Checking the Edubuntu CD for Defects
All of the Ubuntu flavors allow for an error-checking routine to be performed on the CD before installation takes place. This gives you the peace of mind that your CD is a perfect copy of the original disc image and that it has no detectable defects.
Choosing the Check CD for Defects? option will take some time, usually enough to grab a snack.
Then you'll be told that your CD is either defect free or defective. If the CD is found to be defective, it is time to either download and burn a new one or order one from the ShipIt Web site.
After the check has been completed, you will be required to restart your computer and will end up back at the main Edubuntu CD boot menu. From here you can now choose Install to the Hard Disk, and begin setting up and installing your Edubuntu system.
Choosing What to Install
The Edubuntu installation follows almost exactly the same procedure as the standard Ubuntu method. Just as there are two types of CD for Ubuntu, there are also two varieties for Edubuntu: classroom server and desktop. However, the Edubuntu distribution is slightly different in that the server CD will set up and configure the LTSP server, whereas the desktop CD will not set up or install the LTSP environment.
There are three main ways in which Edubuntu can be installed: workstation, server, and integration with an existing Ubuntu install. The workstation install is intended for standalone computers that will not interact with a network much or require other network services such as authentication. This installation will not set up the LTSP server either. You can install Edubuntu in this way either by using the desktop CD or by using the Standalone option on the server CD.
Installing Edubuntu from the Desktop CD
Installing Edubuntu from the desktop CD is probably the easiest way to install Edubuntu. Ubiquity is the desktop CD installer, and the process is identical to the Ubuntu installation described in Chapter 2. Double-clicking on the Install icon present on the desktop will start up Ubiquity and present you with a welcome screen. From here, you can start the install process.
Ubiquity aims to make it as quick as possible to install and configure Edubuntu. The first question you are asked concerns the language you wish to use as your default. After selecting the language settings, you are asked to set the keyboard layout that best suits you. Once you've made your choice, click Continue, and move onto setting up the default time zone.
Next, set up the first user on the system. Remember that this user will have full administration rights. This step requires you to choose a username, a password, and a computer name.
The final step in this procedure is to set up the disks and partitions for the installation. After clicking Continue here, Edubuntu will begin installation. Edubuntu will prompt you when it has been successfully installed on your system.
You will be asked to reboot the computer. Remove the CD from the drive to avoid having your computer reload the Edubuntu desktop CD. You should now see the Edubuntu splash screen and can begin using your new OS. For more general information on using the default Ubuntu desktop installer, see Chapter 2.
Installing from the Server CD
This installation method provides a way to install an LTSP server quickly and easily and also provides the standalone install, which requires no network to operate. The instructions presented later in this section are for the server installation, although the two installation procedures are almost identical.
The standalone installation is ideal for home use or in a situation where a network connection is not always present. It is also advised to use the standalone installation on a machine that doesn't have enough grunt to be a server.
The Edubuntu server install allows a great deal of flexibility and is designed to allow it to fit into any current network configuration. Essentially these fall into two categories: those that use the Edubuntu server as a primary gateway for all their LTSP clients and those that do not. Let's take a few minutes to discuss the relative merits of each system.
Using Edubuntu in its recommended configuration requires the server machine to have two network interface cards (NICs). One of these cards is connected to the rest of the network, that is, to the Internet or to other servers on the internal network. The other card is usually connected to a private subnet of the network where only Edubuntu LTSP clients reside. Figure 10-7 shows this two-NIC setup. No network data is routed from the second network card to the first, so client machines must be authenticated on the Edubuntu server before having access to the Internet or the rest of the network. This makes for a secure network setup.
Figure 10-7 Two-NIC setup
The benefit to this setup is that client computers cannot connect to the network unless the Edubuntu server permits them to. This also reduces network traffic on the rest of the network because while the LTSP clients are booting from the Edubuntu server, data is being transferred only on the private subnet and not on the rest of the network. Also, the clients receive their network addresses from the Edubuntu server, which frees up addresses on the rest of the network.
Using Edubuntu as simply another server on a network allows for a more flexible atmosphere. For a start, you require only one network interface card in the server to run using this configuration. The LTSP clients are connected to the normal network and could, assuming they had the capabilities to boot, access the network without the help of the Edubuntu server. Figure 10-8 shows this one-NIC setup.
Figure 10-8 One-NIC setup
The benefits of this setup are that thin clients can be used with more than one OS. One establishment, for example, runs dual-booting Microsoft Windows and Edubuntu clients. This setup also allows users to have their LTSP thin clients receiving their DHCP network addresses from a single network server.
Essentially the choice of network design layout will impact the number of network cards installed in your server. It is primarily this that affects the difference between the standard Ubuntu install and the Edubuntu install.
