A Comparison of Network Models

A Comparison of Network Models

There are two network models that describe how networks 'work'. The OSI Model, the older model, was designed for the OSI protocol stack. While different organizations were battling over standards, Vint Cerf and Bob Khan worked out the TCP/IP software from which the TCP/IP Model was co-designed. The diagram below shows how the two networking models compare, and how the logical and physical networking protocols relate to the layers in each of the two models.

There are seven layers in the OSI Model, only four in the TCP/IP model. This is because TCP/IP assumes that applications will take care of everything beyond the Transport layer. The TCP/IP model also squashes the OSI's Physical and Data Link layers together into the Network Access Layer. Internet Protocol really doesn't (and shouldn't) care about the hardware underneath, so long as the computer can run the network device and send IP packets over the connection

CLOUD COMPUTING

Cloud computing allows people to connect to their important information anywhere and at any time. This capability is influencing our future technology. We no longer need to carry around portable mass storage devices or expensive, high capacity flash drives. The “office” is becoming any place where one can connect to the Internet. Technology is moving in a direction that relies on cloud computing to deliver its promises.

Basic Linux Commands

Basic Linux Commands

Modes of Operation

The linux operating system used for the PARTICLE DAQ system can be used either in a terminal mode where you type commands or in a Windows Explorer style graphical user interface (GUI).

The Explorer-like GUI can be used for file manipulation functions (e.g., copying a file to a floppy) or deleting or moving files on the disk.  It cannot be used to run the PARTICLE DAQ itself.

To begin using the Explorer-like GUI, double click on the icons on the Desktop.  For the most part, Explorer mode will be familiar from Windows or MAC OS, so with a few exceptions, this information will not focus on this.  Where something is much more easily done from Explorer mode, it will be highlighted here.

To begin working in the terminal mode, you will need to open a terminal.  This can be accomplished by clicking on the terminal icon in the bottom icon bar, by using the main menu (footprint icon in lower left of bottom icon bar) System Tools -> New Terminal. 

The Manual (terminal mode)

man                                This command brings up the online Unix

manual. Use it on each of the commands below.

For Example:   

man pwd                        You will see the manual for the pwd command.

Accessing files in Folders (Directories) in terminal mode

pwd                                Shows what directory (folder) you are in.

In Linux, your home directory is /home/particle

·       Let's suppose you have several data files (data1, data2 ... etc.) in a directory called muondata.

·       Then suppose the directory muondata is an entry in your main home directory, /home/particle .

·       If you are in your home directory (where terminals start) and type pwd, you will see /home/particle.

·       If you were in the muondata directory, pwd would give you /home/particle/muondata instead    

·       The last slash after a directory name is optional.

As you can see, each slash (/) indicates another sub-directory.

cd                                  Changes directories.

Examples of relative movement among directories:

cd muondata                Moves down from your current directory

into the muondata sub-directory

cd ..                            Moves up one directory (yes, include the

two little dots) 

You can also move directly into directories

cd /home/particle/muondata

                   Moves from ANY directory into the muondata

sub-directory of your home directory.

cd ~               Takes you back to your home directory

(/home/particle)

Making or Removing a Directory (terminal mode)

mkdir dirName            Creates a directory with name dirName.

For Example:

mkdir temp             Creates the directory temp.

rmdir dirName      Removes a directory dirName.

For Example:

rmdir temp                  Removes the directory temp.

Looking at or Finding your Files (terminal mode)

ls                                  Lists files.

If you add -al after ls it will give more details for each file. Such as, size, permissions, owners, dates etc.

ls al                          You'll see a huge list of files that you can't see with the 'ls' command alone and lots of details.

If you see such a long list of files that they scroll off the terminal screen, one way to solve the problem is to use:

ls -al |more       Shows one screen of file names at a time.

less data1         Dumps the contents of the data1 file to your screen with a pause at each line so you don't miss any contents as they scroll. You may move through the file using page up, page down, home and end keys.  When done with less you use the q key to get back to the main terminal.

whereis data1      Shows you the location of the data1 file.

Altering your Files

rm data1                      Deletes the file data1 in the current directory. 

rm -i muon*                Removes all of your muon data files

(careful!!  rm * will remove ALL your files) 

The "-i" makes the computer prompt before removing each file.  If you really want to work without a net, omit the "-i".

cp data1 newdata/    will copy the file data1 to the directory newdata (assuming it has already been created)

mv data1 newdata/    moves the file data1 to the folder newdata and deletes the old one.

