| Lifelong Learning | ||||||
| Reports Written In Pursuit Of Professional Diploma On IT | ||||||
|
Contents Report on Educational Technology |
Working With Red Hat Linux Red Hat Linux remains as a viable alternative migration path from Windows NT. Users who are fed up with Microsoft's ingenious marketing strategies are looking to Red Hat Linux as server replacement for Windows NT. Red Hat Linux excels in providing resource sharing and network services that Windows NT have done well in the past. Not only can Red Hat Linux perform those services better, users are provided a way out from Microsoft's proprietary technologies toward a more open and standard TCP/IP based technologies. Small businesses that cannot afford escalating software costs led by Windows based applications could find a cost-effective alternative in the Red Hat Linux platform particularly when it comes to server-based applications. Red Hat Linux offers a formidable alternative to Internet-based database driven applications featuring open source technologies like Apache, mySQL and Php. Red Hat Linux likewise offers a native environment for Java and C++ development. Since more and more companies will more likely consider migrating from Windows NT to Red Hat Linux, future-focused IT technologists would be well-advised to get themselves skilled in Red Hat Linux technologies. A Unix Derivative Red Hat Linux is a Unix derivative wherein applications run in a shell environment that provides utilities for accessing kernel services. Users coming from Windows GUI environment will find a refreshing change in Red Hat's windowing environment with a choice of the more conservative GNOME and the flashy KDE windowing system. Red Hat Linux likewise affords the user with a more complete software experience made possible by the open source computing paradigm. The Red Hat Linux installation CD-ROM includes the complete source code of the operating system which users can compile in their own machine to come up with a genuinely customized system software for their computers. Users coming from the Windows environment will do well to unlearn a few nasty habits that encourage moronic dependence on the software product and doing things in a robot-like manner without understanding the underlying principles involved in the operation. Migration from Windows NT to Red Hat Linux will entail a more intimate knowledge of the computer's hardware platform and system software architecture. Red Hat Linux' sharp learning curve results mainly from the painful unlearning experience that users have to undergo to ease up learning of a new system designed from a different economic principles and development outlook. Installation Red Hat Linux affords users with a bewildering array of installation options that include setup diskette creation, booting from the CD-ROM, network or FTP based installation, different types of install modes such as expert, text and graphical and a choice of install types that includes server, workstation and custom. A detailed hardware inventory and reference to the hardware compatibility list in the Red Hat Linux web site are two essential first steps that will go along way in doing a trouble free operating system installation. A third vital requirement pertains to a unique disk partitioning plan that caters to the needs of the user or the organization that the computer seeks to serve. As of the current version, Red Hat Linux 7.2, users may choose between the older and more familiar Linux Boot Loader (LILO) or the newer and more powerful GRUB program. They may decide to put the boot loader in the master boot record of the hard disk or in the first sector of the /boot partition which should be close enough to the start of the partition to avoid being unreachable by the computer's CMOS program. Dual Booting with Windows Dual booting the computer between a Windows OS and Red Hat Linux has become a favorite transition mechanism that affords using Windows for desktop applications and having a Red Hat Linux server with which to learn the rudiments of the unfamiliar operating system. As the first partition of the bootable hard disk is normally lorded over by the Windows operating system, I can put my /boot partition as far away from the start of the hard disk and use a boot diskette for booting the Red Hat Linux operating system. I can likewise use a commercially available boot program like Partition Magic to be able to boot any number of operating system installed on the computer. My favorite disk partitioning plan is to place the /boot and the root partitions on the first hard disk and put the /home and the swap partitions on the other hard disk. I make a very small /boot partition (no bigger than 50 megabytes) and a fairly large root partition of about 1500 megabytes. I can start with a fairly large /home partition of about 5000 megabytes and a large enough 500 megabytes swap partition. While the server installation type is the best choice, the custom type can give better flexibility if hard disk space becomes a problem. Setup Command The setup command is a text mode tool that can be used for quick post install configuration of the Red at Linux machine. The tool includes among others utilities for configuring network, firewall, authentication, services to be started after boot, X window system, printer and sound. In the X Windows system, the tool can also be executed by clicking on Start, Programs, System and text mode tool. You will normally try to configure and enable your internal and external hardware first before installing and configuring system and application software. The Sound Configuration option in the setup menu enables you to configure your sound card. If automatic detection and configuration did not prove successful, you will need to manually configure your sound card. You can review your sound card's configuration for any emulation or compatibility information with well-known sound cards. Varying the combination of settings can lead you to an optimal configuration that does not conflict