#linux guides

Python:

Introduction to Variables

User Input and Selection

An Introduction to While Loops

Putting it Together

Introduction to Lists

Website:

Into to HTML

Binary:

Decimal to Binary and Vice Versa

Basic Logic Gates

Hacking:

Securing Kali Against Hacking

Finding Open Ports With Nmap

Finding Exploits

Hacking Metasploitable

Staying Safe Online:

Spotting Phishing Attacks

HTTP vs HTTPS

Good Password Etiquette

Proxies and VPNs

MultiFactor Authentication

Virtual Machines:

Kali for VMWare

Kali for VirtualBox

Creating a Live USB

Linux:

Directory Traversal and File Creation/Deletion

Basic Networking Commands

Remote Access

Finding Files

Blue Team:

Static Malware Analysis 101

General Programming:

In the past, I have written guides on how to set up VMs (Virtual Machines) using both VMware and VirtualBox programs, but what if you’re looking to take your hacking on the go? For this you need something more portable. VirtualBox does have the ability to be installed on a thumb-drive or external hard drive, but another way you can achieve this is with a bootable USB.

What is a Live USB?

An operating system can be placed onto a thumb-drive, and it can then temporarily replace the PCs operating system. This can have a variety of uses: from being used to help diagnose problems and fixing the computer, to just taking OS’s for a ‘test drive’.

The drive is inserted into the computer while it is turned off, and then when it is turned on, it boots from the USB instead, allowing you to use the OS on the drive.

How to Create a Live USB?

To create a live USB, you need three things:

A USB stick (at least 4GB)

Rufus (download from here)

Kali live iso (download from here. Make sure you download the live version)

The Rufus download shouldn’t take so long, but the iso file will take some time to download. Sit back, and relax. Maybe read a little, or watch a movie, This tutorial can wait.

Finished? Good.

After downloading the iso, you can check the hash of the file against the hash against the website to confirm that the file hasn’t been corrupted. There are a variety of methods to do this, so you can find one that suits you.

If the hash that you calculated matches the hash of the file listed on the website, then your version of the file is the same as the one on the server and it’s not been corrupted. We can see here that the SHA256 hash I computed does match, so the files are the same.

Creating the Live USB:

To create the USB, the first step is to insert the USB thumb-drive you want to make bootable, and start up Rufus. It is important to note that part of the process is to format the drive, which will delete every file on it. DO NOT KEEP ANY IMPORTANT FILES ON THE DRIVE, BACK UP ANY FILE YOU WANT TO KEEP.

Next you click ‘SELECT’, and navigate to the live .iso file you downloaded. After doing so, options for your live drive will be available. Most of these are advanced option, so for now you can ignore them, but you can change the name of the drive if you want.

After pressing START, you may receive some pop-ups. You can click through these, as the recommended options work. After clicking through the pop-ups, Rufus will start writing to the drive. You can now wait until it is finished, so read some more of your book or watch another film.

Once it is finished, you can eject the drive. Your Live USB is now ready.

Using the Live USB:

To use your live USB, first insert it into the computer while it is turned off. When it turns in, it should boot to a screen where you can select boot options.

(sorry the quality isn’t great)

For basic use, you can select ‘Live system’, but there are more advanced modes that you can use. You can do some research to see what each mode involves, and which is best for a scenario.

After selecting out boot mode, our computer then boots to Kali.

 It happens to everyone: You need a certain file for whatever reason, but you just can’t remember where you saved it. If you’re like me organization may not be your forte and it may be easy to lose files, luckily Linux has ways of finding them. The ‘find’ command is very useful for this, but can take a while to learn. It has a variety of uses, but for this guide we’re just going to use it for finding lost files that we can remember the name of.

(Damn it, where did I save my to-do list?)

The ‘find’ command has four main parts. After the command ‘find’, you need to specify which directory to look through, then you can tell the program the type (the find command can locate both files and directories), then the name. I’ll talk about the last bit in a minute.

Finding a File:

So say I need to find a file called TODO.txt, and I know it’s in my ~/Documents directory. I can use the command ‘find ~/Documents -type f -name TODO.txt’. the ‘-type f’ flag denotes we are looking for a file, and -name is pretty self-explanatory.

Now I have the path to the file.

Finding a Very Lost File:

What if I don’t know where I saved it at all? Well then when specifying the location you use ‘/’, and the output is less pretty:

(I don’t think I have the right permissions to access some of these files)

We can see the file here, but sometimes it can be hard to find in the sea of ‘Permission denied’, this is where the trick I mentioned earlier comes into play. There is a file called /dev/null on Linux where anything written to it is lost. By adding 2>/dev/null to the end we send all errors (represented by 2) to /dev/null.

(Isn’t that much better?)

Finding a Directory:

Finding a directory works very similarly to finding a file, but you change the value of the ‘-type’ flag to ‘d’ instead:

Sometimes you need to do work on a computer, but won’t be able to do it physically. Linux has commands to enable you to use the terminal of another device across the internet. The preferred method of doing this is with a protocol called SSH.

