UNIX: Introduction to Beginners

What is UNIX? 

UNIX is an operating system which was first developed in the 1960s, and has been under constant development ever since. By operating system, we mean the suite of programs which make the computer work. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops.

UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy to use environment. However, knowledge of UNIX is required for operations which aren't covered by a graphical program, or for when there is no windows interface available, for example, in a telnet session.

Types of UNIX :-

There are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, and MacOS X.

Here in the School, we use Solaris on our servers and workstations, and Fedora Linux on the servers and desktop PCs.

The UNIX operating system:-

The UNIX operating system is made up of three parts; the kernel, the shell and the programs. 

The kernel:

The kernel of UNIX is the hub of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to system calls.
As an illustration of the way that the shell and the kernel work together, suppose a user types rm myfile (which has the effect of removing the file myfile). The shell searches the filestore for the file containing the program rm, and then requests the kernel, through system calls, to execute the program rm on myfile. When the process rm myfile has finished running, the shell then returns the UNIX prompt % to the user, indicating that it is waiting for further commands.

What is the Registry?

The Registry is a database used to store settings and options for the 32 bit versions of Microsoft Windows including Windows 95, 98, ME and NT/2000,XP,Vista,7 and above. It contains information and settings for all the hardware, software, users, and preferences of the PC. Whenever a user makes changes to a Control Panel settings, or File Associations, System Policies, or installed software, the changes are reflected and stored in the Registry.
                                                     The physical files that make up the registry are stored differently depending on your version of Windows; under Windows 95 & 98 it is contained in two hidden files in your Windows directory, called USER.DAT and SYSTEM.DAT, for Windows Me there is an additional CLASSES.DAT file, while under Windows NT/2000 the files are contained seperately in the %SystemRoot%\System32\Config directory. You can not edit these files directly, you must use a tool commonly known as a "Registry Editor" to make any changes (using registry editors will be discussed later in the article).

The Structure of The Registry:The Registry has a hierarchal structure, although it looks complicated the structure is similar to the directory structure on your hard disk, with Regedit being similar to Windows Explorer.
                                                                                                       Each main branch (denoted by a folder icon in the Registry Editor, see left) is called a Hive, and Hives contains Keys. Each key can contain other keys (sometimes referred to as sub-keys), as well as Values. The values contain the actual information stored in the Registry. There are three types of values; String, Binary, and DWORD - the use of these depends upon the context.
 
There are six main branches, each containing a specific portion of the information stored in the Registry. They are as follows:


* HKEY_CLASSES_ROOT - This branch contains all of your file association mappings to support the drag-and-drop feature, OLE information, Windows shortcuts, and core aspects of the Windows user interface.

* HKEY_CURRENT_USER - This branch links to the section of HKEY_USERS appropriate for the user currently logged onto the PC and contains information such as logon names, desktop settings, and Start menu settings.

* HKEY_LOCAL_MACHINE - This branch contains computer specific information about the type of hardware, software, and other preferences on a given PC, this information is used for all users who log onto this computer.

* HKEY_USERS - This branch contains individual preferences for each user of the computer, each user is represented by a SID sub-key located under the main branch.

* HKEY_CURRENT_CONFIG - This branch links to the section of HKEY_LOCAL_MACHINE appropriate for the current hardware configuration.

* HKEY_DYN_DATA - This branch points to the part of HKEY_LOCAL_MACHINE, for use with the Plug-&-Play features of Windows, this section is dymanic and will change as devices are added and removed from the system.

Each registry value is stored as one of five main data types:

Pop a banner each time Windows Boots

To pop a banner which can contain any message you want to display just before a user is going to log on, go to the key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WinLogon
Now create a new string Value in the right pane named LegalNoticeCaption and enter the value that you want to see in the Menu Bar. Now create yet another new string value and name it: LegalNoticeText. Modify it and insert the message you want to display each time Windows boots. This can be effectively used to display the company's private policy each time the user logs on to his NT box. It's .reg file would be:

REGEDIT4

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Winlogon]

"LegalNoticeCaption"="Caption here."

What are Exploits? How important are Exploits for Hacking ?

Ref- itpro.co.uk

A tool developed by hackers that is used to perform malicious attacks on computer systems. They are usually scripts that are designed to exploit weaknesses in software over a network, most commonly the Internet.
        "Zero-Day" is a common type of exploit.You can hack in many different ways with many different procedures. Kevin Mitnick created hacking history with just a phone and a dream. Hackers, Exploit writers and Defacers are always the challenge for Security Experts and Compa-
nies.An attacker can write exploits because of some misconfiguration, unsecure development and is lacking IT management.
                 
There are various Exploit Database sites available with thousands of Exploits.

For example:
 

Top 10 Most Notorious Hacker Groups Ever!

Yes, a 'hacker' is a person who has extraordinary knowledge of computers and is skilled at exploiting weaknesses in computer networks. Yes, it is not the perfect definition, but the basic idea is, the 'term' hacker doesn't automatically mean criminal. While some are activists (hacktivists), others are ethical. Then there are those who do use their skills for criminal activities. In any case, one thing that is certain is that a hacker is a person who possesses extraordinary grasp over computers and deserves some respect for the same. When a few of them get together, well, that is indeed a scary proposition!

Here are the 10 most notorious hacker groups to have ever touched a keyboard.

1. Chaos Computer Club: This group made a name for itself by hacking the Bildschirmtext computer in Germany and taking 134,000 Deutsch Marks from a bank in Hamburg. They did this to prove that the security system was flawed and returned the money they took the next day. They also protested against the French nuclear testing using hacking, by exposing a Trojan horse spyware device being used by the Germany government. The group was formed on 12 September 1981 in Berlin.



