What is Cyber Crimes

Cyber crime is a criminal activity committed on the internet.Cyber crime includes data diddling, logic bombing, malicious hacking.Cybercrimes committed against persons include various crimes like transmission of child-pornography, harassment of any one with the use of a computer such as e-mail. The trafficking, distribution, posting, and dissemination of obscene material including pornography and indecent exposure, constitutes one of the most important cybercrimes known today.


Forms of cyber crime:-

1. Cracking -  is amongst the gravest Cyber-crimes known till date. It is a dreadful feeling to know that a stranger has broken into your computer systems without your knowledge and consent and has tampered with precious confidential data and information.


2. Hacking - the act of gaining unauthorized access to a computer system or network and in some cases making unauthorized use of this access.


3. Piracy - the act of copying copyrighted material. The personal computer and the Internet both offer new mediums for committing an 'old' crime. Online theft is defined as any type of 'piracy' that involves the use of the Internet to market or distribute creative works protected by copyright.


4. Cyberstalking - Harassment, bullying and "stalking" persons on the Internet can occur on social networks. It frequently involves repeated and unwelcome contact with the victim by the stalker Harassment, in chatrooms or other Internet social networking sites.
 

5. Denial of service – running a program which sends thousands of requests to a site simultaneously, frequently from more than one source, so that the relevant server slows down considerably or preferably crashes.


6. Spamming - Spamming is the act of sending unsolicited messages to many users at a time, possibly up to thousands, with the usual intention of advertising products to potential customers. Spamming can also be used as a form of irritation by singling out an email address and sending the owner of that address hundreds of emails per second.

What is CRYPTOGRAPHY

Cryptography is the science or study of the techniques of secret writing, especially code and cipher systems.cryptography is now a core part of modern commerce, it is often regarded as a "black art".Today, most cryptography is digital, and the original text ("plaintext") is turned into a coded equivalent called "ciphertext" via an encryption algorithm. The ciphertext is decrypted at the receiving end and turned back into plaintext.Cryptography ensures message security over internet.

Types of Cryptography :-

1. Cryptographic checksums - Checksums help prevent undetected modification of information by encrypting the checksum in a way that makes the checksum unique.

2. Steganography - Steganography is actually the science of hiding information from people who would snoop on you. The difference between this and encryption is that the would-be snoopers may not be able to tell there's any hidden information in the first place.

3. Secret key cryptography - In secret key cryptography a single key is used for both encryption and decryption.A sender uses the key to encrypt the plain text and sends cipher key to the reciever.The reciever applies the same key

to recover the plain text.

4. Hash functions - Hash functions are also called message digests , they are algorithms without any key.A fixed length hash value is computed based upon the plain text to be recovered.Hash functions are used to provide a digital fingerprint of a file's contents to ensure that if the file has been altered by virus

What is GNU

GNU stands for Genuinely Not Unix. It is a Unix-like computer operating system developed by the GNU Project. It is composed wholly of free software. Unlike Linux, it sports the GNU Hard kernel and is intented to be a "complete Unix-compatible software system Development of GNU was initiated by Richard Stallman in 1983 and was the original focus of the Free Software Foundation.The GNU Project recommends that contributors assign the copyright for GNU packages to the Free Software Foundation  , though the Free Software Foundation considers it acceptable to release small changes to an existing project to the public domain.However, this is not required; package maintainers may retain copyright to the GNU packages they maintain, though since only the copyright holder may enforce the license used (such as the GNU GPL), the copyright holder in this case enforces it rather than the Free Software Foundation.
For the software developed under the GNU Project, Stallman wrote a license called the GNU General Public License (first called Emacs General Public License), with the goal to guarantee users freedom to share and change free software.It is also the most commonly used free software license.

Richard Stallman is operating it.

Open Source License

An open source license is a copyright license for computer software that makes the source code available for everyone to use. This allows end users to review and modify the source code for their own customization and/or troubleshooting needs. Open-source licenses are also commonly free, allowing for modification, redistribution, and commercial use without having to pay the original author. All such licenses usually have additional restrictions such as a requirement to preserve the name of the authors and a copyright statement within the code. One popular set of free open-source software licenses are those approved by the Open Source Initiative (OSI) based on their Open Source Definition (OSD).

Command line short cuts in Centos

Desktop and command line short cuts in CENTOS


[Ctrl] + [Alt] + [Backspace] = kills your current X session. Kills your graphical desktop session and returns you to the login screen. Use this if the
 normal exit procedure does not work.

[Alt] + F2 = Show the panel run application dialog 

[Ctrl] + [Alt] + [Delete] = From a non-graphical shell prompt, shuts down your Red Hat Enterprise Linux system. Use only when the normal shutdown procedure does not work. In a graphical desktop session, this shortcut displays the desktop logout screen that allows you to logout, reboot, or shut down your system.

[Ctrl] + [Alt] + [Fn] = switches screens. [Ctrl]+[Alt] + one of the function keys displays an available screen. By default, [F1] through [F6] are text-mode shell prompt screens and [F7] is the graphical desktop screen.

