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LINUX BASICS FOR HACKERS Book

This practical, tutorial-style book uses the Kali Linux distribution to teach Linux basics with a focus on how hackers would use them. Topics include Linux command line basics, filesystems, networking, BASH basics, package management, logging, and the Linux kernel and drivers.

If you're getting started along the exciting path of hacking, cybersecurity, and pentesting, Linux Basics for Hackers is an excellent first step. Using Kali Linux, an advanced penetration testing distribution of Linux, you'll learn the basics of using the Linux operating system and acquire the tools and techniques you'll need to take control of a Linux environment.

First, you'll learn how to install Kali on a virtual machine and get an introduction to basic Linux concepts. Next, you'll tackle broader Linux topics like manipulating text, controlling file and directory permissions, and managing user environment variables. You'll then focus in on foundational hacking concepts like security and anonymity and learn scripting skills with bash and Python. Practical tutorials and exercises throughout will reinforce and test your skills as you learn how to:

• Cover your tracks by changing your network information and manipulating the rsyslog logging utility
• Write a tool to scan for network connections, and connect and listen to wireless networks
• Keep your internet activity stealthy using Tor, proxy servers, VPNs, and encrypted email
• Write a bash script to scan open ports for potential targets
• Use and abuse services like MySQL, Apache web server, and OpenSSH
• Build your own hacking tools, such as a remote video spy camera and a password cracker

Hacking is complex, and there is no single way in. Why not start at the beginning with Linux Basics for Hackers?

Hacking is the most important skill set of the 21st century! Nations are spying on each other to gain secrets, cyber criminals are stealing billions of dollars, digital worms demanding ransoms are being released, adversaries are influencing each other’s elections, and combatants are taking down each other’s utilities. These are all the work of hackers, and their influence over our increasingly digital world is just beginning to be felt.

Any person who wants to become a professional hacker must know Linux and know how to deal with this OS because Almost all the best hacker tools are written for Linux, so some basic Linux skills are a prerequisite to becoming a professional hacker.

This chapter will teach you how to use the file system and the terminal, and give you some basic commands.

• Binaries :- Binaries This term refers to files that can be executed, similar to executables in Windows. Binaries generally reside in the /usr/bin or usr/sbin directory and include utilities such as ps, cat, ls, and cd as well as applications such as the wireless hacking tool aircrack­ng and the intrusion detection system (IDS) Snort.

• Directory :- This is the same as a folder in Windows. A directory provides a way of organizing files, usually in a hierarchical manner.

• Home :- Each user has their own /home directory, and this is generally where files you create will be saved by default.

• root :- is the user name or account that by default has access to all commands and files on a Linux or other Unix-like operating system. It is also referred to as the root account, root user and the superuser.

• Script :- This is a series of commands run in an interpretive environment that converts each line to source code.

• Shell :- is the command interpreter in an operating system such as Unix or GNU/Linux, it is a program that executes other programs. It provides a computer user an interface to the Unix/GNU Linux system so that the user can run different commands or utilities/tools with some input data.

• Terminal :- is a command line interface (CLI).

The Linux filesystem structure is somewhat different from that of Windows. Linux doesn’t have a physical drive (such as the C: drive) at the base of the filesystem but uses a logical filesystem instead. At the very top of the filesystem structure is / (root)

Linux Filesystem

• /root The home directory of the all­powerful root user

• /etc Generally contains the Linux configuration files—files that control when and how programs start up

• /home The user’s home directory

• /mnt Where other filesystems are attached or mounted to the filesystem

• /media Where CDs and USB devices are usually attached or mounted to the filesystem

• /bin Where application binaries (the equivalent of executables in Microsoft Windows) reside

• /lib Where you’ll find libraries (shared programs that are similar to Windows DLLs)

• Finding Yourself with pwd

  pwd => return the present working directory

• Checking Your Login with whoami

  whoami => return the user which logged in

• Changing Directories with cd

  cd dirName => change the directory to dirName directory

  cd .. => move up one level in the file structure

• Listing the Contents of a Directory with ls

  ls => return the contents of current directory (files and directories)

  we can add arguments (flags) to ls command to see extra information such as ls -l this get more information about the files and directories, such as their permissions, owner, size, and when they were last modified.

  or -R flag to list Subdirectories recursively

• Getting Help: Nearly every command, application, or utility has a dedicated help file in Linux that provides guidance for its use.

  to get help for specific commands, add --help to get the help ex:

  ls --help => return short description of the tool and guidance on how to use it.

• Referencing Manual Pages with man

  In addition to the help switch, most commands and applications have a manual (man) page with more information, such as a description and synopsis of the command or application. You can view a man page by simply typing manbefore the command, utility, or application.

  man nmap => opens the manual for nmap, providing you with more detailed information than the helpscreen.

• Creating Files

  1. with touch

     touch file.txt => create a text file

  2. with cat

     cat > file.txt => create a write on it ( to exit write mode click ctrl + D )

• Showing File Content with cat

  cat fileName => return file content

• Creating a Directory with mkdir

  mkdir newDirectory => create a new directory

• Copying a File with cp

  cp oldfile newfile => copy oldfile to newfile

• Renaming a File with mv

  mv oldname newname => rename oldname to newname

• Removing a File with rm

  rm fileName => remove the file

• Removing a Directory with rmdir

  rmdir directoryName => remove the empty directory

• Searching with locate

  locate aircrack-ng => go through your entire filesystem and locate every occurrence of that word.

• Finding Binaries with whereis

  whereis aircrack-ng => return location of binary file, also return its source and man page if they are available.

