1077
Help! My server just got really slow! 1088
Recommended reading 1090
Chapter 30: Data Center Basics 1091
Racks1092
Power 1092
Cooling and environment1096
Data center reliability tiers 1101
Data center security 1102
Tools 1103
Recommended reading 1104
Chapter 31: Methodology, Policy, and Politics 1105
The grand unified theory: DevOps 1106
Ticketing and task management systems 1111
Local documentation maintenance1115
Environment separation 1118
Disaster management1119
IT policies and procedures 1122
Service level agreements 1125
Compliance: regulations and standards 1127
Legal issues 1131
Organizations, conferences, and other resources 1133
Recommended reading 1135
Index 1136
A Brief History of System Administration 1166
Colophon 1176
About the Contributors 1178
About the Authors 1179