 

Using the Floppy Disk Drive in Linux

The simplest way to access the floppy drive under Linux is to use the Explorer-like interface.  However, there is a very important detail!  To access the files on the disk, you have to mount the floppy disk, which means that the operating system will scan the disk so that it can recognize the files on it. Although your computer will be perfectly happy to allow you to remove the disk by pushing the eject key on the laptop floppy drive, this may result in unexpected actions unless you unmount the disk.  For example, your files may be only partly there or not there at all!  (This is no different then under Windows or DOS; its just that those operating systems hide that detail from you a little better.  This is why, for example, you must eject floppy disks from the disk properties menu in Windows.)

In the Explorer interface, to mount the floppy, you just double click on the desktop icon.  This will bring up a window with the contents of the floppy, and you may drag and drop files there, or take any other actions you would with normal files.   (Note: unlike in Windows and MacOS, when you drag a file from your home area to the floppy, it moves the file instead of making a copy.)

To remove the disk, you must first right-click on the desktop icon, and select Unmount volume or Eject (either does the same thing).  When this is complete (and it may take a long time since it may have to complete writing files to the floppy!), you may push the eject button on the floppy to remove it.

Things are more complicated by possible in the terminal mode:

mount              Mounts a drive to the operating system.

Linux does not 'see' the floppy drive until

you tell it to.

For Example:

mount /mnt/floppy    Allows you to use the floppy drive which has directory name /mnt/floppy

cp aFile /mnt/floppy/     Copies the file aFile to the floppy disk.

ls /mnt/qfloppy/          Allows you to see what files are on your floppy.

You may run into problems moving large files onto a 1.44MB floppy disk.  One option to fit larger files is to create a zip archive containing the file onto the floppy.  For Example:

zip /mnt/floppy/myFile.zip muon.myDataRun 

                   Moves the file muon.myDataRun into a zip file on the floppy named myFile.zip

After you are done and before you eject it (this is very, very important), you must unmount the floppy.

umount /mnt/qfloppy     Allows you to remove the floppy disk

·       Make sure you wait for the command prompt to reappear (this might take a few seconds) before ejecting the floppy. 

·       If you eject the floppy before you unmount the floppy, it may corrupt the data on the floppy and cause the system to be confused if you try to use the floppy again. 

·       If you make a mistake like this, it's probably best to reboot.  Sorry.

df                                  Shows the disk usage. This will tell you how much disk space you have left on your hard drive as well as the floppy.

STEGANOGRAPHY

                                                              STEGANOGRAPHY

There are a large number of steganographic methods that most of us are familiar with (especially if you watch a lot of spy movies!), ranging from invisible ink and microdots to secreting a hidden message in the second letter of each word of a large body of text and spread spectrum radio communication. With computers and networks, there are many other ways of hiding information, such as:

• Covert channels (e.g., Loki and some distributed denial-of-service tools use the Internet Control Message Protocol, or ICMP, as the communications channel between the "bad guy" and a compromised system)
• Hidden text within Web pages
• Hiding files in "plain sight" (e.g., what better place to "hide" a file than with an important sounding name in the c:\winnt\system32 directory?)
• Null ciphers (e.g., using the first letter of each word to form a hidden message in an otherwise innocuous text)

Steganography today, however, is significantly more sophisticated than the examples above suggest, allowing a user to hide large amounts of information within image and audio files. These forms of steganography often are used in conjunction with cryptography so that the information is doubly protected; first it is encrypted and then hidden so that an adversary has to first find the information (an often difficult task in and of itself) and then decrypt it.

There are a number of uses for steganography besides the mere novelty. One of the most widely used applications is for so-called digital watermarking. A watermark, historically, is the replication of an image, logo, or text on paper stock so that the source of the document can be at least partially authenticated. A digital watermark can accomplish the same function; a graphic artist, for example, might post sample images on her Web site complete with an embedded signature so that she can later prove her ownership in case others attempt to portray her work as their own.

Stego can also be used to allow communication within an underground community. There are several reports, for example, of persecuted religious minorities using steganography to embed messages for the group within images that are posted to known Web sites.

STEGANOGRAPHIC METHODS

The following formula provides a very generic description of the pieces of the steganographic process:

cover_medium + hidden_data + stego_key = stego_medium

In this context, the cover_medium is the file in which we will hide the hidden_data, which may also be encrypted using the stego_key. The resultant file is the stego_medium (which will, of course. be the same type of file as the cover_medium). The cover_medium (and, thus, the stego_medium) are typically image or audio files. In this article, I will focus on image files and will, therefore, refer to thecover_image and stego_image.

