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OS Installation

OS Installation. OS installation is the process of creating and copying OS system files to a hard disk. Before installation, check whether the OS supports all the software that will be loaded on the system.

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OS Installation

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  1. OS Installation • OS installation is the process of creating and copying OS system files to a hard disk. • Before installation, check whether the OS supports all the software that will be loaded on the system. • Become familiar with the OS itself because during installation process, some important configuration decisions will have to be made. Chapter 8 : OS installation and system logs

  2. OS Installation • Before installation, make sure that the key elements ( CPU, RAM and hard disk space ) of the system hardware meet the minimum requirements of the OS. • Check with the OS and hardware manufacturers to verify that the hardware is compatible with the OS. • The software and hardware manuals may contain compatibility information. Chapter 8 : OS installation and system logs

  3. Hardware Compatibility Lists • The update compatibility information is the World Wide Web. Chapter 8 : OS installation and system logs

  4. Installation Media • Usually, OS is installed using a DVD that contains the system files and an installation program. • It can be installed using local network. • It may also be installed through Internet if there is a high-speed connection. Chapter 8 : OS installation and system logs

  5. BIOS Settings • It is important to set the boot sequence in BIOS before the installation. • For example, if we use a CD ( DVD ) to install the OS, we should set the first boot device to be CD-ROM ( DVD ) in BIOS settings. Chapter 8 : OS installation and system logs

  6. Installation Program • In MS Windows, the installation program is called setup.exe. • In a Red Hat Linux system ( including Fedora ), the installation program is called Anaconda. • The installation program will guide the user through the OS installation process. Chapter 8 : OS installation and system logs

  7. Installation Program • The installation program controls and simplifies the installation process. • The installation program prompts the user for configuration information. • The installation program allows partitioning and formatting of the hard disk before copying system files. Chapter 8 : OS installation and system logs

  8. Installation Program • The installation program will also give the user the option to install a default set of components or choose the components manually. • It is recommended to use the default setting for new users since it will simplify the installation process and ensure a successful installation. Chapter 8 : OS installation and system logs

  9. Update OS • To ensure the security of the OS, update the OS regularly, and as soon as possible after a security announcement is issued. • Updated software packages for the OS will be released throughout the support period of each version. Chapter 8 : OS installation and system logs

  10. Update OS • OS will generate a notification message to the user if updates are found, and you can click the message to update. • To update the OS in Windows, you can click Start > Programs > Windows Update. Chapter 8 : OS installation and system logs

  11. OS Recovery • There are methods in OS to return itself to a usable state even if it is badly damaged. • In Windows, the methods are in Recovery of Control Panel. Chapter 8 : OS installation and system logs

  12. Windows Recovery • The first method uses a type of backup called a system image, which you need to have created earlier. • The second method reinstalls Windows, either from a recovery image provided by your computer manufacturer, or from the original Windows installation files. Chapter 8 : OS installation and system logs

  13. Windows Recovery • The first method is better since most of your files, programs, and settings are preserved on the system image. You will only need to reinstall or restore any programs, updates, or files that you added after the date you created the system image. • However, if the system image was made recently, there is a chance it could contain the problem you are trying to fix. Chapter 8 : OS installation and system logs

  14. System LoggingLog Files • Log files are files that contain message about the system, including kernel, services and applications running on it. • There are different log files for different information. For example, there is a default system log file, a log file just for security messages, and a log file for cron tasks. • Some log files are controlled by a daemon called syslogd. A list of log messages maintained by syslogd can be found in the /etc/syslog.conf configuration file. Chapter 8 : OS installation and system logs

  15. Location of Log Files • Most log files are stored under the /var/log directory. • Some applications such as httpd (apache web server) and samba (for sharing file with MS Windows clients) have a directory within /var/log for their log files. • There are multiple files in the log file directory with numbers after them. These are created when the log files are rotated. Log files are rotated so their file sizes do not become too large. Chapter 8 : OS installation and system logs

  16. Type of Logging • Software logs– Generated by running applications, these show the status of applications, errors and warnings. • System logs– Generated by syslogd, these report the status of disks, hardware and system processes. • Kernel logs– Generated by klogd, these are concerned with kernel processes, statistics and so on. Chapter 8 : OS installation and system logs

  17. Default System Log File • The default system log file is /var/log/messages. • This log file is typically the recipient of all informational class messages generated by the system. Chapter 8 : OS installation and system logs

  18. Why logging is necessary? • Identify hardware problems • Identify software problems • Evidence of hack-in • e.g. IP-Address, actions • Record of user’s activities • e.g. command or script executed Chapter 8 : OS installation and system logs

  19. Why logging policy is necessary? • Disk space is limited (you cannot record all activities related to your system) • Data has limited life cycle. • e.g. log data of hardware may be only useful for a month. Chapter 8 : OS installation and system logs

  20. Logging Policy • Throwing away log files • Reset log files regularly • Rotate log files • Compress and archive logs to other media Chapter 8 : OS installation and system logs

  21. Throwing away log files • Mean do not keep log at all • Not recommended • In real world, it may take long time for you to realize that the system was hacked. • Software and hardware within one month is very useful. Chapter 8 : OS installation and system logs

  22. Reset log files regularly • Allow log file to grow until they reach the pre-defined size, then restart the log from zero. • Do not guarantee that log will be kept for expected time • e.g. if a system is attacked by someone then system write a lot of data to log file. The size of log file will over the limit and re-set quickly. Chapter 8 : OS installation and system logs

  23. Rotating log files • Keeping log for a fixed period • By versioning • Use a script to rename the log files • Rename the current log to older log • Rename the past log to even older log Chapter 8 : OS installation and system logs

  24. Two Approaches on Log Rotation • “version based” • Version based rotated the log in such a way that the old file has a suffix 1, the older file has a suffix 2, etc. Each time log rotate N files are preserved. • “date based” • Date based used daily or weekly of month rotation pattern and each rotated log is marked by timestamp. Chapter 8 : OS installation and system logs

  25. Example – Rotating log files (version based) Chapter 8 : OS installation and system logs

  26. Example – Rotating log files (date based) Chapter 8 : OS installation and system logs

  27. Linux Log Files • Stored in /var/log • syslog – the default logging system • Can be configured by file /etc/syslog.conf • Suggested permission set for log files is 600 • Mean only accessible by root • Log files are useful data for hacker Chapter 8 : OS installation and system logs

  28. Useful commands for Logging • last • Command used to list last logged in user • dmesg • Command used to print out the bootup messages • e.g. which hardware / software are started / initialized • Useful for identify problems Chapter 8 : OS installation and system logs

  29. Viewing Log • Log files are plain text files. • You can find most of the system log files in one directory, /var/log. • The following are some important files • boot.log Boot message • cronCronmessge • maillog All email-related message • message All informational messages except for cron, mail and secure • secure Secure, authentication message Chapter 8 : OS installation and system logs

  30. Application-Specific Log Files • A number of applications, such as Web Server and database servers, store their log files in other location. • You should read the individual application’s documentation or its manual pages for more details. Chapter 8 : OS installation and system logs

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