• Finding Binaries in the PATH Variable with which

  which aircrack-ng => return the location of the binaries in the PATH variable in Linux.

• Filtering with grep

  The grep filter searches a file for a particular pattern of characters, and displays all lines that contain that pattern

  grep "localhost" /etc/hosts => return "localhost" if exists on the file

  we can use it for filtering by piping it to another command ex:

  ls -l | grep "root" => return the contents that contain "root"

• Display information about processes running on the machine with ps

  ps aux => list running processes

This chapter will teach you how to manipulate text to find, examine, and alter software and files.
In this chapter, we will use several commands and techniques for manipulating text in Linux.

• Taking the Head : view the beginning of a file. By default, this command ( head ) displays the first 10 lines of a file.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ head file.txt

  If you want to see more or fewer than the default 10 lines, enter the quantity you want with the dash (-) switch after the call to head and before the filename.
  

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ head -5 file.txt

• Grabbing That Tail : The tail command is similar to the head command, but it’s used to view the last lines of a file.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ tail file.txt

• Numbering the Lines : To display a file with line numbers, we use the nl (number lines) command.
  

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ nl file.txt

• FILTERING TEXT WITH GREP : The grep filter searches a file for a particular pattern of characters, and displays all lines that contain that pattern
  

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ ps aux | grep -i "apache"

• USING SED TO FIND AND REPLACE : The sedcommand lets you search for occurrences of a word or a text pattern and then perform some action on it.

  1. Find a word and replace it with a new one and save the result in a new file
     

     ┌──(m-fadl㉿Fadl)-[~]
     └─$ sed s/oldWord/newWord/g searchedFileName > newFileName

  2. Find a word and replace it on the same file
     

     ┌──(m-fadl㉿Fadl)-[~]
     └─$ sed -i s/oldWord/newWord/g searchFileName

• Controlling the Display with more : The more command displays a page of a file at a time and lets you page down through it using the ENTER key.
  

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ more fileName

• Displaying and Filtering with less : Less is a command line utility that displays the contents of a file or a command output, one page at a time. It is similar to more, but has more advanced features and allows you to search and navigate both forward and backward through the file.
  

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ ps aux | less

This chapter will teach you how to manage networks. You’ll scan for networks, find information on connections, and disguise yourself by masking your network and DNS information.

• ANALYZING NETWORKS WITH IFCONFIG : ifconfig stands for "interface configuration." It is used to view and change the configuration of the network interfaces on your system.

  ex: ifconfig => displays information about all network interfaces currently in operation

  ex: sudo ifconfig wlan0 69.72.169.1 => assign a static IP address to an interface, specify the interface name and the IP address

• CHECKING WIRELESS NETWORK DEVICES WITH IWCONFIG : iwconfig is similar to ifconfig, but is dedicated to the wireless interfaces. It is used to set the parameters of the network interface that are specific to the wireless operation (the wireless frequency, for example). iwconfig may also be used to display those parameters, and the wireless statistics

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ iwconfig

• Assigning New IP Addresses from the DHCP Server : The DHCP protocol allows a host to contact a central server which maintains a list of IP addresses which may be assigned on one or more subnets. A DHCP client may request an address from this pool, and then use it on a temporary basis for communication on network. The DHCP protocol also provides a mechanism whereby a client can learn important details about the network to which it is attached, such as the location of a default router, the location of a name server, etc.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ dhclient eth0

• Examining DNS with dig : The dig command in Linux is used to gather DNS information. It stands for Domain Information Groper, and it collects data about Domain Name Servers. The dig command is helpful for diagnosing DNS problems, but is also used to display DNS information.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ dig www.cisco.com

• Changing Your DNS Server : In some cases, you may want to use another DNS server. To do so, you’ll edit a plaintext file named /etc/resolv.conf on the system. Open that file in a text editor. Then, on your command line, enter the precise name of your editor followed by the location of the file and the filename.

  ex: sudo nano /etc/resolv.conf < Then change name server for google name server change it to 8.8.8.8 & 8.8.4.4 >

  TO KNOW: The most common Linux DNS server is the Berkeley Internet Name Domain (BIND).

• Mapping Your Own IP Addresses : A special file on your system called the hosts file also performs domain name–IP address translation. The hosts file is located at /etc/hosts, and kind of as with DNS, you can use it to specify your own IP address–domain name mapping. In other words, you can determine which IP address your browser goes to when you enter

  ex: sudo nano /etc/hosts < Then add your own IP address >

This chapter will teach you how to add, remove, and update software, and how to keep your system streamlined.

📎 USING APT TO HANDLE SOFTWARE

• Searching for a Package : check whether the package you need is available from your repository using apt-cache search keyword

  ex: apt-cache search snort => Searching the system with apt-cachefor Snort

• Adding a Package : To install a piece of software from your operating system’s default repository in the terminal, use the apt-get command, followed by the keyword install and then the name of the package you want to install.

  syntax: apt-­get install packagename

  ex: apt-­get install snort => Installing Snort with apt-get install

• Removing a Package : To remove software, we use apt-get with the remove option, followed by the name of the software to remove

  syntax: apt­-get remove packagename

  ex: apt-­get remove snort => Removing Snort with apt-get remove

  TO KNOW: The remove command doesn’t remove the configuration files, which means you can reinstall the same package in the future without reconfiguring.

