How to configure a firewall on your netbook

With malicious software blazing across the Internet, your netbook can use even more protection, especially from people trying to connect to your computer to hijack it for their own use or swipe your personal information. "How do intruders get into my computer in the first place?" you may ask.The answer is through ports—little pathways the operating system uses to let connected devices and Internet programs speak to your netbook. Many programs that do business online (web browsers, multiplayer video games, email programs, and so on) use a specific port. But someone who knows how ports work can find an open one and slip in software to take control of your computer.

You can protect your netbook with a security barrier called a firewall. A firewall monitors your computer's ports and stops unauthorized programs from getting into your system—or sending information out from it. Firewalls come in two different flavors: hardware firewalls and firewall software programs.

Hardware firewalls are boxes that go between your computer and your Internet connection. You may already be using one and not know it—many network routers also double as hardware firewalls to shield the network from prying eyes. If your home network router uses network access translation (NAT), you already have a dandy firewall. NAT technology allows connections from your computer but doesn't allow other computers on a different network to connect to yours. (You can read about NAT in detail at http://computer.hows...s.com/nat.htm.)

Software firewalls, on the other hand, are programs you configure to block unwanted network traffic and attention. If you purchase a security suite for your Windows netbook, you may get a personal firewall as part of the package. If you didn't buy a suite, you have a free basic firewall included with Windows. Ubuntu Linux also comes with firewall options.



Windows
The original edition of Windows XP had a firewall tucked inside, but it was turned off and many people couldn't even find the darn thing to turn it on. Fortunately, from Windows XP Service Pack 2 onward, the firewall comes turned on, and it's much easier to find. To see it, choose StartControl PanelSecurity Center. (If you're using the Classic view of the Control Panel area, choose StartControl PanelWindows Firewall.)

The Security Center control panel has icons to click to open settings for the Windows Firewall, Automatic Updates, and Internet Options—a collection of settings for your netbook's web browser and network connections.

In the Windows Firewall control panel, you can see which programs have permission to go through the firewall by clicking the Exceptions tab. A list of programs appears. If you need to add an exception or open a port for a particular program (like a multiplayer game that needs a specific port to play through), click the Add Program or Add Port buttons to set things up—check the software's settings guide for any ports that need opening. Microsoft has further instructions for using Windows Firewall at http://support.micro....com/kb/875356.




Windows Firewall is not the most intuitive software and it's been criticized for only blocking incoming—but not outgoing—traffic. If you want a more robust gatekeeper, consider a commercial firewall program or at least a more versatile freebie like Check Point's free version of the Zone Alarm firewall at http://bit.ly/OBr4S.

Linux
Linux was designed with security in mind and includes a firewall called IPTables tucked away deep in the system. The Ubuntu Community site has a page that explains how it works at https://help.ubuntu....y/IptablesHowTo, but the program is command-line driven, which may not be your thing.

A graphical-oriented program like Firestarter makes it easier to manage the firewall and its rules. To install it on Ubuntu, choose ApplicationsAdd/Remove, search for Firestarter, and install the program.




After you install the software, choose SystemAdministrationFirestarter. When you run the program for the first time, a Windows-like wizard appears on the scene to walk you through the setup procedure. The wizard will ask a few things, including:

• How do you connect to the Internet? Use the pop-up menu to select your connection method, which will probably be an Ethernet device unless you're dialing up with a telephone modem to get online.
• How do you get your IP address? Every computer needs an Internet Protocol address to get on the Internet. Turn on the checkbox for "IP address is assigned via DHCP" if the netbook normally jumps onto a home network. (The eth0 connection is usually your wired Ethernet connection, while eth1 is probably your wireless connection.)
• Do you share your Internet connection? Unless you're letting someone else connect to the Internet through your computer, leave the "Enable Internet connection sharing" checkbox turned off.

When you get to the last screen, make sure the "Start firewall now" checkbox is turned on and click the Save button. Once you start the firewall, it runs quietly in the background in a secure mode.

To see Firestarter in action, choose SystemAdministrationFirestarter. The three-tabbed box shows you the Status (the network activity), Events (connections the firewall has blocked), and Policy (where you can set up rules for special programs that need to get through the firewall).

You may not ever need to set up any policies for programs in Firestarter, but if you do, the program has thorough documentation on how to do it at www.fs-security.com.