Internet Filters and Censorship: distinguishing between oppression and age-appropriate information dissemination.

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This page contains information on the various types of filtering software and how they work, the features of each, and a list of some of the various commercial filtering software companies and some of their products. The material on this page was compiled from a variety of resources, and hopefully organized in a manner that will appear a logical to persons interested in gaining a better understanding the sorts of software available.

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Filtering Software Types

• Client software (individual workstations) ? installed on individual computers. Can be useful for selective filtering, rather than imposing filters on all terminals. Cost effectiveness diminishes as number of terminals grows. Most useful for those without dedicated internet access and with limited numbers of computers. Be sure to carefully note de-installation procedures, since client filtering software is designed to set the gremlins loose on computers if the software is simply deleted from the computer. Cyber sitter, Surfwatch, Cyber Patrol

• Standalone proxy server software (Internet gateway for server) ? Generally used by sites with internal Internet services, most Windows NT based. Can be very inexpensive. Skilled automation support is required to maintain a proxy server, but can have little system impact, be easy to configure (system level), and cost-effective. May have additional software, hardware, and configuration requirements (e.g. recent version of NT, etc.). The standalone proxy server acts as the Internet gateway, and thus should be carefully studied for performance prior to purchase.

• Firewall software (sits on a Unix firewall) ? Installed at firewall level, require pretty high automation support levels, generally only block web requests.

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Other Filter Types

• Remote proxy servers ? most useful for smaller settings or limited filtering. Based on subscription services. All Internet requests pass through a remote proxy server. Configure each browser to point towards the remote proxy server (the companies have prepared for all types of sneaky roundabouts). May result in bottlenecking if too many demands on the proxy server are received at once. Bess

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Filter Features

Determining whether or not to use a filter, or what filter is right for a specific situation, it is useful to understand some specific information about filter features. Some information changes dynamically as technology changes and advances. Other information changes little. There may be certain aspects or features that are important in a useful filtering system. Some of these may be:

• The filter should only block what you want it to, and when, and where.
• You should be able to know what has been blocked.
• You should be able to change blocking parameters if desired.
• The filter should be compatible with the operating system of the computor to which it is applied, and not create extra work or difficulties.

Some of these issues are difficult to resolve, for example the point about knowing what has been blocked. Filtering companies that use lists are very protective of them, and will not share with customers.

There are five main categories to consider when examining filter features:

software capabilities,

precision of blocking by filters,

site lists (how they are determined, etc.),

time/place/manner filtering,

categories of filters,

and some other features. Some of the main points of each have been listed below.

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Software Capabilities

• Block Reporting and Monitoring:
  • Block reporting is a useful tool for gaining an understanding of how the filter is working. Reports allow a review of what is being blocked and what is not at each workstation being filtered.
  • Monitoring by the filter creates a report on all Internet sites visited, creates categories and classifies the types of sites visited into these categories without blocking access to any of them. Monitering is useful for analysis purposes.
  • Two internet filters were designed specifically for monitoring capabilities: On Guard and Cybersnoop. This feature is available primarily with server-based filters, but some client-based filters also have this capability.
• Client or server-based software: either one or the other is found in all types of filters.
  • Server-based filters:
    • Generally rely on site blocking, as opposed to keyword blocking;
    • Are generally easier to maintain, and
    • Create less interference with other types of software, but
    • May cost more to use.
    • Requires expert installation.
    • Fall into four general types:
      • Filtering software used along with currently existing proxy servers
      • Networked versions of client software
      • Preconfigured hard- and soft-ware packages
      • Standalone proxy servers placed on an Internet server
  • Client-based filters:
    • are more useful for individual terminals in small numbers, since maintenance issues become more difficult as more computers are added. Each must be maintained individually.
    • Is usually outperformed by server-based software.
    • Often causes software conflicts with other programs.
    • Can be more difficult to configure than server-based software.
• Fail-safe availability in case of filter failure:
  • Not available with a standalone server to which the system has been configured, but available with some filters.
  • A question to ask the vendor is whether the Internet can be accessed in the event of a filter failure.
• Preconfigured server filter packages available:
  • Currently available with most server-based filters
  • Occasionally will be configured by the vendor on-site.
• Remote Administration:
  • Allows computer support staff to monitor, and reconfigure if necessary, during off-hours.
  • Available in certain server-based filters.
• Shared Remote Proxy Servers: currently only offered by Bess.
  • Categories cannot be selectively enabled.
  • A viable option for large groups such as consortiums or multiple-county systems.
  • Configuration is generally controlled by a central location, so local control may be limited.