  If we want to remove the configuration files at the same time as the package, we use the purge option

  ex: apt-­get purge snort => Removing Snort and the accompanying configuration files with apt-get purge

• Updating Packages : updates the list of packages available for download from the repository, but they don't install automatically, we need to upgrade them.

  syntax: apt­-get update => Updating all out­of­date packages

• Upgrading Packages : To upgrade the existing packages on your system, use apt-get upgrade. This command will upgrade every package on your system that apt knows about.

  syntax: apt­-get upgrade => Upgrading all out­of­date packages

📎 ADDING REPOSITORIES TO YOUR SOURCES.LIST FILE

each distribution of linux has it's own repository that contain the packages and softwares we can add another repository to our source.list files

leafpad/etc/apt/sources.list

we can add another repository by editing this file

📎 USING A GUI-BASED INSTALLER

we can use GUI installer instead of terminal you can use synaptic tool to do this.

📎 INSTALLING SOFTWARE WITH GIT

Sometimes the software you want isn’t available in any of the repositories—especially if it’s brand new—but it may be available on github, a site that allows developers to share their software with others to download, use, and provide feedback.

Once you’ve found the software on github, you can install it from the terminal by entering the git clone command followed by its github URL.

┌──(m-fadl㉿Fadl)-[~]
└─$ git clone https://www.github.com/repoName

This chapter will teach you how to manipulate file and directory permissions to control who can access what. You’ll also learn some privilege escalation techniques.

in Linux, the root user is allpowerful. The root user can do basically anything on the system. Other users on the system have more limited capabilities and permissions and almost never have the access that the root user has

there is three types of users:

• owner
• group
• others

Each and every file and directory must be allocated a particular level of permission for the different identities using it. The three levels of permission are as follows:

• r Permission to read.
• w Permission to write.
• x Permission to execute.

• Granting Ownership to an Individual User: Move ownership of a file to a different user so that they have the ability to control permissions, we use chown command

  syntax: chown newOwner fileName => change FileName Owner to newOwner

• Granting Ownership to a Group: Transfer ownership of a file from one group to another, we can use the chgrp command

  syntax: chgrp newGroup fileName => change FileName Group to newGroup

• 📎 CHECKING PERMISSIONS:

  To find out what permissions are granted to what users for a file or directory, use the ls command with the –l to display the contents of a directory in long format this display permissions.

  ls -l this will display:

  1. file type
  2. permissions on the file for owner, groups, and users, respectively
  3. The number of links
  4. The owner of the file
  5. The size of the file in bytes
  6. When the file was created or last modified
  7. The name of the file

• 📎 CHANGING PERMISSIONS: We have 3 types of permissions for for each type of users UGO == (User [owner],Group,Others)

  Octal Notation	Permissions	Symbolic Representation
  0	No Permissions	---
  1	Execute Permission only	--x
  2	Write Permission only	-w-
  3	Write & Execute Permissions	-wx
  4	Read Permission only	r--
  5	Read & Execute Permissions	r-x
  6	Read & Write Permissions	rw-
  7	Read, Write & Execute Permissions	rwx

  We can change the permissions with chmod command by 2 Ways:

  1. Changing Permissions with Decimal Notation: Add to each user number refer to the permissions you need.
     
     ex: chmod 774 fileName => Give all permissions to owner, group and only read permission to others users.

  2. Changing Permissions with UGO: change permissions to specific user by add type of user (UGO)
     synax: chmod userSymbol operator(+ or -) PermissionSymbol
     
     ex: chmod g-wx fileName => Remove write & execute permissions from fileName Group.

• 📎 DEFAULT PERMISSIONS WITH MASKS:

  By default any new file & directory take permissions based on your umask value which saved in /home/username/.profile

  you can know this value by umask command

  suppose you find it 022, then your default permission is 644 for files and 755 for directories.

  if you want to change this value chang umask value in this file: /home/username/.profile

• 📎 Granting Temporary Root Permissions with SUID: the SUID bit says that any user can execute the file with the permissions of the owner but those permissions don’t extend beyond the use of that file.

  To set the SUID bit, enter a 4 before the regular permissions, so a file with a new resulting permission of 644 is represented as 4644 when the SUID bit is set.

• 📎 Granting the Root User’s Group Permissions SGID: the SGID bit says that any user can execute the file with the permissions of the owner group but those permissions don’t extend beyond the use of that file.

  To set the SGID bit, enter a 2 before the regular permissions, so a file with a new resulting permission of 644 is represented as 2644 when the SGID bit is set.

• 📎 The Outmoded Sticky Bit:

  The sticky bit is a permission bit that you can set on a directory to allow a user to delete or rename files within that directory.

  However, the sticky bit is a legacy of older Unix systems, and modern systems (like Linux) ignore it.

• 📎 Find Files that takes SUID or SGID:

  use find to get this information

  ex: find / -user root -perm -4000 => find files with SUID in root directory.

  ex: find / -user root -perm -2000 => find files with SGID in root directory.

This chapter will teach you how to manage services, including starting and stopping processes and allocating resources to give you greater control.

In Linux processes can be of two types:

• Foreground Processes:

  depend on the user for input also referred to as interactive processes.

• Background Processes:

  run independently of the user referred to as non-interactive or automatic processes.

A process in Linux can go through different states after it’s created and before it’s terminated.

These states are:

• Running:

  A process in running state means that it is running or it’s ready to run.

• Sleeping:

  The process is in a sleeping state when it is waiting for a resource to be available.

  A process in Interruptible sleep will wakeup to handle signals, whereas a process in Uninterruptible sleep will not

• Stopped:

  A process enters a stopped state when it receives a stop signal.

• Zombie:

  Zombie state is when a process is dead but the entry for the process is still present in the table.

• 📎 The top Command for Mananging Linux Processes:

  To track the running processes on your machine you can use the top command.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ top

  

  Top command displays a list of processes that are running in real-time along with their memory and CPU usage. Let’s understand the output a little better:

  • PID: Unique Process ID given to each process.

