| The best protection from Internet-based intruders is having a firewall program. Just as firewalls in cars and office buildings prevent the spread of fire, firewall programs provide a protective barrier between your computer and the denizens of the Internet. If you have a router between your broadband Internet modem and the rest of your network, that router should also have a built-in firewall. This built-in firewall serves as a great first line of defense to your network, but it does not take the place of software firewalls installed on each computer on your network. Configuring the Windows firewall Follow these steps to configure the Windows firewall: 1. Choose Start --> Control Panel to open the Windows Control Panel. 2. Double-click the Security Center icon.  | The Security Center icon is only available if you have Windows XP SP2 or better installed. If you don't see the Security Center icon in your Windows XP Control Panel, use Windows Update to download and install the SP2 update. |
3. In the resulting Windows Security Center window, click the Windows Firewall link. 4. In the resulting Windows Firewall dialog box, click the General tab and select the On radio button, as shown in Figure 1.
Figure 1: The Windows Firewall dialog box.
| If you are using your computer at a public Wi-Fi hotspot, select the Don't Allow Exceptions check box. When you enable the Don't Allow Exceptions option, you can use Web browsers and email programs, but you cannot use Internet messaging programs, FTP programs, and other programs which must access the Internet. Disallowing such programs protects your computer from being accessed by other people at the hotspot. |
5. Click the Advanced tab. 6. Review the network connections to which the Windows Firewall is applied and select or deselect them as needed. | Normally you should leave all network connections checked, as shown in Figure 3. However, if you have trouble using devices (other than networking devices) that are connected to your IEEE-1394 port, you may want to uncheck 1394 Connection. This connection will not be listed if your computer doesn't have an IEEE-1394 (also called FireWire) port. |
7. Click the Settings button in the Security Logging area. 8. In the resulting Log Settings dialog box, select both the Log Dropped Packets and Log Successful Connections check boxes. By logging dropped packets you may be able to determine whether network problems are due to a poor Wi-Fi signal. Lots of dropped packets may indicate a poor or intermittent signal. Logging successful connections can also help you troubleshoot connection issues; if you don't see any successful connections in the log, then you know that you aren't connecting to the network. 9. Click OK to close the Log Settings dialog box. 10. Click OK to close the Windows Firewall dialog box. Activating the Mac OS X firewall Use these steps to activate the Mac OS X firewall: 1. Choose Apple --> System Preferences. 2. In System Preferences, click the Sharing icon. 3. In the Sharing window, click Firewall to open the Personal Firewall settings (see Figure 2).
Figure 2: Enable the OS X personal firewall.
4. Click Start to start the firewall. 5. Close the Sharing window. |