with other hardware on your computer. If your network card had not been successfully detected, you will need to install the driver manually either by compiling and putting the executable in its proper place or by just copying the pre-compiled executable from the card's diskette to the modules folder in the kernel library under the /etc directory. Finally, use the netconf command to specify the kernel module and enable the network adapter. Netconf will automatically restart the network services and if no errors are reported, you have successfully configured your network card. The modem tool enables you to detect, test, initialize and connect your computer's modem to an available serial port. The printtool command is a wizard style tool for configuring your computer's printer which may be attached to your parallel or USB port or connected to the network using SMB or TCP/IP. The tool enables you to specify the hardware driver for the printer and any additional settings that may be required for the printer to operate properly. We are well advised not to manually edit the printer capability file (/etc/printcap) and just let printtool do it for us since the printcap file is cryptic and difficult to understand. Ntsysv is a tool that we can use to specify what services we want to be started at boot time. It can be run by choosing the services option in the setup program or by typing the ntsysv command in a terminal window. Position the cursor to the name of the services that should be started at boot time and press the space bar to select the service. You will need to reboot the computer to check if the service was indeed started. We can tell if the service is running by piping the results of the ps command to the grep command with the name of the service. We can also use the service configuration tool in the GNOME or KDE System menu to automatically start a service at boot time. This utility can also be used to stop and start the service under a simple graphical interface. GUI Configuration Tools Linuxconf is a great way to configure Red Hat Linux using a text mode, GUI, or web-based interface. We install it using the rpm command or the GNORPM tool. The installation will automatically update the ntsysv tool to start the program at boot up. You can enable the web-based interface by enabling it in the GUI or text mode version and updating the ntsysv tool to start the web-based interface at boot time. Test the web-based interface by entering the url http://hostname:98/ in Netscape Navigator or the Mozilla browser after the computer reboots. You can know more about linuxconf by visiting its web site at www.solucorp.qc.ca/linuxconf/. Webmin provides a more sophisticated web-based Linux configuration tool. We can download its rpm installation package from www.webmin.com and install the program using the rpm command or the GNORPM tool. Webmin includes a version of SWAT for configuring the Red Hat Linux Samba server. Its configuration tools are neatly organized into intuitive categories like system, server, hardware and others. It also includes a capable file manager that can display the computer's directory tree in a Windows like manner. We can use it by typing http://hostname:10000/ in the address bar of the Netscape Navigator or Mozilla browser. NFS Network file system (NFS) is network resource sharing mechanism developed by Sun Microsystems. To share resources, edit the /etc/exports file and include the folders and files to be shared and the hostnames or IP addresses of computers to be allowed access to the resource. We can specify whether to allow read only or read/write access by typing ro or rw on the line identifying the resource. Check if the NFS daemon is running by typing /etc/rc.d/init.d/nfs status and start the daemon if it is stopped. We can make all the shares specified in the /etc/exports file available in the network by running the exportfs -a command. The exportfs -ua command can be used to stop the sharing of everything in the /etc/exports file. We can enable nfs to run automatically at boot time by turning nfs on using the ntsysv command. Mount the shares at the client side using the format hostname or IP address:path of the share to be mounted or use the fsconf command to mount NFS shares. The netconf command can also be used to enter the resources that need to be shared including the hosts to be allowed together with their access permissions. Apache Red Hat Linux automatically installs the Apache web server by default. The first thing to do is to save the original configuration file under a .bak filename. We can then edit the /etc/httpd/conf/htttpd.conf file by typing the computer's hostname after the ServerName directive and saving the configuration file. Start the server using the /etc/rc.d/init.d/httpd start command and use the ntsysv command to make the server run automatically at boot time. Copy the html files in the default html root at /var/www/html. CGI scripts must be placed in the cgi-bin folder under the html root. We can use the VirtualDirectory directive in the Apache configuration file to specify any type of virtual directory that we may want to set up. Set up a new domain in the network's DNS server that will point to the computer's IP address and make the two required zone files for the domain. Restart the DNS server using the /etc/rc.d/init.d/dns restart command. Copy a test html file in the root html folder specified in the VirtualDirectory directive and try to access the file using the lynx command. Make the test file world readable using the chmod o+r command if you get a file access error. We can use limuxconf, webmin or the apacheconf tool to configure the Apache server in a Red Hat Linux computer. DHCP Dynamic Host Configuration protocol (DHCP) is a TCP/IP standard for managing TCP/IP configuration across the network. Red Hat Linux can be set up to become a DHCP server that can distribute IP address and other TCP/IP configuration items to computers in the network. It can be installed using the rpm -ivh command or