  • User: Username of the process owner.

  • PR: Priority given to a process while scheduling.

  • NI: nice value of a process.

  • VIRT: Amount of virtual memory used by a process.

  • RES: Amount of physical memory used by a process.

  • SHR: Amount of memory shared with other processes.

  • S: state of the process

    • D = uninterruptible sleep
    • R = running
    • S = sleeping
    • T = traced or stopped
    • Z = zombie

  • %CPU: Percentage of CPU used by the process.

  • %MEM: Percentage of RAM used by the process.

  • TIME+: Total CPU time consumed by the process.

  • Command: Command used to activate the process.

• 📎 ps command:

  ps command is short for 'Process Status'. It displays the currently-running processes. However, unlike the top command, the output generated is not in realtime.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ ps

  

  The terminology is as follows :

  Output	Meaning
  PID	process ID
  TTY	terminal type
  TIME	total time the process has been running
  CMD	name of the command that launches the process

  
  
  

  To get more information using ps command use:

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ ps -u

  
  

  To show all processes running on the system for all users using ps command use:

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ ps aux

  

To stop a process in Linux, use the kill command. kill command sends a signal to the process.

There are different types of signals that you can send. However, the most common one is kill -9 which is 'SIGKILL'.

You can list all the signals using:

┌──(m-fadl㉿Fadl)-[~]
└─$ kill -L

The default signal is 15, which is SIGTERM. Which means if you just use the kill command without any number, it sends the SIGTERM signal.

The syntax for killing a process is:

┌──(m-fadl㉿Fadl)-[~]
└─$ kill [pid]

Alternatively you can also use :

┌──(m-fadl㉿Fadl)-[~]
└─$ kill -9 [pid]

This command will send a ‘SIGKILL’ signal to the process. This should be used in case the process ignores a normal kill request.

To Know PID use pidof command

┌──(m-fadl㉿Fadl)-[~]
└─$ pidof [processName]

In Linux, you can prioritize between processes. The priority value for a process is called the ‘Niceness’ value. Niceness value can range from –20 to 19. 0 is the default value.

The fourth column in the output of top command is the column for niceness value.

To start a process and give it a nice value other than the default one, use:

┌──(m-fadl㉿Fadl)-[~]
└─$ nice -n [value] [process name]

To change nice value of a process that is already running use:

┌──(m-fadl㉿Fadl)-[~]
└─$ renice [value] -p 'PID'

This chapter will teach you how to manage environment variables for optimal performance, convenience, and even stealth. You’ll find and filter variables, change your PATH variable, and create new environment variables.

Environment variables are valuable bits of information, and they can be manipulated to enhance and change your user experience.

• Environment: Environment variables are system wide variables built into your system and interface that control the way your system looks, acts, and “feels” to the user, and they are inherited by any child shells or processes.

  Environment variables are always uppercase

• Shell: Shell variables, on the other hand, are typically listed in lowercase and are only valid in the shell they are set in.

• VIEWING ENVIRONMENT VARIABLES:

  1. env Command

     You can view all your default environment variables by entering env into your terminal from any directory.

     ┌──(m-fadl㉿Fadl)-[~]
     └─$ env

     Display all default environment variables

     
     

  2. set Command

     To view all environment variables, including shell variables, local variables, and shell functions such as any user defined variables and command aliases, use the set command.

     This command will list all environment variables unique to your system, which in most cases will give you an output so long you won’t be able to view it all on a single screen.

     You can request to view each variable, line by line, in a more accessible fashion using set and piping it to the more command

     ┌──(m-fadl㉿Fadl)-[~]
     └─$ set | more

• Filtering for Particular Variables

  you can use the filtering command grep to find your variable of interest

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ set | grep HISTSIZE

• Changing Variable Values for a Session

  you can change variable value in the session you use by entering the variable name & value

  Values can be assign by different ways ex:-

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ KEY=value
  
  ┌──(m-fadl㉿Fadl)-[~]
  └─$ KEY=value1:value2
  

  Note: that change only occurs in that particular environment; in this case, that environment is the bash shell session. This means that when you close the terminal, any changes you made are lost

• Making Variable Value Changes Permanent

  If you want to make the changes permanent, you need to use the export command.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ export name=[value]

• CHANGING YOUR SHELL PROMPT

  Your shell prompt, another environment variable, provides you with useful information such as the user you’re operating as and the directory in which you’re currently working.

  default shell prompt in Kali takes the following format:

  • as a normal user:

    username@hostname:current_directory

  • as a root user:

    root@hostname:current_directory

  You can change the name in the default shell prompt by setting the value for the PS1 variable.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ PS1="PROMPT Shell Changed: "

• CHANGING YOUR PATH

  the most important variables in your environment is your PATH variable, which controls where on your system your shell will look for commands you enter, such as cd, ls, and echo. Most commands are located in the sbin or bin subdirectory.

  You can find out which directories are stored in your PATH variable by this command

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ echo $PATH

  You can add to Path Variables another value by this command

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ PATH=$PATH:/root/dirName

• CREATING A USER-DEFINED VARIABLE

  You can create your own custom, user defined variables in Linux by simply assigning a value to a new variable that you name.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ MYVARIABLE="THEVALUE"

• Deleting A VARIABLE

  If you want to delete this new variable, or any variable, use the unset command

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ unset MYVARIABLE

This chapter will introduce you to bash scripting, a staple for any serious hacker. You’ll learn the basics of bash.

Shell scripting is an powerful way to automate tasks that you regularly execute on your computer.

