What are Private and Public IP Addresses

Internet Protocol (IP) addresses are usually of two types: Public and Private. If you have ever wondered to know what is the difference between a public and a private IP address, then you are at the right place. In this post I will try to explain the difference between a public and a private IP addres in layman’s terms so that it becomes simple and easy to understand.

What are Public IP Addresses?

A public IP address is assigned to every computer that connects to the Internet where each IP is unique. Hence there cannot exist two computers with the same public IP address all over the Internet. This addressing scheme makes it possible for the computers to “find each other” online and exchange information. User has no control over the IP address (public) that is assigned to the computer. The public IP address is assigned to the computer by the Internet Service Provider as soon as the computer is connected to the Internet gateway.

A public IP address can be either static or dynamic. A static public IP address does not change and is used primarily for hosting webpages or services on the Internet. On the other hand a dynamic public IP address is chosen from a pool of available addresses and changes each time one connects to the Internet. Most Internet users will only have a dynamic IP assigned to their computer which goes off when the computer is disconnected from the Internet. Thus when it is re-connected it gets a new IP.

You can check your public IP address by visiting www.whatismyip.com

What are Private IP Addresses?

An IP address is considered private if the IP number falls within one of the IP address ranges reserved for private networks such as a Local Area Network (LAN). The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private networks (local networks):

10.0.0.0 – 10.255.255.255 (Total Addresses: 16,777,216)
172.16.0.0 – 172.31.255.255 (Total Addresses: 1,048,576)
192.168.0.0 – 192.168.255.255 (Total Addresses: 65,536)

Private IP addresses are used for numbering the computers in a private network including home, school and business LANs in airports and hotels which makes it possible for the computers in the network to communicate with each other. Say for example, if a network X consists of 10 computers each of them can be given an IP starting from 192.168.1.1 to 192.168.1.10. Unlike the public IP, the administrator of the private network is free to assign an IP address of his own choice (provided the IP number falls in the private IP [...]

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JULY 08 E-PAPER BY EENADU

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WORLD TOP MOST FIGHT SCENE

WORLD TOP MOST FIGHT SCENEYOU NEVER SEEN IT ANY WHERE

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Free .com domain Registrations. Offer till 30 June

Free registration for .com domain is going on at 1and1 up to 30 June. Yes its not a fake call.

1and1.com is providing free registrations for .com domains up to 1 year validity and after one year you have to pay for the next term, the cool thing is their price after one year the is same as it is now .

Just choose your Address and register. Note for the registrations you must have a verified PayPal account.

If you have it then congrats you will now be having your own .com for free.

Hurry till offers ends.

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JUNE 24 E-PAPER BY EENADU

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Know Whats Hidden Inside that Short URL!

These days, we see a lot of “Short” URLs on the net. People use several URL shorteners to shorten lengthy URLS for ease of use. But a short URL won’t tell us where we are going. If some one have shorted a URL of a malware site.. we won’t know that we are been tricked until we visit that site! That’s why we should know where we are going!

If you use Twitter, you might have noticed that everyone use short URLS. Even if we use a long URL, Twitterwill automatically shrink it. But nobody knows where these URLS will take you until that page loads in your browser. Because of this problem, recently, Twitter got some big spam and phishing attacks. Some used short URLS to direct you to a false Twitter login page which will steal your login details and use your accountto send more spam!

Recently few bloggers introduced a system which will help you to extract the short URL and tell you where that URL will direct you! KnowURL.com supports almost all the URL shortening sites like bit.ly and tinyurl. Now you can learn where your heading before you step into trouble.

To use this service, simply put your short URL in the given text field and click on “Show URL”. After that they will reveal the true identity of your link within few seconds!

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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 form while signing up for Gmail or Yahoo account. The following image shows the typical samples of CAPTCHA.

Almost every Internet user will have an 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 will find a detailed information on how CAPTCHA works and why they are used.

What Purpose does CAPTCHA Exactly Serve?

CAPTCPA is mainly used to prevent automated software (bots) from performing actions on behalf of actual humans. For example while signing 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 the 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 softwares 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 Gmail, 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 Gmail, 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 more harder for computers to figure out the patterns.

Most, but not all, CAPTCHAs rely on a visual test. Some Websites implement 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 (AI) 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.

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