What is CAPTCHA and how it works...

CAPTCHA or Captcha (pronounced as cap-ch-uh) which stands for “completely automated public Turing test to tell computers and humans apart” is a type of challenge-response test to ensure that the response is only generated by humans and not by a computer. In simple words, CAPTCHA is the word verification test that you will come across the end of a sign-up from while signing up for G mail or Yahoo account. The following image shows the typical samples of CAPTCHA.

Almost every internet user will have a experience of CAPTCHA in their daily internet usage, but only a few are aware of what it is and why they are used. So in this post you fill find detailed information on how CAPTCHA works and why they are used.

What purpose does CAPTCHA Exactly Serve?

CAPTCHA is mainly used to prevent automated software (bots) from performing actions on behalf of actual humans. For example while singing up for a new email account, you will come across a CAPTCHA at the end of the sign-up form so as to ensure that the form is filled out only by a legitimate human and not by any of the automated software or a computer bot. the main goal of CAPTCHA is to put forth a test which is simple and straight forward for any human to answer but for a computer, it is almost impossible to solve.

What is Need to Create a Test that Can Tell computers and Humans Apart?

For many the CAPTCHA may seem to be silly and annoying, but in fact it has the ability to protect systems from malicious attacks where people try to game the system. Attackers can make use of automated software’s to generate a huge quantity of requests thereby causing a high load on the target server which would degrade the quality of service of a given system, whether due to abuse or resource expenditure. This can affect millions of legitimate users and their requests. CAPTCHAs can be deployed to protect systems that are vulnerable to email spam, such as the services from G mail, Yahoo and Hotmail.

WHO Uses CAPTCHA?

CAPTCHAs are mainly used by websites that offer services like online polls and registration forms. For example, Web-based email services like G mail  Yahoo and Hotmail offer free email accounts for their users. However upon each sign-up process, CAPTCHAs are used to prevent spammers from using a bot to generate hundreds of spam mail accounts.

Designing a CAPTCHA System

CAPTCHAs are designed on the fact that computers lack the ability that human beings have when it comes to processing visual data. It is more easily possible for humans to look at an image and pick out the patterns than a computer. This is because computers lack the real intelligence that humans have by default. CAPTCHAs are implemented by presenting users with an image which contains distorted or randomly stretched characters which only humans should be able to identify sometimes characters are striked out or presented  with a noisy  background to make it even harder for computers to figure out the patterns.

Most, but not all, CAPTCHAs rely on a visual test. Some websites implemented a totally different CAPTCHA system to tell humans and computers apart. For example, a user is presented with 4 images in which 3 contains picture of animals and one contain a flower. The user is asked to select only those images which contain animals in them. This Turing test can easily be solved by any human, but almost impossible for a computer.

Breaking the CAPTCHA

The challenge in breaking the CAPTCHA lies in real hard task of teaching a computer how to process information in a way similar to how humans think. Algorithms with artificial intelligence (Al) will have to be designed in order to make the computer think like humans when it comes to recognizing the patterns in images. However there is no universal algorithm that could pass through and break any CAPTCHA system and hence each Captcha algorithm must have to be tackled individually. It might not work 100 percent of the time, but it can work often enough to be worthwhile to spammers.

World’s Top 5 White Hat Hackers...

White  hat hackers, also known as ethical hackers, or white knights, are computers security experts, who specialize in penetration testing, and other testing methodologies, to ensure that a company’s information system are secure. Such people are employed by companies where these professionals are sometimes called “sneakers.” Groups of these people are often called tiger teams or red teams. These security experts may utilize a verity of methods to carry out their tests including social engineering tactics, use of hacking tools and attempts to evade security to gain entry in to secured areas.

1.       Stephen wazniak

Stephen wazniak, one of the founders of apple computer and a long time hacker hero, recalled the days when a young hacker could twiddle the phone system and make a free phone call to the pope without fear that a goofi prank would turn into an international incident.