A shell is an interface between the user and the operating system that enables you to manipulate files and run commands, utilities, programs, and much more.

Bash Scripts is a file with extension .sh

First Create bash file

┌──(m-fadl㉿Fadl)-[~]
└─$ touch script.sh

If you notice that file not executable by default, so you need to change the permissions.

Let's change it

┌──(m-fadl㉿Fadl)-[~]
└─$ chmod u+x script.sh

Now open it with your favorite editor and let's code it 😀

The important thing is that it must start with a "shebang" on the first line, then follow the shebang (#!) with /bin/bash to indicate that you want the operating system to use the bash shell interpreter

#!/bin/bash

Now you can execute the script if you are in the same folder by calling it ./script.sh, or using the full path to it.

• Comments

  Comments are one of the most important things when writing programs. A line starting with the # symbol is a comment.

  # this is a comment

• Variables

  You can set variables by using the = operator:

  # Syntax: name=value
  
  # Exambles
  
  NUMBER=285
  name="Mohamed"
  nickname="Fadl"

• Printing

  You can print anything to the screen using the echo command You can print a variable by using the echo built-in command and prepending a $ sign to the var name

  echo "Hello World"
  echo $name

• Reading input

  You can make your scripts interactive by using the read built-in command. This command reads a line from the standard input, and it can format input in a very flexible way.

  echo "Age:"
  read age

This is a very basics summary for bash scripting.

This chapter will teach you how to compress and archive files to keep your system clean.

Compression, as the name implies, makes data smaller, thereby requiring less storage capacity and making the data easier to transmit.

• TARRING FILES TOGETHER:

  the first thing you do when compressing files is to combine them into an archive. In most cases, when archiving files, you’ll use the tar command. Tar stands for tape archive.

  ┌──(m-fadl㉿Fadl)-[~]
  └─$ ls -l
  
    rwxrxrx 1 root root 22311 Nov 27 2018 13:00 hackersarise1.sh
    rwxrxrx 1 root root 8791 Nov 27 2018 13:00 hackersarise2.sh
    rwxrxrx 1 root root 3992 Nov 27 2018 13:00 hackersarise3.sh

  If you want to combine these files together we will use tar command

  ┌──(root💀Fadl)-[~]
  └─# tar
  
    <!-- tar Options:  -->
    A  -- append to an archive
    c  -- create a new archive
    f  -- specify archive file or device
    t  -- list archive contents
    u  -- update archive
    v  -- verbose output
    x  -- extract files from an archive

  ┌──(root💀Fadl)-[~]
  └─# tar tar -cvf HackersArise.tar hackersarise1.sh hackersarise2.sh hackersarise3.sh

  this command will take all three files and create a single file, HackersArise.tar

  If you want to extract the files use:

  ┌──(root💀Fadl)-[~]
  └─# tar tar -xf HackersArise.tar

• TARRING FILES TOGETHER:

  Linux has several commands capable of creating compressed files. We will look at these:

  • gzip, which uses the extension .tar.gz or .tgz
  • bzip2, which uses the extension .tar.bz2
  • compress, which uses the extension .tar.z

  These all are capable of compressing our files, but they use different compression algorithms and have different compression ratios.

• Compressing with gzip:

  You can compress your HackersArise.tar file by entering the following

  ┌──(root💀Fadl)-[~]
  └─# gzip HackersArise.tar

  You can decompress that same file by using the gunzip command, short for GNU unzip.

  ┌──(root💀Fadl)-[~]
  └─# gunzip HackersArise.tar.gz

• Compressing with bzip2:

  Another of the other widely used compression utilities in Linux is bzip2, which works similarly to gzip but has better compression ratios, meaning that the resulting file will be even smaller. You can compress your HackersArise.tar file by entering the following:

  ┌──(root💀Fadl)-[~]
  └─# bzip2 HackersArise.tar

  To uncompress the compressed file, use bunzip2, like so:

  ┌──(root💀Fadl)-[~]
  └─# bunzip2 HackersArise.tar.bz2

• Compressing with compress:

  you can use the command compress to compress the file. This is probably the least commonly used compression utility.

  ┌──(root💀Fadl)-[~]
  └─# copress HackersArise.tar

  To decompress the same file, use uncompress:

  ┌──(root💀Fadl)-[~]
  └─# uncopress HackersArise.tar.Z

• CREATING BIT-BY-BIT OR PHYSICAL COPIES OF STORAGE DEVICES

  Within the world of information security and hacking, one Linux archiving command stands above the rest in its usefulness. The dd command makes a bit by bit copy of a file, a filesystem, or even an entire hard drive.

  This means that even deleted files are copied (yes, it’s important to know that your deleted files may be recoverable), making for easy discovery and recovery

  It’s critical to note that the dd command should not be used for typical day to day copying of files and storage devices because it is very slow.

  The basic syntax for the dd command is as follows:

  ┌──(root💀Fadl)-[~]
  └─# dd if=inputfile of=outputfile

  make a physical copy of your flash drive, assuming the flash drive is sdb

  ┌──(root💀Fadl)-[~]
  └─# dd if=/dev/sdb of=/root/flashcop

This chapter will give you some essential file system management skills, and get information on files and connected disks.

For you as a hacker, it’s necessary to understand the file and storage device management system, both on your own system and, often, the system of your target. Hackers commonly use external media to load data, hacking tools, or even their OS.

Linux has a special directory that contains files representing each attached device: the appropriately named /dev directory.

Linus uses logical lables for devices that are then mounted on the filesystem. The labels vary depending on where the drives are mounted.

