To configure an instant messaging proxy on an appliance, you need to configure the relevant parts of the Proxies settings of the Configuration top-level menu.
These are mainly settings for:
- Enabling an instant messaging proxy
- IP address and ports for listening to requests sent by instant messaging clients
- Settings for instant messaging servers
- Timeouts for instant messaging communication
Default values are preconfigured for all these settings after the initial setup of an appliance.
Instant messaging going on under the following protocols can be filtered:
- Windows Live Messenger
- XMPP, which is the protocol used for Google Talk, Facebook Chat, Jabber, and other instant messaging services
The rules that are processed on an appliance for filtering instant messaging traffic are those that have Requests (and IM) configured as the processing cycle in the settings of their rule sets.
However, the Responses cycle can also be involved when instant messaging under the Yahoo protocol is filtered. Under this protocol, a requested file is transferred to a client in a response of the same kind as a response used for transferring files in normal web traffic. The file is stored on a server and retrieved by the client under HTTP, for example, using a suitable URL.
When problems arise in the communication between instant messaging client and proxy under a particular protocol, the client can also switch to using a different protocol and bypass the proxy this way. The client can even use a protocol for normal web traffic. On the dashboard of an appliance, this would result in a decrease of the IM traffic and an increase of the web traffic that is displayed.