Archive for the ‘Computer’ Category

How different Linux distros are related?

2013/07/29

If you are new to Linux, you may be confused with so many different Linux distros (i.e. flavors) available.

Following hierarchy chart will help you to understand the relationship between them.

This chart is prepared based on how each distro manages its software installation (similar to add/remove programs in Windows). Note that 2 most common flavors are Debian and Red Hat (RPM). Many popular Linux distros are derived from it.

 

Linux Tree

There can be separate classification based on front end (or user interface) where same distro can use different interfaces like Gnome etc.

If you have never used Linux before and want to test the experience, I suggest you try any of the following (in no particular order).

  • Ubuntu (or any of its flavors)
  • Mint (may have issues with AMD computers)
  • Fedora (easy to run from USB)
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How bitcoin works?

2013/06/24

Bitcoin is a virtual currency. In real currency, you have notes and coins which you can exchange for goods or services.

Bitcoin is a string of characters like 31uEbMgunupShBVTewXjtqbBv5MndwfXhb, (the real bitcoin is different, but lets assume it for the sake of argument).

There is an algorithm (not secret) which validates whether a bitcoin string is valid or not and whether it has been used previously (in other transactions or not). This transaction ledger is known as blockchain (analogous to a bank account or credit card statement).

You must have bought goods with your credit card. When placing order online, the merchandiser establishes a connection with the bank to validate your card is valid and has enough credit to spend.

In a similar fashion, for each bitcoin transaction, a bitcoin bank (some designated computer servers) validates the bitcoin string you are using and ensures it has not been used before.

So how bitcoins are generated? One needs a massive amount of processing power (thus multiple computers connected together) to generate a new bitcoin (i.e. to generate a string which is valid as per bitcoin algorithm). This process is called mining. The bitcoin algorithm suggests that only 21 million strings can be generated which will be a valid bitcoin. So far 50% of those have already been generated. The rest 50% is expected to be generated in next 5-10 years.

Just like you stash cash in your wallet, bitcoins are stored in a digital wallet. If not careful, your cash may be stolen and someone can use it on for their own purchase. In a similar fashion, if you don’t guard your digital wallet, someone can steal your bitcoins! Bitcoin wallets have addresses (like your Paypal address is your email etc.) like this one – 1JArS6jzE3AJ9sZ3aFij1BmTcpFGgN86hA. When transacting with bitcoin, one must send a bitcoins to receiver’s valid wallet address. However, to prevent someone stealing your coins, there is a safeguard concept called private key. You can say this is like a real key to your chest. If someone has the key, he/she can open your chest and get all your money (i.e. bitcoins) out.

The bitcoin addresses can be calculated from private key but not the other way round. So it is important that you do not lose your bitcoin private key!

Buying and selling bitcoin is similar to buying/selling any other currency. Its exchange rate also fluctuates like any real currency.

Why Microsoft created Windows 8 Metro interface?

2013/04/21

There was nothing wrong as such in Windows 7. However, unless businesses can make working things obsolete via upgrade to newer versions they won’t make enough money!

So Microsoft introduced Windows 8. However, unlike previous versions of Windows, they tried to force new Metro interface which is more suitable for touch screen devices. Most users were unhappy and wanted to revert to Windows 7 like interface. But why Microsoft introduced it in first place?

Metro and legacy Windows applications are not compatible. An app designed for Metro interface won’t run in traditional Windows environment. Metro apps can only be downloaded via Windows Marketplace. Now this is a very crucial difference. In earlier Windows, you could download apps from literally millions of websites. However, in Metro interface, your only option is Windows market place. This is similar to Apple’s AppStore concept. Microsoft did at because they wanted to capture 30% of all app sales. They can only do it if those apps are sold using their own app store only.

The trouble for Microsoft started when consumers did not like Windows 8. In fact various statistics show PC sales have been slowed down because consumers shunned Windows 8. Now Microsoft is caught between devil and deep sea. Backtracking from their Metro interface means potential loss of profit in future and acceptant strategic failure. However, if they continue to force Windows 8 Metro interface to consumers they may face continued backlash.

This is also the reason why Microsoft does not offer any option to start Windows 8 straight into legacy desktop! Because they want consumers to adopt their new Metro interface. Some consumers are using third oath apps to make Windows 8 behave like Windows 7.

But now you know why Microsoft did not offer these simple options themselves!