Precision of Filter Blocking

• Ability to resolve IP addresses from Hostnames
  • Some filters are able to translate hostnames into IP addresses (the numerical address that is the literal location of a web site). The worded address in the URL bar is simply a translation created by the DNS, or Domain Naming System, to make it easier for people to remember net addresses. Someone particularly computer savvy might be able to enter the numerical address and bypass the filter in this way. So a filter that has the capability to recognize this attempt would be very desirable.
• Blocking of Only Specifically Targeted Content:
  • Not available with any filter product yet produced, though the ads sound good.
• File-level Filter Blocking/Enabling:
  • Feature available in most filter products.
  • Performance varies widely from filter to filter, so spend some time doing your homework on those you are considering.
  • File level blocking means that while access to a site may be allowed, some sub-levels of the site may be blocked.
• Keyword Blocking:
  • Be sure to find out if keyword-blocking can be disabled.
  • Some keyword-blocking can only be disabled by vendor technicians.
  • This feature is available with most filters, but is less than effective in its primary purpose.
• Total Blocking of Targeted Content:
  • Not available with any filter product, though the advertising may lead prospective clients to believe this is a possiblity.

Site Lists

• Automatic Update / Daily Maintenance
  • Automatic update is available with most server-based filter products, and some client-based products.
  • Some filters only update weekly, or less frequently, but the majority update daily.
• Blocked Site List
  • Can it be viewed? Currently only Net Nanny and The Library Channel offer administrative viewing privelages of blocked site lists. This is an issue for those concerned with Freedom of Information.
  • Blocked site lists are often considered proprietary and private by filtering companies.
  • Can it be edited? Only those with viewable lists can be edited.
• Extensiveness of Site Lists
  • The more extensive the list, the better, since if you are intent on blocking certain types of sites you must have as complete a list as possible of those sites you wish to block.
  • Creating a local site list can be very labor intensive.
  • Maintence of a site list is just as time consuming.
  • Testing is essential to provide feedback on the comprehensiveness of the list.
• Local Access / Deny List
  • Are local access/deny lists supported by the filter? These are useful tools since they provide a list of sites that may need to be added or deleted from either the local or vendor site list.
  • Be sure to ask how long the list can be.
  • Find out if the list can categorize URLs.
• Shared Lists / Third-Party Lists / Customized Lists
  • In theory, the ability to share, exchange, combine, and/or customize site lists.
  • Not widely available.

Time/Place/Manner Filtering

• Barcode Access
  • Currently in the development stages.
• Multiple Access Levels
  • Useful when differing access levels are needed: children/adults, staff with differing security/access needs, etc.
  • There are some filters offering this now, and more will in the future.
• Protocol Block
  • The ability to block certain types of access/protocol. For example it is possible to eliminate e-mail or chat protocol, or interactive gaming.
  • Available with most filter products.
• Time Block
  • The ability to block access at certain types of day, for instance it is possible to block chat during heavy use times, such as late afternoon or early evening using a combination of both protocol and time blocking.
  • Available with some filter products.
• Time Outs
  • Session time-outs, while highly desireable and consistantly asked for by libraries, are not yet available.
• Warning Messages
  • Filter provides a warning message to users instead of blocking the site - can identify sites as being pornographic, violent, etc.
  • Can be used in conjunction with blocking software to provide multiple levels of access.
  • Currently available on a limited basis.

Categories of Filters

• Categorized Site Lists
  • Allow disabling of specified categories.
  • Categories can be arbitrary, and are designed for wide audiences.
  • Widely available
• Client-Defined Categories
  • Allows creation of local category lists.
  • Available with some filter products.

Other Features

• Changes for the Vendor Master List
  • This feature is generally built into the filter system, and allows recommendations for changes to master site lists.
  • Widely available.
• Examinations of Usage and Feedback
  • Refers to the information provided by a filter when a site has been blocked, such as a block code or message.
  • Options for feedback/usage information vary widely by product type and vendor.
• PICS
  • Although this feature for site rating has been or will be available from most vendors, it is still in a very preliminary state, and as yet highly unreliable.

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Internet Filtering Products

The following list is of some of the filter products and companies currently marketing products. There are no reviews listed, because it was found that success/failure rates varied pretty widely from test to test, although there was consistancy in the aspect of failure v. total success (not one of the products listed here has a 100% success/block rating). Filter failure ratings must be tested for oneself to determine which filter will work the best in a given situation, since the features vary from filter to filter. Just don't expect complete success from any of them.