Steve wazniak got the first inspiration by his father jerry, which worked as an engineer at Lockheed, and by the fiktionalen miracle boy tom swift. His father stuck on it with the fascination for electronics and examined frequently the inventions of his son. Tom swift was on the other hand for it the product of creative liberty, scientific knowledge and the ability to find problem solution. Tom swift showed it also the large prizes, which expected him as inventers. Until today Stephen wazniak returns to the world from tom swift and reads out the books to its own children, in order to inspire it.

2.       Tim Berners-Lee

Burners-lee is famed as the inventor of the World Wide Web, the system that we use to access sites, documents and files on the internet.  He has received numerous recognitions, most notably the millennium technology. While working with CERN, a European nuclear reach organization, burners-lee created a hyper text prototype system that helped researchers share and update information easily. He later realized the hyper text could be joined with the internet.  Burners-lee recounts how he put them together. “I just had to take the hypertext idea and connect it to the TCP and DNS ideas and “ta-da!” the World Wide Web.”

Since his creation of the World Wide Web, Berners-lee founded the World Wide Web consortium at MIT. The W3c describe itself as “an international consortium where member organizations, a full-time staff and the public work together to develop web standards.” Berners-Lee’s World Wide Web idea, as well as standards from the W3C, is distributed freely with no patent or royalties due.

3.       Linus Torvalds

In 1991 linus torvalds was a college student at the University of Helsinki. Starting with the basics of a UNIX system, he wrote the kernel- original code- for a new system for his x86 pc that was later dubbed Linux (pronounced linn-ucks). Torvalds revealed the original source code for free – making him a folk hero among programmers – and users around the world began making additions and now continues to tweak it. Linux is considered the leader in the practice of allowing users to re-program their own operating systems. Currently, Torvalds  serves as the Linux ringleader, coordinating the code that volunteer programmers contribute to the kernel. He has had an asteroid named after him and received honorary doctorates from Stockholm university and university of Helsinki. He was also featured in the time magazine’s “60 years of heroes.”

4.       Richard Stallman

Richard Matthew Stallman (born March 16, 1953), often abbreviated “rms”,(1) is an American software freedom activist, and computer programmer. In September 1983, he launched the GNU project to create a free Unix-like operating system, and has been the project’s lead architect and organizer. With the launch of the GNU project, he initiated the free software movement and, in October 1985, set up the Free software Foundation. Stallman’s life continues to resolve around the promotion of free software. He works against movements like Digital Rights Management (or as he prefers, Digital Restrictions Management)   through organizations like Free Software Foundation and League for programming Freedom. He has received extensive recognition for his work, including awards, fellowships and four honorary doctorates.

5.       Tsutomu Shimomura

Shimomura reached frame in an unfortunate manner: he was hacked by Kevin Mitnick. Following this personal attack, he made it his cause to help the FBI capture him. Shimomura’s work to catch Mitnick is commendable, but he is not without his own dark side. Author Bruce Sterling recalls: “He pulls out this AT&T cell phone, pulls it out of the shrink wrap, finger-hacks it, and starts monitoring phone calls going up and down Capitol Hill while and FBI agent is standing at his shoulder, listening to him.” Shimomura out-hacked Mitnick to bring him down. Shortly after finding out about the intrusion, he rallied a team and got to work finding Mitnick. Using Mitnick’s cell phone, they tracked him near Raleigh-Durham international Airport.

The article, “SDSC computer experts help FBI captured computer terrorist” recounts how Shimomura pin pointed mitnicks location. Armed with a technician from the phone company Shimomura “used a cellular frequenct direction- finding antenna hooked up to a laptop to narrow the search to an apartment complex.” Mitnick was arrested shortly the reafter. Following the pursuit,  shimomura wrote a book about the incident with journalist John mark off, which was later turned into a movie. 

World’s top 5 black hat hackers...

What can hackers do to our PC? Are they really can break our security? The portrayal of hackers in the media has ranged from the high –tech super –spy, as in Mission Impossible where Ethan Hunt repels from the ceiling to hack the CIA computer system and steal the  “NOC list, “ to the lonely anti-social teen who is simply looking for entertainment.

