Web Security, Privacy & Commerce, 2nd Edition

Anonymous Browsing

Although they’re great for blocking advertisements and crushing cookies, there’s one thing that HTTP proxies can’t do, and that’s hide your IP address. Fundamentally, there is no way for a proxy to change your IP address, because if it did, the remote web server wouldn’t be able to send you back the web pages that you request!

But despite the apparent difficulty of doing so, there are good reasons for wanting to protect your IP address from other computers on the Internet: IP addresses and hostnames can contain personal information and, like cookies, they can be used for correlating browsing activities across different web sites. Finally, your IP address can be used to track back seemingly “anonymous” web transactions to uncover your true identity—something that you may wish to prevent from happening.

Consider these hostnames and IP addresses that were recovered from log files:

daily-bugle.media.mit.edu 18.85.13.120

This hostname and its matching IP address belonged to a desktop computer at the MIT Media Lab in the early 1990s. Because this computer was only used by one person, wherever this person went on the Internet, he left tracks in log files that could be traced directly back to him. As the computer daily-bugle was also used to send mail and post to the Usenet, it was relatively simple to determine the identity of the person using this computer.

h00a0c030202a.ne.mediaone.net 108.21.147.24

This hostname was assigned by Media One to a cable modem subscriber in Cambridge, ...