Newer SATA interface drives and SCSI hard drives are represented as sda. Drives are sometimes split up into sections known as partitions, which are represented in the labeling system with numbers.

When systems have multiple hard drives, Linux names them serially by incrementing the last letter in alphabetical order.

linux lables each partition with a minor number that comes after the drive designation. The first partition on the first SATA drive would be sda1.

You may want to view the partitions on your Linux systems to see which ones you have and how much capacity is available in each. Use the fdisk -l to list all partitions.

┌──(root💀Fadl)-[~]
└─# fdisk -l

Linux uses a number of filesystems...ext2, ext3 and ext4. HPFS, NTFS and exFAT are not native to Linux systems but to macOS and Windows systems.

Character device are represented by c. External devices that interact with the system by sending and receving data character by characterm such as mice or keyboards. Block devices, by d. They communicate blocks of data and include devices like hard drives and DVD drives. These devices require higher-speed data throughput and therefore send and receive data in blocks.

lsblk, list block, lists some basic info about each block device. It will also display devices with multiple partitions in a kind of tree, showing each device with its partitions as branches and does not require root privileges to run.

┌──(root💀Fadl)-[~]
└─# lsblk

The two main mount points in Linux are /mnt and /media. Internal hard drives are mounted at /mnt and external drives are mounted at /media.

The mount point for the device should be an empty directory; if you mount a device on a directory that has subdirectories and files, the mounted device will cover the contents of the directory, making them invisible and unavailable.

Mount the new hard drive sdb1 at /mnt.

┌──(root💀Fadl)-[~]
└─# mount /dev/sdb1 /mnt

Mount the new hard drive sdc1 at /media.

┌──(root💀Fadl)-[~]
└─# mount /dev/sdc1 /media

The filesystems that are mounted on a system are kept in a file at /etc/fstab

Similar to the mount command, you can unmount a second hard drive by entering the umount command followed by the file entry of the device in the /dev directory, such as /dev/sdb.

┌──(root💀Fadl)-[~]
└─# umount /dev/sdb1

The command df will provide us with basic information on any hard disks or mounted devices. Without any options, df defaults to the first drive on your system.

┌──(root💀Fadl)-[~]
└─# df

The fsck command checks the filesystem for errors and repairs the damage or else puts the bad area into a bad block table to mark it as bad. Run the fsck command requires specifying the filesystem, else it defaults to ext2, and the device file to check. You must unmount the drive before running a filesystem check.

┌──(root💀Fadl)-[~]
└─# umount /dev/sdb1

┌──(root💀Fadl)-[~]
└─# fsck -p /dev/sdb1

This chapter will teach you how use and manipulate the logging system to get information on a target’s activity and cover yourcown tracks.

Log files store information about events that occur when the operating system and applications are run, including any errors and security alerts.

Linux uses a daemon called syslogd to automatically log events on your computer.

Searching for all files related to rsyslog.

┌──(root💀Fadl)-[~]
└─# locate rsyslog

Like nearly every application in Linux, rsyslog is managed and configured by a plaintext configuration file located.

the configuration file is located at /etc/rsyslog.conf

┌──(root💀Fadl)-[~]
└─# leafpad /etc/rsyslog.conf

In the output you’ll find the Rules section down to below line 50.

The rsyslog rules determine what kind of information is logged, what programs have their messages logged, and where that log is stored.

Each line is a separate logging rule that says what messages are logged and where they’re logged to. The basic format for these rules is as follows:

facility.priority action

• The facility keyword references the program, such as mail, kernel, or lpr, whose messages are being logged

• The priority keyword determines what kind of messages to log for that program.

• The action keyword, on the far right, references the location where the log will be sent

Let’s look at some examples of log rules:

mail.* /var/log/mail

This example will log mail events of all (*) priorities to /var/log/mail.

Log files take up space, so if you don’t delete them periodically, they will eventually fill your entire hard drive.

On the other hand, if you delete your log files too frequently, you won’t have logs to investigate at some future point in time. You can use logrotate to determine the balance between these opposing requirements by rotating your logs.

You can configure the logrotate utility to choose the regularity of your log rotation with the /etc/logrotate.conf text file.

┌──(root💀Fadl)-[~]
└─# leafpad /etc/logrotate.conf

You will see that the system save your activity every 4 Weeks, change it if you want.

• Removing Evidence:

  When you delete a file from Linux or from any os, then the file is not deleted permanently from the hard disk. When a file is deleted it first gets moved to the trash and as soon as you clear off the trash the files get deleted for the file system. But the file is still there in your hard drive and it could be recovered.

  When you delete a file permanently or delete it from the trash, the pointer pointing to the file leaves the address of it and the data of the file is sent to a sector in hard disk and is considered as unallocated space and it can be recovered easily. The file gets permanently deleted when the OS writes over the sector of the file which was considered as unallocated. So, in order to delete a file completely from hard disk “shred” is used in Linux. This command overwrites the contents of a file multiple times, using patterns chosen to maximize the destruction of the residual data, making it harder for even very expensive hardware probing to recover it.

  Syntax:

  shred [OPTION]... FILE...

  We need the –f option to give us permission to shred auth files, and we follow the –n option with the desired number of times to overwri

  shred -f -n 10 /var/log/auth.log.

• Disabling Logging:

  Another option for covering your tracks is to simply disable logging. When a hacker takes control of a system, they could immediately disable logging to prevent the system from keeping track of their activities.

  To disable all logging, the hacker could simply stop the rsyslog daemon.

  ┌──(root💀Fadl)-[~]
  └─# service rsyslog stop

  Linux will stop generating any log files until the service is restarted.