How does Microsoft verify whether your Windows copy is genuine?

2012/07/25

For retail version of Windows, usually you can install it on a single computer at same time. With each retail version of Windows, you are provided a license key. When you activate your copy of Windows, Microsoft checks against their database to verify whether it is a valid license key and whether it has been used before.

If it is valid and key has not been used before (it also takes a note of computer’s configuration), it will activate the copy of Windows without any problem. However, if you use same Windows DVD to install another copy in second computer, it will see that same license key has already been activated. So now it will flag both copies of Windows as non-genuine!

What if your computer crashes and you want to install it in second computer? Then you can call Microsoft support and explain the situation. Then they will reset the license key as not used so that you can install Windows on second computer. However, if your original computer did not crash (and you lied as it crashed) then very soon it will flag up in Microsoft’s database (Windows service packs contain codes to talk with Microsoft over the web) as being used in more computers than its license term allows. So Microsoft will flag them as non-genuine!

When you buy new computer, Windows usually come as preloaded and pre-activated. So more often than not, this Windows activation is transparent to you. Microsoft charges the Original Equipment Manufacturers (i.e. OEM or your computer makers) a fee for supplying Windows which is included in retail price. So, you don’t really get free copies of Windows with your new laptop!

How do hackers develop bootleg copies of Windows then?

There are various way to hack this but the most common one is to patch the license checking module. A well known hack RemoveWAT (i.e. Remove Windows Activation Technology) simply makes this module as inaccessible. When Microsoft’s genuine Windows check code block tries to execute, this patch feeds them to believe everything is in place and there is nothing to check for them. There is another hack called 7Loader, which (when executed over a non-genuine Windows version) makes Windows believe that installed version was by OEM and hence Windows activates it permanently.

The hacking process is a cat-and-mouse game between hackers and Microsoft. Once a patch works, Microsoft finds a way to defeat it, then hackers find another way to make it work again and this process goes on.

Some versions of Windows do have have genuine checking in same way. This is especially true for corporate multi-PC licenses.

Disclaimer: This article is for informational purpose only and does not encourage to bypass Windows Genuine Advantage checking.

Why do people think Windows 8 will be bad?

2012/07/24

Within next few months, Windows 8 will be available to retail consumers. It is very likely that all new computers will come with preinstalled Windows 8.

Most people is actually not looking forward to Windows 8. This is because Microsoft is making some big changes to their new operating system!

So what exactly are the changes?

For the first time, Windows will have 2 different flavors. One is traditional Windows 7/XP/Vista like appearance which is now known as legacy interface and the other one is new Metro interface.

It is the Metro interface which may cause problem to users! This is more suitable for touch screen tablet devices rather than PCs. So far, all Windows have been mostly backward compatible i.e. programs for older version of Windows worked in newer versions of Windows [with few exceptions].

But the new Metro interface will be a totally new environment. It looks similar to Apple’s Mac OS/iOS interface to a great extent. For example, you don’t close programs in traditional sense. ¬†Windows will auto close them depending on memory load.

Also some Microsoft development tools will now work only for Metro interface. For example free version of Visual Studio can be used to develop applications for Metro only.

Although you can still get traditional interface via legacy mode, Microsoft has removed Start button and you have to use Charm bar instead! But don’t worry – you can get back Start button via some 3rd party apps.

Business users are naturally not looking forward to Windows 8.

 

32-bit vs 64-bit computer

2012/07/24

Windows Vista or Windows 7 are available as either 32-bit or 64-bit versions.

Most computers nowadays come with pre-installed version of 64-bit Windows.

But how does it affect consumers?

First let us understand what is the difference between 32 & 64-bit applications.

As 64 is twice of 32, a 64-bit system will handle double the amount of RAM at the same time. Thus, theoretically a 64-bit system will handle twice the amount of data compared to a 32-bit system. You can assume that these are like pipes for carrying water (= data). The 64-bit system is like having 2 32-bit pipes which can carry twice the amount of water than a single 32-bit pipe.

If you are using a complex number crunching operation, 64-bit will outperform 32-bit almost twice as much. However, if you are writing a letter to your mother in Word, you can hardly feel the advantage of 64-bit over 32-bit.

Usually, applications written for 32-bit (most common) will run fine on 64-bit (but the opposite is not true) except applications like anti virus, device driver etc. which may or may not work correctly. For this reason, you may discover your old peripheral no longer works with your new computer.