The Installation Procedure
The installation procedure from the Edubuntu server CD looks very different than that of the desktop CD, but the questions asked are largely the same. The server CD is all text based, which can be a little daunting at first, but you will find installing Edubuntu in this way quicker, as it doesn't require the entire desktop session to be loaded.
After the CD has booted, choose the Install to the Hard Disk option, and confirm by pressing Enter to begin the installation. Notice also the workstation and command-line options at this point.
The first question you are asked simply sets up the language used for the install procedure, as well as the language for the final system. You are then asked to choose your location.
Now you must choose your keyboard layout. The text-based installer has an auto-detection routine that will ask you to press a series of keys on the keyboard. From these keys, the installer can work out which keyboard layout will best suit you. If there are any keyboard variations, these are now presented for you to choose from.
The installer will now load various components. If you have more than one NIC in your computer, you will be asked to choose the primary card for the installation (Figure 10-9). By this, the installer wishes to know which network card is connected to the outside network or the Internet.
Figure 10-9 Selecting the primary network interface
If your network has DHCP enabled, this card will be set up with an IP address from the network. You will then be prompted to choose a hostname for the Edubuntu server. If your network doesn't have DHCP enabled, you will have to set up the IP address manually.
The next step is to set up the hard disk ready for installation. By far the easiest method here is to select the default option of Guided Partitioning. If you wish to use LVM, please refer to the section on LVM in Chapters 2 and 5. If you require more in-depth partitioning or already have data on the hard drive that you do not want to lose, you will have to plan how you are going to proceed. If you are installing onto a computer that has partitions Edubuntu can resize, it will offer you that option. Doing this will allow you to have two operating systems installed on one computer and to switch between them at bootup. Whichever method you select, you will then be asked to confirm your partitioning choices.
After this, you must choose whether or not your clock is set to Coordinated Universal Time (UTC). Your system clock should be set to UTC. Your OS is then responsible for converting the system time into local time. Unless you have another OS that expects the system time to be the local time, you should answer yes here.
Now it's time to set up the first user on the system. Remember that this user will have full administrative rights. First, enter the user's full name, then the desired username, followed by the password twice. After this, the base system is installed.
After plowing through several steps, you are presented with a question about screen resolutions. For the type of system you are installing, a very high screen resolution could result in a slow connection between the server and the client. The default options are fine.
When this is completed, the installer begins building the LTSP client root filesystem (Figure 10-10). This is the very small version of Ubuntu mentioned earlier in this chapter. Essentially it consists of just a kernel and an X server.
Figure 10-10 Building the LTSP filesystem
Once the installation is complete, a prompt will ask you to remove the CD and press Enter to reboot the system into your new Edubuntu server.
Initial LTSP Server Setup
The DHCP server installed on your Edubuntu machine should start up automatically, so all that is left to do is to make your thin clients bootable from the network. If you are using the single network card setup described earlier and your network already has a DHCP server running, do not start the Edubuntu DHCP server, as this will likely cause both DHCP services to be unavailable.
Initial LTSP Client Setup
Modifying a client computer to boot from the network is usually done by altering a setting in the machine's BIOS. It's a good idea to look at the manual for the computer's motherboard to find out how to alter these settings. For most machines it will simply be a case of entering the BIOS by pressing the Delete key at bootup and changing the boot device priority.
Once you've set up your client machines to boot from the network card, you should see a screen similar to the one Figure 10-11 shows on each of the clients. This means that the client machine has been issued with a DHCP address and that the PXELinux file has been loaded from the network.
Figure 10-11 DHCP boot
If your client boots up to the graphical login and the screen looks like that shown in Figure 10-12, congratulations—you have successfully set up your LTSP thin client system. If not, refer to the Troubleshooting LTSP section near the end of this chapter.
Figure 10-12 LDM login screen
Switching to Edubuntu If Ubuntu Is Already Installed
Just like Kubuntu, Edubuntu is simply a set of customized packages from the Ubuntu repository. In your chosen package manager, look for the package called edubuntu-desktop. This package will install both the Edubuntu desktop and all the other educational applications required. This step will also install the latest Edubuntu artwork package, which will customize your desktop with the latest educational wallpapers and themes. If you ever need to go back to the Ubuntu desktop for any reason, just install the ubuntu-desktop package, and your system will be returned to its pre-Edubuntu-looking state. If you require an LTSP setup, you will have to do a fair amount of manual configuration.
