CHAPTER 9 (Web hosting) HOW TO SECURE YOUR COMPUTER
CHAPTER 9 HOW TO SECURE YOUR COMPUTER Once the downloads have finished, you probably won t need to reboot unless the kernel file has been updated. The Software Update program will inform you if you need to restart the computer. The Ubuntu Firewall A firewall is a set of programs that protects your PC when it s online. It does this by watching what data attempts to enter your PC from the Internet and allowing in only what it is sure is secure (which usually is what you ve asked for). It also attempts to close off various aspects of your Internet connection, so that crackers don t have a way in should they target your system. Although Ubuntu includes a powerful firewall in the form of iptables, you ll also need a program that can manage it. Here, I ll show you how to use Firestarter, available from the Ubuntu software repository, for this purpose. Together with the built-in firewall, this really does provide industrial-level protection. The benefit of configuring the firewall is that even if your system has security vulnerabilities because of buggy software, crackers will find it a lot harder to exploit them across the Internet. When someone attempts to probe your system, it will appear to be virtually invisible. Caution Although software firewalls such as the one built into Linux offer a high level of protection, it s best to use them in concert with a hardware firewall, such as that provided by most DSL/cable broadband routers (curiously, some of these routers actually use Linux s iptables software as well). Many security experts agree that relying solely on a software firewall to protect a PC affords less than the best level of protection. Installing Firestarter Let s get started by downloading and installing Firestarter. Follow these steps: 1. Select System . Administration . Synaptic Package Manager. Click the Search button and enter firestarter as a search term. In the list of results, locate the program and click the check box. Then choose to install the package. 2. After installing Firestarter, log out and then back in again (to update the menus to show Firestarter). 3. Once the desktop is back up and running, select Applications . System Tools . Firestarter. When you run Firestarter for the first time, it will walk you through a wizard. 4. Click to continue the wizard beyond the introductory page. 5. The first step asks which network interface Firestarter should configure, as shown in Figure 9-4. If you use an Ethernet card, have a wireless card, or attach a broadband modem directly to your computer, the answer will probably be eth0 or wlan0. However, if you use a modem, the answer is ppp0.