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Web Filtering: Home

Resources related to the "Web Filtering" Tech Talk


This guide is a companion to the Tech Talk "Web Filtering" that was scheduled for 10/16/2015. Specific products on this page are for illustrative purposes only and do not constitute endorsement by the Alaska State Library.

CIPA Requirements

The Children's Internet Protection Act (CIPA) makes filtering and the possession of an Internet Safety Policy requirements for libraries to receive erate discounts.

Methods of Web Filtering

Web filters review every request for web pages and other computer resources, then then block anything that is unauthorized. Web filters do this by a combination of the following methods:

  • Address filtering - blocking on the basis of lists (often secret) of internet addresses.
  • Keyword filtering - blocks pages based on a check of a banned words list.
  • Filtering by service / format of content - blocking video/audio streaming, IM clients, etc, even if the surrounding page is passed by the web filter.
  • Whitelisting - Build a list of approved sites, often block anything not on approved list

Most web filtering software allows blocking of sites by subject categories using a mix and match of the methods above. 

Domain Name Service (DNS) Filtering

DNS filtering works by routing your computer's "domain name" requests through a filtering provider. That provider uses the address to decide whether to provide the page to your computer. 

Specific DNS filter suggestions from Idaho

We're sharing suggestions for DNS filters made by Dylan Baker of the Idaho Commission for Libraries because they seem useful to us. You might find the rest of his filtering guide useful as well. We're not afraid of second opinions.

Computer Based Filtering Programs

If you are only looking to filter a few computers in your home or library, a computer based web filtering program may be for you. Here are a few examples along with a buying guide. 

Router / Hardware Filtering

If you are looking to provide filtering at the level of your home / small office/library network, you may want to use a hardware solution. These pieces of hardware often function as wifi hotspots in addition to providing web filter services. The following products are examples of this type of technology. 

General Filtering Resources

Over and Under Blocking

Internet and Technology Consultant

Daniel Cornwall's picture
Daniel Cornwall