Using SSH:

To SSH into a device, you need two pieces of information: the IP of the server, and a username on the server to log in as. I’m going to be connecting to my metasploitable VM, so I know the username is ‘msfadmin’ and I can find out the IP. I can then start to connect with the command ‘ssh [username]@[IP]

When you first connect to a server, you’ll be greeted with something looking like this. This can be used to help you authenticate that the server you’re connecting to is the one you’re intending to, but for now you can just type ‘yes’ to connect

After entering ‘yes’, you should be greeted with a login prompt, where you can enter your password (’msfadmin’ in this case) to log into the server and be given a prompt. In this example I think I took too long and the connection closed, but just restarting the connection worked.

You can now run commands as you would on your local machine:

Using SSH Instead of  Telnet:

Ping:

Ping is the networking command I use most often. It is used to test if you can reach a device, and if so how quick the connection is. To use this command, you type the word ‘ping’ followed by either a domain (google.com) or an IP address.

Ping send a stream of packets to the location you give it, and waits for a response. After running the command, we can see the response (64 bytes from...), and on the end of the line is the time it has taken to get that response in milliseconds. The ping command will run indefinitely, so to end it you use the keyboard shortcut CTRL+C. You can then get some statistics about the connection. If you don’t have a connection to the device you’re pinging, you will see something like this:

Note that ping can also be used to give you an IP address of a domain. After pinging a domain, it will give an IP address. Here I find an IPv6 address after pinging bing.com:

ip address:

This command tells you your local IP address. There’s a lot of information that may not be useful to you however.

(I used my own Kali machine for this, because my tutorial one has too many IPs and the output was cluttered)

For a start, we can ignore everything in section 1. This is the loopback interface and while it can be useful for diagnosing connection problems, it doesn’t tell us our IP: for that we need to look at section 2. Your internal IP address is listed under inet (in this case it’s 192.168.129.132), with your IPv6 address listed under inet6.

That is a lot of information to take in, but all you really need to know is that your IP address on your current network is found next to ‘inet’.

Conclusion:

This is a quick crash course on some of the basic Linux commands to enable you to use the terminal. We will be using a Kali Virtual Machine for this (for a guide on how to set up a VM, see my earlier posts on the topic)

The first thing you should know about is the prompt. By default the prompt tells you the current signed-in user, the hostname of the computer, and the current directory (We’ll discuss this further later). On Kali it will look like this:

It is formatted as ‘user@hostname:dir$’

This is a little confusing as by default both the username and hostname is ‘Kali’, but it is telling us we are signed in as ‘Kali’, the hostname is ‘Kali’, and the ‘~’ tells us we are in our current home directory.

The first command is “ls”. This command lists all the files and directories in the current directory (’directory’ is a synonym to what are commonly referred to as ‘folders’ in the windows GUI). A standard home directory will look something like this:

We use the command ‘cd’ to Change Directory. Let’s change to the ‘Documents’ dir with the command ‘cd Documents’. You should have noticed how the last part of the prompt has changed to ~/Documents. If we use ‘ls’ we should see that nothing happens.

This is because the current directory is empty. Many commands have extra options called ‘flags’ which allow you to change how the command runs. One of the flags for ‘ls’ is ‘-a’, which outputs everything in the current directory including hidden documents and directories. To use these options we type the command, and then the flag.

Here you can see there are actually two directories in ~/Documents/, these being ‘.’ and ‘..’. In Linux, the ‘.’ directory is the current directory, and ‘..’ is the directory above it. We can ‘cd’ to these directories like any other.

As you can see, ‘cd .’ didn’t do anything because we were trying to change to the directory we were already in, but ‘cd ..’ took us to our home directory.

It’s looking a bit empty, so let’s learn how to create, see, and edit files. 

To create an empty file, we use the command ‘touch [file name]’, so to create a file called ‘hello.txt’ we use the command ‘touch hello.txt’. Let’s cd back to Documents and then try creating a new file.

hello.txt has been created. To view files in the terminal, we use the command ‘cat’ (so called because of it’s ability to concatenate files).

Nothing happened because the file was empty, so now we can use a text editor to edit the file. Linux comes preloaded with some text editors. Personally I prefer Nano but there are others to choose from.

After typing ‘nano hello.txt’, nano opens the file like this:

Feel free to type whatever you want here.

To exit nano we type Control X:

then y:

and then enter:

Now if we type ‘cat hello.txt’, it will output what we wrote.

To remove files, we can use the ‘rm’ command, with the name of the file to remove:

To create directories, we use the ‘mkdir [directory name]’ command, and we can use rm with the ‘-rf’ flag to remove empty directories.

You have now learned the beginning of how to navigate around directories and files with a Linux terminal. There is a lot more but that can be learned over time. This was just a quick crash course. I would advise you play around the terminal and learn for yourself. The terminal may look imposing but it is essentially just what you would do on the user interface.