This article discusses how you can control Browser Cookies and stop, at least, some advertising sites from tracking your history.
Browser Cookies (small data-files that web-sites leave on your hard disk) are good and bad. Your online banking site, blogging tools, or Amazon.com legitimately use these files to help you log in and remember preferences and in general, you must allow Cookies for websites that have login screens or data-entry forms -- but even then, the cookies are only needed at the moment of log in and can usually be discarded. Most people do not have their browsers set in this fashion.
For a majority of other sites, cookies are optional and they offer no benefit to you. Almost every banner ad generates a cookie. These "3rd-party" cookies track which websites you have visited, how long you were there and how frequently you visit. They use this information to display targeted advertising and then sell the demographic information gathered to other companies.
Most cookies are an invasion of privacy and they slow down your computer. An average computer has thousands of cookies, occupying disk space and internet bandwidth. Here is how you can tame them in both FireFox and Internet Explorer.
MOZILLA FIREFOX BROWSER OPTIONS
Modifying your Browser's Cookie options.
1. With Mozilla's Firefox, select Tools, Options, Privacy.
Check these boxes:
[X] Accept cookies from sites
[X] Accept third-party cookies
Select "Keep until 'I close Firefox'"
2. Click "Show Cookies" and browse the list, noting those sites which are obviously advertising sites. In particular, note doubleclick.net, which is one of the main targets of this article.
3. In the same Firefox Privacy-screen, click the "Exceptions" button.
Block "doubleclick.net" and any other site that caught your attention by typing the name.
If you have multiple user-accounts on the same computer, you will have to do these steps for each account.
Later in this article are other methods for blocking these types of sites.
INTERNET EXPLORER BROWSER OPTIONS
To make the same changes with Internet Explorer, do the following:
1. Select Tools, Internet Options, Privacy-tab.
2. Set the "Settings" slider-bar to Medium High.
3. Click the "Advanced" button.
[X] Override automatic Cookie Settings,
[X] Accept First-Party,
[X] Block third-party Cookies
[X] Always allow session Cookies
4. Return to the first Privacy screen, click "Sites"
5. Add "doubleclick.net" to the Exclusion list.
If you have multiple user-accounts on the same computer, do these steps for each account.
Using the etc/Hosts file to block Sites:
Another popular, although somewhat geeky way to block a site, is to use the "etc/hosts" file (pronounced "etsy-hosts"). In the past, this simple file translated friendly names into IP addresses, but with the advent of DNS routing servers on the internet, the file fell into dis-use and yours is likely empty.
You can also use this file to redirect websites into the proverbial bit-bucket. I use this method for high-volume sites like doubleclick.net and it works for all browsers.
Steps to Modify the HOSTS file:
1. With Windows Vista, click Start, Programs, Accessories. "Other-mouse-click" Notepad and select "Run as Administrator."
With Windows XP, click Start, Run, type "Notepad.exe" and press enter.
2. File-open this filename:
(where you must type the dot, no extension)
The file is a simple ascii-text file, mostly composed of #comments. Click the illustration below to view; click your browser's back-arrow to return.
3. Copy the text from the chart below and paste into the file. Paste after the first localhost statement. You can optionally type the statements by hand; be sure to include the "127.0.0.1" and separate the columns with spaces. Don't worry, you can't really mess this up, even if you type them wrong (the worse that could happen is it doesn't block the site) but one warning: Do not add legitimate websites to this list unless you want them disabled.
Initial Recommended List:
How it works:
If any website tries to connect to "doubleclick.net", the hosts file intercepts the call (by design, this checks the name-resolution before the ISP's DNS server does). When the name is found, it looks across for the IP address. Since this address is the "localhost", this part of the webpage goes nowhere and the advertisement is stopped. On a screen, offending advertisements may "disappear," leaving a hole in the web page. Webpages will load faster.
4. Close and save the file.
Changes take effect immediately.
If you can't save the file (Vista), you probably did open Notepad as an Administrator or, if Windows XP, the file may be flagged Read-Only in Explorer; you can unflag the file by looking at the file's properties.
Also, if you are running a decent virus or spyware scanner, it will intercept writes to this file (in year's past, many-a-virus fiddled with this file). Grant permission to update. For example, Vista's "Windows Defender" prompts with this screen and you need to click "Ignore":
If you were to search, you would find other Internet sites with lists that are thousands of entries long and I'm sure they are all good sites to block, but many will be obscure and you may never visit them. My belief is this list can get too cumbersome. Without better information, I recommend keeping the list relatively short, at most a couple of hundred entries.
Making these changes will cut down on the number of cookies your computer accepts; this will improve your privacy and has the potential to stop some advertisements from reaching your browser. If you use Mozilla's Firefox, consider also a fabulous program called "AdBlock Plus", which is free. See this article: Recommended Firefox Plugins
Finally, this note: This blogging tool, hosted by blogspot.com, is owned by Google and Google is the same company who bought doubleclick.net. Doubleclick.net is notorious for the amount and quality of information they gather on web-surfers. Tracking is theoretically "not personally identifiable", but when capturing IP Addresses, they come remarkably close. This is one place where Google caught a lot of heat and seems to violate their own company policy of "doing no evil." [Update: At the end of 2008, Double-Click announced it would no longer track surfing habits, noting consumer feedback. Some advertisers balked at being associated with Double-Click. Even though Double-Click will stop tracking, this articles premise still holds: why even allow your browser to connect.]
You may find these articles informative: Wikipedia: Doubleclick.net