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Linux 101 Week 2
Transcript of Linux 101 Week 2
The System Settings panel allows you to control most of the basic configuration options and desktop settings such as specifying the screen resolution, managing network connections, or changing the date and time of the system.
The Displays panel under System Settings (or Display and Monitor panel under Configure Desktop) contains the most common settings for changing the desktop appearance. These settings function independently of the specific display drivers you are running.
Date and Time Settings
Launching Terminal Windows
Introduction to Linux Documentation Sources
One OS to rule them all,
UBT - University of business and technology
Network Associate,CISCO IT & CCNA
Fundamental of Network Security
MITX: Introduction to Computer Science and
Programming Using Python
HarvardX: CS50x Introduction to Computer Science
BerkeleyX: CS169.1x Engineering Software as a Service
IITBombayX: CS101.1x Introduction to Computer Programming
FLOSSK - Free Libre Open Source Software Kosova
Bugzilla - Mozilla
CEO @ HelloWorld
Python for Pentesters System Programming and Security Network Security Programming – Sniffers and Packet Injectors Security Web Applicaion Exploitation Techniques Malware Analysis and Reverse Engineering Other skills . Network Security Server and Client Side Exploitation Web Server security. Web Server vulnerabilities SQL Server vulnerabilities Web Application Vulnerabilities. Web application threats Buffer Overflows Cryptography Trojans and Backdoors Denial of Service attacks.
When did Linus Torvalds
start writing the Linux kernel?
The Date and Time Settings window can be accessed from the System Settings window. Alternatively, you can right-click Date and Time on the top panel to access the Date and Time Settings window.
All Linux distributions have network configuration files, but file formats and locations can differ from one distribution to another. Hand editing of these files can handle quite complicated setups, but is not very dynamic or easy to learn and use. The Network Manager utility was developed to make things easier and more uniform across distributions. It can list all available networks (both wired and wireless), allow the choice of a wired, wireless or mobile broadband network, handle passwords, and set up Virtual Private Networks (VPNs). Except for unusual situations, it’s generally best to let the Network Manager establish your connections and keep track of your settings.
Introduction to the Command Line
To open a terminal in CentOS:
On the CentOS desktop, in the upper-left corner, click Applications.
From the System Tools menu, select Terminal.
To open a terminal in openSUSE:
On the openSUSE desktop, in the upper-left corner of the screen, click Activities.
From the left pane, click Show Applications.
Scroll-down and select the required terminal.
To open a terminal in Ubuntu:
In the left panel, click the Ubuntu icon.
Type terminal in the Search box.
All the demonstrations created have a user configured with sudo capabilities to provide the user with administrative (admin) privileges when required. sudo allows users to run programs using the security privileges of another user, generally root (superuser). The functionality of sudo is similar to that of run as in Windows.
Working with Files
Wired and Wireless Connections
Wired connections usually do not require complicated or manual configuration. The hardware interface and signal presence are automatically detected, and then Network Manager sets the actual network settings via DHCP (Dynamic Host Control Protocol).
For static configurations that don't use DHCP, manual setup can also be done easily through Network Manager. You can also change the Ethernet Media Access Control (MAC) address if your hardware supports it. (The MAC address is a unique hexadecimal number of your network card.)
Configuring Wireless Connections in Ubuntu
In top panel, click Network Manager.
Click Enable Wi-Fi - to display a list available Wireless Networks.
Click the desired Wireless Network.
For a secured network, enter the password.
To modify saved wireless network settings, click Edit Connections.
Installing and Updating Software
Each package in a Linux distribution provides one piece of the system, such as the Linux kernel, the C compiler, the shared software code for interacting with USB devices, or the Firefox web browser.
Packages often depend on each other; for example, because Firefox can communicate using SSL/TLS, it will depend on a package which provides the ability to encrypt and decrypt SSL and TLS communication, and will not install unless that package is also installed at the same time.
Debian Family System
Let’s look at Package Management in the Debian Family System.
dpkg is the underlying package manager for these systems; it can install, remove, and build packages. Unlike higher-level package management systems, it does not automatically download and install packages and satisfy their dependencies.
For Debian-based systems, the higher-level package management system is the apt (Advanced Package Tool) system of utilities. Generally, while each distribution within the Debian family uses apt, it creates its own user interface on top of it (for example, apt-get, aptitude, synaptic, Ubuntu Software Center, Update Manager, etc). Although apt repositories are generally compatible with each other, the software they contain generally isn’t. Therefore, most apt repositories target a particular distribution (like Ubuntu), and often software distributors ship with multiple repositories to support multiple distributions. The demonstration using the Ubuntu Software Center is shown later in this section.
Red Hat Packet Manager (RPM)
Red Hat Package Manager (RPM) is the other package management system popular on Linux distributions. It was developed by Red Hat, and adopted by a number of other distributions, including the openSUSE, Mandriva, CentOS, Oracle Linux, and others.
The high-level package manager differs between distributions; most use the basic repository format used in yum (Yellowdog Updater, Modified - the package manager used by Fedora and Red Hat Enterprise Linux), but with enhancements and changes to fit the features they support. Recently, the GNOME project has been developing PackageKit as a unified interface; this is now the default interface for Fedora.
openSUSE’s YaST Software Management
Before openSUSE 13.1, Apper was used for Software Management. Now it has been replaced by the YaST (Yet another System Tool) Software Manager.
