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Filtering Options in AllegroSurf


Welcome to another installment of the newsletter. You are getting this newsletter because you signed up on our web site. If you would like to stop receiving these newsletters, please visit:

The intent of this newsletter is to give you some pointers on our products. This newsletter explains how to use AllegroSurf's many filtering options.

Using Approved Sites vs. Banned Sites

Filtering objectionable content is one of the more difficult tasks for IT administrators and home users alike. AllegroSurf places a great number of filtering options at your command.

The majority of AllegroSurf proxy servers are configured for content- based filtering and "Banned Sites." The Banned Sites list allows a specific list of sites to be blocked, but access to other sites is allowed. The content-based filtering removes access to websites based on specific keywords in the title or meta-tag descriptions of the site. When combined, these filtering options effectively block most undesired content, and can be customized to block any desired site, as well as allowing the greatest overall access while keeping filtering intact. Operating AllegroSurf in this manner is also referred to as "black list" mode.

Enabling this type of filtering is simple. Inside the WWW Proxy Server, make certain "Enable Filtering" is checked under "General." Then, under "Content Filtering," check the boxes for the types of content that should be filtered out. The options allow for filtering of anything from bandwidth-wasting advertisements to pop-up images and adult content. It is recommended to also select "Automatically add to banned sites" in this interface, so any site that gets blocked based on one of these rules is also placed in the list of "Banned Sites." This can be a useful tool for the Administrator to see and review sites that users have attempted to visit.

Sometimes the filtering will disable a site that has a legitimate purpose. In a family setting, a child may be doing research for a paper on a subject that is flagged by a keyword. In the health care industry, many topics of use to doctors or nurses may end up being caught by a filter. If a site is inaccessible due to filters, an "Exception URL" can be created that allows that page to bypass the filters. The easiest way to accomplish this is to select the entry for the site under "Banned Sites," right click it, and select "Move to Approved Exception." This ensures that the site is allowed through the filtering, but flags it as an exception, rather than an "Approved Site." If a site is set as "Approved" without being configured as an exception, AllegroSurf enters White List mode, and only allows access to sites on the "Approved Sites" list. If a site gets added as an Approved Site by mistake, it can be corrected by editing the Approved Site and checking the "Exception URL" checkbox.

The most restrictive way to access content with AllegroSurf is through the "Approved Sites" interface. If sites are entered into this interface without marking them as "Exception URLs," AllegroSurf treats the Approved Sites list as a "White List," restricting users' access to only the sites that have been explicitly approved. This is useful in a secure environment where users are only allowed by IT policy to visit a very specific range of websites, or where you need to be certain exactly which sites can be accessed by a tightly controlled list, such as publicly accessible computers at a child care center.

AllegroSurf Case Studies

Customizing Content Filtering in AllegroSurf

Blocking Advertisements

The "Ad Database" and "Ad Sites" provide the guidelines used by the "Advertisements" filter in AllegroSurf. The "Ad Database" contains a number of filenames and site names known to be ad hosts or file names used by known ad websites. is always updating our list of ad sites. The knowledge base article linked below explains how to modify the ad database and how to get the latest version of this database from our website.

Updating the AllegroSurf Ad Database

Overriding Site Filter Rules for Specific Sites

Custom filtering allows sites to be exempted from certain types of filtering, whereas allowed sites are entirely exempt from filtering.

Many times, sites with legitimate information get blocked by one of the content-based filters. The filters are intentionally very broad. Also, certain websites do not work well when any filtering is applied. If a site has content that needs to be unfiltered, AllegroSurf allows you to exempt the site from specific types of filtering or from filtering altogether.

  • Right-click "Site Filter Settings."
  • Select "New."
  • Place the URL for the site requiring custom filtering under "Domain Name or IP Address." Enter a description as well if needed.
  • The gray checkboxes indicate which settings will use the Global filtering settings. To override a global setting, make sure the checkbox is clear to remove a filter or that a black checkmark is placed in the box to apply a specific filter.

The specified site is now configured for custom filtering.

Importing Third Party Banned/Approved Sites

A number of organizations provide lists of inappropriate or appropriate web sites of various sorts. AllegroSurf can import these lists directly from a text file to the Banned or Approved site group. Importing a banned site list is the most common use of this function:

  • Acquire a text-format list of sites to block access to.
  • Right-click "Banned Sites."
  • Select "Import."
  • Browse to the text file containing the list of sites to ban.
  • Select "Open."
  • "Import Sites" will appear. Select the column containing URLs(websites)
  • Click "Mapping."
  • Select "Banned URL" from the "Map Selected Field To:" dropdown
  • Click "OK."
  • Click "OK" at "Import Sites."

AllegroSurf will import the entire text list of sites into its list of banned URLs. These sites are now blocked.

Instant Messaging Services

Instant messenger services can frequently prove to be a workplace distraction. AllegroSurf can block the messaging services by removing users' access to the messaging server. If a message server is placed in the "Banned Sites" list, users will be unable to send messages to that server. This prevents users from establishing a connection for the chat service. Because they are subject to change, locations of these servers are not listed here, but a copy of a specific chat client will contain the URL for the server it connects to.

If, on the other hand, you need to utilize one or more of these services, we have instructions on our website explaining how to configure them for AllegroSurf.

AllegroSurf Configuration for Common IM Services:

AOL Instant Messenger

Yahoo Messenger


Google Talk


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Thanks for reading!

Louis C. Branch - Technical Support Engineer
Voice: +1(262) 560-9627
FAX: +1(262) 560-9628

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