�FILTER NAME	WEBSITE	�TYPE	PLATFORM	FREE TRIAL
�AOL's Young Teen Control	http://www.aol.com	proxy server	most	�web request
�AUP Action Tools	�http://www.aupaction.com	server/client	most	?
Bess	�http://www.bess.net/	�proxy server	most	by arrangement
Cyber Patrol (Surf Control)	�http://www.surfcontrol.com	client/LAN/proxy server/firewall/others	most	�by download
Cyber Snoop (X Stop product)	http://www.pearlsw.com/	client / preconfigured server	�	by download
CyberSitter	http://www.solidoak.com	client	Windows 95, 98, Me, NT, 2000	by download
IF - the Big IF	http://turner.com	client/proxy server	�most	no
�Guard One	http://www.guardone.com	proxy server	most	by download
I-Gear	http://www.urlabs.com	server: NT plugin for MSproxy, Unix	Windows NT, Unix	by download
Internet Guard Dog�	�http://www.mcafee-at-home.com	�	Windows 95, 98, Me�	by download
Library Channel	http://www.vimpact.net	client	Windows 95, NT	by web request
Net Nanny	http://www.netnanny.com	client	Windows 95b, 98, NT, 2000	by download
Norton Internet Security 2001	http://www.symantec.com	client	Windows 95, 98, Me, NT, 2000; Mac	web request
On Guard	http://www.on.com	packet filter	Windows NT	web request
Safe Surf	http://www.safesurf.com	proxy server	most	?
Smart Filter	http://www.webster.com	proxy server	most	web request
SurfControl Super Scout	http://www.surfcontrol.com	proxy server	most	by download
SurfControl Cyber Patrol for home	http://www.surfwatch.com	client	most	by download
SurfControl CyberPatrol for Education	http://www.surfwatch.com	client	most	by download
SurfControl for OEM	http://www.surfwatch.com	server	most	by download
Websense�v.4.3	http://www.netpart.com	proxy server/firwall/client/others	most	by download
X-Stop (this vendor now has multiple products available)	http://www.xstop.com	�client/LAN/proxy server/add-ons	most	by download

This list is by no means all inclusive, but it is intended to give a jumping-off place for deciding which filtering solution, if any, will be best for a specific situation. For a list that includes some other filters see Yahoo's list of internet filtering companies: http://dir.yahoo.com/business_and_economy/shopping_and_services/computers/software/internet/blocking_and_filtering/

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Features Checklist

As filters are reviewed the features described above should be checked for in each product to be sure that the product being used is the best one for the job. The following is a quick checklist of those features:

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• Automated list download
  
• Block v. monitoring
  
• Categories are company-defined
  
• Category blocking/enabling
  
• Company supplied site list
  
• Deny-message editing allowed
  
• Editable site list
  
• File level blocking
  
• IP address configuration
  
• IP resolution by host
  
• Keyword filtering
  
• Keyword filtering can be disabled
  
• List maintenance staff size
  
• Local deny/access lists
  
• Multiple user access levels
  
• Patron barcode support
  
• PICS support
  
• Protocol blocking
  
• Reconsideration email link
  
• Remote administration
  
• Report capabilities
  
• Third-party list support
  
• Time blocking
  
• Time-out support
  
• Update frequency for site list
  
• User ID configuration
  
• Viewable site list
  
• Warning v. block option
  

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Bibliography

Aftab, Parry (2000). The Parent's Guide to Protecting Your Children in Cyberspace. McGraw-Hill, New York.

Bess: the Internal Retriever (N2H2). http://www.n2h2.com/

Children and the Internet: Guidelines for Developing Public Library Policy (1998). The American Library Trustee Association (ALTA), the Association for Library Service to Children (ALSC), and the Public Library Association (PLA).

Computer Professionals for Social Responsibility: Filtering FAQ. http://www.cpsr.org/filters/faq.html

Consumer Reports Online: Internet Filters. http://www.consumerreports.org/main/detail.jsp?CONTENT%3C%3Ecnt_id=18867&FOLDER%3C%3Efolder_id=18151&bmUID=993422068601

Cyber Patrol. http://www.cyberpatrol.com/

CYBERSitter. http://www.cybersitter.com/

Intellectual Freedom for Children: the censor is coming (2000). The Intellectual Freedom Committee, Association for Library Service to Children..

Internet Filters 101: Evaluating Internet Filters for the Public Library http://tln.lib.mi.us/~amutch/pro/filter/lom2001/

Net Nanny. http://www.netnanny.com/home/home.asp

Net Shepherd. http://www.netshepherd.com/main.htm

Parental Controls / Internet Filters. http://www.microweb.com/pepsite/Software/filters.html

Platform for Internet Content Selection (PICS): Internet site ratings. http://www.w3.org/PICS/

Schneider, Karen G. (1997). A Practical Guide to Internet Filters. Neal-Schuman Publishers, Inc., New York

Smart Filter. http://www.securecomputing.com/index.cfm?skey=85

Smut Sieve: why Internet filters aren't enough to protect your kids. http://www.zdnet.com/anchordesk/stories/story/0,10738,2690741,00.html

Surf Control. http://www1.surfwatch.com/home.html

The Big IF. http://www.turnercom.com/if/index.html

TIFAP: The Internet Filter Assessment Project. http://www.bluehighways.com/tifap/

X Stop. http://www.xstop.com/

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Pamela Force

Independent Study IRLS699

University of Arizona

School of Information Resources and Library Science

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last update 9/23/03

created by Pam Force