Black Hat Hackers-

A black hat hacker, also known as a cracker or a dark side hacker (this last definition is a direct reference to the star Wars movies and the dark side of the force) is someone who uses his skills with a criminal intent.   Some examples are; cracking bank account in order to make transferences to their own account, stealing information to be sold in the black market, or attacking the computer network of an organization for money.

1.Jonathan James

James cracked into NASA computers, stealing software worth approximately $1.7 million. According to the department of justice, “the software supported the international space station’s physical environment, including control of the temperature and humidity within the living space. “NASA was forced to shut down its computer systems, ultimately racking up a $41,000 cost. James explained that the downloaded the code to supplement his studies on C programming, but connected”, the code itself was crappy… certainly not worth $ 1.7 million like they claimed”.

2.Adrian Lamo

Adrian Lamo around computers as a very young child. He had a commodore 64 when he was like 6 or so. And his first interest in seeing how things worked behind the scenes wasn’t all about technology necessarily, and his interest in what you might call hacking isn’t really primarily about technology… he said”  it’s not sexy when I’m exploring less obvious aspects of the world that don’t involve multibillion on-dollar corporations. There’s a certain amount of tunnel vision there.” Last year, Lamo earned the disapproval of his probation officer in the closing months of his two year probation term when he refused to provide a blood sample for the FBI’s DNA database. The combined DNA index system, or CODIS, was created to catalog violent criminals and sexual predators, but the 2004 justice for all act expanded the system to include samples from all newly convicted federal felons, including drug offenders and white-collar criminals.

3.Kevin Mitnick

Kevin David Mitnick (born august 6, 1963) is a computer security consultant and author. In the late 20th century, he was convicted of various computer-and communications-related crimes. At the time of his arrest, he was world-famous as the most-wanted computer criminal in the United States. Mitnick gained unauthorized access to his first computer network in 1979, at 16, when a friend gave him the phone number for the Ark, the computer system digital equipment corporation (DEC) used for developing their RSTS/E operating system software. He broke into DEC’s computer network and copied DEC’s software, a crime he was changed with and convicted of in 1988. He was sentenced to 12 months in prison followed by three years of supervised release. Near the end of his supervised release, Mitnick hacked into pacific bell voice mail computers.

After a warrant was issued for his arrest, Mitnick fled, becoming a fugitive for two and a half years. According to the U.S. department of justice, Mitnick gained unauthorized access to dozens of computer. Networks while he was a fugitive. He used cloned cellular phones to hide his location and, among other things, copied valuable proprietary software from some of the country’s largest cellular telephone and computer companies. Mitnick also intercepted and stole computer passwords, altered computer networks, and broke into and read private e-mail mitnick was apprehended in February 1995 in North Carolina. He was found with cloned cellular phones, more than 100 clone cellular phone codes, and multiple pieces of false identification.

4. Kevin Poulsen

Kevin Poulsen was among the most accomplished, multi-talented hackers. He worked for SRI international by day, and hacked at night under the handle “Dark Dante”. He trained to be the complete hacker, and even taught himself lock picking. Among other things, poulsen reactivated old yellow page escort telephone numbers for an acquaintance that then ran a virtual agency. When the FBI started pursuing poulsen, he went underground as a fugitive. When he was featured on NBC’s unsolved mysteries, the show’s 1-800 telephone lines mysteriously crashed. He was finally arrested in February, 1955.

Poulsen’s best known hack was a takeover of all of the telephone lines for los angeles radio station  KIIS-FM, guaranteeing that he would be the 102nd caller, and winning a Porsche 944 s2. In june 1994, poulsen pleaded guilty to seven counts of mail, wire and computer fraud, money laundering, and obstruction of justice, and was sentenced to 51 months in prison and ordered to pay $56,000 in restitution. It was the longer sentence ever given for hacking up to that time. He also later pleaded guilty to breaking into computers and obtaining information on undercover businesses run by the FBI.

