The IP address is an unique indentifier assigned to each computer in a network. That is the definition of the IP address, probably you know this. Many questions raise from this sentence and you put yourself those questions many times: "How they can know where i am from?", "IF they have my IP address they can find out my street address", "They can find my name based on my IP address", "They can get into my computer using my IP address", "Why the IP address those websites show me is not the IP address that i got from my ISP" and many more questions regarding IP addresses.

Maybe when internet was explained to you for the first time you have seen a image with a cloud and everything connected to it. That image is logical and that is probably the right way to think the internet but in reality, the internet looks more like the image above.

You are connected first to your local internet service provider, which is connected to a large internet service provider in your country who is connected to the internet network. Different setups may have many levels between the main network and your computer.

The communication in network is made trough IP ( internet protocol ) addresses. First of all, your computer have send and receive data from the computers in the local network. All those computers have an IP address asssociated. When a package is sent his header contains data that specifies what computer should receive the message. I'm afraid i'm going too technicaly and i will stop to enter in more details and i will skip these technical stuff which will be explained in later posts.

One or more of the computers in your network is connected to a computer outside the local netwourk. That computer is usually called server. When your computer want to send a message to a computer outside the local network, it will be sent to the server and he know where he have to send it. Your local server is conected to a server where other computer is connected to the other network and so on until all computers are connected to each other and forms the Internet, this big collection of networks. The IP address of a computer should be unique in his local network. 2 Computers in different interconected networks can have the same IP address, but there will be a problem with addressing packages one to each other. Unless the server is registered to forward the packages based on some other identifier, they can't connect. If they are using different IP address the connection will be possible if the server of the network is set to forward packages to each computer

Well, this is how internet works, IP addresses from the main network are assigned to subnetworks for "direct connection". We are used to call a Direct Connection when we put the IP address where we want to send a message or a file. That doesn't mena that the connection is made direct. It will hop to each server on each network he is passing trough. To see this, if you are on windows press start and select "Run" and a black window will open. Then type "tracert" followed by the IP address you want to find out how the connection is made.

In the image above i trace routed an IP address in same country but other internet service provider. The connection was made over 8 hops. First is my wireless router, the second is the ip address of my speedtouch lan modem given to me by my internet service provider. The third is the ip address of one of their networks and the IP address starting with 10 are the ones who really make the internet keep going.

In the second image i ran tracert one of goolge IP's We can see that it also pass trough my router, my modem and those ips starting with 10 and then he trace google. If you type that ip into your browser the google homepage will appear. This means that the ip can be addressed directly but this don't mean it it a direct connection.

For the main network the IP address are associated with Internet service provider which can have a lot of addresses assigned to them, and they can assign a unique IP to every client.

The Internet service provider can provide you with Internet access in many ways:

• It is giving you a unique IP address that is registered in main network and it is directly accessible.
• It is giving you a IP address that is always the same but it is shared between more clients. In this way it is not directly accessible so if someone try to ping that IP address he may not receive a response because the ISP want more details about the computer you want to send the message.
• It has a range of IP addresses assigned to your area and your IP address will change every time you connect on the web, it can be unique or not
• It assign the same IP address to all of it's client, that will make all computers in your network to be seen with the same IP address.

Now that we know a little about IP addresses let's try to find answers together to the questions at the top of this article.

How they can know where i am from?

The IP address that your computers gets to browse the web has a public description that is available on the web on the website of institute responsible with IP addresses, you can find the details on ripe.net . The company that has that IP address is registered in a country and a city, based on that the ip address databases are build. This can be inaccurate trough, if the IP address has that IP registered for another country or region, the look up will give wrong data. But they can't go further Internet service provider.

IF they have my IP address they can find out my street address ?

Well, unless the IP address is registered directly to you, which is not the case, but once i seen a IP address registered directly to a person, probably his ISP did that, and i searched on ripe and the name and address of that person appeared. I was a little surprised but several years ago when were not so many computers connected to the Internet, and my country had so few Internet users that was possible.

In almost all other cases, the name and street address is not public, so they can't get it. But, if you make some damage or something stupid on the web, they know your Internet Service Provider and you ISP know your name and street address. They have logs with everything, which computer from their internal network made a connection to the computer that you made problems too and if they have the time too, you are very easy to be tracked. If they provide enough data that shows the damage made by you the ISP is forced to disclose your name.

Unless you do something bad, they won't find who are you unless they work for your Internet service provider

They can find my name based on my IP address ?

The answer to this questions is the similar to the answer above. Actually is possible from someones to steal your private data from a website you registered to because many websites keep in their databases the ip addresses too, and they know the IP address your account was registered from. But if you are in the case that you share the IP with others or your IP changes every time you connect on the web, the info they will get will be false in most cases.

They can get into my computer using my IP address ?

This is a question that have the answer in more technical stuff. A superficial answer can come from the explanations above. If your computer is directly accessible from other networks they have a chance to get into your computer, but that happens only if your computer software have vulnerabilities. If you use a
firewall you will be OK. If you use windows without firewall you are at high risk and i urge you  to get a real firewall now. I recommend Kaspersky Internet Security 2010, i'm using it and it gives good protection. I'm using kaspersky while I'm on windows and it gives me complete protection.

Depending on how you have your IP address assigned by your ISP, you can be a little protected from users outside the network. It is practically like a filter that blocks messages coming on different ports. This is a good protection, in the past years i've seen viruses trying to get into computers using windows vulnerabilities on different ports. Ports are like doors, but i will discuss about them in later posts. Anyway, the software vulnerabilities can't be exploited if you computer is not directly accessible.

Why the IP address those websites show me is not the IP address that i got from my ISP ?

This will happen because on the local network, the one between you and ISP computers your computer has a local IP address. For the main network the IP other computers see is either the shared IP that more computers are using, either the random IP that you get.

I hope i was clear enough in my explanations and answers, if you have more questions about IP address just send them to me and i will give you the answer for it. If it is something that you did not understand tell me so i can explain you what i've missed. Feedback is appreciated.

I will write more articles about IP address and Internet security, if you want them you can subscribe in a reader or to receive them by e-mail using the subscription boxes in the right top of the website.

Tags: computers, connection, forwarding, internet security, Ip address, networking, router, server, trace route