If converting to a Linux system from a Microsoft Windows system, you probably experienced a fair share of trouble caused by multiple kinds of viruses and worms spreading over the Internet via e-mail. Now that you have made the switch to Linux, you can at least put that fear aside, because these cannot harm a Linux system as easily as a Windows system.

As mentioned in Section 1.2, “The User Concept of Linux”, Linux knows two different kinds of users, a superuser (root) and normal users. root has access to all system resources and is allowed to change all aspects of the system's configuration. Switching from your normal user account to root for administrative tasks and switching back for your normal work sounds tedious and perhaps unnecessary because root has ultimate power over the system. Still, switching back to the normal user account after accomplishing the administrative jobs adds to security, because any mistake made as root can have severe consequences. The whole system might be affected, not just the normal user account. Thus, preserve your system's integrity by clearly distinguishing between the different roles (“normal user” and “superuser”).

Keeping your system up to date by always applying the software updates provided by SUSE (see Section 1.7.2, “Retrieving and Applying Software Updates”) adds to the security of your system. These updates fix possible exploits contained in the application code.

Protect your system or your network against external “visitors” by running a firewall. A preconfigured firewall is started on installation, providing maximum security to your network. If you need to add support for certain services and do not maintain your system yourself, ask your system administrator to make the necessary adjustments in the firewall settings. Otherwise read the chapter about security in the Administration Guide and learn how to secure your network using SuSEFirewall.