BleepingComputer.com: How can websites know where i am?

Sorry if this is the wrong forum, but:

I often notice that sites with adds seem to know where i am. I receive adds relevant to my location, dynamic adds containing words involving my location and google seems to prioritise search results from sites i visit often. I would like to know how this is achieved (and through that how to prevent it).

Edit: Moved topic from Networking to the more appropriate forum. ~ Animal

If the website didn't know where you are, how would it send you the webpage in the first place? It has to have an address to send it to, otherwise the only thing it would know is "someone somewhere wants to see your website". The address to send the webpage to tells the website where you are.

Whenever you visit a website your IP Address is sent to the server, and depending on how that server is configured it can perform an IP address to name lookup which often times gives someone a general idea of where you are. I will use my IP as an example:

Quote

As you can see my IP has the static hostname of the above.

So common sense and reasoning would suggest that I am somewhere near Baltimore, Maryland. Which is true as denoted to the left under my user name.

Also your network may give the following information: Network Information for 96.244.76.112/29

Normally google and search engines do this to find more relevant information for you (ie: ads in your area). Which is a nice gesture as I guess if I wanted to look at ads then I would want relevant ads but most people don't want big brother watching them. There are ways that you can keep old big brother from knowing where you are at.

TOR (The Onion Router) is a program which allows your to virtually mask your public IP so it looks like you are connecting from somewhere else. The way it works is that your packet gets securely bounced around the TOR network and exits out of the network at some random location (like Sweden or Canada (but you can tell it where you want to exit)). Your internet browsing speeds will decrease but your security will increase.

The other thing that it might be is I have seen it happen when you get a Rootkit on your machine where it makes a fake page that tells you the city that you live in and looks like a newspaper. If that might be the case then post in the "I think that I am infected" forum and those guys can help you remove it.

There is a mode in another way to protect your self by using a mode in Firefox called private browsing (Chrome has one called Incogneto and Internet explorer 8 has one called private browsing). Once active it basically doesn't save any browsing cookies or history on the computer and once your done it deletes your session. It is another way to stay safe on the net especially when banking or when your in porn mode (not saying I do this but this is one of the uses for it).

Hope that gives you somewhere to start.
uByte

If you want to hear how these ad guys can really track you online try listening to the episode of Security Now called Evercookie (ep.270). You will be suprised to hear what they go through in order to track where you go online.

uByte

Besides the above stated.

If you use Firefox you may want to read THIS then maybe THIS.

Thank you for all the replies, it was very informative

hope it helps.