Appendix 1 - Modify your HOSTS file

The last version of this guide contained a section about using a modified HOSTS file. The authors of this document have differing opinions on this issue so we've put that section in an appendix.

Eric's thoughts-

"I've come to find this practice unsatisfactory for 2 reasons. 1 - It requires upkeep. 2 - Most HOSTS files on the internet not only block so-called "bad" sites but legitimate ads as well. Advertising is the lifeblood for most of the sites you visit. IMHO unless it is a pop-up, pop-under, pop-over, ads with sound ( I view these as invasive) they shouldn't be blocked.

For geeks - I believe using a HOSTS file for added protection can be another tool in your security arsenal but it requires constant attention on your part. Using a HOSTS file for security is not a replacement for any other security tool/method."

This step is recommended, but if you are uncomfortable modifying your HOSTS file, it may be skipped.  What is a HOSTS file?  The Internet uses addresses, like phone numbers, to identify places in the Internet.  They are numerical, and are in the format of xxx.xxx.xxx.xxx.  There is a unique address which identifies “Local Host”, or your own system, and that address is 127.0.0.1.  What this means is that any Internet address identified as 127.0.0.1 is directed to your own system and any program that looks for that address is redirected to your local system and not to the external Internet.  The HOSTS file can therefore be used to block access, whether intentional or accidental to sites on the Internet by forcing software trying to access these sites to your Local Host, and not to the Internet.  Thus, you can use this feature to block advertisements, prevent access to sites that are potentially dangerous, etc.  This is accomplished by adding a line to your HOSTS file that looks like this:

127.0.0.1 www.unwantedsite.com

Whenever a program tries to go to unwanted site, it is blocked from doing so.

The HOSTS file, which is a plain text file without any extension, is located in XP in the folder C:\WINDOWS\system32\drivers\etc.  To add a line like the above to your HOSTS file, simply open the file in a plain text editor like Notepad.  Add the line “127.0.0.1 www.unwantedsite.com” (without quotes, of course) at the bottom of the file, save it and you are done.  Remember that the file must be named HOSTS with no extension.

On the other hand, there are thousands of advertising and objectionable sites on the Internet, and identifying and typing them into the HOSTS file one-by-one would be an arduous task indeed.  Fortunately there are a number of available HOSTS files that are both well constructed and current.  A good, frequently maintained file is available here.   First, backup your current HOSTS file by copying it to HOSTS.bak.  That way, if something gets messed up for you, you can always revert to your old HOSTS file by deleting the new one, and renaming your old one back to just plain HOSTS.  To add these sites to your HOSTS file simply open HOSTS in notepad, open the downloaded and unzipped file, copy and paste the downloaded text into your current HOSTS file, and then save it as HOSTS.  Once you have done that, any request to one of these sites by any software on your system will fail, because they are effectively blocked and forced to your Local Host.  One final step is needed to prevent a Trojan or spyware from changing your HOSTS file without your permission.  Right clock on your new HOSTS file and select Properties from the pop-up menu.  Check the check box to the right of Attributes labeled Read-Only, then click Apply, and finally OK.  Once you have done that, XP will not permit any program to change your HOSTS file, thus protecting it from unwanted changes.  Remember, if you need to add additional, or to delete some lines from your new HOSTS file, you must reverse this last step, and uncheck the Read-Only Attribute before attempting to edit HOSTS.

Remember too, if there is a site listed in your HOSTS file that for some reason you do want to visit (generally not a recommended thing to do), search for the site using Notepad's search feature, and then delete the lines that refer to it from your modified HOSTS file, save the result as HOSTS, and the site will no longer be blocked.