Security Management with Java 2

In this article we show you how to apply the security features of Java 2 to applets and applications running on your system. Applying a Security Manager to Applets and Applications The security manager is invoked by all the Java system code to perform access control checks based on the security policy currently in effect. … Read more

Kernel Modules Versus Applications

Before we go further, it’s worth underlining the various differences between a kernel module and an application. Whereas an application performs a single task from beginning to end, a module registers itself in order to serve future requests, and its “main” function terminates immediately. In other words, the task of the function init_module (the module’s entry … Read more

Version Numbering & License Terms

Version Numbering Before digging into programming, we’d like to comment on the version numbering scheme used in Linux and which versions are covered. First of all, note that every software package used in a Linux system has its own release number, and there are often interdependencies across them: you need a particular version of one … Read more

Security Issues

Security is an increasingly important concern in modern times. We will discuss security-related issues as they come up. There are a few general concepts, however, that are worth mentioning now. Security has two faces, which can be called deliberate and incidental. One security problem is the damage a user can cause through the misuse of … Read more

Classes of Devices and Modules

The Unix way of looking at devices distinguishes between three device types. Each module usually implements one of these types, and thus is classifiable as a char module, a block module, or a network module. This division of modules into different types, or classes, is not a rigid one; the programmer can choose to build … Read more

Splitting the Kernel

In a Unix system, several concurrent processes attend to different tasks. Each process asks for system resources, be it computing power, memory, network connectivity, or some other resource. The kernel is the big chunk of executable code in charge of handling all such requests. Though the distinction between the different kernel tasks isn’t always clearly … Read more

DEVICE DRIVERS

The Role of the Device Driver As a programmer, you will be able to make your own choices about your driver, choosing an acceptable trade-off between the programming time required and the flexibility of the result. Though it may appear strange to say that a driver is “flexible,” we like this word because it emphasizes … Read more

GNU and Linux

Where did the name GNU/Liux come from? You’ve certainly heard of Linux before, and you may have heard of the GNU Project.You may not have heard the name GNU/Linux, although you’re probably familiar with the system it refers to. Linux is named after Linus Torvalds, the creator and original author of the kernel that runs … Read more