How to display a file from one line number to another in Linux

If you need to read a file and print from a range of line numbers (including the last one), you can use the command as shown below.

cat <filename> | awk 'NR >=linenumber1 && NR <=linenumber2'

To read and display a file along with the line numbers, you can use the following format:.

cat -n <filename>

Example:

cat -n sample.txt

display line number
For example:

To print lines starting from line 2 to line 7, then you can use the following command.

cat sample.txt | awk 'NR >=2 && NR <=7'

Sample Output:

use cat and awk to print range of line numbers in linux
If for any reason you need to display the line numbers along with the output, then you can pass the -n argument to cat before piping it to awk as shown below.

cat -n sample.txt | awk 'NR >=2 && NR <=7'

Sample Output:

print with line numbers

[Note: There are multiple methods to do the same procedure. This method is intended for beginners who are just getting started in Linux.]

Hope this helps!

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Source: Link

Install Kali Linux in virtualbox (using ova file)

This is how I installed Kali Linux in virtualbox using the ova file method in my windows 10 PC along with its screenshots.

Requirements:

  1. Kali Linux 2016.1 Preinstalled ImageDownload Link (Torrent)  (~2.83 GB) => [Note: New Version of Kali is released = Download Link (Torrent) ~ 3.2GB]
  2. VirtualBox: Download Link (~107 MB)
  3. CPU that supports Virtualization.
  4. Atleast 8GB of free disk space. 
  5. 7-zip: Download Link (~1.31 MB) [ Note: Winrar is another alternative you could use instead of 7-zip.]
  6. Virtual Box Extension Pack: Download Link (~15.6 MB) [Optional]

Installation Procedure:

The first thing you need to do is go ahead download and install Virtualbox in your system. Then download the Kali Linux ova file mentioned above and extract it using 7-zip or Winrar. The extracted file would be a .ova file format which is a pre-installed Kali Linux machine. Using a pre-installed file saves us a lot of time as we don’t have to go through the whole installation process.

Now, open VirtualBox:

open virtualbox

Then click on “File” and then click on “Import Appliance“.

click file import appliance

Click on the folder icon as shown below.

import ova file window

Now, browse to and select the extract .ova Kali Linux image file and click on “Open“.

select kali linux ova file

You would now see a window called “Appliance settings” where you can configure stuff like the name of your VM, the amount of RAM to be allocated to your Kali Linux VM etc.

kali linux appliance settings

If you want to change the name of the VM, simply click on the text and you can change it according to your will.

changing vm name

Finally, click on “Import” and wait for a few moments to import the Kali Linux Appliance.

click import to load kali linux appliance

importing kali linux appliance progress bar

Now, right click on your Kali Linux Virtual machine as shown below and click on “Settings“.

open kali linux virtual machine Settings

If you need to adjust the amount of RAM, click on “System” and you can move the slider accordingly. I would suggest atleast a minimum of 1024 MB (1GB) of RAM.

select ram for your Kali Linux VM

Now, click on “Network” as shown below and select “Bridged Adapter” and then click on “OK“.

Select Kali Linux network mode to Bridged Adapter

Click on your Kali Linux VM and then click on Start as shown below.

start kali linux in virtualbox

You should now be able to see the grub menu. Hit “Enter” in your keyboard.

kali linux grub menu

Now, login to your Kali Linux machine with the default username as root and password toor.

kali username

kali password

You should now be booted into your Kali Linux desktop.

kali linux logged in

Customize Kali (Optional): 

I would like to make some minor changes to make sure the VM is not interrupted during pen testing. This section is purely optional, you can skip to the next section if you don’t want to customize it.

Click on the triangle pointing downwards in the upper right corner and then click on the “Settings” icon.

Kali Linux drop down menu

This will bring you the “All Settings” window as shown below. Click on “Date & Time“.

all settings menu

You can change the time zone to your time zone.

change time zone

Now, go back to the “All Settings” window and then click on “Privacy“.

select privacy in all setting menu

You would see a screen similar to the one below:

default privacy settings

Now, disable “Automatic Screen Lock” by moving the slider.

disable auto screen lock

Go back to “All Settings“, then click on “Power“.

click on power in all settings

Now, select Blank Screen option as “Never” and turn off  “Automatic Suspend” as shown below.

disable blank screen and automatic suspend

Update Kali Linux:

Open the terminal window by clicking on the icon as shown below:

open terminal

This is what the terminal window would look like in a Kali Linux system.

Kali Linux Terminal

Enter the following commands in the terminal to update your Kali Linux system.

apt-get clean && apt-get update -y
apt-get upgrade -y && apt-get dist-upgrade -y

This may take a while depending on your internet connection for the update to complete.

And that is it for setting up Kali Linux in virtualbox to get started with pentesting (only for ethical hacking and for purely educational purposes).

If you have any sort of queries regarding this installation, just leave a comment and will get back to you. I will be posting some ethical hacking tutorials in the future, so stay tuned.

How to install apache from source in Centos 6.7

This is a simple guide on how to configure Apache from source in Centos 6.7 + installing APR, APR-UTIL and PCRE to make it work.

