Topic Last Modified: 2010-04-30
The Intelligent IM Filter tool helps protect your Microsoft Communications Server 2010 deployment against the spread of the most common forms of viruses with minimal degradation to the user experience. Use Intelligent IM Filter to configure filters to block unsolicited or potentially harmful instant messages from unknown endpoints outside the corporate firewall. You configure filters by specifying the criteria to be used to determine what should be blocked, such as instant messages containing hyperlinks with specific prefixes and files with specific extensions.
Intelligent IM Filter provides the following:
- Enhanced URL filtering.
- Enhanced file transfer filtering.
Configuring Intelligent IM Filter includes the following:
- Configuring URL filtering.
- Configuring file transfer filtering.
How Filtering Options Are
Applied to Instant Messages
Before you deploy the Intelligent IM Message Filter tool, you need to understand how filtering options are applied as messages are routed from one Communications Server 2010 server to another. The way these filtering options are applied is consistent, regardless of whether the servers are located in a single organization or across organizational boundaries. This consistency applies to the way that the customized notice and warning texts are inserted into messages and sent across servers.
 Note: |
|---|
| The instant message filter increases the amount of CPU resources required to process URLs in a message. This increase in CPU demand also affects the performance of Communications Server 2010. |
By using the URL Filter tab in the IM and Presence category in Communications Server Control Panel, you can block some or all hyperlinks or configure a warning. The warning is inserted at the beginning of an instant message that contains a hyperlink when you choose the Hyperlink prefix option Send warning message.
When an instant message travels from one server to another, the following general guidelines apply:
- If a server blocks an instant message (because you selected the
Block URLs with file extension check box on the URL
Filter tab or because you chose the Hyperlink prefix
option Block hyperlinks), an error is returned to the
client. Subsequent servers do not receive this instant message.
- If a server (Server1) adds a warning to an instant message that
contains an active hyperlink, a subsequent server (Server2) that
receives this instant message can still take a different action
based on this active hyperlink present in the instant message and
block the instant message or add a warning. If Server2 is
configured only to add a warning for this URL, the earlier warning
added by Server1 is removed, and the warning configured on Server2
is added to the beginning of the instant message.
| Note: |
|---|
| If you are running Communications Server 2010 in a mixed environment, Live Communications Server 2005 with SP1 is the minimum version required to use the Intelligent IM Filter application. The Intelligent IM Filter is not supported on Live Communications Server 2005 without SP1. |
URL Filtering
URLs are filtered according to their hyperlink prefix. The following examples are valid prefixes:
- www*.
- ftp.
- http:
If you do not configure the instant message filter to perform any URL filtering, all URLs contained in instant messages are passed unmodified through the server. If you configure the instant message filter to perform URL filtering, URLs in instant messages are filtered according to the options that you select in the Edit URL Filter or New URL Filter dialog box.
- Enable URL filter. This option enables URL filtering for
the global deployment or for the site that you select.
- Block URLs with file extension. The instant message
filter blocks any active intranet or Internet URL that contains a
file with an extension listed under File type extensions to
block on the Edit File Filter dialog box. When a URL is
blocked, an error message is displayed to the sender. When
selected, this option takes precedence over all other filtering
options for any file extensions defined under File type
extensions to block.
Important:Filtering of file extensions is limited to standard file names. Filtering may not work with file extensions embedded in other names.
To configure how hyperlinks are handled in instant message conversations, you select one of the following options under Hyperlink prefix:
- Do not filter. URLs in messages are sent through the
server. When you choose this option, the Allow message box
is displayed. In the Allow message box, you specify the
notice that you want to insert at the beginning of each instant
message containing hyperlinks. This notice can consist of no more
than 300 characters.
- Block hyperlinks. Delivery of instant messages
containing active hyperlinks is blocked by Communications Server
2010, and an error message is displayed to the sender.
- Send warning message. Communications Server 2010 permits
active hyperlinks in instant messages, but it includes a warning.
When you choose this option, the Warning message box is
displayed. In the Warning message box, you must type the
warning that you want to include with instant messages containing
active hyperlinks. For example, this warning might state the
potential dangers of clicking an unknown link, or it might refer to
your organization’s relevant policies and requirements. The warning
can be no more than 300 characters.
If you select Block hyperlinks or Send warning message, the following options are available:
- Exclude local intranet hyperlinks. The instant message
filter blocks only Internet URLs. URLs for locations within your
intranet are passed unmodified through the server. However, the
intranet URLs that individual Communications Server 2010 servers
pass depend on which types of local websites are considered part of
their intranet zone. To check a server’s intranet zone settings,
see To configure your intranet settings in Internet
Explorer.
- Filter these hyperlink prefixes. To choose which
prefixes you want to block, click Select, and then, in the
Select Hyperlink Prefix dialog box, add the prefixes to the
Hyperlink prefixes list.
All prefixes except href must end with a period or a colon, or an asterisk followed by a period. Each prefix you enter must be separated by a space. Valid prefixes can contain any characters in the set of valid URL characters except the asterisk (*). The set of valid URL characters is: #*+/0123456789=@ABCDEFGHIJKLMNOPQRSTUVWXYZ^_` abcdefghijklmnopqrstuvwxyz|~
File Transfer Filtering
Filter transfer filtering affects both instant messages and conferencing meetings. For meetings, these settings affect the handout feature in the Office Live Meeting 2007 client and multimedia playback features.
| Note: |
|---|
| Microsoft Communicator "14" also offers file transfer setting options. This server-side option is offered in addition to the client-side controls available in Communicator "14". |
You can filter file transfers during instant message conversations, when you are using the handout feature in the Office Live Meeting 2007 client, and for multimedia playback features for all file types. You can set the following options to control file transfers:
- Enable file filter. This option enables file filtering
for the global deployment or for the site that you select.
When you enable the file filter, you can choose one of the following options in the File transfer drop-down list box:
- Block specific file types. You specify which file
transfer requests are filtered by the server by specifying a list
of file extensions to block. Entries in the list can contain all
standard characters, but not the wildcard character (*). In the
Office Live Meeting 2007 client the handout feature is enabled, but
any file with this extension cannot be uploaded or downloaded. If
you select the Block URLs with file extension check box on
the settings for a URL filter listed on the URL Filter tab,
the URL filter uses this same list to block active hyperlinks that
contain any of these file extensions. To choose which file types
you want to block, click Select, and then, in the Select
File Type dialog box, add the file type extensions to the
Selected file type extensions list.
- Block All. The server drops all instant messages that
contain file transfer requests and returns an error message to the
sender of the request. The handout feature in the Office Live
Meeting 2007 client is disabled.
- Block specific file types. You specify which file
transfer requests are filtered by the server by specifying a list
of file extensions to block. Entries in the list can contain all
standard characters, but not the wildcard character (*). In the
Office Live Meeting 2007 client the handout feature is enabled, but
any file with this extension cannot be uploaded or downloaded. If
you select the Block URLs with file extension check box on
the settings for a URL filter listed on the URL Filter tab,
the URL filter uses this same list to block active hyperlinks that
contain any of these file extensions. To choose which file types
you want to block, click Select, and then, in the Select
File Type dialog box, add the file type extensions to the
Selected file type extensions list.
| Important: |
|---|
| Filtering of file extensions is limited to standard file names. Filtering may not work with file extensions embedded in other names. |