Debian Administration Training Course

Debian Distribution

What is Debian?

• Choosing a Debian version
• Debian support and help
• The Debian community

Console basics

• The shell prompt
• The shell prompt under X
• The root account and root shell prompt (su, sudo, running programs as root under X)
• GUI system administration tools
• Virtual consoles
• How to exit the command prompt
• How to shut down the system
• Recovering a functional console
• Additional package suggestions for newcomers
• Adding an extra user account
• Configuring sudo

The filesystem

• Filesystem permissions
• Controlling permissions for newly created files: umask
• Permissions for groups of users (group)
• Timestamps
• Links
• Named pipes (FIFOs)
• Sockets
• Device files
• Special device files
• procfs and sysfs

Midnight Commander (MC)

• Customising MC
• Starting MC
• The file manager in MC
• Command-line tricks in MC
• The internal editor in MC
• The internal viewer in MC
• Auto-start features of MC
• The FTP virtual filesystem in MC

The basic Unix-like work environment

• The login shell
• Customising bash
• Special keystrokes
• The pager
• Setting a default text editor
• How to exit vim
• Recording shell activities
• Basic Unix commands

The simple shell command

• Command execution and environment variables
• The "$LANG" variable
• The "$PATH" variable
• The "$HOME" variable
• Command-line options
• Shell globbing
• The command's return value
• Typical command sequences and shell redirection
• Command aliases

Unix-like text processing

• Unix text tools
• Regular expressions
• Replacement expressions
• Global substitution with regular expressions
• Extracting data from text file tables
• Script snippets for piping commands

Debian package management

Prerequisites for Debian package management

• Package configuration
• Basic precautions
• Living with perpetual upgrades
• Debian archive basics
• Package dependencies
• The event flow of package management
• Initial response to package management issues

Basic package management operations

• apt-get / apt-cache versus aptitude
• Basic package management operations via the command line
• Interactive use of aptitude
• Key bindings in aptitude
• Package views in aptitude
• Search method options with aptitude
• The aptitude regex formula
• Dependency resolution in aptitude
• Package activity logs

Examples of aptitude operations

• Listing packages with regex matching on package names
• Browsing with regex matching
• Purging removed packages permanently
• Tidying auto/manual install status
• System-wide upgrade

Advanced package management operations

• Advanced package management operations via the command line
• Verification of installed package files
• Safeguards against package problems
• Searching package metadata

Debian package management internals

• Archive metadata
• The top-level "Release" file and authenticity
• Archive-level "Release" files
• Fetching package metadata
• The package state for APT
• The package state for aptitude
• Local copies of fetched packages
• Debian package file names
• The dpkg command
• The update-alternatives command
• The dpkg-statoverride command
• The dpkg-divert command

Recovery from a broken system

• Incompatibility with legacy user configurations
• Different packages with overlapping files
• Fixing broken package scripts
• Rescuing with the dpkg command
• Recovering package selection data

Tips for package management

• How to select Debian packages
• Packages from mixed archive sources
• Tweaking the candidate version
• Updates and Backports
• Automatic download and upgrade of packages
• Limiting download bandwidth for APT
• Emergency downgrading
• Who uploaded the package?
• The equivs package
• Porting a package to the stable system
• Proxy server for APT
• Small public package archives
• Recording and copying system configuration
• Converting or installing an alien binary package
• Extracting a package without dpkg
• Further reading on package management

System initialization

• An overview of the bootstrap process
• BIOS, boot loader, and the mini-Debian system
• The meaning of runlevels
• Configuring runlevels
• A runlevel management example
• Default parameters for each init script
• The hostname
• The filesystem
• Network interface initialization
• Network service initialization
• The system message
• The kernel message
• The udev system
• Kernel module initialization

Authentication and Security

• Normal Unix authentication
• Managing account and password information
• Choosing a good password
• Creating encrypted passwords
• PAM and NSS
• Configuration files accessed by PAM and NSS
• Modern centralised system management
• "Why GNU su does not support the wheel group"
• Stricter password rules
• Other access controls
• sudo
• SELinux and AppArmor
• Restricting access to certain server services
• Authentication security
• Secure passwords over the Internet
• Secure Shell
• Extra security measures for the Internet
• Securing the root password

