Linux fundamentals

Linux fundamentals

• 1.
  Linux Fundamentals “EXPERIENCE THEFUN IN LINUX” by Deepak Upadhyay
• 2.
  What is Linux? Linux:  Linux is an open-source operating system and has existed for decades and its system base-UNIX is the foundation of both Microsoft Windows and Apple(Macintosh).  Accounts on Linus are either Root or User and a user can enact permissions that are based on root privileges.  There are hundreds of Linux distributions and a distribution is a type of Linus platform that has been created for a specific purpose or design that separates itself from other distributions.  Some of the most common types of Linux systems consist of Ubuntu, Debian, Fedora, and Red Hat.
• 3.
  Why Use Linux? Linux uses less resources and computing power than other operating systems such as Microsoft Windows.  It will increase the ability to learn the use of other software and specifically, information security tools.  The open-source platform enables multiple systems to have an operating system without limitations of product keys and licenses.  Although Linux is still vulnerable to malware, the majority of present malware is crafted to target Windows because it is still the most widely used operating system.
• 4.
  Command Line Syntax The command line is made up of three components:  Command  Option  File/Location ► Example: root@mint:Desktop/cat cybrary.txt ► The <cat> is the command that instructs the computer to read the contents of the file, and <cybrary.txt> is the file itself. ► The location should be correct BEFORE executing the command because otherwise the file will not be found, rendering the command ineffective.
• 5.
  Linux File andFolder Structure  The layout of Linux resembles the design of Windows but there are some variances.  Linux begins with the root directory and it contains a </> slash  Multiple folders are extensions from root and are: /home, /bin, /sbin, /usr, /mnt, /etc, /dev  /etc has sub folders: /etc/passwd & /etc/shadow  The home directory contains all directories in home  etc contains the passwords and files related to administrators. The shadow folder holds the encrypted passwords.  Dev (short for device) contains locations of storage and optical drives.
• 6.
  How to UseLinux: Terminal  Terminal:  The terminal is the command shell of Linux and it is the hub for the majority of the operations in Linux.  Commands:  ifconfig – Very similar to ipconfig in Windows. Displays network information.  Passwd – Changes the password  Clear – Clears the terminal (Helps when you have a full screen)  Cat – Displays the contents of a file  cd – Change the directory  Cd.. – moves up one level in a directory tree  ls – List files and directories  Pwd – Displays path and name of current directory  su – Become the root user.  Sudo – Run command with root authority  There are hundreds of commands in a Linux system yet I wanted to highlight some of the more common ones.
• 7.
  Linux In Action OpenTerminal in Kali Linux
• 8.
  Linux In Action KaliLinux ► A file titled Cybrary-Note was created. ► I changed the directory to Desktop ► The ‘cat’ command was used to read the file’s contents.
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  Linux In Action KaliLinux ► The directory was changed to ‘dev’ ► A ‘ls’ was executed to list all in ‘dev’
• 10.
  Linux In Action KaliLinux ► The file was read by using cat and then a ‘mv’ command was done. ► ‘mv’ tells the system to rename the file. ► Renaming files and other things can be done by using the terminal.
• 11.
  Linux In Action Mint Distribution Mintis a popular Linux Distribution
• 12.
  Linux In Action Mint ►The user “cybrary” was added by using ‘sudo’ and ‘adduser’ Sudo enables permissions without being a root user. ► A UNIX password was given to the user. ► Also a few fictional phone #s for fun.
• 13.
  Linux In Action Mint ►After changing the directory to /etc , the command to read the shadow file was executed /etc $ cat shadow ► Shadow contains the encrypted passwords and the screenshot shows how the password to cybrary is encrypted (Bottom of the screenshot).
• 14.
  Linux Commands -Common • cd – Change Directory • Cd.. Move up one level in the directory • Logout – Close the session • Ls – List all files • Mv – Rename file • Rm – Delete the file • Clear – Clear screen • Kill – Kill the running process • Su – Become root user • Sudo – use root privileges • Exit – Exit terminal • Cat – Display contents of file • ifconfig – Display network configurations • Open – open the application • Apt-get update – update package • passwd – change password • pwd – Display the directory path and name • mkdir – make new directory • locate – locate files with specific name • chmod – modify permissions for files and directories