the GNORPM tool. To facilitate server configuration, find the dhcpd.conf.sample file in your Red Hat Linux computer and copy the file to /etc/dhcpd.conf. Edit the file by adding the configuration items that need to be distributed to all computers in the network. Specify the IP address range to be leased and the default and maximum lease time in seconds. Finally, make an empty file named dhcpd.leases under the /etc folder. We can start the DHCP server by entering the /etc/rc.d/init.d/dhcpd start command. The ntsysv command can be used to start the server automatically at boot time. Test if the server can lease addresses by configuring a Windows desktop to request TCP/IP configuration at boot time. We can look at the TCP/IP configuration of a Windows Millennium desktop by entering the winipcfg command and the Windows 2000 computer by using the ipconfig command. DNS The Red Hat Linux computer can also be used to provide a domain name service (DNS) to the network. We need to install DNS using the rpm command or the GNORPM tool to run the bind rpm package. Next, we need to add a new zone for our domain name and our domain's reverse mapping to the /etc/named.conf file using the netconf tool. This will create two new zone files in the /var/named folder of the Red Hat Linux computer. We can also use the netconf tool to add entries to the zone files like our www and mail servers. Start the server using the /etc/rc.d/init.d/dns start command and run ntsysv to add dns to services that need to be started at boot time. We can also configure the DNS server by using the bindconf tool which can be started by entering the bindconf command in a shell or by clicking the DNS Configuration in the System menu. We can configure the DNS client using the netconf tool or by editing some TCP/IP configuration files in the /etc folder of the Red Hat Linux computer. The resolv.conf file identifies the IP address of the domain name server that the computer will contact for host name resolution. The hosts file contains IP address to host name mappings that can be referred to if dns server is not working. The hosts.conf file specifies what name resolution order the computer will follow in attempting to find the IP address of any host the computer wants to connect to. Lastly, we can use the nslookup or the dig command to test if our dns server is operating correctly. Samba Samba is a file and printer sharing protocol that enables Unix boxes to share file and print resources with Windows based computers. Its client component also allows Unix computers to access file and print resources on Windows based machines. Red Hat Linux can become a Samba server by installing the Samba rpm package either through the command line or the GNORPM tool. The next step is to edit the /etc/smb.conf file after copying it to a file with the .bak extension. It takes a bit of trial and error to come up with a good configuration that works. The testparms command can be used to check for errors in the /etc/smb.conf file. Make sure that the server is restarted after every configuration change using the /etc/rc.d/init.d/smb restart command. To avoid any permission problems, make sure that an smb password file is created using the smbpasswd command. Linuxconf and webmin can also be used to configure the Samba server using a nicely formatted GUI or web-based interface. SWAT is a web-based Samba configuration tool which can also be accessed inside webmin. Other Commands and Tools The crontab command is used to schedule regular execution of jobs. It uses the /etc/crontab file to determine what jobs are to executed and when they need to be run. To use crontab, create a jobs file that includes the jobs to be run and their schedules and submit the same using the crontab command. The at command can also be used to schedule a job that is only to be run once. We can also use the Task Scheduler under the GNOME or KDE System menu to add or edit scheduled jobs. The tar command is used to archive and extract the contents of a folder in the Red Hat Linux computer. It can be used with the -z option to compress the files using the gzip program. We use the -c option to create an archive and the -x option to extract the contents of the archive. The useradd and the groupadd commands can be used to add users and groups to the Red Hat Linux computer while the usermod and groupmod commands can be used to modify their properties. The userconf tool is a graphical tool that can be used to manage accounts and policies. Both the GNOME and the KDE desktops also offer user manager tools under their respective System menus. The man command is used to display manual contents for a particular command. Usually, however, a quick help can be obtained by typing the command with the --help option. The info command is another way of getting help information on the different Linux commands. The newgrp command is used to change the user's group affiliation on the fly. The chgrp command is used to change group ownership of files and folders. The chown command is used to change the file's user and group owners. The df command shows the percentage utilization of all partitions defined for the Red Hat Linux computer. The du command is used to find out how much space is used by the files in a Red Hat Linux directory. The top command shows statistics for running programs. The programs can be rearranged based on statistics for a particular system object. The same performance information can be obtained using the system monitor tool under the GNOME or KDE system Menu which is a graphical version of the top command. The /var/log/messages file contains system wide error messages that can guide administrators in troubleshooting problems on using the Red Hat Linux computer. Some daemons have their own logs which can be checked for any error messages. The dmesg command shows messages displayed during boot up of the Red Hat Linux computer. Download MS Word Version (.doc) of this document. |
|
||||
|
Copyright 2008 Aureo P. Castro Email: [email protected] |
||||||