Linux in Action

386 Pages·2018·17.04 MB·English

by  David Clinton

David Clinton
M A N N I N G
Linux in Action topics
Chapter Skill domains Tools
1 Welcome to Linux Shells, partitions, and file Bash, man
systems
2 Linux virtualization: Building a Virtualization, file systems VirtualBox, LXC, apt, yum/dnf
safe and simple Linux
working environment
3 Remote connectivity: Safely Security, remote connectivity ssh, scp, systemctl, ps, grep
accessing networked machines
4 Archive management: Backing Partitions and file systems, text tar, dd, redirects, rsync, locate, split,
up or copying entire file systems streams chmod, chown
5 Automated administration: Scripts, system process Scripts, cron, anacron, systemd
Configuring automated offsite management, security timers
backups
6 Emergency tools: Building Partitions and file systems, device parted, GRUB, mount, chroot
a system recovery device management
7 Web servers: Building a Databases, networking, package PHP, MySQL (MariaDB), Apache web
MediaWiki server management server, package dependencies
8 Networked file sharing: Building Package management, snapd, file systems, encryption
a Nextcloud file-sharing server networking, security
9 Securing your web server Networking, security, system Apache, Iptables, /etc/group,
monitoring SELinux, apt, yum/dnf, chmod,
chown, Let’s Encrypt
10 Secure your network connections: Networking, security Firewalls, ssh, Apache, OpenVPN,
Creating a VPN or DMZ sysctl, easy rsa
11 System monitoring: Working System monitoring, text streams, grep, sed, journal ctl, rsyslogd,
with log files security /var/log/, Tripwire
12 Sharing data over a private Networking, partitions, file nfs, smb, ln, /etc/fstab
network systems
13 Troubleshooting system System monitoring, system top, free, nice, nmon, tc, iftop, df,
performance issues process management, networking kill, killall, uptime
14 Troubleshooting network issues Networking ip, dhclient, dmesg, ping, nmap,
traceroute, netstat, netcat(nc)
15 Troubleshooting peripheral devices Device management lshw, lspci, lsusb, modprobe, CUPS
16 DevOps tools: Deploying a scripted Scripts, virtualization Ansible, YAML, apt
server environment using Ansible
Linux in Action
DAVID CLINTON
MANNING
SHELTER ISLAND
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ISBN 9781617294938
Printed in the United States of America
1 2 3 4 5 6 7 8 9 10 – DP – 23 22 21 20 19 18
brief contents
1 ■ Welcome to Linux 1
2 ■ Linux virtualization: Building a Linux working
environment 22
3 ■ Remote connectivity: Safely accessing networked
machines 49
4 ■ Archive management: Backing up or copying entire file
systems 68
5 ■ Automated administration: Configuring automated offsite
backups 90
6 ■ Emergency tools: Building a system recovery device 109
7 ■ Web servers: Building a MediaWiki server 130
8 ■ Networked file sharing: Building a Nextcloud file-sharing
server 155
9 ■ Securing your web server 174
10 ■ Securing network connections: Creating a VPN or
DMZ 203
11 ■ System monitoring: Working with log files 229
12 ■ Sharing data over a private network 251
13 ■ Troubleshooting system performance issues 268
iii
iv BRIEF CONTENTS
14 ■ Troubleshooting network issues 289
15 ■ Troubleshooting peripheral devices 308
16 ■ DevOps tools: Deploying a scripted server environment
using Ansible 322
contents
preface xi
acknowledgments xii
about this book xiv
about the author xviii
about the cover illustration xix
1 Welcome to Linux 1
1.1 What makes Linux different from other operating systems 2
1.2 Basic survival skills 3
The Linux file system 4 ■ Getting around: Linux navigation
tools 5 ■ Getting things done: Linux file management tools 9
Keyboard tricks 13 ■ Pseudo file systems 14 ■ Showing ’em
who’s boss: sudo 15
1.3 Getting help 16
Man files 16 ■ Info 16 ■ The internet 17
2 Linux virtualization: Building a Linux working environment 22
2.1 What is virtualization? 23
2.2 Working with VirtualBox 26
Working with Linux package managers 26 ■ Defining a virtual
machine (VM) 33 ■ Installing an operating system (OS) 36
Cloning and sharing a VirtualBox VM 39
v
vi CONTENTS
2.3 Working with Linux containers (LXC) 41
Getting started with LXC 41 ■ Creating your first container 42
3 Remote connectivity: Safely accessing networked machines 49
3.1 The importance of encryption 50