5. Robert Tappan Morris

Morris, son of former national security agency scientist Robert morris, is known as the creator of the morris worm, the first computer worm to be unleashed on the internet. As a result of this crime, he was the first person prosecuted under the 1986 computer fraud and abuse act. Morris wrote the code for the worm while he was a student at cornell. He asserts that he intended to use it to see how large the internet was. The worm, however, replicated itself excessively, slowing computers down so that they were no longer usable. It is not possible to know exactly how many computers were affected, but experts estimate an impact of 6,000 machines. He was sentenced to three years probation, 400 hours of community service and a fined $10,500.

Upgrade windows 7 to any higher version

How to upgrade windows 7 to any higher version for free

You brought a new computer with a per-installed Starter/Home Premium/Professional(Genuine)versions of windows 7 and want to upgrade to Professional or Ultimate for free in as few as 10 minutes.

Your per-installed version of windows 7 actually includes all files that are necessary to perform an in-place local upgrade without downloading anything from the internet. One simply needs unlocking features included in higher versions.

Here’s what you need to do:

To upgrade from one edition of windows 7 to another edition of windows 7, use windows Anytime Upgrade. On your PC, open windows Anytime Upgrade by clicking the start button, typing windows ANYTIME upgrade in the search box, and then clicking Windows Anytime Upgrade in the list of results. You will be presented with a screen offering 2 options, one of the suggesting you have a valid Windows Anytime upgrade key.

Once the key has been copied into the appropriate field, it will be verified by MS and the upgrade process will take place. The whole process actually doesn't last longer than 10 minutes your computer will reboot once or twice. Upon restart, you will notice it now runs a genuine higher version of Windows 7.

You can use Windows anytime Upgrade to upgrade from a 32-bit version of windows 7 to a 32 bit version of windows 7  and from a 64 bit version of windows 7, but you can’t upgrade from a 32-bit version of Windows 7 to a 64-bit version of Windows 7 or vice versa.

Windows Anytime Upgrade isn't available in all editions of windows 7 –obviously not in Ultimate version

“Download Windows Anytime Upgrade key from here: HTTP;//u.to/Msek “   

How to secure your Wi – Fi connection...

•             Install a Firewall A firewall helps protect your pc by preventing unauthorized users from gaining access to your computer through the internet or a network. It acts as a barrier that checks any information coming from the internet or a network, and then either blocks the information or allows it to pass through to your computer.

•           Change the administrative password on your wireless routers each manufacture chips their wireless routers with a default password for easy initial access. These passwords are easy to find on vendor support sites, and should therefore be changed immediately.

•           Change the default SSID name and turn off SSID broadcasting this will require your wireless client computers to manually enter the name of your SSID (Service Set identifier) before they can connect to your network, greatly minimizing the damage from the casual user whose laptop is configured to connect to any available SSID broadcast it finds. You should also change the SSID name from the factory default, since these are just has well known has the default password.

•            Disable DHCP for a SOHO network with only a few computers consider disabling DHCP (dynamic host configuration protocol) on your router and assigning IP addresses to your client computers manually. On newer wireless routers you can even restrict access to the router to specific MAC address.

•            Replace WEP with WPA WEP (wired equivalent privacy) is a security protocol that was designed to provide a wireless computer network with a level of security and privacy comparable to what is usually expected of a wire computer network. WEP is a very week form of security that uses common 60 or 108 bit key shared among all of the devices on the network to encrypt the wireless data. Hackers can access tools freely available on the internet that can crack a WEP key in as little has 15 minutes. Once the WEP key is cracked, the network traffic instantly turns into clear text-making it easy for the hackers to treat the network like any open network. WPA (Wi-Fi protected access ) is a powerful, standards –based , interoperable security technology for wireless computer networks. It provides strong data protection by using 128-bit encryption keys and dynamic session keys to ensure a wireless computer network’s privacy and security, many cryptographers and confident that WPA address all the known attacks on WEP. It also adds strong user authentication which was absent in WEP.