Ethical Hacking

They dedicate their skills to serve their clients. Instead of spending long nights inside obscure rooms filled with computers looking for some victim, they work inside corporations, finding ways to protect the networks and computer systems.

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OPERATING SYSTEM:-

            An operating system is the interface between the user and the

architecture.

          EXAMPLES:-WINDOWS XP,WINDOWS 7,WINDOWS 8,WINDOWS VISTA

                    LINUX,UNIX,MAC ETC.

 

LINUX:-

        The Nineties started with Linus Torvalds, a Swedish speaking Finnish student,

buying a 386 computer and writing a brand new POSIX compliant kernel. He put

the source code online, thinking it would never support anything but 386 hardware.

Many people embraced the combination of this kernel with the GNU tools, and the

rest, as they say, is history.

Today more than 90 percent of supercomputers (including the complete top 10), more

than half of all smartphones, many millions of desktop computers, around 70 percent

of all web servers, a large chunk of tablet computers, and several appliances (dvdplayers,

washing machines, dsl modems, routers, ...) run Linux. It is by far the most

commonly used operating system in the world.

      

DISTIBUTIONS:-

             A Linux distribution is a collection of (usually open source) software on top of a

Linux kernel. A distribution (or short, distro) can bundle server software, system

management tools, documentation and many desktop applications in a central secure

software repository. A distro aims to provide a common look and feel, secure and

easy software management and often a specific operational purpose.

Red Hat:-

        Red Hat is a billion dollar commercial Linux company that puts a lot of effort in

developing Linux. They have hundreds of Linux specialists and are known for their

excellent support. They give their products (Red Hat Enterprise Linux and Fedora)

away for free. While Red Hat Enterprise Linux (RHEL) is well tested before release

and supported for up to seven years after release, Fedora is a distro with faster updates

but without support.

OPEN SOURCE:-

           of or relating to or being computer software for which the source code is freely availabl

KERNEL:-

        A kernel is the core of an operating system. The operating system is all of the programs that manages the hardware and allows users to run applications on a computer. The kernel controls the hardware and applications. Applications do not communicate with the hardware directly, instead they go to the kernel. In summary, software runs on the kernel and the kernel operates the hardware.

 Without a kernel, a computer is a useless objec

http://thelinuxdesk.com/2012/09/07/operating-system-kernel-types/

HOW CAN WE BREAK THE WE-FI PASSWORD

You already know that if you want to lock down your Wi-Fi network, you should opt for WPA encryption because WEP is easy to crack. But did you know how easy? Take a look.

Note: This post demonstrates how to crack WEP passwords, an older and less often used network security protocol. If the network you want to crack is using the more popular WPA encryption, see our guide to cracking a Wi-Fi network's WPA password with Reaver instead.

Today we're going to run down, step-by-step, how to crack a Wi-Fi network with WEP security turned on. But first, a word: Knowledge is power, but power doesn't mean you should be a jerk, or do anything illegal. Knowing how to pick a lock doesn't make you a thief. Consider this post educational, or a proof-of-concept intellectual exercise.

Dozens of tutorials on how to crack WEP are already all over the internet using this method. Seriously—Google it. This ain't what you'd call "news." But what is surprising is that someone like me, with minimal networking experience, can get this done with free software and a cheap Wi-Fi adapter. Here's how it goes.

What You'll Need

Unless you're a computer security and networking ninja, chances are you don't have all the tools on hand to get this job done. Here's what you'll need:

• A compatible wireless adapter—This is the biggest requirement. You'll need a wireless adapter that's capable of packet injection, and chances are the one in your computer is not. After consulting with my friendly neighborhood security expert, I purchased an Alfa AWUS050NH USB adapter, pictured here, and it set me back about $50 on Amazon. Update: Don't do what I did. Get the Alfa AWUS036H, not the US050NH, instead. The guy in this video below is using a $12 model he bought on Ebay (and is even selling his router of choice). There are plenty of resources on getting aircrack-compatible adapters out there.
• A BackTrack Live CD. We already took you on a full screenshot tour of how to install and use BackTrack 3, the Linux Live CD that lets you do all sorts of security testing and tasks. Download yourself a copy of the CD and burn it, or load it up in VMware to get started.
• A nearby WEP-enabled Wi-Fi network. The signal should be strong and ideally people are using it, connecting and disconnecting their devices from it. The more use it gets while you collect the data you need to run your crack, the better your chances of success.
• Patience with the command line. This is an ten-step process that requires typing in long, arcane commands and waiting around for your Wi-Fi card to collect data in order to crack the password. Like the doctor said to the short person, be a little patient.

