COMPUTER THREATS:

One reads about Web site security problems in the newspaper almost weekly. The situation is really pretty grim. Let us look at a few examples of what has already happened. First, the home page of numerous organizations has been attacked and replaced by a new home page of the crackers' choosing. (The popular press calls people who break into computers ''hackers,'' but many programmers reserve that term for great programmers. We prefer to call these people ''crackers.'') Sites that have been cracked include Yahoo, the U.S. Army, the CIA, NASA, and the New York Times. In most cases, the crackers just put up some funny text and the sites were repaired within a few hours.

Now let us look at some much more serious cases. Numerous sites have been brought down by denial-of-service attacks, in which the cracker floods the site with traffic, rendering it unable to respond to legitimate queries. Often the attack is mounted from a large number of machines that the cracker has already broken into (DDoS atacks). These attacks are so common that they do not even make the news any more, but they can cost the attacked site thousands of dollars in lost business.

In 1999, a Swedish cracker broke into Microsoft's Hotmail Web site and created a mirror site that allowed anyone to type in the name of a Hotmail user and then read all of the person's current and archived e-mail.

In another case, a 19-year-old Russian cracker named Maxim broke into an e-commerce Web site and stole 300,000 credit card numbers. Then he approached the site owners and told them that if they did not pay him $100,000, he would post all the credit card numbers to the Internet. They did not give in to his blackmail, and he indeed posted the credit card numbers, inflicting great damage to many innocent victims.

In a different vein, a 23-year-old California student e-mailed a press release to a news agency falsely stating that the Emulex Corporation was going to post a large quarterly loss and that the C.E.O. was resigning immediately. Within hours, the company's stock dropped by 60%, causing stockholders to lose over $2 billion. The perpetrator made a quarter of a million dollars by selling the stock short just before sending the announcement. While this event was not a Web site break-in, it is clear that putting such an announcement on the home page of any big corporation would have a similar effect.

We could (unfortunately) go on like this for many pages. But it is now time to examine some of the technical issues related to Web security. For more information about security problems of all kinds, see (Anderson, 2001; Garfinkel with Spafford, 2002; and Schneier, 2000). Searching the Internet will also turn up vast numbers of specific cases.

ADD IN YOUR KNOWLEDGE :
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1.DO YOU KNOW WHAT IS THE BLUETOOTH TECHNOLOGY:-
In 1994, the L. M. Ericsson company became interested in connecting its mobile phones to other devices (e.g., PDAs) without cables. Together with four other companies (IBM, Intel, Nokia, and Toshiba), it formed a SIG (Special Interest Group, i.e., consortium) to develop a wireless standard for interconnecting computing and communication devices and accessories using short-range, low-power, inexpensive wireless radios. The project was named Bluetooth, after Harald Blaatand (Bluetooth) II (940-981), a Viking king who unified (i.e., conquered) Denmark and Norway, also without cables.
Although the original idea was just to get rid of the cables between devices, it soon began to expand in scope and encroach on the area of wireless LANs. While this move makes the standard more useful, it also creates some competition for mindshare with 802.11. To make matters worse, the two systems also interfere with each other electrically. It is also worth noting that Hewlett-Packard introduced an infrared network for connecting computer peripherals without wires some years ago, but it never really caught on in a big way.
Undaunted by all this, in July 1999 the Bluetooth SIG issued a 1500-page specification of V1.0. Shortly thereafter, the IEEE standards group looking at wireless personal area networks, 802.15, adopted the Bluetooth document as a basis and began hacking on it. While it might seem strange to standardize something that already had a very detailed specification and no incompatible implementations that needed to be harmonized, history shows that having an open standard managed by a neutral body such as the IEEE often promotes the use of a technology. To be a bit more precise, it should be noted that the Bluetooth specification is for a complete system, from the physical layer to the application layer. The IEEE 802.15 committee is standardizing only the physical and data link layers; the rest of the protocol stack falls outside its charter.
Even though IEEE approved the first PAN standard, 802.15.1, in 2002, the Bluetooth SIG is still active busy with improvements. Although the Bluetooth SIG and IEEE versions are not identical, it is hoped that they will soon converge to a single standard.
4.6.1 Bluetooth Architecture
Let us start our study of the Bluetooth system with a quick overview of what it contains and what it is intended to do. The basic unit of a Bluetooth system is a piconet, which consists of a master node and up to seven active slave nodes within a distance of 10 meters. Multiple piconets can exist in the same (large) room and can even be connected via a bridge node. An interconnected collection of piconets is called a scatternet.
. Two piconets can be connected to form a scatternet.