The YaST Software Manager is similar to other graphical package managers. It is an RPM-based application. You can add, remove, or update packages using this application very easily. To access the YaST Software Manager:
In the Search box type YaST
Click the YaST icon
Click Software Management
openSUSE’s YaST Software Management application is similar to the graphical package managers in other distributions. The demonstration of the YaST Software Manager is shown later in this section.
Linux system administrators spend a significant amount of their time at a command line prompt. They often automate and troubleshoot tasks in this text environment. There is a saying, "graphical user interfaces make easy tasks easier, while command line interfaces make difficult tasks possible." Linux relies heavily on the abundance of command line tools. The command line interface provides the following advantages:
No GUI overhead.
Virtually every task can be accomplished using the command line.
You can script tasks and series of procedures.
You can log on remotely to networked machines anywhere on the Internet.
You can initiate graphical apps directly from the command line.
Logging In and Out
Rebooting and Shutting Down
When you first log into a system or open a terminal, the default directory should be your home directory; you can print the exact path of this by typing echo $HOME. (Note that some Linux distributions actually open new graphical terminals in $HOME/Desktop.) The following commands are useful for directory navigation:
Exploring the Filesystem
Traversing up and down the filesystem tree can get tedious. The tree command is a good way to get a bird’s-eye view of the filesystem tree. Use tree -d to view just the directories and to suppress listing file names.
The following commands can help in exploring the filesystem:
Searching for Files
The locate utility program performs a search through a previously constructed database of files and directories on your system, matching all entries that contain a specified character string. This can sometimes result in a very long list.
To get a shorter more relevant list we can use the grep program as a filter; grep will print only the lines that contain one or more specified strings as in:
$ locate zip | grep bin
When no arguments are given, find lists all files in the current directory and all of its subdirectories. Commonly used options to shorten the list include -name (only list files with a certain pattern in their name), -iname (also ignore the case of file names), and -type (which will restrict the results to files of a certain specified type, such as d for directory, l for symbolic link or f for a regular file, etc).
Searching for files and directories named "gcc":
$ find /usr -name gcc
Searching only for directories named "gcc":
$ find /usr -type d -name gcc
Searching only for regular files named "test1":
$ find /usr -type f -name test1
touch and mkdir
is often used to set or update the access, change, and modify times of files. By default it resets a file's time stamp to match the current time.
However, you can also create an empty file using touch:
$ touch <filename>
is used to create a directory.
To create a sample directory named sampdir under the current directory, type mkdir sampdir.
To create a sample directory called sampdir under /usr, type
Removing a File
Renaming or Removing a Directory
Filesystem Hierarchy Standard
Partitions in Linux
Each filesystem resides on a hard disk partition. Partitions help to organize the contents of disks according to the kind of data contained and how it is used. For example, important programs required to run the system are often kept on a separate partition (known as root or /) than the one that contains files owned by regular users of that system (/home). In addition, temporary files created and destroyed during the normal operation of Linux are often located on a separate partition; in this way, using all available space on a particular partition may not fatally affect the normal operation of the system.
Before you can start using a filesystem, you need to mount it to the filesystem tree at a mount point. This is simply a directory (which may or may not be empty) where the filesystem is to be attached (mounted). Sometimes you may need to create the directory if it doesn't already exist.
Certain filesystems like the one mounted at /proc are called pseudo filesystems because they have no permanent presence anywhere on disk.
The /proc filesystem contains virtual files (files that exist only in memory) that permit viewing constantly varying kernel data. This filesystem contains files and directories that mimic kernel structures and configuration information. It doesn't contain real files but runtime system information (e.g. system memory, devices mounted, hardware configuration, etc). Some important files in /proc are:
The /bin and /sbin Directories
The /bin directory contains executable binaries, essential commands used in single-user mode, and essential commands required by all system users, such as:
The /dev Directory
The /dev directory contains device nodes, a type of pseudo-file used by most hardware and software devices, except for network devices.
The /var and /etc Directories
directory contains files that are expected to change in size and content as the system is running (var stands for variable) such as the entries in the following directories:
directory is the home for system configuration files. It contains no binary programs, although there are some executable scripts. For example, the file resolv.conf tells the system where to go on the network to obtain host name to IP address mappings (DNS). Files like passwd,shadow and group for managing user accounts are found in the /etc directory.
The /boot Directory
The /boot directory contains the few essential files needed to boot the system. For every alternative kernel installed on the system there are four files:
the compressed Linux kernel, required for booting
the initial ram filesystem, required for booting, sometimes called initrd, not initramfs
the kernel configuration file, only used for debugging and bookkeeping
kernel symbol table, only used for debugging
The Grand Unified Bootloader
files (such as
/boot/grub/grub.conf or /boot/grub2/grub2.cfg)
are also found under the /boot directory.
The /lib and /media Directories
contains libraries (common code shared by applications and needed for them to run) for the essential programs in /bin and /sbin. These library filenames either start with ld or lib, for example, /lib/libncurses.so.5.7.
directory is typically located where removable media, such as
CDs, DVDs and USB drives
are mounted. Unless configuration prohibits it, Linux automatically mounts the removable media in the /media directory when they are detected.
Additional Directories Under /:
Subdirectories under /usr
Backing Up Data
There are many ways you can back up data or even your entire system. Basic ways to do so include use of simple copying with cp and use of the more robust rsync.
is a very powerful utility. For example, a very useful way to back up a project directory might be to use the following command:
$ rsync -r project-X archive-machine:archives/project-X
File data is often compressed to save disk space and reduce the time it takes to transmit files over networks.
Linux uses a number of methods to perform this compression including:
Compressing Data Using gzip
Compressing Data Using bzip2
Compress Data Using xz
Handling Files Using zip