You cannot install 64-bit operating system in your computer unless your CPU is also 64-bit (or higher like 128-bit).

If you buy computer from large retailers, you often won’t have a choice of which version of Windows you want to install as these will be pre-installed for you.

Easiest way to encrypt your data in your computer

2012/06/30

There are many ways to encrypt your data in the computer. You can use specific applications to encrypt files. But the process described here is free and easy to use.

Download (Truecrypt) and install it. Then create a container file of fixed size for example myfile.tc which will hold a complete file system inside it.

You will be asked to create a password using which your container file will be mounted as a disk drive. Use a string and long password.

If you look at your container file outside Truecrypt, it will appear as a normal file. However, when you mount it via Truecrypt, it will just appear as a separate drive like F:\ or Z:\ based on which drive letter you specified during mounting.

Once the container is mounted as a drive, you can just use it like any standard drive. All encryption will be transparent to you. If you want to hide the container from prying eyes, you just need to dismount it using Truecrypt.

How strong is Truecrypt encryption? Well, research showed that if you use a strong password even FBI could not decrypt it.

Lorem ipsum dolor sit amet

2012/06/23

You might have seen this garbled message is many template documents. This is used as placeholder text to show how a document template will look like when filled with text.

The message is entirely meaningless. This text is used instead of any meaningful text so that users concentrate on the actual layout of the document and does not get distracted by what is written on the text.

The full text for is is given below.

Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Nam cursus. Morbi ut mi. Nullam enim leo, egestas id, condimentum at, laoreet mattis, massa. Sed eleifend nonummy diam. Praesent mauris ante, elementum et, bibendum at, posuere sit amet, nibh. Duis tincidunt lectus quis dui viverra vestibulum. Suspendisse vulputate aliquam dui. Nulla elementum dui ut augue. Aliquam vehicula mi at mauris. Maecenas placerat, nisl at consequat rhoncus, sem nunc gravida justo, quis eleifend arcu velit quis lacus. Morbi magna magna, tincidunt a, mattis non, imperdiet vitae, tellus. Sed odio est, auctor ac, sollicitudin in, consequat vitae, orci. Fusce id felis. Vivamus sollicitudin metus eget eros.
Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. In posuere felis nec tortor. Pellentesque faucibus. Ut accumsan ultricies elit. Maecenas at justo id velit placerat molestie. Donec dictum lectus non odio. Cras a ante vitae enim iaculis aliquam. Mauris nunc quam, venenatis nec, euismod sit amet, egestas placerat, est. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Cras id elit. Integer quis urna. Ut ante enim, dapibus malesuada, fringilla eu, condimentum quis, tellus. Aenean porttitor eros vel dolor. Donec convallis pede venenatis nibh. Duis quam. Nam eget lacus. Aliquam erat volutpat. Quisque dignissim congue leo.
Mauris vel lacus vitae felis vestibulum volutpat. Etiam est nunc, venenatis in, tristique eu, imperdiet ac, nisl. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. In iaculis facilisis massa. Etiam eu urna. Sed porta. Suspendisse quam leo, molestie sed, luctus quis, feugiat in, pede. Fusce tellus. Sed metus augue, convallis et, vehicula ut, pulvinar eu, ante. Integer orci tellus, tristique vitae, consequat nec, porta vel, lectus. Nulla sit amet diam. Duis non nunc. Nulla rhoncus dictum metus. Curabitur tristique mi condimentum orci. Phasellus pellentesque aliquam enim. Proin dui lectus, cursus eu, mattis laoreet, viverra sit amet, quam. Curabitur vel dolor ultrices ipsum dictum tristique. Praesent vitae lacus. Ut velit enim, vestibulum non, fermentum nec, hendrerit quis, leo. Pellentesque rutrum malesuada neque.
Nunc tempus felis vitae urna. Vivamus porttitor, neque at volutpat rutrum, purus nisi eleifend libero, a tempus libero lectus feugiat felis. Morbi diam mauris, viverra in, gravida eu, mattis in, ante. Morbi eget arcu. Morbi porta, libero id ullamcorper nonummy, nibh ligula pulvinar metus, eget consectetuer augue nisi quis lacus. Ut ac mi quis lacus mollis aliquam. Curabitur iaculis tempus eros. Curabitur vel mi sit amet magna malesuada ultrices. Ut nisi erat, fermentum vel, congue id, euismod in, elit. Fusce ultricies, orci ac feugiat suscipit, leo massa sodales velit, et scelerisque mi tortor at ipsum. Proin orci odio, commodo ac, gravida non, tristique vel, tellus. Pellentesque nibh libero, ultricies eu, sagittis non, mollis sed, justo. Praesent metus ipsum, pulvinar pulvinar, porta id, fringilla at, est.
Phasellus felis dolor, scelerisque a, tempus eget, lobortis id, libero. Donec scelerisque leo ac risus. Praesent sit amet est. In dictum, dolor eu dictum porttitor, enim felis viverra mi, eget luctus massa purus quis odio. Etiam nulla massa, pharetra facilisis, volutpat in, imperdiet sit amet, sem. Aliquam nec erat at purus cursus interdum. Vestibulum ligula augue, bibendum accumsan, vestibulum ut, commodo a, mi. Morbi ornare gravida elit. Integer congue, augue et malesuada iaculis, ipsum dui aliquet felis, at cursus magna nisl nec elit. Donec iaculis diam a nisi accumsan viverra. Duis sed tellus et tortor vestibulum gravida. Praesent elementum elit at tellus. Curabitur metus ipsum, luctus eu, malesuada ut, tincidunt sed, diam. Donec quis mi sed magna hendrerit accumsan. Suspendisse risus nibh, ultricies eu, volutpat non, condimentum hendrerit, augue. Etiam eleifend, metus vitae adipiscing semper, mauris ipsum iaculis elit, congue gravida elit mi egestas orci. Curabitur pede.
Maecenas aliquet velit vel turpis. Mauris neque metus, malesuada nec, ultricies sit amet, porttitor mattis, enim. In massa libero, interdum nec, interdum vel, blandit sed, nulla. In ullamcorper, est eget tempor cursus, neque mi consectetuer mi, a ultricies massa est sed nisl. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos hymenaeos. Proin nulla arcu, nonummy luctus, dictum eget, fermentum et, lorem. Nunc porta convallis pede.

