This page is based on www.mvps.org/winhelp2002/hosts.htm by Mike Burgess (but it explains the issue better).
A very simple way to block some ads and malicious or pornographic web sites is with the HOSTS file, which is part of TCP/IP a set of rules and protocols that computers use to communicate. In the old days when TCP/IP was developed (before the Internet) the number of computers connected in a network was small. We now refer to this as a LAN, a Local Area Network to differentiate from larger networks. There was a computer nerd in charge of the networking (now much of this runs automatically) who manually configured each computer on the network. Part of this configuration was the HOSTS file.
The word "host" in this context means a computer on a network. Every computer that uses TCP/IP to communicate is assigned a number, called an IP address. People don't want to refer to computers by a long string of numbers, so they are also given names. The Hosts file was in charge of translating between the name of a computer and its number. The TCP/IP software actually used the numbers (IP addresses) while us humans used the names. The hosts file consists of many entries, each entry is the name of a computer and its IP address. In the old days, computer networking nerds edited these files by hand.
Nowadays, the translation between a computer name and its IP address is done
automatically using the DNS system. However, the TCP/IP software still looks for
a hosts file, just like in the old days. On modern Windows computers, the hosts
file consists of just a single dummy entry that looks like this
127.0.0.1
localhost
The details of exactly what this dummy entry does, are not relevant to this
discussion.
The HOSTS file, that you can see here plain
text format (149 kb) is a large file with many entries for
"bad" (my term) web sites. Most of the "bad" web sites serve
up ads, some serve up assorted malware. A small sample follows:
127.0.0.1 ads.inet1.com
127.0.0.1 banners.inetfast.com
127.0.0.1 ads.infi.net
127.0.0.1 ads.infospace.com
The basic idea is to use this Hosts file instead of the default one (with just a
single dummy entry) and your web surfing will be faster (not as many ads) and
safer.
To swap Hosts files, you rename the existing one on your computer (in case you want to go back to it later) and place this Hosts file in the same official directory. The official directory used by Windows for the Hosts file varies.
The web site says that the HOSTS file must be in capital letters. This was
not my experience under Windows 2000. Still, in this MS KB article How to Use a HOSTS File to Test a Site that Uses Host Headers on an Intranet
it specifically says the HOSTS file should be upper case. On my Windows 2000
computer however, the existing HOSTS file was in lower case. Conflicting signals
from Microsoft. Not the first time. Mike Burgess was nice enough to respond to
an email and he warned that testing he and others did has found that the HOSTS file may still
function in lower case, but there were several cases where it either became
corrupted or failed to function properly.
The web page also suggests making the HOSTS file read-only to provide protection from some malware programs that modify it for bad reasons and it goes into some detail on the format of the HOSTS file in case you want to directly update it yourself.
Should anything go wrong, all you need to do is rename a couple files and restore your original HOSTS file. There is no software to install/uninstall and no need to reboot.
Problems:
In fairness, this will never be a perfect ad/parasite blocking scheme, but it helps and at very little cost.
For more see What is the Hosts file?
If you really want to get into this subject in detail, here are some links courtesy of www.smartin-designs.com
| Page last updated: March 31, 2004 |