3.2 Getting started with OpenSSH 51
3.3 Logging in to a remote server with SSH 53
3.4 Password-free SSH access 55
Generating a new key pair 56 ■ Copying the public key over a
network 57 ■ Working with multiple encryption keys 59
3.5 Safely copying files with SCP 59
3.6 Using remote graphic programs over SSH connections 60
3.7 Linux process management 61
Viewing processes with the ps command 62 ■ Working with
systemd 64
4 Archive management: Backing up or copying entire
file systems 68
4.1 Why archive? 69
Compression 69 ■ Archives: Some important considerations 70
4.2 What to archive 71
4.3 Where to back up 73
4.4 Archiving files and file systems using tar 74
Simple archive and compression examples 74 ■ Streaming file
system archives 76 ■ Aggregating files with find 78 ■ Preserving
permissions and ownership…and extracting archives 79
4.5 Archiving partitions with dd 83
dd operations 83 ■ Wiping disks with dd 84
4.6 Synchronizing archives with rsync 85
4.7 Planning considerations 86
5 Automated administration: Configuring automated
offsite backups 90
5.1 Scripting with Bash 91
A sample script for backing up system files 91 ■ A sample script for
changing filenames 95
CONTENTS vii
5.2 Backing up data to AWS S3 97
Installing the AWS command-line interface (CLI) 97
Configuring your AWS account 98 ■ Creating your first
bucket 99
5.3 Scheduling regular backups with cron 100
5.4 Scheduling irregular backups with anacron 103
Running the S3 sync job 103
5.5 Scheduling regular backups with systemd timers 104
6 Emergency tools: Building a system recovery device 109
6.1 Working in recovery/rescue mode 111
The GRUB bootloader 111 ■ Using recovery mode on
Ubuntu 112 ■ Using rescue mode on CentOS 113 ■ Finding
command-line rescue tools 113
6.2 Building a live-boot recovery drive 114
System rescue images 115 ■ Writing live-boot images to USB
drives 116
6.3 Putting your live-boot drive to work 120
Testing system memory 120 ■ Damaged partitions 122
Recovering files from a damaged file system 124
6.4 Password recovery: Mounting a file system using chroot 126
7 Web servers: Building a MediaWiki server 130
7.1 Building a LAMP server 131
7.2 Manually setting up an Apache web server 133
Installing the Apache web server on Ubuntu 133 ■ Populating
your website document root 134
7.3 Installing an SQL database 134
Hardening SQL 136 ■ SQL administration 137
7.4 Installing PHP 140
Installing PHP on Ubuntu 140 ■ Testing your PHP installation 140
7.5 Installing and configuring MediaWiki 141
Troubleshooting missing extensions 142 ■ Connecting MediaWiki
to the database 145
7.6 Installing the Apache web server on CentOS 146
Understanding network ports 147 ■ Controlling network
traffic 148 ■ Installing MariaDB on CentOS 149
Installing PHP on CentOS 149
viii CONTENTS
8 Networked file sharing: Building a Nextcloud
file-sharing server 155
8.1 Enterprise file sharing and Nextcloud 156
8.2 Installing Nextcloud using snaps 157
8.3 Installing Nextcloud manually 159
Hardware prerequisites 159 ■ Building a LAMP server 161
Configuring Apache 161 ■ Downloading and unpacking
Nextcloud 163
8.4 Nextcloud administration 166
8.5 Using AWS S3 as the primary Nextcloud storage 169
9 Securing your web server 174
9.1 The obvious stuff 175
9.2 Controlling network access 177
Configuring a firewall 177 ■ Using nonstandard ports 183
9.3 Encrypting data in transit 185
Preparing your website domain 187 ■ Generating certificates
using Let’s Encrypt 187
9.4 Hardening the authentication process 189
Controlling file system objects with SELinux 189 ■ Installing and
activating SELinux 191 ■ Applying SELinux policies 193
System groups and the principle of least privilege 194
Isolating processes within containers 196 ■ Scanning for
dangerous user ID values 197
9.5 Auditing system resources 197
Scanning for open ports 198 ■ Scanning for active services 198
Searching for installed software 199
10 Securing network connections: Creating a VPN or DMZ 203
10.1 Building an OpenVPN tunnel 204
Configuring an OpenVPN server 205 ■ Configuring an
OpenVPN client 212 ■ Testing your VPN 214
10.2 Building intrusion-resistant networks 215
Demilitarized zones (DMZs) 216 ■ Using iptables 218
Creating a DMZ using iptables 218 ■ Creating a DMZ using
Shorewall 221
10.3 Building a virtual network for infrastructure testing 224