tictech: Simple Internet Filtering...the HOSTS file

From: Wes Felty (wfelty@gte.net)
Date: Thu Sep 26 2002 - 20:54:12 PDT

  • Next message: Mary K. Conner: "Re: tictech: Simple Internet Filtering...the HOSTS file"

    -tictech message:

    There is a system built into Windows that allows a number of Internet
    options including faster name resolution, letting you use shortcut names
    rather than IP addresses to contact other computers, and to do some
    Internet filtering. This involves a file in Windows named "hosts". I've
    held off posting this since I'm having trouble getting it working at
    Ingraham (it works great at home). I don't know if the problem is related
    to Ingraham or everywhere inside Seattleschools WAN. So, I hope a few
    people will try it and report if it works at their school site. Here is
    how it works.

    Computers on the Internet are not identified by names, but by numbers which
    we call IP (or TCP/IP) addresses. For example, we call one Web site
    "Apple.com". But computers call it "17.254.3.183". It is easier for
    humans to work with URL names like "Apple.com", but on the Internet itself,
    the address "17.254.3.183" is used. The system that usually converts the
    names to IP addresses is usually DNS. This is a set of special internet
    servers setup to make these translations and your computer is configured to
    know where to find some of these DNS servers. So, in the internet, when
    you enter a URL like "apple.com", Windows sends the URL name to the DNS
    servers that the computer is configured to use and that DNS server converts
    it to its IP address, "17.254.3.183" and sends it on down the wire. Some
    computers are not registered in DNS servers and therefore you have to enter
    their IP addresses. Or, if you entered in your web browser
    "http://17.254.3.183", your connection to Apple.com will happen much
    faster since it doesn't have to go through a DNS server.

    But, Windows supplies a shortcut. If there is a special file in Windows
    called "hosts", it can do the translation before a URL goes out to a DNS
    server and send the signal directly down the wire. This file contains URL
    names and their IP addresses. If a URL you are using is in this "hosts"
    file, nothing is supposed to go to a DNS server. So, this file can make
    faster connections, allow you to makeup your own names, and allow you to
    redirect a web URL to somewhere else. This is how you get the Internet
    filtering. In the Hosts file, you put a URL that you do not want your kids
    going to and send it to somewhere else, a more appropriate web site (like
    maybe Google.com), to a web server with a "no-no" message, or out to
    "la-la" land. For an example of this middle option, go to
    "http://IngrahamMWS.ssd.k12.wa.us". You will get redirected to
    Altavista.com. At my school, you would be redirected to our Follett
    Library Automation Web Site. (That Ingy web page is a unique piece of
    programming). Here is an example of a "hosts" file.

    127.0.0.1 localhost
    10.94.11.2 mws
    209.73.164.90 clickagents.com
    127.0.0.1 ads.rmbclick.com
    10.94.11.2 www.bestweb.net
    10.94.11.2 www.my-stats.com
    10.94.11.2 www.loveproblem.com
    10.94.11.2 media7.fastclick.com
    127.0.0.1 pop3.norton.antivirus # Added by Norton AntiVirus for e-Mail
    scanning
    127.0.0.1 pop3.spa.norton.antivirus # Added by Norton AntiVirus for e-Mail
    scanning

    This is just a plain text file. The second column is the URL and the first
    column is the IP address to direct it to. "10.94.11.2" probably won't work
    in any building but Ingraham. That is the IP address of my MicroWebServer
    "IngrahamMWS.ssd.k12.wa.us". The IP address "209.73.164.90" is
    "www.altavista.com", so anyone trying to go to "clickagents.com" will get
    redirected to "www.altavista.com". And, when I want to go to my
    MicroWebServer, instead of "IngrahamMWS.ssd.k12.wa.us", I just enter
    "mws". The first line should always be as shown and Norton's antivirus
    added the last two lines. Some people use the localhost address
    "127.0.0.1" like the fourth example. To use a message like I did above,
    you need to have a dedicated web server setup to do that.

    Now, this file has to be named "hosts" and that is with no extension on the
    name. Use a plain text processor like NotePad to create it, but almost all
    word processors will try to add an extension to make it "hosts.txt". Your
    Windows probably won't show the ".txt" extension even if it is there. One
    way to do this is to surround the name "hosts" with quotation marks in the
    Save As,,, dialog.

    Where do you put this file? You should already have one in "c:\Windows"
    for Win 98 and "C:\WINNT\system32\drivers\etc" in WInNT and Win2000.

    So, that's the whole story. Let me know if it does or does NOT work for
    you. Maybe if it this works we can get the district to give us a page to
    link to for a "no-no" message.

    -Wes
    Wes Felty <wfelty@gte.net>

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