What is a Computer IP Internet Address?
PC Network Address Tracking, Web Security and Privacy
Jul 1, 2009
Understanding how IP addresses work will help Internet users understand Internet security and privacy issues.
What is a Computer IP Internet Address?
An IP (Internet Protocol) address is used to identify computers on the Internet (Inter-network, a group of interconnected computer networks). Without one, a computer cannot communicate with other computers on the Internet.
It's like a phone number for computers. Without a phone number, a telephone cannot call other telephones and other telephones cannot call it.
An IP address consists of 4 numbers, each number ranging from 0 to 255. For example: 152.206.043.129. This gives 256 x 256 x 256 x 256 = 4 billion individual addresses.
This works the same way whether a Microsoft Windows, Apple MacIntosh, Linux or Unix computer is used.
How IP Addresses are Assigned
IP number ranges are assigned to each network in the Internet (the Internet is made up of many computer networks). For example, an Internet Service Provider (ISP) has a range of IP addresses assigned to it for use on its network. This is roughly equivalent to the area codes and IDD codes used in the telephone network.
A computer that connects to the ISP's network to get to the Internet, will be given an IP number within this range. There are freely available databases that, given an IP address; will tell you the ISP's name, country, city and street address.
An ISP can sell some of these IP addresses to corporations. In this case, the corporation's name and address will be in the database, not the ISP's.
This means that given a computer's IP address, it's location (down to its ISP's or corporation's street address) can be known.
The ISP keeps a record of which IP address is assigned to which subscriber. This is normally kept confidential, so the subscriber's name and address is not known to outsiders even if the IP address is known. However the ISP will reveal this information to the police if there is a court order (depending on local laws).
Who can See a Computer's IP Address?
A telephone (A) connects to another telephone (B) by dialing B's number. The connection is made by and through the telephone company's computer.
This means that A must know B's number, but B need not know A's number. The telephone company can choose to send A's number to B using the Caller ID feature, but this is optional.
The Internet doesn't work this way. The telephone network is centralized. The Internet is decentralized. The way the Internet works, A must know B's IP and B must know A's IP otherwise they cannot communicate. This means that if a computer connects to a web server, the web server will know the computer's IP address.
Websites such as What is My IP Address will display the IP address of computers that visit their website.
How to Hide IP Addresses: Web and Other Proxies
Understanding the actual underlying network connection path is crucial in knowing which IP address is revealed to others.
By using an intermediary computer (proxy) to connect to other computers, the original computer's IP address can be hidden. Only the proxy's IP address is revealed to outsiders.
More than one computer can connect to the same proxy. To the outside Internet, all of these computers seem to have the same IP address: the proxy's IP address.
The degree to which the original computer's location is hidden depends on its relationship with the proxy.
- If a corporate proxy is used, the computer's corporation's name and address is revealed.
- If an ISP's proxy is used, the computer's ISP's name and address is revealed.
- If a third party proxy is used, nothing about the original computer is revealed. This is because the relationship between the original computer and the third party proxy is not known to outsiders. Some websites do offer such anonymizing proxy services.
Can an IP Address be Faked?
It is possible to force a computer to change the IP address, and not use the IP address assigned to it by the ISP. However there isn't much point in doing so. If the wrong IP address (one not assigned by the ISP) is used, other computers will not know how to reach the computer. The computer is effectively cut off from the Internet.
IP Addresses and Internet Security
Understanding Internet security requires some knowledge of how the Internet works, the different ways in which computers can connect to each other (email, web, instant messaging, peer-to-peer, Skype).
While not effortless, such understanding is within the grasp of the interested layman.
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