10 reasons why PC’s crash ?...

Fatal error: the system has become unstable or is busy, “ it says .” Enter to return to windows or press control –Alt-Delete to restart your computer. If you do this you will lose any unsaved information in all open application”

You have just been struck by the blue screen of death. Anyone who uses Microsoft windows will be familiar with this. What can you do? More importantly, how can you prevent it happening?

1.       Hardware conflict-

The number one reason why window crashes is hardware conflict. Each hardware device communicates to other devices through an interrupted request channel (IRQ). These are supposed to be unique for each device.

For example, a printer usually connects internally on IRQ 7. The keyboard usually uses IRQ 1 and the floppy disk drive IRQ 6. Each device will try to hog a single IRQ for itself.

If there are a lot of devices, or if they are not installed properly, two of them may end up sharing the same IRQ number. When the user tries to use both devices at the same time, a crash can happen .The way to check if your computer has a hardware conflict is through the following route:

·         Start-Settings Control Panel-Device Manager.

Often if a device has a problem a yellow ‘!’ appears next to its description in the Device Manager. Highlight Computer (in the Device Manager) and press properties to see the IRQ numbers used by your computer.  If the IRQ number appears twice, two devise may be using it.

Sometimes a devise might share an IRQ with something described as IRQ holder for PCI steering ‘. This can be ignored the best way to fix this problem is to remove the problem devise and reinstall it.

Sometimes you may have to find more recent drivers on the internet to make the device function properly. A good resource is www.driverguide.com. If the device is a soundcard, or a modem, it can often be fixed by moving it to a different slot on the motherboard (be careful about opening your computer, as you may void the warranty).

When working inside a computer you should switch it off, unplug the mains lead and touch and unpainted metal surface to discharge any static electricity.

To be fair to Microsoft, the problem with IRQ numbers is not of its making. It is a legacy problem going back to the first PC designs using the IBM 8086 chip. Initially there were only eight IRQS. Today there are sixteen IRQs in a PC. It is easy to run out of them. There plans to increase the number of IRQS in feature designs

2.       Bad RAM-

RAM- (random-access memory) problem might bring on the blue screen of death with a message saying Fatal Exception Error. A fatal error indicates a serious hardware problem. Sometimes it may mean a part is damaged and will need replacing.

But a fatal error caused by ram might be caused by a mismatch of chips. For example, mixing 70-nanosecond (70ns) ram with 60ns ram will usually force the computer to run the entire ram at the slower speed. This will often crash the machine if the ram overworked.

One way around this problem is to entire BIOS settings and increases the wait state of the ram. This can make it more stable. Another way to trouble shoot a suspected Ram problem is to rearrange the ram chips on the motherboard, or take some of them out. Then try to repeat the circumstances that caused the crash. When handling Ram try not to touch the gold connections, as they can be easily damaged.

Parity error messages also refer to Ram. Modem Ram chips are either parity (ECC) or non parity (non-ECC). It is best not to mix the two types, as this can be a cause of trouble.

EMM386 error message s refer to memory problems but may not be connected bad Ram. This may be due to free memory problems often linked to old Dos-based programs.

3.       BIOS setting

               Every motherboard is supplied with a range of chipset settings that are decided in                                    the factory. A common way to access these settings is to press the F2 or delete button during the first few seconds of a boot-up.

Once inside the BIOS, great care should be taken. It is a good idea to write down on a piece of paper all the settings that appear on the screen. That way, if you change something and the computer becomes more unstable, you will know what setting to revert to.

A common BIOS error concerns the CAS latency. This refers to the ram. Older EDO (extended data out) ram has a CAs latency of 3. Newer SDRam has a CAS latency of 2. Setting the wrong figure can cause the Ram to lock up and freeze the computer’s display.