Crack That WEP

To crack WEP, you'll need to launch Konsole, BackTrack's built-in command line. It's right there on the taskbar in the lower left corner, second button to the right. Now, the commands.

First run the following to get a list of your network interfaces:

airmon-ng

The only one I've got there is labeled ra0. Yours may be different; take note of the label and write it down. From here on in, substitute it in everywhere a command includes (interface).

Now, run the following four commands. See the output that I got for them in the screenshot below.


airmon-ng stop (interface)
ifconfig (interface) down
macchanger —mac 00:11:22:33:44:55 (interface)
airmon-ng start (interface)

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If you don't get the same results from these commands as pictured here, most likely your network adapter won't work with this particular crack. If you do, you've successfully "faked" a new MAC address on your network interface, 00:11:22:33:44:55.

Now it's time to pick your network. Run:

airodump-ng (interface)

To see a list of wireless networks around you. When you see the one you want, hit Ctrl+C to stop the list. Highlight the row pertaining to the network of interest, and take note of two things: its BSSID and its channel (in the column labeled CH), as pictured below. Obviously the network you want to crack should have WEP encryption (in the ENC) column, not WPA or anything else.

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Like I said, hit Ctrl+C to stop this listing. (I had to do this once or twice to find the network I was looking for.) Once you've got it, highlight the BSSID and copy it to your clipboard for reuse in the upcoming commands.

Now we're going to watch what's going on with that network you chose and capture that information to a file. Run:

airodump-ng -c (channel) -w (file name) —bssid (bssid) (interface)

Where (channel) is your network's channel, and (bssid) is the BSSID you just copied to clipboard. You can use the Shift+Insert key combination to paste it into the command. Enter anything descriptive for (file name). I chose "yoyo," which is the network's name I'm cracking.

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You'll get output like what's in the window in the background pictured below. Leave that one be. Open a new Konsole window in the foreground, and enter this command:

aireplay-ng -1 0 -a (bssid) -h 00:11:22:33:44:55 -e (essid) (interface)

Here the ESSID is the access point's SSID name, which in my case is yoyo. What you want to get after this command is the reassuring "Association successful" message with that smiley face.

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You're almost there. Now it's time for:

aireplay-ng -3 -b (bssid) -h 00:11:22:33:44:55 (interface)

Here we're creating router traffic to capture more throughput faster to speed up our crack. After a few minutes, that front window will start going crazy with read/write packets. (Also, I was unable to surf the web with the yoyo network on a separate computer while this was going on.) Here's the part where you might have to grab yourself a cup of coffee or take a walk. Basically you want to wait until enough data has been collected to run your crack. Watch the number in the "#Data" column—you want it to go above 10,000. (Pictured below it's only at 854.)

Depending on the power of your network (mine is inexplicably low at -32 in that screenshot, even though the yoyo AP was in the same room as my adapter), this process could take some time. Wait until that #Data goes over 10k, though—because the crack won't work if it doesn't. In fact, you may need more than 10k, though that seems to be a working threshold for many.

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Once you've collected enough data, it's the moment of truth. Launch a third Konsole window and run the following to crack that data you've collected:

aircrack-ng -b (bssid) (file name-01.cap)

Here the filename should be whatever you entered above for (file name). You can browse to your Home directory to see it; it's the one with .cap as the extension.

If you didn't get enough data, aircrack will fail and tell you to try again with more. If it succeeds, it will look like this:

The WEP key appears next to "KEY FOUND." Drop the colons and enter it to log onto the network.

Problems Along the Way

With this article I set out to prove that cracking WEP is a relatively "easy" process for someone determined and willing to get the hardware and software going. I still think that's true, but unlike the guy in the video below, I had several difficulties along the way. In fact, you'll notice that the last screenshot up there doesn't look like the others—it's because it's not mine. Even though the AP which I was cracking was my own and in the same room as my Alfa, the power reading on the signal was always around -30, and so the data collection was very slow, and BackTrack would consistently crash before it was complete. After about half a dozen attempts (and trying BackTrack on both my Mac and PC, as a live CD and a virtual machine), I still haven't captured enough data for aircrack to decrypt the key.

So while this process is easy in theory, your mileage may vary depending on your hardware, proximity to the AP point, and the way the planets are aligned. Oh yeah, and if you're on deadline—Murphy's Law almost guarantees it won't work if you're on deadline.

SEE MORE:::::::
             http://lifehacker.com/5305094/how-to-crack-a-wi+fi-networks-wep-password-with-backtrack