[Alt] + [Tab] = switches tasks in a graphical desktop environment. If you have more than one application open at a time, you can use [Alt] + [Tab] to switch among open tasks and applications. 

[Ctrl] + [a] = moves cursor to the beginning of a line. This works in most text editors and in the URL field in Mozilla.

[Ctrl] + [d] = logout of (and close) shell prompt. Use this quick shortcut instead of typing exit or logout.

[Ctrl] + [e] = moves cursor to end of a line. This works in most text editors and in the URL field in Mozilla.

[Ctrl] + [l] = clears the terminal. This shortcut does the same thing as typing clear at a command line.

[Ctrl] + [u] = clears the current line. If you are working in a terminal, use this shortcut to clear the current line from the cursor all the way to the beginning of the line. 

[Tab] = command autocomplete. Use this command when using a shell prompt. Type the first few characters of a command or filename and then press the [Tab] key. It will automatically complete the command or show all commands that match the characters you typed.

[Up] and [Down] Arrow = shows command history. When using a shell prompt, press the [up] or [down] arrow to scroll through a history of commands you have typed from the current directory. When you see the command you want to use, press [Enter]. 

[!!] = Repeat Last Command

[Alt] + [f] = Move the cursor to the end of the next word. Again, like with all shortcuts that use Alt as the modifier, this may not work in all graphical terminal emulators

[Ctrl] +[w] = Delete the word before the cursor.

[Ctrl] + [k] = Delete the line from the position of the cursor to the end of the line.

[Alt] + [b] = Move the cursor to the beginning of the current or previous word. Note that while this works in virtual terminals, it may not work in all graphical terminal emulators, because many graphical applications already use this as a menu shortcut by default.

Job scope for girls in computer science

When it comes to the computer science and technology industry, girls are an endangered species.College-aged women are realizing the opportunity that awaits them in the computer science field, even though it has been traditionally male-dominated. However, the field is growing rapidly and more minds than ever are needed to keep up with the demand.

  Demand for web designing positions tends to stay consistent, even during recessions.It has been researched in U.S that girls are more interested in the creative side, while boys are more interested in the competitive side.So the girls can use their creative mind in web development/designing viz. PHP.

 They need to do a PHP course. It includes loads of practical application-building exercises and real-life examples.

     PHP  contents:- 

1.Essential PHP elements: language structure, data types, operators, application design

2.Strings and Functions.

3.Control Statement.

4.PHP with (X)HTML

5.HTTP & HTTPS

6.Forms

7.Cookies and Sessions

8.Files management & Uploading to Server.

9.MySQL Integration.

What is Web Hosting

Web hosting is a service that allows organizations and individuals to submit a website or a web page on the Internet.The task of a web hosting provider is to provide the services required for a web site to be seen and accessed on the internet.

In the whole process ,servers are used to store and host web sites and web pages.Web hosting is designed to communicate between servers and users.To obtain space in a web hosting environment you become a member and agree to terms and conditions of renting the space - just as if you were to rent a house or commercial premises for your business.Once you agree and become a member, you are given an access code, a key, to your piece of cyberspace. This key, in the form of a login and password, allows you to connect to the web hosting server and upload your web site so it can be accessed on the internet.


Web hosting was quite simple in the beginning but it has now become more complex.The advent of audio-visual applications has added great freedom of entertainment to web hosting world.


Our company is the business of web hosting , there are some advantages which we give while hosting sites to our clients :-

1. Maximum space - We would provide an enormous space for the site so that the owner does not face any difficulty while uploading his content.


2. Less cost - We charge very nominal fees for hosting a site.


3. Quick service -  The navigation of web pages of the hosted site will be very quick because we offer a high bandwidth.


4. Web security - Security will be set up correctly on that site to prevent hacking so that any hacker cannot steal the confidential data of our clients.The security applied will be monitored regularly.


5. Automated tasks - Some routine tasks and commands will be automated with the help of scripts so that our client need not waste his time on daily tasks.Client can select a script according to his requirement and purchase from us.

Advantages of Linux Over Windows

1.Hardware issues -Linux has been developed to work across a wide range of hardware. It can be installed on computers old and new, and can be scaled to work quickly with limited resources.In contrast, each new edition of Windows requires greater and greater processing capacity, memory, and storage.


2.Cost -The greatest advantage of linux is that it is available completely and legally for free. This not only includes the operating itself, but includes several of the available programs. Whereas a copy of Windows 7 Home Premium can cost $130 for the complete package. However, on top of that, one must buy Microsoft Office, a firewall and anti-virus software, at the minimum. With Linux, there are several free office suites and several free firewalls.


3.Data failure -Windows always fails  when it comes to data. In Linux, you can backup the home directory and know that you should be able to transplant it to another system.

4.Solution to virus attacks -In case of Linux, threat detection and solution is very fast, as Linux is mainly community driven and whenever any Linux user posts any kind of threat, several developers start working on it from different parts of the world where as after detecting a major threat in Windows OS, Microsoft generally releases a patch that can fix the problem and it can take more than 2/3 months.