Why iOS applications do not offer time limited trial version?

2012/05/28

In Windows environment, many applications offer time limited trial version after which the software is disabled or feature restricted. But in Apple’s iPhone or iPad, you can’t find similar apps. You can get feature limited apps but nothing based on time trial.

 

This is down to the fact how iOS was designed. In Windows, you have a registry where every application can write something. But in iOS, each application runs within its sandbox. It can’t access anything outside its sandbox. When an app is deleted, all traces of the app is just gone from the device (although Appstore remembers that you installed the app so that it won’t charge you next time). So iOS apps are unable to access anything outside their own sandboxes. This is also good for preventing any malware as damage is minimal and once app is removed, nothing to worry about.

 

In Windows since any application can mess with registry, any rogue application can create lots of trouble. Microsoft addressed this issue in later version of Windows (Windows Vista upward) where one needs admin password to update some system areas.

 

The sandbox design does create a problem though. In Windows, say you have a document file. You can either open it using Microsoft Word or Open Office Writer. Both applications can access your file wherever you kept it in your file system. But in iOS, each app can only access documents within its own sandbox. Thus, in iOS, you must have local copies of your data file specific to each app.

 

What your ISP can see?

2012/05/26

What your ISP (Internet Service Provider) knows about you?

Well, they know a lot. Usually they don’t examine your web browsing log unless there is a specific reason for it (like information request from police etc.)

They can track what websites you visited, what files you uploaded/downloaded to/from where. However, if your files are encrypted, they cannot examine the content.

However, they cannot see any information you transfer via https sites. For example, when you connect to your bank via https sites, they can’t see your password, account statement etc. Although they can still track which bank you connected to. This is analogous to what your phone operator sees. They can check what number you dialed but may not necessarily interpret what you talked over phone.

If you connect via proxy server, they can see that you connected to a proxy server but can’t track what you are doing after connecting to that proxy. Any browsing you do thru proxy is not visible to your ISP. Same goes for VPN. Once you are connected to VPN (note that ISP sees that you connected to a VPN) anything you do inside VPN is not visible to ISP.

If you use any anonymous IP address altering software, your ISP can see that. But any website you visit, they see your fictitious IP address.

Your computer also keeps lots of information about your browsing – unless you always browse in private mode.