Hardening Linux Systems

Source: Linux Magazine

System security is always a trade-off between convenience and features on the one hand and protectiveness and removing unnecessary risks on the other. As the cliché goes, security is inversely proportional to convenience: the easier a system is to use, the less secure it's likely to be. In contrast to many discussions in this column, this month we turn our attention to the "secure if inconvenient" end of the spectrum.
As installed in "normal" mode from most current distributions, Linux tends to be a feature-rich yet very insecure operating system. For example, some distributions install an active Web server by default. While this is very convenient -- the system can start serving files almost immediately and Web-based administrative tools will work right away -- it also exposes the system to many sorts of security threats. If a very secure system is your goal, then there's still a lot of work to be done.