Configuring URL Filtering

Topic Last Modified: 2009-03-02

The URL Filter tab controls the way in which hyperlinks are handled during an instant messaging (IM) conversation. Use the following information and the procedures in this section to configure URL filtering.

• If you do not select the Enable URL filtering check box, the Intelligent IM Filter does not perform any URL filtering: all hyperlinks contained in instant messages are passed through the server.
• If you select the Enable URL filtering check box, the Intelligent IM Filter performs filtering according to the options that you select:
  • Block all hyperlinks, both intranet and Internet, that contain any of the file extensions defined on the File Transfer Filter tab. If you select this check box (the default), the Intelligent IM Filter blocks any active intranet or Internet hyperlink that contains a file with an extension listed on the File Transfer Filter tab. When the instant message is blocked, an error message is returned to the sender. When selected, this option takes precedence over all other filtering options. For example, if you select both this check box and either Allow instant messages that contain hyperlinks, but convert the links to plain text or Allow instant messages that contain hyperlinks, the server would continue to block any hyperlinks that contained the file extensions defined on the File Transfer Filter tab.
  • Allow local intranet URLs. If you select this check box, only Internet URLs are blocked. URLs for locations within your intranet are passed through the server; however, individual Office Communications Server 2007 R2 servers may define an intranet URL differently, depending on the browser settings on the server.

• Blocking action. The client experience for blocked hyperlinks is determined by which of the three following options you choose:
  • Block instant messages that contain hyperlinks. If you choose this option, delivery of instant messages containing active hyperlinks is blocked by Office Communications Server 2007 R2, and an error message is sent back to the sender.
  • Allow instant messages that contain hyperlinks, but convert the links to plain text. Enter the notice you want to insert at the beginning of each instant message containing hyperlinks. If you choose this option, URLs in messages are sent through the server, but these links are prefixed by an underscore so that the links are no longer active and a user cannot click them. You need to specify the notice you want to insert at the beginning of each instant message containing hyperlinks. This notice can consist of no more than 300 characters.
  • Allow instant messages that contain active hyperlinks. Enter the warning you want to insert at the beginning of each instant message containing hyperlinks. If you choose this option, Office Communications Server 2007 R2 permits active hyperlinks in instant messages, but it sends a warning. You must specify the warning that you want to insert into messages containing active hyperlinks. For example, this warning might state the potential dangers of clicking an unknown link, or it might refer to your organizations relevant policies and requirements. The warning can be no more than 300 characters.
• Enter the prefixes, separated by a space, that you want the URL filter to block. A default list of URL types appears in this box. You can configure this list by adding or removing entries. All entries except for href must end with a period or a colon or with an asterisk followed by a period. Valid entries in this box can contain any characters in the set of valid URL characters except the asterisk (*). The set of valid URL characters is: #*+/0123456789=@ABCDEFGHIJKLMNOPQRSTUVWXYZ^_` abcdefghijklmnopqrstuvwxyz|~

The following examples are valid entries:

• www*.
• ftp.
• http: