Configure the Windows Firewall to Allow IM

In order for instant messages to get from one computer to another, the firewall must first allow this kind of traffic. Fortunately, the Windows Firewall installed with Service Pack 2 is by default set up to allow this kind of traffic.

When troubleshooting IM communication problems, however, you probably want to eliminate this as a possible cause of the trouble. To do so, follow these steps:

1.	Open the Security Center using either the Control Panel or the System Tray icon. Under the "Manage security settings for:" section, choose Windows Firewall.
2.	As shown in Figure 12-21, make sure that MSN Messenger is enabled as one of types of traffic the firewall allows through. Figure 12-21. Make sure the Windows Firewall allows IM traffic.

Additional configuration may be needed if passing IM traffic through a SOHO router. Check your router's documentation for details.