Do you want to browse the web without a trace? Easy! Just use your browser’s Private Browsing Mode! Wrong!
So “private” mode isn’t really “private”? Well, in a way, no, it’s not. Even in Private Mode, you’re still leaving traces behind.
Isn’t Clearing the Browser ‘Private Data’ Enough?
Modern browsers contain a feature known as ‘Clear Private Data’, which will delete all history, cookies, and cache or does it? While it does delete your browser history, cookies, and cache, there are still DNS Cache entries and the far worse, flash cookies, sitting around on your system.
When you browser in Private Browsing Mode, the browser might not be saving history or cookies after the session closes, but your system is still holding onto the DNS Cache and Flash Player still holds the flash cookies.
DNS Cache Entires
Whenever you visit a website URL, your browser looks up the IP Address of that URL and then connects you to that IP Address. To speed up the process, these entries, known as Domain Name System (DNS), are cached for future reference so if you ever visit that same URL again, looking up the site is not necessary. Unfortunately, this can actually serve as a web history of sites you visited.
If you’re interested in viewing your DNS cache, use the following command on Windows:
ipconfig /displaydns. There might be more entries than the command prompt can hold in one view. Want proof that private browsing still caches your websites here? Open up a new private browsing window and visit a site that you normally don’t visit. There’s a good chance that the new website will end up on the DNS cache list.
To clean the DNS Cache, run the command:
Mac OS X Leopard or later:
Mac OS X 10.5.1 or earlier:
Get Rid of the Flash Cookies
Here’s the big one. That’s right. Flash. Flash Cookies are stored in these locations:
%AppData%\Macromedia\Flash Player\#SharedObjects and
Mac OS X Websites:
Mac OS X Adobe AIR Apps:
~/Library/Preferences/[package name (ID) of your AIR app]
You can have some fun viewing all the flash cookies that were stored. When you’re done, you can delete any or all of them. Alternatively, users can visit the Adobe Flash Player Settings manager to delete cookies.
CCleaner for Windows
A useful and free utility known as CCleaner can handle all the cleaning for you, including DNS Cache Entries and Flash Cookies. Be sure to select ‘DNS Cache’ (under System) and ‘Adobe Flash Player’ (under Multimedia).
In addition, keep in mind that sites like Google collect data of search results you visit. Most sites also contain server logs. If you’re not leaving a trace on your own computer, you probably left a trace on a server that you have no control over.
Of course, if there happens to be a security camera near you or someone is just peering over your shoulder, then well, your browsing session isn’t very private regardless of how you clean up afterward.
So next time you try to visit a website without anyone knowing, think twice before simply using Private Browsing.