Instant Messaging Proxies

Instant messaging proxies can be set up on an appliance to filter instant messaging (IM) chat and file transfer.

When users of your network participate in instant messaging communication, they send, for example, chat messages to an instant messaging server, receive responses to their messages, or send and receive files. An instant messaging proxy on an appliance can intercept and filter this traffic according to the implemented filtering rules. For this purpose, instant messaging traffic is redirected to the appliance.

The following network components are involved in the filtering process:

• Instant messaging proxies — Proxies can be set up on an appliance to filter instant messaging under different protocols, for example, a Yahoo proxy, a Windows Live Messenger proxy, and others.
• Instant messaging clients — These clients run on the systems of the users within your network to enable communication with instant messaging servers.
• Instant messaging servers — These are the destinations that are addressed by client from within your network.
• Other components of your network — Other components involved in instant messaging filtering can be, for example, a firewall or a local DNS server that redirects instant messaging traffic to an appliance.

When configuring instant messaging filtering, you need to complete configuration activities for the instant messaging proxy or proxies to ensure they intercept and filter the instant messaging traffic.

You also need to ensure that the instant messaging traffic is redirected to the instant messaging proxies.

However, configuration activities for this are not performed on the clients, but on other components of your network. For example, DNS redirects or firewall rules are configured in a suitable manner.

An instant messaging proxy on an appliance is mainly intended to be used together with vendor IM client software that is provided, for example, by Yahoo, Microsoft, ICQ, or Google. But this client software can still change its behavior, for example, use a new logon server, without advance warning after a hidden update.

When using third-party client software, you should generally be aware that logon servers, protocol versions, or authentication methods could have been modified in comparison to those of the original client software, which can prevent an instant messaging proxy on an appliance from intercepting and filtering instant messaging traffic.