Sri lanka web server - CHAPTER 9 How to Secure
CHAPTER 9 How to Secure Your Computer Linux is widely considered to be one of the most secure operating systems around. On a basic level, Linux is built from the ground up to be fundamentally sound, and it forces users to work with security in mind. For instance, it enforces the system of ordinary users who are limited in what they can do, thus making it harder for virus infections to occur. In addition, Linux contains a firewall that is hard-wired into the kernel. It s called iptables (www.netfilter.org) and is considered among the best by practically all computer security experts. Not only that, but it can protect your home PC just as well as it can protect the most powerful supercomputer. But, as with many Linux kernel components, iptables is difficult to use. It requires in-depth knowledge of how networks operate and an ability to hack configuration files, both of which are beyond the skills of many ordinary computer users. Fortunately, several programs act as interfaces to iptables and make it simple to operate (or at least as simple as any equivalent Windows-based software firewall, such as Zone Labs ZoneAlarm). Perhaps surprisingly, Ubuntu doesn t install any firewall configuration program by default. According to the official FAQ (www.ubuntulinux.org/support/documentation/faq), the developers consider Ubuntu to have no need for such a thing. However, configuring the firewall with a program like Firestarter, which we examine later in this chapter, can be done so quickly and with such little effort that there s no reason not to make use of the Linux firewall. In this chapter, you ll learn how to configure the Linux firewall, but first, you ll spend some time examining more basic security concepts. Following that, we ll look at some elementary steps that you can take to protect your system. Windows Security vs. Linux Security If you ve switched to Ubuntu from Windows, there s a very good chance that the security failings of Windows featured in your decision. By any measure, Microsoft s record on security within its products is appalling. A new and serious security warning appears seemingly on an ongoing basis, and a new and devastating virus makes news headlines with similar frequency (usually described as a PC virus rather than what it actually is: a Windows virus). One argument is that Windows is the target of so many viruses merely because it s so popular. Although it s true that some of the underground crackers who write viruses dislike Microsoft, there s also little doubt that Windows has more than its fair share of security issues.