Installing the LTSP Environment in Ubuntu or on a Desktop Installation
Perhaps you already have an Ubuntu machine and wish to make it available in an LTSP setup. To do this is a simple procedure and requires very little configuration. To begin, you must decide whether you require a DHCP server. If so, install the ltsp-server-standalone package. If you already have a DHCP server and are going to configure it to point to the LTSP server, by modifying the filename, next-server, and root-path options, you should install the ltsp-server package. Along with this, you will need the openssh-server package.
The easiest way to do this is to open a terminal window via the Applications > Accessories > Terminal link in the main menu. Once here, you should type the following commands to install the LTSP server and the SSH server. In our example, a DHCP server was not required.
sudo apt-get install ltsp-server openssh-server
All that is left to do now is to install the client chroot by running the following command:
After this you should be able to boot your first thin client.
Special LTSP Cases
Setting Up Edubuntu to Coexist with an Existing DHCP Server
Sometimes you might not want your machines to be on a totally separate subnetwork. However, the problem then becomes that the current DHCP server will not be set up to serve the correct options to enable the clients to boot from the network. Modifying a Linux-based DHCP server is well documented; however, some establishments will require the modification of a Microsoft Windows DHCP server to allow network clients to boot from the network.
The following setup assumes that there are currently no thin client systems running on the Windows network. Opening up the Windows DHCP administration tool will allow you to create reservations for your machines. A reservation is an IP address tied to a specific MAC address. In this way, each time a machine requests an IP address from the DHCP server, it is always given the same IP address. This has its benefits as you can then set advanced options for the client as well.
For each client, you will need to create a reservation and then add the following options to each one (Figure 10-13).
- 017 Root Path: /opt/ltsp/i386
- 066 Boot Server Host Name: <server ip>
- 067 Bootfile Name: /ltsp/i386/pxelinux.0
Figure 10-13 Windows DHCP Reservations
It is recommended that you restart the DHCP server. After this, the clients should be able to correctly pick up their IP address from the server and then boot from the Edubuntu server via NFS.
Dual-Booting with Another Operating System on the Hard Disk
Perhaps you have a suite of computers that are already happily running another OS, and you would prefer to keep both systems running for a while. Hopefully after using Edubuntu for any length of time you will eventually make the switch permanent. In these situations it is easy to set up the server to allow the client to boot from either the network or the first hard disk in the computer.
The bulk of the editing takes place in the pxelinux.cfg/default configuration file in the directory /var/lib/tftpboot/ltsp/<arch>/. The format of this file is very similar to the old LILO configuration syntax (for those of you familiar with that bootloader). The following sample configuration will present a message to the client, which is explained later. The user can then choose to either allow the system to boot its default configuration, which in this example would be the local hard disk, or to type in the word linux and press Enter, which would load the LTSP thin client.
DEFAULT localboot TIMEOUT 50 PROMPT 1 DISPLAY display.msg LABEL linux KERNEL vmlinuz APPEND ro initrd=initrd.img quiet splash LABEL localboot LOCALBOOT 0
Let's take a look at the configuration file and break it down so that you can create your own to suit your environment. (If this sample file fits the bill for you, you can skip down to the part about creating the display.msg file.)
The DEFAULT keyword specifies which boot option will be chosen once the timeout expires. The TIMEOUT option specifies how long to wait before booting the default option. This timeout is measured in 1/10 of a second, thus a value of 50 sets it for 5 seconds. The PROMPT option specifies whether the PXE software displays the boot: prompt to enable users to choose an operating system. The DISPLAY option displays a text file on the screen as an introduction. In this case, the file is called display.msg and must be placed in the root LTSP directory, alongside the pxelinux.0 file. An example of this file is proposed a little later.
The three lines starting with LABEL linux define the linux option for booting. This is configured by the KERNEL and APPEND options, which you will notice are extracted from the original default file, as shown here:
DEFAULT vmlinuz ro initrd=initrd.img quiet splash
All that is needed now is the option for booting from the local hard drive, shown by the two lines starting LABEL localboot. These lines define the localboot option as used with the DEFAULT keyword earlier in the file. The only definition included in this option is the LOCALBOOT option, with a parameter of 0. This provides normal hard disk booting. Other parameters are available, as you can see by visiting the Syslinux home page, http://syslinux.zytor.com/.
The display.msg file should contain some information that tells the user what to do to choose an operating system. Below is an example file that is suitable for the configuration above. When creating this file, it is suggested to use a number of blank lines before the text actually begins. This has the effect of clearing the screen so that users don't get confused by the PXELinux start-up text.
================================================================== Welcome to the Multiboot System The system will start in 5 seconds... for Linux users type : linux at the boot: prompt and press <enter> ==================================================================
After rebooting the client, you should now see the text from the display message file. It should look similar to that shown in Figure 10-14.
Figure 10-14 Multiboot system in action