2. Global kOS: Pronounced Global Chaos, this group created as much of it as they could, that too on a global scale. Their members included AcidAngel, Shadow Hunter, The Assassin etc. and the group has been credited with providing a number of automated hacker tools to the world. One of the most famous out of these tools was ‘Up Yours’, which was used to bring down the websites of 40 politicians, MTV and the Ku Klux Klan. There are also tools like kOS crack and BattlePong.

3. The Level Seven Crew: This hacker crew took its name from the seventh level of hell, as depicted in Dante’s Inferno. In this, the seventh level is ‘the violent’ level. In 1999, the first crew hacked into 60 high profile computer systems. These included names like NASA, Sheraton Hotels and The First American National Bank. They are believed to be the first group to have hacked into a Moroccan domain. The group was known for their hacktivism and disbanded in 2000.



4. globalHell: This group was co-founded by Patrick Gregory, a street-gang member from Houston, Texas. It has been said to be behind the destruction of data on 115 websites, information trafficking and millions of dollars worth of damages. Ironically, Gregory had turned towards computers to escape his gang life. Rather, he ended up creating a 60 member crew of hackers, who treated the internet like their streets and wreaked havoc. 

Gregory’s crew has also been credited with online extortion and defacing the United States Army’s website when they wrote “global hell will not die”, on it. Interestingly, Chad Davis, another co-founder for the group, was arrested in 1999 and sent to prison for six months, along with a fine of $8,054, became an independent security consultant later.

5. TeaMp0isoN: This group was started in 2010 by a 16-year-old hacker with the alias TriCk. TeaMp0isoN was responsible for hacking into NATO, Facebook and the English Defense League. In addition, this group stole personal data from Tony Blair by hacking into his email account. They also attacked Research In Motion, the company that developed the BlackBerry, in 2011, by defacing their blog. They did this because the company planned to help the police during the England riots that year. The group wrote on the blog, “We are all for the rioters that are engaging in attacks on the police and government.”

10 Tech Job Interview Questions Asked By Real Companies..!

Interviews can be very interesting sometimes. No matter how many books you read, some interviews will still surprise you. The good folks over at CIO.com compiled this list of odd questions that were asked at real interviews for tech jobs. Take a look and see if you have any answers for them...

1. “If you were a pizza delivery man, how would you benefit from scissors?”

This question was asked at an Apple interview for the position of Specialist.

2. “Why is a tennis ball fuzzy?”

This was an interview question asked to a candidate trying for the position of client manager for Xerox.

3. “If you could throw a parade of any caliber through the Zappos office, what type of parade would it be?”

Employer Zappos asked this question off a candidate interviewing for Customer Loyalty Team Member.

4. “How does the Internet work?”

Akamai asked this question to a candidate applying for the position of Director.

9 Ways To Sort Files In Linux Environment

Sorting files is important for meaningful output and is useful while dealing with DB files, CSV, xls, log files and text files. By default, the sort command will sort according to alpha-bates, sorting according to single character vertically. If it finds the same character in two lines, then it will move on to sort the second character.

There are 9 ways to do that according to www.linuxnix.com. You can mix and match them as per your requirement.

• 1:To sorting file names according to alpha-bates: sort filename.txt.

• 2: If you have a file with host names in the third column, to sort it according to the column, use K for sorting that. Like, sort k3 filename.txt.

• 3: To sort/ etc/password file according to home directories, sort will by default take space/tabs as field separators. In etc/passwd file, the field separator is : and this can be done with t option. sort -t: -k6 /etc/passwd 

• 4: To sort according to number, etc/passwd file according to UID, use -n option to do that. Sort will not understand numbers by default, so, use -n to make sure sort command understands it.sort -n -t: -k3 /etc/passwd. Without -n option sort will by default sort only first numerical char. 

10 Mistakes People Often Make On Facebook!

Social networking is at the core of everyone's lives today. There is a lot of talk about what to do and what not to do. But there are some common mistakes that people make on the website, which often even result in hilarious stories. Here are 10 of the most common ones!
                                                          

1. Too many petitions for causes: It is very good to be concerned about social and other just causes, but that doesn’t mean you can flood other’s timelines. Post it as your own status if you must, it gives others the option to decide whether they want to read it or not. 

2. Updating status messages about things you did when you were under the influence of alcohol: An US teen got arrested after he posted a status message about driving drunk. His status said, “Driving drunk…classic ;) but to whoever’s vehicle I hit I am sorry. :P.” Not only is it uncool, it is often of no consequence to anyone but you.

3. Photos of you as a kid on your profile picture: Make an album, post those pictures to that, share that album, make it public if you want, but don’t make it your profile picture. Many or most of your friends didn’t see you when you were that young. A recent profile picture is easier for them to relate too and doesn’t leave them confused amongst all the posts showing on their News Feeds.

Top 12 Linux Distros And Their Usage

While many would argue that the list is not complete but we have tried to bring to you some of the key Linux distros. That's not it. This article also helps you determine the best distro that suits your need.
          Let's analyse certain major Linux distros and their anticipated purpose:

1) Ubuntu: Ubuntu was once considered as the standard Linux distribution for beginners, but due to Ubuntu Unity, that title no longer belongs to Ubuntu, but that doesn’t mean it is useless. Very soon, Ubuntu is likely to emerge with the first trustworthy Linux tablet

2) Linux Mint: This is the effective standard for beginners. Linux Mint introduced great and user friendly features in Ubuntu and enhanced GNOME 3- a combination that provided an incredible environment for beginners as well as old users of Linux.

3) Fedora: If you want an advanced version of Linux, go for Fedora. Even those, looking for pure take on GNOME 3, opt for Fedora.