Java Questions

Here we presenting some tricky question for java readers :

1.  What gets displayed on the screen when the following program is compiled and run. 
     Select the one correct answer. 
   
     protected class example {
     public static void main(String args[]) {
     String test = "abc";
     test = test + test;
     System.out.println(test);
     }
     }
   
   
   (A). The class does not compile because the top level class cannot be protected. 
   (B). The program prints "abc" 
   (C). The program prints "abcabc" 
   (D). The program does not compile because statement "test = test + test" is illegal. 
2. Several questions about static:
      
   (A). Can a static variable be declared within a method?
   (B). Can a static method contain an inner class?
   (C). Can a static method contain an static inner class?
3.  TreeMap class is used to implement which collection interface. 
     Select the one correct answer. 
      
   (A). Set 
   (B). SortedSet 
   (C). List 
   (D). Tree 
   (E). SortedMap 
4. Which of the following are legal declaration and definition of a method. 
     Select all correct answers. 
      
   (A). void method() {}; 
   (B). void method(void) {}; 
   (C). method() {}; 
   (D). method(void) {}; 
   (E). void method {};
5.  abstract class C1{
     public void m1(){ //1
     }}
     abstract class C2{
     public void m2(){ //2
     }}
   
   
   (A). compile time error at line1  
   
   (B). compile time error at line2
   
   (C). The code compiles fine
   
   (D). None of the above

                                               ~  Answers ~ 

Ans. 1. (A)

Ans. 2.
  (A). No, not in Java, but yes in C++
  (B). Yes
  (C). No
  The simplest way to have your doubts clarified is to write a short program, then compile it to see the result.
  CODE, Code, code, ... please!

Ans. 3. (E)

Ans. 4. (A)

Ans. 5. (C) // since the class C2 is abstract it can contain abstract methods

HACKING TIPS:
Hacking Windows XP?
Is it possible to hack Windows XP many people say yes, but Microsoft has put a lot of effort in to making Windows XP un-hackable (new ``Product Activation'' feature meant individual customers had to buy separate copies of the software, activated by sending a code over the Internet when they first installed the software).
Hacked copies of Windows XP install files and lists of product keys are widely available on such Usenet newsgroups as alt.binaries.cd.image and alt.binaries.warez.ibm-pc, as well as on various "warez" channels on Internet Relay Chat (IRC) and peer-to-peer protocol to share files such as BareShare LimeWire, Morpheus and some web sites.
There are a number of hacks and patches designed to circumvent the operating system's controversial Activation process, a new antipiracy measure.
Here I will hi-light some but, not all of the methods used to hack Windows XP. Some of the hacks are fairly complicated, requiring file installations and edits to the Windows registry. Some XP hacks floating around the Internet claim to either disable the Activation feature or circumvent it.
One hack claims to reset the computer's internal clock so Windows XP constantly thinks the user has 60 days to register the software. And another claims to disable the Activation feature entirely. One patch purports to replace files that need to be activated with non-activated versions from the corporate edition.
Note: Some of the hack and cracking programs are mined with viruses.
Opinion: Using hack and cracks on Windows XP is the same as playing Russian roulette with you PC. Your personal computer holds a lot of your important files - email, word files, Mp3s, digital photos, games, passwords, favorite - bookmarks, and more. Even if you backup your PC everyday (most people don’t) you will lose a lot of your files if something goes wrong.
Note: The information on this page hasn't been up-dated for a long time.

How to Install RAM

Most of the time, installing RAM is a very simple and straightforward procedure. The key is to do your research. 
Here's what you need to know:

•   How much RAM you have
•   How much RAM you wish to add 
•   Form factor
•   RAM type 
•   Tools needed 
•   Warranty
•  Where it goes 

RAM is usually sold in multiples of 16 megabytes: 16, 32, 64, 128, 256, 512, 1024 (which is the same as 1GB). 
This means that if you currently have a system with 64 MB RAM and you want at least 100 MB RAM total, then you will probably need to add another 64 MB module. 
Once you know how much RAM you want, check to see what form factor (card type) you need to buy. You can find this in the manual that came with your computer, or you can contact the manufacturer. An important thing to realize is that your options will depend on the design of your computer. Most computers sold today for normal home/office use have DIMM slots. High-end systems are moving to RIMM technology, which will eventually take over in standard desktop computers as well. Since DIMM and RIMM slots look a lot alike, be very careful to make sure you know which type your computer uses. Putting the wrong type of card in a slot can cause damage to your system and ruin the card. 

You will also need to know what type of RAM is required. Some computers require very specific types of RAM to operate. For example, your computer may only work with 60ns-70ns parity EDO RAM. Most computers are not quite that restrictive, but they do have limitations. For optimal performance, the RAM you add to your computer must also match the existing RAM in speed, parity and type. The most common type available today is SDRAM. 

Additionally, some computers support Dual Channel RAM configuration either as an option or as a requirement. Dual Channel means that RAM modules are installed in matched pairs, so if there is a 512MB RAM card installed, there is another 512 MB card installed next to it. When Dual Channel is an optional configuration, installing RAM in matched pairs speeds up the performance of certain applications. When it's a requirement, as in computers with the Mac G5 chip(s), the computer will not function properly without matched pairs of RAM chips. 