This chapter will teach you how to use and abuse three core Linux services: Apache web server, OpenSSH, and MySQL

A service is an application that runs in the background waiting for you to use it.

you can use service command to start, stop, or restart the service.

Syntax: service servicename start|stop|restart

┌──(root💀Fadl)-[~]
└─# service apache2 start

To learn how to set up a web server with Apache, physically spy with OpenSSH, access data with MySQL, and store your hacking information with PostgreSQL. You should see this chapter in the book.

This chapter will teach you how to stay secure and anonymous with proxy servers, the Tor network, VPNs, and encrypted email.

everything we do on the internet is tracked. Whoever is doing the tracking—whether it be Google tracking our online searches, website visits, and email or the National Security Agency (NSA) cataloging all our activities—our every online move is being recorded, indexed, and then mined for someone’s benefit.

• To see what hops a packet might make between you and the destination, you can use the traceroute command

  ┌──(root💀Fadl)-[~]
  └─# traceroute google.com

  this command will send out packets to the destination and trace the route of those packets.

Packets sent over Tor are not sent over the regular routers so closely monitored by so many but rather are sent over a network of over 7,000 routers around the world. On top of using a totally separate router network, Tor encrypts the data, destination, and sender IP address of each packet.

To enable the use of Tor, just install the Tor browser from https://www.torproject.org/

Another strategy for achieving anonymity on the internet is to use proxies, which are intermediate systems that act as middlemen for traffic: the user connects to a proxy, and the traffic is given the IP address of the proxy before it’s passed on When the traffic returns from the destination, the proxy sends the traffic back to the source. In this way, traffic appears to come from the proxy and not the originating IP address.

Kali Linux has an excellent proxying tool called proxychains that you can set up to obscure your traffic. The syntax for the proxychains command is straightforward, as shown here:

┌──(root💀Fadl)-[~]
└─# proxychains <the command you want proxied> <arguments

┌──(root💀Fadl)-[~]
└─# proxychains nmap -sT -Pn<IPaddress>

This would send the nmap–sSstealth scan command to the given IP address through a proxy. The tool then builds the chain of proxies itself,

┌──(root💀Fadl)-[~]
└─# proxychains firefox www.hackers-arise.com

This successfully opens https://www.hackers­arise.com/ in Firefox through my chosen proxy and returns the results to me.

Dynamic Chaining:

Go back into your proxychains configuration file, find the dynamic_chainline , and uncomment it, as shown next. Also make sure you comment out the strict_chainline

Random Chaining:

Go back inside the /etc/proxychains.conf file and comment out the lines dynamic_chain and strict_chainby adding a #at the start of each line; then uncomment the random_chain line.

all traffic between you and the VPN device is encrypted, so even your internet service provider can’t see your traffic.

One way to prevent eavesdropping on your email is to use encrypted email.

ProtonMail encrypts your email from end to end or browser to browser. This means that your email is encrypted on ProtonMail servers even the ProtonMail administrators can’t read your email.

This chapter will teach you how to deals with wireless networks. You’ll learn basic networking commands, then crack Wi­Fi access points and detect and connect to Bluetooth signals.

The ability to scan for and connect to other network devices from your system is crucial to becoming a successful hacker, and with wireless technologies like WiFi and Bluetooth becoming the standard, finding and controlling WiFi and Bluetooth connections is key.

• AP (access point) This is the device wireless users connect to for internet access.

• ESSID (extended service set identifier) This is the same as the SSID.

• BSSID (basic service set identifier) This is the unique identifier of each AP, and it is the same as the MAC address of the device.

• SSID (service set identifier) This is the name of the network.

• Channels WiFi can operate on any one of 14 channels (1–14). In the United States, WiFi is limited to channels 1–11.

• Power The closer you are to the WiFi AP, the greater the power, and the easier the connection is to crack.

• Security This is the security protocol used on the WiFi AP that is being read from. There are three primary security protocols for WiFi (WEP, WPA, WPA2PSK)

• Modes WiFi can operate in one of three modes: managed, master, or monitor. You’ll learn what these modes mean in the following section.

• Wireless range In the United States, a WiFi AP must legally broadcast its signal at an upper limit of 0.5 watts. At this power, it has a normal range of about 300 feet (100 meters).

• Frequency WiFi is designed to operate on 2.4GHz and 5GHz. Modern WiFi APs and wireless network cards often use both.

• Display information about all network interfaces currently in operation.

  ┌──(root💀Fadl)-[~]
  └─# ifconfig

• If you just want to see your Wi­Fi interfaces and their statistics

  ┌──(root💀Fadl)-[~]
  └─# iwconfig

• If you are not certain which WiFi AP you want to connect to, you can see all the wireless access points your network card can reach using the iwlist command.

  # Syntax: iwlist interface action
  
  ┌──(root💀Fadl)-[~]
  └─# iwlist wlan0 scan

• nmcli is a command-line tool which is used for controlling NetworkManager. nmcli commnad can also be used to display network device status, create, edit, activate/deactivate, and delete network connections.

  ┌──(root💀Fadl)-[~]
  └─# nmcli dev wifi

• addition to displaying the WiFi APs info, nmcli can be used connect to APs.

  # Syntax: nmcli dev wifi connect AP-SSID password APpassword
  
  ┌──(root💀Fadl)-[~]
  └─# nmcli dev wifi connect Hackers password 12345678

• check whether theBluetooth adapter on the system we’re using is recognized and enabled so we can use it to scan for other devices.