Network setup

The basic network infrastructure

• The domain name
• Hostname resolution
• The network interface name
• The network address range for the LAN
• Network device support

Modern network configuration for desktops

• GUI network configuration tools

Low-level network configuration

• Iproute2 commands
• Safe low-level network operations

Network optimisation

• Finding the optimal MTU
• Setting the MTU
• WAN TCP optimisation

Netfilter infrastructure

Network applications

The mail system

• Modern mail service basics
• Mail configuration strategy for workstations

Mail transport agent (MTA) and Mail user agent (MUA)

• Overview of exim4
• Basic MUA: Mutt

Mail delivery agent (MDA) with filtering

• maildrop configuration
• procmail configuration
• Redelivering mbox contents

POP3/IMAP4 server

The remote access server and utility (SSH)

• SSH basics
• Port forwarding for SMTP/POP3 tunneling
• Connecting without remote passwords
• Dealing with alien SSH clients
• Setting up ssh-agent
• How to shut down the remote system via SSH
• Troubleshooting SSH

Other network application servers

Other network application clients

Diagnosing system daemons

The X Window System

• Setting up the desktop environment
• The server/client relationship
• The X server
• Starting the X Window System
• Starting an X session with gdm
• Customising the X session (classic method)
• Customising the X session (new method)
• Connecting a remote X client via SSH
• Securing an X terminal over the Internet
• X applications
• X office applications
• X utility applications

System tips

The screen program

• Use scenarios for screen(1)
• Key bindings for the screen command

Data recording and presentation

• The log daemon
• Log analyser
• Recording shell activities cleanly
• Customised display of text data
• Customised display of time and date
• Colourised shell echo
• Colourised commands
• Recording editor activities for complex repeats
• Recording the graphic image of an X application
• Recording changes in configuration files

Data storage tips

• Disk partition configuration
• Accessing partitions using UUID
• Filesystem configuration
• Filesystem creation and integrity checks
• Filesystem optimisation via mount options
• Filesystem optimisation via superblock
• Hard disk optimisation
• Using SMART to predict hard disk failure
• Expanding usable storage space via LVM
• Expanding usable storage space by mounting another partition
• Expanding usable storage space using symlinks
• Expanding usable storage space using aufs

Data encryption tips

• Removable disk encryption with dm-crypt/LUKS
• Encrypted swap partition with dm-crypt
• Automatically encrypting files with eCryptfs
• Automatically mounting eCryptfs

Monitoring, controlling, and starting program activities

• Timing a process
• Scheduling priority
• The ps command
• The top command
• Listing files opened by a process
• Tracing program activities
• Identifying processes using files or sockets
• Repeating a command at a constant interval
• Repeating a command looping over files
• Starting a program from the GUI
• Customising programs to be started
• Killing a process
• Scheduling tasks once
• Scheduling tasks regularly
• Alt-SysRq key

System maintenance tips

• Who is on the system?
• Warning everyone
• Hardware identification
• Hardware configuration
• System and hardware time
• Terminal configuration
• The sound infrastructure
• Disabling the screensaver
• Disabling beep sounds
• Memory usage
• System security and integrity checks

The kernel

• Kernel parameters
• Kernel headers
• Compiling the kernel and related modules
• Compiling the kernel source: the Debian standard method
• Compiling the module source: the Debian standard method
• Non-free hardware drivers

Virtualised systems

• Virtualisation tools
• Virtualisation workflow
• Mounting the virtual disk image file
• Chroot system
• Multiple desktop systems

Data management

Sharing, copying, and archiving

• Archive and compression tools
• Copy and synchronisation tools
• Idioms for archiving
• Idioms for copying
• Idioms for file selection
• Backup and recovery
• Backup utility suites
• An example script for system backup
• A copy script for data backup
• Removable storage devices
• Sharing data via network
• Archive media

The binary data

• Viewing and editing binary data
• Manipulating files without mounting disks
• Data redundancy
• Data file recovery and forensic analysis
• Splitting large files into smaller files
• Clearing file contents
• Dummy files
• Erasing an entire hard disk
• Erasing unused areas of a hard disk
• Undeleting deleted but still open files
• Searching all hardlinks
• Invisible disk space consumption

Data security infrastructure

• Key management for GnuPG (signing and encrypting)
• The MD5 sum