Microsoft windows is better at allocating IRQ numbers than any BIOS. If possible set the IRQ numbers to auto in the BIOS. This will allow windows to allocate the IRQ numbers (make sure the BIOS setting for plug and play BIos is switched to ‘yes’ to allow windows to do this)

4.       Hard disk drives-

After a few weeks, the information on a hard disk drive starts to become piecemeal or fragmented. It is a good idea to defragment the hard disk every week or so, to prevent the disk from causing a screen freeze. Go to

Start-programs-Accessories-System Tools-Disk Defragmenter

This will start the procedure. You will be unable to write data to the hard drive (to save it ) while the disk is defragmenting, so it is a good idea to schedule the procedure for a period of inactivity using the task scheduler.

The task scheduler should be one of the small icons on the bottom right of the windows opening page (the desktop).

Some lockups and screen freezes caused by hard disk problems can be solved by reducing the read-ahead optimization. This can be adjusted by going to

Start-settings-control panel-system icon-performance-file system-hard disk

Hard disk will slow down and crash if they are too full. Do some housekeeping on your hard drive every few months and free some space on it. Open the windows folder on the C drive and find the temporary internet files folder. Deleting the contents (not the folder ) can free a lot of space

Empty the recycle bin every week to free more space. Hard disk drives should be scanned every week for errors or bad sectors. Go to

Start-programs-accessories=system tools-scandisk

Otherwise assign the task scheduler to perform this operation at night when the computer is not in use.

5.       Fatal OE exceptions and VXD errors-

Fatal OE exception errors and VXD errors are often caused by video card problems.

These can often be resolved easily by reducing the resolution of the video display. Go to

Start-settings-control panel-Display-settings

Here you should slide the screen area bar to the left. Take a look at the color settings on the left of that window. For most desktops, high color 16-bit depth is adequate.

If the screen freezes or you experience system lockups it might be due to the video card. Make sure it does not have a hardware conflict. Go to

Start-settings-control panel-system-device manager

Here, select the + beside Display Adapter. A line of text describing your video card should appear. Select it (make it blue) and press properties. Then select resources and select each line in the window. Look for a message that says NO conflicts.

If you have video card hardware conflict, you will see it here. Be careful at this point and make a note of everything you do in case you make things worse.

The way to resolve a hardware conflict is to uncheck the use automatic settings box and hit the change settings button. You are searching for a setting that will display a no conflicts message.

Another useful way to resolve video problems is to go to

Start-settings-control panel-system-performance-graphics

Here you should move the hardware acceleration slider to the left. As ever, the most common cause of problems relating to graphics card is old or faulty drivers (a driver is a small piece of software used by a computer to communicate with a device).

Look up your video card’s manufacture on the internet and search for the most recent drivers for it.

6.       Viruses-

Often the first sign of a virus infection is instability. Some viruses erase the boot sector of a hard drive, making it impossible to start. This is why it is a good idea to create a window start-up disk. Go to

Start-settings-control panel-Add/Remove programs

Here, look for the start up disk tab. Virus protection requires constant vigilance.

A virus scanner requires a list of virus signatures in order to be able to identify viruses. These signatures are stored in a DAT file. DAT files should be updated weekly from the website of your antivirus software manufacture.

An excellent antivirus program is MCAfee virus scan by network associates (www.nai.com). Another is Norton antivirus 2000, made by Symantec (www.symantec.com).

7.       Printers-

The action of sending a document to print creates a bigger file, often called a postscript file.

Printers have only a small amount of memory, called a buffer. This can be easily overloaded. Printing a document also uses a considerable amount of CPU power. This will also slow down the computer’s performance.

If the printer is trying to print unusual characters, these might not be recognised, and can crash the computer. Sometimes printers will not recover from a crash because of confusion in the buffer. A good way to clear the buffer is to unplug the printer for ten seconds. Booting up from a powerless state, also called a cold boot, will restore the printer’s default settings and you may be able to carry on.

8.       Softwares-

A common cause of computer crash is faulty or badly-installed software. Often the problem can be cured by uninstalling the software and then re installing it. Use Norton uninstall or uninstall shield to remove an application from your system properly. This will also remove references to the programme in the system registry and leaves the way clear for a completely fresh copy.