5.Supported file systems -Linux supports Ext2, Ext3, Ext4, Jfs, ReiserFS, Xfs, Btrfs, FAT, FAT32, NTFS file systems where as windows supports only FAT, FAT32, NTFS, exFAT.

 
6.Stability -Linux is very stable,linux systems rarely crash, and when they do, the whole system normally does not go down on the other hand windows frequently crash.


7.Swift booting -Linux boots in a very less time as compared to windows.

Autobiography of Linus torvaldsa

Linus Torvalds is the world's most famous computer programmer and also its most famous Finn. He is the founder and coordinator of Linux, the Unix-like operating system that is beginning to revolutionize the computer industry and possibly much else as well. His is truly one of the great tales in the history of the computers. 

Linus Benedict Torvalds was born on December 28, 1969 in Helsinki, the capital and largest city in Finland.Many members of the family were journalists. His parents, Nils and Anna Torvalds, were both radicals at the University of Helsinki during the 1960s. His father was a Communist who spent a year studying in Moscow in the mid-1970s and later became a radio journalist. His mother worked for a Finnish newspaper as a translator and a creator of news graphics. 

 In 1987 Torvalds used his savings to buy his first computer, a Sinclair QL. This was one of the world's first 32-bit computers for home use. With its Motorola 68008 processor  running at 7.5MHz  and 128KB of RAM , this was a big step up from his grandfather's Commodore Vic 20. However, he soon became unhappy with it because of it could not be reprogrammed due to the operating system residing in ROM.

In 1988 Torvalds followed in the footsteps of his parents and enrolled in the University of Helsinki, the premier institution of higher education in Finland. By that time he was already an accomplished programmer, and, naturally, he majored in computer science. In 1990 he took his first class in the C programming language, the language that he would soon use to write the Linux kernel. 
After a visit to Transmeta in late 1996, Torvalds accepted a position at the company in California, where he would work from February 1997 until June 2003. He then moved to the Open Source Development Labs, which has since merged with the Free Standards Group to become the Linux Foundation, under whose auspices he continues to work. In June 2004, Torvalds and his family moved to Portland, Oregon, to be closer to the OSDL's Beaverton, Oregon–based headquarters.From 1997 to 1999 he was involved in 86open helping to choose the standard binary format for Linux and Unix. In 1999 he was named by the MIT Technology Review TR100 as one of the top 100 innovators, under the age of 35, in the world.

In 1999 Red Hat and VA Linux, both leading developers of Linux-based software, presented Torvalds with stock options in gratitude for his creation. That same year both companies went public and Torvalds' share value temporarily shot up to roughly $20 million.
Till 2003 Torvalds worked at Transmeta Corp. in California as a software developer while continuing to supervise the development of the Linux kernel. In 2003 he became a fellow at Open Source Development Labs (OSDL), a Linux-development consortium in Beaverton, Oreg.; OSDL was merged in 2007 into the Linux Foundation (est. 2007), which now sponsors his work. He became a U.S. citizen in 2010.

In 1998 Torvalds received an EFF Pioneer Award. In 2000 he was awarded the Lovelace Medal from the British Computer Society.In 2001, he shared the Takeda Award for Social/Economic Well-Being with Richard Stallman and Ken Sakamura. In 2008, he was inducted into the Hall of Fellows of the Computer History Museum in Mountain View, California. He was awarded the C&C Prize by the NEC Corporation in 2010 for contributions to the advancement of the information technology industry, education, research, and the improvement of our lives.

On April 23, 2012 at Internet Society's Global INET conference in Geneva, Switzerland, Torvalds was one of the inaugural inductees into the Internet Hall of Fame, one of ten in the Innovators category and thirty-three overall inductees.

Lessons we should learn from Linus Torvalds:-

His motivating factor, then, was not to earn money from a superior product, but just simply to build a better quality, more reliable operating system. He was described as a perfectionist and sore loser. He was very focused on computers and ignored other activities such as sports to program in solitude.

HOW TO USE “alias” COMMAND IN LINUX

The alias command used to rename Linux operating system commands.

For Example..

[root@www ~]# alias show="ll"

With the help of this command (written above) we can modify our command. In simple words we can rename the linux OS commands with this command. Now we can get results of LL command by writing Show.

[root@www ~]# show

-rw-------. 1 root root 1336 Nov 28 19:45 anaconda-ks.cfg

drwxr-xr-x. 4 root root 4096 Nov 30 16:38 Desktop

drwxr-xr-x. 2 root root 4096 Nov 28 19:55 Documents

drwxr-xr-x. 2 root root 4096 Nov 28 20:21 Downloads

-rw-r--r--. 1 root root 49919 Nov 28 19:45 install.log

-rw-r--r--. 1 root root 10261 Nov 28 19:40 install.log.syslog

drwxr-xr-x. 2 root root 4096 Nov 28 19:55 Music

drwxr-xr-x. 2 root root 4096 Nov 28 19:55 Pictures

drwxr-xr-x. 2 root root 4096 Nov 28 19:55 Videos

[root@www ~]#