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 Appl.