The system registry can be corrupted by old references to obsolete software that you thought was uninstalled. Use Reg cleaner by jouni  vuorio to clean up the system registry and remove obsolete entries. It works on Windows 95, windows 98, windows 98 SE (second edition), windows millennium edition (ME), NT4 and windows 2000.

Read the instructions and use it carefully so you don’t do permanent damage to the registry. If the registry is damaged you will have to re install your operating system. Reg cleaner can be obtained from www.jv16.org

Often a windows problem can be resolved by entering safe mode. This can be done during start-up. When you see the message “starting windows” press F4. This should take you into safe mode.

Safe mode loads a minimum of drivers. It allows you to find and fix problems that prevent windows from loading properly.

Sometimes installing windows is difficult because of unsuitable BIOS settings. If you keep getting SUWIN error messages (window setup) during the windows installation, then try entering the BIOS and disabling the CPU internal cache. Try to disable the level 2 (L2) cache if that doesn't work.

Remember to restore all the BIOS settings back to their former setting following installation.

9.       Overheating-

Central processing units (CPUs) are usually equipped with fans to keep them cool. If the fan fails or if the CPU gets old it may start to overheat and generate a particular kind of error called a kernel error. This is a common problem in chips that have been over clocked to operate at higher speeds than they are supposed to.

One remedy is to get a bigger better fan and install it on top of the CPU. Specialist cooling fans/heat sinks are available from www.computernerd.com or www.coolit.com

CPU problems can often be fixed by disabling the CPU internal cache in the BIOS. This will make the machine run more slowly, but it should also be more stable. 

10.   Power supply problem-

With all the new construction going on around the country the steady supply of electricity has becomes disrupted. A power surge or spike can crash a computer as easily as a power out

If this become a nuisance for you then consider buying a uninterrupted power supply(UPS). This will give you a clean power supply when  there is electricity, and it will give you a few minutes to perform a controlled shutdown in case of a power out

It is a good investment if your data are critical, because a power cut will cause any unsaved data to be lost.

What Is MD5 Hash & How to Use It?...

  

In this post I will explain about an interesting cryptographic algorithm called MDS (message-digest algorithm 5). This algorithm is mainly used to perform file integrity checks under most circumstances. Here I will not jump into the technical aspects of this algorithm, rather will tell you about how to use of this algorithm in your daily life. Before I tell you about how to use MD5, I would like to share one of my recent experiences which made me start using MD file algorithm. Recently I made significant change and updates to my website and has obvious I generated a complete backup of the site on my server. I downloaded this backup on to my PC and deleted the original one on the server. But after a few days something went wrong and I wanted to restore the backup that I downloaded. When I tried to restore the backup I was shocked! The backup file that I used to restore was corrupted. That means, the backup file that I downloaded on to my PC wasn’t exactly the one that was on my server. The reason is that there occurred some data loss during download process. Yes, this data loss can happen often when a file is downloaded from the internet. The file can be corrupted due to any of the following reasons.

Ø  Data loss during the download process, due to instability in the internet connection /server

Ø  The file can be tampered due to virus infection or,

Ø  Due to hacker attacks

So whenever you download any valuable data from the internet it is completely necessary that you check the integrity of the downloaded file. That is need to ensure that the downloaded file is exactly the same as that of the original one. In this scenario the MD5 hash can become handy. All you have to do is generate MD5 hash (or MD5 check-sum) for the intended file on your server. After you download the file on to your PC, again generate MD5 hash for the downloaded file compare this to hashes and if it matches then it means that the file is downloaded perfectly without any data loss.

A MD5 hash is nothing but a 32 digits hexadecimal number which can be something has follows

A simple MD5 Hash

e4d909c290d0fb1ca068ffaddf22cbd0

this hash is unique for every file irrespective of its size and type. That means two.exe files with the same size will not have the same MD5 hash even though they are of same type and size. So MD5 hash can be used uniquely identified a file.

