Some Commands of Linux

pwd - It prints the current working directory

Is - This command is used to list information or content in a particular file/folder.

cd - It is used to change the current working directory. Example: cd Desktop

mkdir - Create a new folder

man - Displays the help manual for a

particular command. Example: man Is

shutdown: Shutdown or restart your system

rmdir: Used to remove/delete a directory/folder

clear: Clear the terminal

apt-get update: Update kali Linux

apt-get install: To install a new program.

Example: apt-get install leafpad

ifconfig: It is similar to the windows command ipconfig. It shows basic network details such as IP addresses, broadcast address, mac

address, and much more.

iwconfig: It is similar to the ifconfig command. It is more focussed on only wireless network

interfaces.

ping: It is usually used as a simple way to verify that a computer can communicate over the network with another computer or network device.

arp: It is used to find IP to MAC address mappings. ARP, which stands for Address Resolution Protocol, is a protocol used to map

a MAC address (or hardware address) to an IP address.

netstat: It delivers basic statistics on all network activities and informs users on which ports and addresses the corresponding connections (TCP, UDP) are running and which ports are open for tasks.

route: It fetches the routing table. It basically tells where all the network is actually routed.

grep: It is used to search a given file for patterns specified by the user. Basically 'grep' lets you enter a pattern of text and then it searches for this pattern within the text that you provide it.

tr: The tr command is used for translating or deleting characters.

cat: cat command allows us to create single or multiple files, the view containing the file, concatenate files, and redirect output in

terminal or files.

cut: It is used to extract sections from each line of input – usually from a file.

echo: It is used to print anything on the console.

If:

if [ expression

then

Statement(s) to be executed if expression is true

else

Statement(s) to be executed if expression is not true

fi

Sudo: The Sudo command allows you to run programs with the security privileges of another user (by default, as the superuser). It prompts you for your personal password and confirms your request to execute a command by checking a file, called sudoers, which the system administrator configures.

For Loop: The for loop operates on lists of items. It repeats

 a set of commands for every item in a list. It is

  used to iterate over something.

                Example:

         for var in 0 123456789

         do

          echo $var

         done

   Output: It will print numbers from 0 to 9

The Script:

Below is the IP Sweeper script,

#!/bin/bash

for ip in seq 1 254 ; do

ping -c 1 $1.$ip I grep "64 bytes" | cut -d ""-f 4||

tr -d “:" &

done

This script will execute and return the ip address

in the specified domain range that had  responded to the ping.

Write the above script in ipsweep.sh file.

Breaking down

  #!/bin/bash

It's basically a comment. We are telling the computer that, it is a bash script.

for ip in seq 1 254 ; do

This is for loop. We want to execute the command for every ip in the given network range.

Thus, we write a for loop and execute it in a range for 1-254 that is, the number of ip addresses in a

particular network.

ping -c 1 $1.$ip | grep "64 bytes" | cut -d "" -f 4|

tr -d “:" &

• ping: To ping the ip address

• -c 1: Ping one ip at a time

$1.$ip: $1 will be the user input. We will input the first three ranges of the IP and the last

 range will be taken from the for loop. Example: If user input was 192.68.1 then in the first run

of for loop $ip will be 1. Thus $1.$ip will result in 192.68.1.1 and it will ping this ip.

grep “64 bytes": Try running a ping command to an ip. If the ip responds, the result will be "64 bytes from (given_ip)". Thus, if the ip is active, it will respond and the response will contain the term "64 bytes ". Thus, grep "64 bytes" will simply filter out the ip's that responded from a total of 254 ip addresses.

ping -c 1 $1.$ip I grep "64 bytes" | cut -d ""-f 4||

tr -d “:" &

We know that if the ip is active it will respond. The demo of responding will be something like this, '64 bytes from given_ip' where given_ip will be the ip pinged too.

Thus, from the whole response now, we will need only the ip address of the responded ip.

 cut -d “" -f 4:

This command basically does the same thing. It cuts the whole response with the delimiter(-d) whitespace(“ ") and picks the 4th term(-f 4) from it, that will be the ip.

The cut command will basically produce output

             like 192.68.1.1

Here, we don't need the colon(:). We just need

    the ip, thus we run the tr command.

 tr -d “:": Here we pass colon(:) as a delimiter and tr command deletes it.

 &: This basically allows the thread to work simultaneously

  I (pipe): It basically joins all the above

 commands as a single command

How to Run?

Now save the file and hit the below command on

      the terminal to run the script.

   .lipsweep.sh [First three ranges of your ip]

     Example: ./ipsweep.sh 192.186.1

This will run the file and sweep all the active ip's

in the given range in the text file. Later we can

   perform many network-related hacking

        operations on these IPs.