An IPv6 address has a few differences from IPv4. The first is that it is in hexadecimal instead of decimal. The second is that it is split up into larger segments and more of them. The third is that it uses colons (:) rather than periods (.) to divide these segments. In the end, one does not resemble the other. This is good because it prevents confusing the two.

Hexadecimal is better than decimal for a few reasons. For one, it takes up less space. The number “255″ is “FF” in hex; that is %50 smaller. Hexadecimal also relates more closely to binary. The number “1111″ is “15″ in decimal but “F” in hex. So “11111111″ is “FF” in hex, which is a much cleaner conversion than “255″ is. The downside is that humans typically think in decimal, so working with hex takes some getting used to.

IPv6 has a much larger address size. It has eight sections to it. IPv4 had half of that. The sections themselves are larger too: each one has four digits. IPv4 could only have three, and that only went to 255 tops. It should be obvious why this new address can afford all the room we have come to need. Hopeful it will for a long time. Here is a sample address.

FF00:00FF:0000:0000:0000:02f3:0000:0001

At this point, you may begin to see the down side to IPv6: it is long and hard to remember. To make them more human readable, there are a few conventions to short address when you have a lot of zeros present. First of all, you can skip leading zeros, so “0001″ becomes “1″ and “02f3″ becomes “2f3″ (IPv4 did this too). Second, groups of all zeros can be abbreviated to “::” (a double colon) once; you put nothing there. That makes “:0000:0000:0000:” reduce to “::” but “:0000:” cannot as it would be ambiguous. You can apply the first rule, making it “:0:” now. Putting all these rules into place gives us the following address.

FF00:FF::2f3:0:1

This address is about as long as an IPv4 number. Notice how the “00FF” shrank to “FF” and the “FF00″ did not. That was done intentionally to show the difference between leading and trailing zeros.

There is one more thing you really need to know if you are working with IPv6. The loop-back address, which was 127.0.0.1 in IPv4, is ::1 now. It works exactly the same way. You will have to use the ping6 command in Windows or Linux, so ping6 ::1 is what you would type into the command line. This will give many XP users an error as IPv6 may not be enabled on your computer. We have guides on how to enable IPv6 in XP, and how to assign IPv6 addresses in Linux.

Some other factoids about IPv6 are that it has is easier to route, more secure, and works better with mobile technology. There are changes to the way the packets of information are sent that makes it more efficient (e.g. better headers). It is more secure because it requires the use of IPSec, which is only optional in IPv4. IPv6 has an address recovery system, so when you change locations, it tries to keep the same address. These are are some of the that US government is switching over to it.

I should note that IPv6 has been found to have vulnerabilities. Malware tunneling is described in an article (note: a .pdf file) from the us-cert.gov site. It often has to do with how firewalls are configured. Different sources may give different opinions on how secure IPv6 is.

Wondering what happend to IPv5? It did exist. It was developed in the 1970′s to be used in audio and video streaming. It was called the Internet Stream Protocol. It did not get far past the experimental stage and was never adopted. Ideas from it helped to form IPv6.

How to look up the private IP address

The easiest option to look up the private IP address on PCs running the Microsoft Windows operating system is to press Win-R, type cmd and hit enter. This opens a command line prompt. Entering the command ipconfig will display the private IP address of every network adapter of the computer.

How to look up your public IP address

The public IP address is usually assigned to the computer by an Internet Service Provider (ISP). They can be divided into static and dynamic IPs with dynamic IPs assigned to home owners usually.

The easiest way to lookup the public IP address is to use a script on a website that displays it. You can for instance point your web browser to http://ghacks.net/ip/ to look it up.

Computer users without a router, e.g. those on a dialup connection, can issue a command to find out their public IP address much like they can find out their private IP.

They need to enter the command line again in Windows (press Win-R, type cmd and hit enter). The command netstat -n will display the active connections. The IP address is shown in the left column of the output.

Users with a router can find out the public IP address by loading the router’s administration interface. Most routers display the public IP address in that interface.

Do you have another tip to display the public or private IP address easily? Let us know in the comments.

As I said it’s pure entertainment. The website seems to be highly popular because it already analyzed more than 380K IPs over the course of several years. My current IP scored a whopping 10 which is bad if you consider that the leading IP received 86 points but not so bad again if you consider that there are negative scores as well with the lowest being -4 currently.

The only two tests that my IP scored was the poker hand where it qualified for a pair (+5) and that it got only even numbers (+5). Users can take a ride with the random IP script and enter an IP manually to see how other IPs are doing on that website or take a look at the leading or last IPs. As I said pure fun for a little while, nothing more.

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. 64.202.163.79 would be an IP address.

You can see that it consists of four 8bit octets each separated by “.” ranging from 0 to 255.

The most important question is of course: What does the Ip address tell others about the user behind the IP ?

Most people are not good remembering numbers, that’s one of the reasons why the DNS system, Domain Name System, exists. The DNS turns the IP numbers into textform, there are online tools that do that for you, for example dnswatch.info

If you go to the site and enter the Ip 64.202.163.79 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 dialups have these kind of IP addresses.

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. One website that offers the service: 1. whatismyipaddress.com

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 [24.20.255.46])
by server6.xlhost.de (Postfix) with ESMTP id D885256215
for [block]3[/block]
To: admin@ghacks.net
Message-ID:
Subject: Account has been created
...


This line “Received: from friko7.onet.pl (c-24-20-255-46.hsd1.or.comcast.net [24.20.255.46])” is the important one. The Ip of the sender is clearly shown 24.20.255.46, 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 address 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 receive a 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 ? Everything 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 that your IP did the following at a specific day and time.

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 asked 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 law enforcement agency asks for the information.

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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