  ┌──(root💀Fadl)-[~]
  └─# hciconfig

• To check that the connection is enabled

  ┌──(root💀Fadl)-[~]
  └─# hciconfig hci0 up

• Scanning for Bluetooth Devices

  ┌──(root💀Fadl)-[~]
  └─# hcitool scan

• gather more information about the detected devices with the inquiry function

  ┌──(root💀Fadl)-[~]
  └─# hcitool inq

• Scanning for Services with mac address ,able to pull information on all the services this device is capable of using.

  ┌──(root💀Fadl)-[~]
  └─# sdptool browse 76:6E:46:63:72:66

• Seeing Whether the devices are reachable with l2ping using mac address

  ┌──(root💀Fadl)-[~]
  └─# l2ping 76:6E:46:63:72:66 -c 4

This chapter dives deeper into Linux itself with a high level view of how the kernel works and how its drivers can be abused to deliver malicious software.

The kernel is the central nervous system of your operating system, controlling everything it does, including managing interactions between hardware components and starting the necessary services.

The kernel operates between the user applications you see and the hardware that runs everything, like the CPU, memory, and hard drive.

Linux is a monolithic kernel that enables the addition of kernel modules.

These modules are referred to as loadable kernel modules, or LKMs.

LKMs have access to the lowest levels of the kernel by necessity.

• CHECKING THE KERNEL VERSION

  ┌──(root💀Fadl)-[~]
  └─# uname -a
  
    OR
  
  ┌──(root💀Fadl)-[~]
  └─# cat /proc/version

• KERNEL TUNING WITH SYSCTL

  Modern Linux kernels use the sysctl command to tune kernel options. All changes you make with sysctl remain in effect only until you reboot the system. To make any changes permanent, you have to edit the configuration file for sysctl directly at /etc/sysctl.conf.

  ┌──(root💀Fadl)-[~]
  └─# sysctl -a | less

  take a look at the contents of sysctl The line net.ipv4.ip_forward=0is the kernel parameter that enables the kernel to forward on the packets it receives.

  To enable IP forwarding, change the 0 to a 1

  ┌──(root💀Fadl)-[~]
  └─# sysctl -w net.ipv4.ip_forward=1

• MANAGING KERNEL MODULES

  Linux has at least two ways to manage kernel modules.

  The older way is to use a group of commands built around the insmod suite—insmod stands for insert module and is intended to deal with modules.

  The second way, using the modprobe command

  To list the installed modules in the kernel,as well as information on their size and what other modules may use them.

  ┌──(root💀Fadl)-[~]
  └─# lsmod

• Finding More Information with modinfo

  To learn more about any of the kernel modules, we can use the modinfo command.

  ┌──(root💀Fadl)-[~]
  └─# modinfo bluetoot

• Adding and Removing Modules with modprobe

  Most newer distributions of Linux, including Kali Linux, include the modprobe command for LKM management. To add a module to your kernel, you would use the modprobe command with the -a (add) switch, like so:

  ┌──(root💀Fadl)-[~]
  └─# modprobe -a <module name>

  To remove a module, use the -r (remove) switch with modprobe followed by the name of the module:

  ┌──(root💀Fadl)-[~]
  └─# modprobe -r <module name>

• Test whether the new module loaded properly

  To test whether the new module loaded properly, you can run the dmesg command, which prints out the message buffer from the kernel, and then filter for "video" and look for any alerts that would indicate a problem:

  ┌──(root💀Fadl)-[~]
  └─# dmesg | grep video

you’ll learn essential scheduling skills in order to automate your hacking scripts.

In this chapter, you’ll learn more about how to use the cron daemon and crontab to set up scripts to run automatically, even while the system is unattended.

You’ll also learn how to set up startup scripts that automatically run whenever the system is booted, which will provide you with the necessary services that you’ll need to run during your busy day of hacking.

Linux Crontab Format:

MIN HOUR DOM MON DOW CMD

Crontab Fields and Allowed Ranges (Linux Crontab Syntax)

Scheduling a Job For a Specific Time

┌──(root💀Fadl)-[~]
└─# 30 08 10 06 * /home/maverick/full-backup

Cron special keywords and its meaning

┌──(root💀Fadl)-[~]
└─# @yearly /home/maverick/bin/annual-maintenance

you’ll learn core Python concepts, and you’ll script two hacking tools. a scanner to spy on TCP/IP connections, and a simple password cracker.

Basic scripting skills are critical to becoming a master hacker.

Without having developed some basic scripting skills, a beginner hacker who simply uses tools created by someone else will be condemned to the realm of script kiddies.

This means that you will be limited to using tools developed by someone else

• Using pip Python has a package manager specifically for installing and managing Python packages known as pip (Pip Installs Packages).

  we need to install pip for python3 from kali repo by entering the following:

  ┌──(root💀Fadl)-[~]
  └─# apt-get install python3-pip

  Now, to download modules from PyPI, you can simply enter this:

  ┌──(root💀Fadl)-[~]
  └─# pip3 install <package name>

• Installing Third-Party Modules

  To install a thirdparty module created by another member of the Python community, you can simply use wget to download it from wherever it is being stored online, uncompress the module, and then run the python setup.py install command.

  Examble:

  ┌──(root💀Fadl)-[~]
  └─# wget http://xael.org/norman/python/python-nmap/python-nmap-0.3.4.tar.gz
  
  #Then uncompress the file 
  
  ┌──(root💀Fadl)-[~]
  └─# tar -xzf python-nmap-0.3.4.tar.gz
  
  ┌──(root💀Fadl)-[~]
  └─# cd python-nmap-.03.4/
  
  ┌──(root💀Fadl)-[~]
  └─# ~/python-nmap-0.3.4 >python setup.py install

You want to know PYTHON for learn it see documention