Linux Process Management & Installation process of Kali Linux

 

Process Management

 

Process management describes the starting, pausing, resuming, and terminating of processes. The concepts behind  starting and terminating processes are fairly straightforward, but describing how a process uses the CPU in its

normal course of operation is a bit more complex. On any modern operating system, many processes run “simultaneously.” For example, you might have a web browser and a spreadsheet open on a desktop computer at the same time. However, things are not as they appear:

The processes behind these applications typically do not run at exactly the same time. Consider a system with a one-core CPU. Many processes may be able to use the CPU, but only one process may actually use the CPU at any given

time. In practice, each process uses the CPU for a small fraction of a second, then pauses; then another process uses the CPU for another small fraction of a second; then another process takes a turn, and so on. The act of one process giving up control of the CPU to another process is called a context switch. Each piece of time— called a time slice—gives a process enough time for significant computation (and indeed, a process often finishes its current

task during a single slice). However, because the slices are so small, humans can’t perceive them, and the system appears to be running multiple processes at the same time (a capability known as multitasking). The kernel is responsible for context switching. To understand how this works, let’s think about a situation in which a process is running in user mode but its time slice is up. Here’s what happens:

 

·         The CPU (the actual hardware) interrupts the current process based on an internal timer, switches into kernel mode, and hands control back to the kernel.

 

·         The kernel records the current state of the CPU and memory, which will be essential to resuming the process that was just interrupted.

·         The kernel performs any tasks that might have come up during the

·         preceding time slice (such as collecting data from input and output, or I/O, operations).

 

·         The kernel is now ready to let another process run. The kernel analyzes the list of processes that are ready to run and chooses one.

·         The kernel prepares the memory for this new process, and then prepares the CPU.

 

·         The kernel tells the CPU how long the time slice for the new process will last.

·       The kernel switches the CPU into user mode and hands control of the  CPU to the process.

 

Installing Kali

Let's now quickly take a look at how to get up and running with Kali.

Kali will be installed on the laptop that will serve as the penetration tester's machine

for the rest of the book.

Time for action – installing Kali

Kali is relatively simple to install. We will run Kali by booting it as a live DVD, and then install

it on the hard drive.

Perform the following instructions step by step:

1. Burn the Kali ISO (we are using the Kali 32-bit ISO) you downloaded, onto a

bootable DVD.

2. Boot the laptop with this DVD and select the option Install from Boot menu:

3. If booting was successful, then you should see an awesome retro screen as

shown in the following screenshot:

4. This installer is similar to the GUI-based installers of most Linux systems and should

be simple to follow. Select the appropriate options on every screen and start the

installation process. Once the installation is done, restart the machine as prompted

and remove the DVD.

5. Once the machine restarts, a login screen will be displayed. Log in as root and the

password is whatever you set it to during the installation process. You should now

be logged into your installed version of Kali. Congratulations!

6. I will change the desktop theme and some settings for this book. Feel free to use

your own themes and color settings!

 

We can also install Kali within virtualization software such as VirtualBox. If you don't

want to dedicate a full laptop to Kali, this is the best option. Kali's installation process

in VirtualBox is exactly the same. The only difference is the pre-setup, which you

will have to create in VirtualBox. Have a go at it! You can download VirtualBox from

http://www.virtualbox.org.

One of the other ways in which we can install and use Kali is via USB drives. This is

particularly useful if you do not want to install on the hard drive, but still want to store

persistent data, such as scripts and new tools, on your Kali instance. We encourage you to try

this out as well!

 

Three types of WLAN frame are : 

 

Management frames: Management frames are responsible for maintaining

communication between access points and wireless clients. Management frames

can have the following subtypes:

 Authentication

Deauthenticatio

Association request

Association response

Reassociation request

Reassociation response

Disassociation

Beacon

Probe request

Probe response

 

Control frames: Control frames are responsible for ensuring a proper exchange

of data between access points and wireless clients. Control frames can have the

following subtypes:

Request to Send (RTS)

Clear to Send (CTS)

Acknowledgement (ACK)

 

Data frames: Data frames carry the actual data that is sent on the wireless network.

There are no subtypes for data frames.

 

Let's now set our wireless adapter to monitor mode.

Follow these instructions to get started:

1. Boot Kali with your adapter connected. Once you are within the console, enter

iwconfig to confirm that your card has been detected and the driver has been

loaded properly:

2. Use the ifconfig wlan0 up command to bring the card up (where wlan0 is your

adapter). Verify whether the card is up by running ifconfig wlan0. You should

see the word UP in the first line of the output as shown in the following screenshot:

3. To put our card into monitor mode, we will use the airmon-ng utility that is

available by default on Kali. First run the airmon-ng command to verify whether it

detects the available cards. You should see the wlan0 or wlan1 interface listed in

the output:

4. Now enter the airmon-ng start wlan0 command to create a monitor mode

interface corresponding to the wlan0 device. This new monitor mode interface will

be named wlan0mon. (You can verify if it has been created by running airmon-ng

without arguments again):

5. Also, running ifconfig wlan0mon should now display a new interface

called wlan0mon.