For complete guidelines on setting up Dual Channel configuration on Intel Pentium 4-based systems, check out this guide. 

Before you open your computer, check to make sure you won't be voiding the warranty. Some manufacturers seal the case and request that the customer have an authorized technician install RAM. If you're set to open the case, turn off and unplug the computer. Ground yourself by using an anti-static pad or wrist strap to discharge any static electricity. Depending on your computer, you may need a screwdriver or nut-driver to open the case. Many systems sold today come in tool-less cases that use thumbscrews or a simple latch. 


  
To install more RAM, look for memory modules on your computer's motherboard. At the left is a Macintosh G4 and on the right is a PC. 

The actual installation of the memory module does not normally require any tools. RAM is installed in a series of slots on the motherboard known as the memory bank. The memory module is notched at one end so you won't be able to insert it in the wrong direction. For SIMMs and some DIMMs, you install the module by placing it in the slot at approximately a 45-degree angle. Then push it forward until it is perpendicular to the motherboard and the small metal clips at each end snap into place. If the clips do not catch properly, check to make sure the notch is at the right end and the card is firmly seated. Many DIMMs do not have metal clips; they rely on friction to hold them in place. Again, just make sure the module is firmly seated in the slot. 

Once the module is installed, close the case, plug the computer back in and power it up. When the computer starts the POST, it should automatically recognize the memory. That's all there is to it!


        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Types of RAM

The following are some common types of RAM:

• SRAM: Static random access memory uses multiple transistors, typically four to six, for each memory cell but doesn't have a capacitor in each cell. It is used primarily for cache.
• DRAM: Dynamic random access memory has memory cells with a paired transistor and capacitor requiring constant refreshing.
• FPM DRAM: Fast page mode dynamic random access memory was the original form of DRAM. It waits through the entire process of locating a bit of data by column and row and then reading the bit before it starts on the next bit. Maximum transfer rate to L2 cache is approximately 176 MBps.
• EDO DRAM: Extended data-out dynamic random access memory does not wait for all of the processing of the first bit before continuing to the next one. As soon as the address of the first bit is located, EDO DRAM begins looking for the next bit. It is about five percent faster than FPM. Maximum transfer rate to L2 cache is approximately 264 MBps.
• SDRAM: Synchronous dynamic random access memory takes advantage of the burst mode concept to greatly improve performance. It does this by staying on the row containing the requested bit and moving rapidly through the columns, reading each bit as it goes. The idea is that most of the time the data needed by the CPU will be in sequence. SDRAM is about five percent faster than EDO RAM and is the most common form in desktops today. Maximum transfer rate to L2 cache is approximately 528 MBps.
• DDR SDRAM: Double data rate synchronous dynamic RAM is just like SDRAM except that is has higher bandwidth, meaning greater speed. Maximum transfer rate to L2 cache is approximately 1,064 MBps (for DDR SDRAM 133 MHZ).
• RDRAM: Rambus dynamic random access memory is a radical departure from the previous DRAM architecture. Designed by Rambus, RDRAM uses a Rambus in-line memory module (RIMM), which is similar in size and pin configuration to a standard DIMM. What makes RDRAM so different is its use of a special high-speed data bus called the Rambus channel. RDRAM memory chips work in parallel to achieve a data rate of 800 MHz, or 1,600 MBps. Since they operate at such high speeds, they generate much more heat than other types of chips. To help dissipate the excess heat Rambus chips are fitted with a heat spreader, which looks like a long thin wafer. Just like there are smaller versions of DIMMs, there are also SO-RIMMs, designed for notebook computers.
• Credit Card Memory: Credit card memory is a proprietary self-contained DRAM memory module that plugs into a special slot for use in notebook computers.
• PCMCIA Memory Card: Another self-contained DRAM module for notebooks, cards of this type are not proprietary and should work with any notebook computer whose system bus matches the memory card's configuration.
• CMOS RAM: CMOS RAM is a term for the small amount of memory used by your computer and some other devices to remember things like hard disk settings -- see Why does my computer need a battery? for details. This memory uses a small battery to provide it with the power it needs to maintain the memory contents.
• VRAM: VideoRAM, also known as multiport dynamic random access memory (MPDRAM), is a type of RAM used specifically for video adapters or 3-D accelerators. The "multiport" part comes from the fact that VRAM normally has two independent access ports instead of one, allowing the CPU and graphics processor to access the RAM simultaneously. VRAM is located on the graphics card and comes in a variety of formats, many of which are proprietary. The amount of VRAM is a determining factor in the resolution and color depth of the display. VRAM is also used to hold graphics-specific information such as 3-D geometry data and texture maps. True multiport VRAM tends to be expensive, so today, many graphics cards use SGRAM (synchronous graphics RAM) instead. Performance is nearly the same, but SGRAM is cheaper.

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