Step 1. Install gcc:

Open up your terminal window and type the following command:

yum install gcc gcc-c++

Now, change to following directory:

cd /usr/src/

Step 2: Download and configure APR :

To download the APR file, use the below command:

wget http://a.mbbsindia.com//apr/apr-1.5.2.tar.gz

Now extract the downloaded file:

tar -zxvf apr-1.5.2.tar.gz

Change to the extracted folder and run the following commands to configure apr:

cd apr-1.5.2
./configure –prefix=/usr/src/apr
make
make install

Step 3. Download and configure apr-utils:

Change to following /usr/src/ directory:

cd /usr/src/

To download the APR-UTIL file, use the below command:

wget http://mirror.fibergrid.in/apache//apr/apr-util-1.5.4.tar.gz

To extract file, change to extracted folder and to configure apr, run the following commands:

tar -zxvf apr-util-1.5.4.tar.gz

cd apr-util-1.5.4
./configure –prefix=/usr/src/apr-util –with-apr=/usr/src/apr/
make
make install

Step 4. Download and config PCRE:

Change to /usr/src/ directory:

cd /usr/src/

To download pcre2-10.21.tar.gz type the following your terminal:

wget ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/pcre2-10.21.tar.gz

To extract file, change to extracted folder and to configure pcre2-10.21, run the following commands:

tar -zxvf pcre2-10.21.tar.gz

cd pcre2-10.21
./configure –prefix=/usr/src/pcre2
make
make install

Step 5. Download Apache / httpd:

Now, change to following directory:

cd /usr/src/

To download httpd tar ball type the following your terminal:

wget http://a.mbbsindia.com//httpd/httpd-2.4.18.tar.gz

To extract file, change to extracted folder and to configure httpd, run the following commands:

tar -zxvf httpd-2.4.18.tar.gz

cd httpd-2.4.18
./configure –prefix=/usr/local/apache2 –with-apr=/usr/src/apr –with-apr-util=/usr/src/apr-util –with-pcre=/usr/src/pcre2/bin/pcre2-config
make
make install

Step 6. Start and test your apache server 

service httpd start
httpd -v

You can also open your browser and go to:

http://localhost/

And it should give you the Apache Welcome page.

And Voila! You have successfully configured apache from source. Hope this helps!

[DISCLAIMER: This guide is strictly for the purpose of learning how to configure apache from source for beginners. This should not to be used in a real production server as no security measures has been discussed or implemented in this tutorial.]

If you liked this article, do leave a comment below. You can also share this article by clicking on the social media buttons below. 

Source: ApacheTroubleshooting source: APR troubleshooting

How to setup Cloudflare CDN with Bigrock (manually) + Screenshots

This is a guide on how to setup Cloudflare CDN with BigRock (similar for Bluehost,Godaddy, Dreamhost, Hostgator) for your website or blog . You can follow the steps below:

Step 1. Create an account with Cloudflare:

Go to https://www.cloudflare.com and click on the “Signup” button.

 

cloudlare signup

Fill in your details, tick on “Agree” and then click on “Create Account“.

cloudflare create account

Step 2. Add your website

Now, in the text box below, type your website address and then click on “Scan DNS Records“as shown below.

cloudflare add site and scan dns

It will take a few moments for the scanning to complete.

 

cloudflare scanning dns records

Once, the scanning is complete, click on “Continue“.

 

cloudflare dns scanning complete

Now, click on “Continue” in the bottom corner:

cloudflare click continue

 

 

Step 3. Select Cloudflare Plan

Now, select the “Free Website” package as shown below and click on “Continue“.

 

select cloudflare free plan

Step 4. Get new name servers

Now, you will see the Cloudflare name servers as shown below. [This may vary for your website]

cloudflare name servers

As you see, for my website it is requesting to change the name server from

dns1.bigrock.in to linda.ns.cloudflare.com
dns2.bigrock.in to rob.ns.cloudflare.com

Also, also to remove the following nameservers:

dns3.bigrock.in 
dns4.bigrock.in 

[Note: The nameservers that you may see in your screen may be different.]

Step 4: Change your name servers to Cloudflare

Now, open up a new tab and login to your domain host panel (i.e. from where you bought your domain name from eg BigRock, Goddady, Hostgator, Bluehost etc). I have my domain from BigRock so I will be loggin in to my Bigrock account.

domain hosting bigrock login

Now, click on the domain you need to change the name servers to.

 

bigrock select domain

Now, click on “Name Servers” 

 

bigrock manage name servers

 

 

And you will see your default nameservers as shown below:

default bigrock name servers

Now, change your nameserver to the ones provided by cloudflare. In my case, after changing the nameserver, it will look like this:

 

cloudflare nameservers update

Now, click on “Update Name Servers“.

domain bigrock nameserver change success

Step 5: Verify in Cloudflare

Now, go back to your cloudflare tab and click on “Continue“.

cloudflare dns nameserver

It should show you show you a green banner with the status: “Active” as shown below.

 

cloudflare cdn active status[NOTE: If you the status does not show as “Active” then you can click on “Recheck Status” and it then should show that its “Active”]

[IMPORTANT: It would take about 24-48 hours for the DNS to get updated.]

And Voila! You have successfully configured Cloudflare CDN for your blog/website and should load faster.

Do check the  performance of your website after 24-48 hours and let me know in the comments sections below if there was any speed improvement.

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