How to use MD5 Hash to check the Integrity of Files?

Suppose you have a file called backup. Tar on your server. Before you download, you need to generate MD5 hash for this file on server. To do so use the following command.

For UNIX  

md5sumbackup.tar

When you hit ENTER you’ll see something has follows

e4d909c290d0fb1ca068ffaddf22cbd0

This is the MD5 hash for the file backup.tar. After you download this file onto your PC, you can cross check it’s integrity by gain re-generating MD5 hash for the downloaded file. If both the hash matches then it means that the file is perfect. Otherwise it means that the file is corrupted. To generate the MD5 hash for the downloaded file on your windows PC use the following freeware tool.

“you can Download  MD5 Summer Form Here: http://www.md5summer.org/downloadhtml”

What Are Key Loggers?..

Key loggers definition

Keyloggers is a software program or hardware device that is used to monitor and log each of the keys a user types in to a computer keyboard.

The user who installed the program or hardware device can then view all keys typed in by that user. Because this programs and hardware devices monitor the keys typed in user can easily find user password and other information a user may not wish others to know about.

Keyloggers, as a surveillance tool, are often used by employers to ensure employers use work computers for business purposes only.

Unfortunately, key loggers can also be embedded in spyware allowing your information to be transmitted to an unknown third party.

About keyloggers

A keylogger is a program that’s runs in the background, recording all the keystrokes.

Once keystrokes are logged, they are hidden in the machine for later retrieval, or shipped raw to the attacker. The attacker then peruses then carefully in the hopes of either finding passwords, or possibly other useful information that could be used to compromise the system or be used in a social engineering attack. For example, a keylogger will reveal the contents of all e-mail composed by the user. Keylogger is commonly included in rootkits.

A keylogger normally consists of two files: a DLL which does all the work and an EXE which loads the DLL and sets the hook. Therefore when you deploy the hooker on a system, two such files must be presented in the same directory.

There are other approaches to capturing info about what you are doing.

·         Some keyloggers capture screens, rather than keystokes.

·         Other keyloggers will secretly trun on video or audio recorders, and transmit what they capture over your internet connection.

 Akeyloggers might be as an exe and a dll that are placed on a machine and invoked at boot via an entry in the registry. Or a keyloggers could be which boastes this features

·         Stealth “invisible in process list

·         Includes kernel keylogger driver that captures keystrokes even when user is logged of(windows 2000 / XP)

·         ProBot program files and registry entries are hidden( windows 2000 / XP)

·         Includes remote deployment wizard

·         Active window titles and process names logging

·         Keystrokes / password logging

·         Regional keyboard support

·         Keylogging in NT console windows

·         Launched applications list

·         Text snapshots of active applications

·         Visited internet URL logger

·         Capture HTTP post data ( including logins / passwords)

·         File and folder creations / removal logging

·         Mouse activities

·          Workstation user and timestamp recording

·         Log file archiving, separate log files for each user

·         Log files secure encryption

·         Password authentication

·         Invisible operation

·         Native GUI session log presentation

·          Easy log file reports with instant viewer 2 web interface

·         HTML and text log file export

·         Automatic email log file delivery

·         Easy setup and install wizard

·         Support for windows (R) 95/98/ME and windows (R) NT/2000/XP

Because a keylogger can involves dozens of files, and has as a primary goal complete stealth from the user, removing one manually can be terrifying challenge any computer user. Incorrect removal effort can result in damage to the operating system, instability, inability to use the mouse or keyboard, or worse. Further, some keyloggers will survive manual efforts to remove them, reinstalling them self before the user even reboots.

Some Famous key loggers.

1.      Actual spy.

“You can download actual spy from here: http://u.to/tCWk”.

2.      Golden keylogger

“You can download golden keylogger from here: http://u.to/0iWk”.

3.      Remote key logger

“You can download remote keylogger from here: http://u.to/3iWk”.