DDoS ATTACK CONCEPT

What is "DDoS"?

Denial of Service attacks(or Distributed Denial of Service attacks[DDoS]) are a form of organized attacks with the goal of taking down a server by overloading it. Often by sending useless information(packets) to a server in massive amounts.

In-fact about a year ago I found one of my websites was accidentally DoS-ing darksunlight.com(I use darksunlight as my webhost) because my PHP script made an infinite loop that sent the same information over and over and over into darksunlight's SQL databases. This one page took this EXTREMELY powerful server down twice in less than a minute. That site has since been deleted.
That story demonstrates that it does not take more than a simple "error" in your code to overload a server.

Keep in mind that altough spreading knowledge is my main goal, performing DDoS attacks is indeed a federal crime in the US.
It is also an international offence and will be punished according to the local laws of the individual's country.

But enough talk. I will now show you a quick example of a DoS attack of sorts you can do on your local computer.

Sample
Keep in mind that this is NOT a real DoS attack, but rather an example to visualize how a DoS attack works.

We will take down YOUR computer.
Step 1
Open up notepad, mousepad, or your favored equivalent.
Step 2
Type in this simple batch command
Code:
:a
start
goto a
Step 3
Save as "dossample.bat" making sure you select "All files" from the "File Type" dialog.
Step 4
Run that sucker, but save your work first, as this will crash even the best computers in a matter of minutes.

What did you learn from this?
Observe how the file rapidly replicates itself, opening a new CMD right after it opens another.
An infinite loop has been created that has filled the RAM with useless and massive amounts of CMDs(or Terminals for you Unix folk)

DDoS attacks work much the same way, except instead of replicating an infinite number of CMDs, they send information(packets) to the server over and over and over again until the server crashes.

What information you may ask?
Anything. Your login name, your 'online' status, a new comment, the number of views on a video, your new high score. Absolutely any information that could be resent a massive amount of times to the same server.

Next we will be discussing the simplest form of DDoS.

DDoS by Ping Flood

Please note that I will be pinging my Localhost. You should too.

Perhaps one of the simplest ways to DoS is by using the 'ping' command built into most operating systems, including all windows and Linux distributions.
Step 1
Start up your server. Mine is apache, but that is beside the point, the server type does not matter. If it has an IP address, it can be pinged.
Step 2
Type in the ping command
Code:
ping -t -a -l 65500 localhost
Step 3
Press enter and watch it ping the localhost over and over until[/b]
your server crashes, or you get tired of waiting for it to crash.
Since most modern servers can take the stress of the ping flood, you will need to get all your friends to help you ping to bring your server down. Or even slow it down.

Command Explained
ping - tells the computer to ping a server
-t - It will continue to ping the server until the command is closed, or stopped.
-a - Resolves the adress to host names.
-l - Size.

By default the ping will send 32bytes of data to the server, so you must change this to a bigger number. The maximum is 65,500bytes, so that is what we used.

If you send a server any number higher than 65,500bytes it will instantly crash. This is called "Ping of Death".
Like any other thing with the suffix "of Death" it is very rare, and hard to accomplish indeed.
In order to learn more about the Ping of Death, read my huge response to this very thread, here!

DDoS by Reloading
Something as simple as reloading a page can take down a server if done enough times.
Step 1
Make a page that lets you submit forms. Method='GET' is better than method='POST' for this, but both will work.
(If you do not understand step 1, just find a page that lets you submit information, like a new comment or upload a picture)
Step 2
Fill out the forms and submit
Step 3
Reload the page
If the page uses the POST method your browser will display a dialog asking if you are sure you want to resend the information, or something to that effect. Simply click "Continue" or "OK".(see now why GET is better?)
Step 4
Keep reloading until server is down.
Their are many add ons and tools that allow you to auto-reload a page. It is a matter of googleing for them. They are widely available and free.

I have just created a program that allows you to Auto-refresh a page using IE. If you are interested please download from:
Host: Darksunlight.com | Size: 9kb | Format: .zip ultra compressed | Platform: Windows

This method is very primitive as you can see, but it is probably the best way to DDoS.
In order to learn more about DDoS by reload, read my huge response to this very thread, here!

Low-Orbit Ion Cannon
LOIC (Low Orbit Ion Cannon) is an app, written in C# and developed by praetox, that was used by Anonymous during Project Chanology. It attempts to DoS the target site by using all its bandwidth, sending TCP, UDP, or HTTP requests to the server until it crashes.

Download:
LOIC | Host: SourceForge | Size: 130kb
Step 1
Download and extract LOIC
Step 2
Open LOIC.exe and fill out the required information.

[Image: 618px-Low_Orbit_Ion_Cannon.png]

Instructions for filling out:
IP or URL = IP or URL that you wish to DoS
TCP / UDP message = information being sent, just write something random. Or leave it as default.
Port = Server's port
Method = Server's Method, leave as TCP if unknown
If you are gonna try to take down a website then use HTTP
Speed = set to "<= faster"
Threads = How many users it should simulate, the higher the number the faster it will crash. Set to 10,000. Note that this might make your computer lag, if so, set to a lower amount.
Step 3
Click on "IMMA CHARGIN MAH LAZER"
This starts your program.
Warning: This tool might not seem like much, but many people of all ages have been arrested and convicted for knowingly using this tool. Remember DoS and DDoS are federal crimes, however insignificant it may seem. Use at your own discretion.