Technology Blog

what is virtual memory? Virtual Memory is a HDD space that uses some portion of it as the memory. It is used to store application data and instruction that is currently not needed to be process by the system. During the program loading process, the system will copy the application data and its instruction from the HDD into the main memory (system memory). Therefore the system can use its resources such as CPU to process and execute it. Once the system memory gets filled up, the system will start moving some of the data and instruction that don't need to process anymore into the Virtual Memory until those data and instruction need to process again. So the system can call the next application data and instruction and copy it into the main memory in order for the system to process the rest and load the program. When the data and instruction that is in the Virtual Memory needs to process again, the system will first check the main memory for its space. If there is space, it ...

What is a Firewall? A firewall is a tool that monitors communication to and from your computer. It sits between your computer and the rest of the network, and according to some criteria, it decides which communication to allow, and which communication to block. It may also use some other criteria to decide about which communication or communication request to report to you (either by adding the information to a log file that you may browse whenever you wish, or in an alert message on the screen), and what not to report. What Is...

What are Registry? The Registry is a database used to store settings and options for the 32 bit versions of Microsoft Windows including Windows 95, 98, ME and NT/2000. It contains information and settings for all the hardware, software, users, and preferences of the PC. Whenever a user makes changes to a Control Panel settings, or File Associations, System Policies, or installed software, the changes are reflected and stored in the Registry. The physical files that make up the registry are stored differently depending on your version of Windows; under Windows 95 & 98 it is contained in two hidden files in your Windows directory, called USER.DAT and SYSTEM.DAT, for Windows Me there is an additional CLASSES.DAT file, while under Windows NT/2000 the files are contained seperately in the %SystemRoot%\System32\Config directory. You can not edit these files directly, you must use a tool commonly known as a "Registry Editor" to make any changes (using registry editors wil...

How Linux boots As it turns out, there isn't much to the boot process:    1. A boot loader finds the kernel image on the disk, loads it into memory, and starts it.    2. The kernel initializes the devices and its drivers.    3. The kernel mounts the root filesystem.    4. The kernel starts a program called init.    5. init sets the rest of the processes in motion.    6. The last processes that init starts as part of the boot sequence allow you to log in. Identifying each stage of the boot process is invaluable in fixing boot problems and understanding the system as a whole. To start, zero in on the boot loader, which is the initial screen or prompt you get after the computer does its power-on self-test, asking which operating system to run. After you make a choice, the boot loader runs the Linux kernel, handing control of the system to the kernel. There is a detailed discussion of the kernel elsewhere in this b...

All About Backdoors. Since the early days of intruders breaking into computers, they have tried to develop techniques or backdoors that allow them to get back into the system.   In this paper, it will be focused on many of the common backdoors and possible ways to check for them.  Most of focus will be on Unix backdoors with some discussion on future Windows NT backdoors.  This will describe the complexity of the issues in trying to determine the methods that intruders use and the basis for administrators understanding on how they might be able to stop the intruders from getting back in.  When an administrator understands how difficult it would be to stop intruder once they are in, the appreciation of being proactive to block the intruder from ever getting in becomes better understood.  This is intended to cover many of the popular commonly used backdoors by beginner and advanced intruders.  This is not intended to cover ever...