There are several organizations in the world for which keeping communication behind closed doors is paramount to their existence—the kind whose employees sleep with Colt .45s under their pillows. If you look closely, our current Openfire setup is perfectly suitable for such an organization. All current Openfire communication happens behind what we call a walled garden—Openfire lets users interact with others connected to the server, but not with anyone else. Unless your organization operates in a cocoon, you'll want to interact with the external world—after all, even spies have external contacts!
As you might have guessed, Openfire does let you talk to your contacts outside the network. In this chapter, we'll configure Openfire to allow users on the local network to connect to their contacts who use IM services provided by external, publically-accessible networks such as Yahoo! Messenger, AOL, and Google Talk.
But before we get to the configuration bit...