Filtering Products

When selecting an Internet filtering product for your library's compliance with CIPA/NCIPA, it's a good idea to be sure you understand what filters are, and the various ways they work. Start with our Brief Technical Description of Filtering.

Look for a product that is technically suited to your library, and has the features and abilities you need. As we gather more information, we will begin to provide comparisons of some commonly sought features and most readily available products in a Table of Filter Comparisons.

For more information, we've created a list of links to other filtering resources. Your suggestions for additional links are always welcome and appreciated.

A Brief Technical Description of Filtering

by Thomas Reddick, Automation Coordinator
Northeast Kansas Library System

Internet content filters have two very basic jobs:

1. To prevent access to undesired content.
2. To allow access to desired content.

Filters work primarily in two ways. The first way is as an individual software install on the individual computer to be filtered. These filters are software that is installed on a local machine and maintained and configured much as anti-virus software or some other application would be. The other way is as a network filter. These filters filter a network, acting much as a firewall and analyzing any traffic that somes in or out of the internet connection itself. These filters are typically software that is loaded on a server, or a hardware/software combination.

Both of these types of filters perform their function either by maintaining a database of blacklisted sites or by attempting to determine the desirability based upon keyword blocking, "intelligent expressions" or some other analytical method of determining the nature of the content requested. Some filters use a combination of these methods to filter.

Generally speaking, the more aggressive a filter is in doing its first job, the more poorly it performs in performing its second. Similarly, if a filter is aggressive in fulfilling the job of allowing access to desired content, the more likely it is to allow access to undesired content. The best path for a library to take is to select a filter that performs its two functions in the best way possible for the library's needs. The decisions as to whether to select a network filter or a local install filter and whether to filter based upon keyword or blacklist is a decision which will vary based largely based upon individual circumstances. This description is intended to provide information about the choices that exist, not to recommend a best practice.

Links to other filtering resources

• Library Software Filters
  Comparison of 17 different products prepared by Lori Bowen Ayre for California's Infopeople project.
• Children's Internet Protection Act: Study of Technology Protection Measures in Section 1703
  Report to Congress by the National Telecommunications and Information Administration, U.S. Department of Commerce, as requested in the CIPA legislation.
• Acceptable Use and Computer Policies
  A resource page of Web Junction, the public access computing information source developed by OCLC and others in partnership with the Bill & Melinda Gates Foundation
• Plain Facts About Internet Filtering Software .
  Written by Karen Schneider as part of PLA's Tech Notes.
• Internet Filter Feature Guide from internet-filters.net
  Detailed reviews of many well-known products.
  Note: At this writing the site provides no information about Internet-filters.net - who they are or how to contact them.
• GetNetWise: Tools for families
  A site developed for parents and families; lets you search for products based on desired features and characteristics.
• Compatibility of Internet Filtering Products with the Windows 2000 Gates Library Computer
  Note that Gates Library Computers in Kansas will be upgraded to Windows XP in late summer 2003.
• Kansas Library Association Statement on Internet Filtering
• Internet Filtering, Legislation, and Policy Resources
  Also from the Web Junction site: "a list of websites with information about Internet use policies, filtering, and Internet access management"

Please direct comments to: Jeff Hixon, Director,
Library Information Technology Division
Kansas State Library
Last Updated 2/10/2004

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