Before I start I would like to tell you that there are ways to hide the real IP so that it is not exposed on the Internet (for example by using a proxy server). This is slightly more secure than browsing with your real IP, but its definitely not 100% anonymous.
Whenever you connect to a website, start a ftp session, write an email or use a chat client your IP address is transmitted. IP stands for Internet Protocol and is a 32 bit number that is assigned to every computer connected to the internet. 18.104.22.168 would be an IP address. You can see that it consists of four 8bit octets each separated by "." ranging from 0 to 255.
Note: This is only true for IPv4 addresses. Consult the following article for additional information about the upcoming IPv6 standard.
The most important question is of course: What does the IP address tell others about you?
Most people are not good at remembering numbers, that's one of the reasons why the DNS system, Domain Name System, exists.Computers on the other hand work with numbers and the DNS is used to translate between the computer and the user. There are online tools that do that for you, for example dnswatch.info
If you go to the site and enter the IP 22.214.171.124 you see that the look up reveals www.ghacks.net, the website you are surfing atm. You could easily exchange www.ghacks.net with the IP and still surf the site, try it if you like.
There are static and dynamic IP addresses. Static means, the IP is not changing, most websites have static IPs. Dynamic means it is changing, mostly dial-ups have these kind of IP addresses. So, when you log on to the Internet you get a free IP address that your provider selects for you, that has been used before by other customers.
Now, you probably want to find out about your own IP I suppose ? There are numerous services that display your IP address when you visit their websites, there are scripts e.g in forum signatures that do the same.
If you want to try others simply use Google and search for "what is my ip"
The DNS you find gives you detailed information about the internet provider you use. It sometimes also gives more information, for example a country code clearly shows where the internet provider is located. (for example .de mean Germany, .fr is France aso.)
You can find a comprehensive list of country codes here
Let us look at an specific example. Most of you receive spam mails every day. You normally only see a basic header of the email, giving you basic information like from, to, date and subject for instance. Most mail tools have an option to also display extended header information, that's where the senders IP address is located.
Here is a typical extended header
Received: from friko7.onet.pl (c-24-20-255-46.hsd1.or.comcast.net [126.96.36.199])
by server6.xlhost.de (Postfix) with ESMTP id D885256215
for ; Fri, 28 Oct 2005 06:58:33 +0200 (CEST)
Date: Fri, 28 Oct 2005 08:06:06 +0300
From: "Lon Martin"
To: [email protected]
Subject: Account has been created
This line "Received: from friko7.onet.pl (c-24-20-255-46.hsd1.or.comcast.net [188.8.131.52])" is the important one. The Ip of the sender is clearly shown 184.108.40.206, so is the DNS c-24-20-255-46.hsd1.or.comcast.net
There are numerous mail tutorials that describe this procedure in greater detail, for now this is all you need to know for our article.
Lets take a look at another example. Maybe you are using an instant messenger and would like to know the IP addresses of the people you are chatting with. On Windows XP, select START, then run. Enter "cmd" and then "netstat -n" to see a list of all your active connections.
To display an IP address you need to have a session open with someone, private chat, file transfer etc.. If you do the netstat command without a session you only see the IP of the server that you are connected to, you simply do not need to know the IP addresses of the other users who are connected until you communicate with them directly.
This have been two examples, I could give you more (for websites, IRC, Bittorent) but that's not part of this tutorial.
What have we learned so far? Anything you do on the internet also transmits your IP Address.
Your next question probably is the following: If someone has my IP how can he find out more about me?
As we have seen the DNS lookup gives you information about the provider. They could easily file a complaint at your provider for example.
Or, they could hire a lawyer in your country and file a complaint against the user that used the IP at a specific day and time. They normally don't know your name until a law enforcement agency asks the provider for all the details they have about this IP at the given time. I can't speak for every country but for the moment most providers only give out specifics about their users when a court order has been issued.
To clear things up a little bit. Your provider has logs for x days. These logs show at least every IP address assigned to users with information how long the user was online. If someone complained against you the provider simply would search for the specified IP address in their logs and get all the information about the user behind the IP.
I suggest you ask your provider for how long the logs are stored. Mine for example stores them only for a maximum of 24 hours, but I heard of some that save them for up to six months.
That means, for as long as your internet provider has your connection information in their logs someone could find out about you.
I hope you found the information provided useful, I will write an anonymity tutorial soon.
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Ghacks is a technology news blog that was founded in 2005 by Martin Brinkmann. It has since then become one of the most popular tech news sites on the Internet with five authors and regular contributions from freelance writers.