This chapter is from the book
This chapter is from the book
This chapter is from the book
What Is LTSP?
Perhaps the most useful feature present in the Edubuntu OS is the LTSP environment. It's worth spending a few minutes reading this section to understand exactly what the LTSP system is and what it can do for you. You'll soon realize its applications are not limited just to education.
LTSP stands for Linux Terminal Server Project. It aims to give the same functionality to current client/server models that were present in the mainframe/dumb terminal setups, prevalent many years ago.
How Does LTSP Work?
The LTSP model centers around one powerful machine that acts as a server and several often much lower-powered machines that act as clients. The machines are all connected on a local area network.
This network allows all data required for booting the client's computer, which is normally held on the client's hard drive, to be served to the client over the network. If all the data required for booting the computer is provided over the network, the client machine requires no storage media at all and hence leads to the term diskless clients.
Technical Details of the Edubuntu Boot Process
A client machine is switched on. After the hardware is initialized, the network card looks for an IP address via the DHCP protocol. The Edubuntu server in most cases acts as the DHCP server to the local network and sends the client machine its IP address. Figure 10-1 shows a diagram of the LTSP booting process.
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Figure 10-1 LTSP booting process
Once the network card has bound the IP address to itself, it then makes a connection to the Edubuntu server and asks for the PXE configuration file. The Edubuntu server sends this file back to the client machine, which then makes a request for the kernel image. This is the base of the OS, which provides the client with all the hardware drivers required to communicate with the server.
After this, an NFS connection is set up with the server. This is almost like a standard network share. The NFS share holds a very cut-down installation of Ubuntu, which consists almost entirely of an X server and an SSH-based login manager to connect to the server. Once the client machine has finished booting this small version of Ubuntu, the login screen is displayed to the user.
When a user logs in, an SSH tunnel is opened to the server, and an X session is initiated through this tunnel. All programs are run on the server, and it is only really the graphical interface that is piped back to the client machine. This allows the user to interact with the session and use a computer as normal.
The whole process is totally transparent to the user, but it is important to have a basic understanding of the underlying technologies present in LTSP to assist in the troubleshooting process and to be able to evaluate LTSP for a given task.
The Benefits of LTSP
Booting computers in this way does have some distinct advantages over the current preferred model of many powerful desktops, particularly where only a low budget is available.
- Singular point of administration: Working with this model means that only one computer needs to be installed with new software. By using the Add/Remove tools as demonstrated later in this chapter, you can make applications automatically available to clients as they are essentially all using the same machine.
- Low-cost hardware: Thin client machines are not required to be incredibly powerful since all processing is done by the server. This allows people to use much older hardware for their client machines, often reusing machines that were taken out of service for being sluggish several years ago.
- Diskless clients: Anyone who has spent time administrating a network knows that often a computer used regularly suffers from corrupt files on the hard disk and needs reinstalling. If a client has no disk, there is no chance of a user corrupting data on the client's hard drive.
- Easy replacement: If one of your thin client machines breaks down, you still have all your data stored on the server. Just replace the client hardware and carry on working. It really is as easy as changing a light bulb.
Other Uses
The LTSP system has its uses in many other applications too. Imagine you are running an Internet cafe, where many people use the computers in exactly the same way. Each workstation would need the same set of applications installed. The tasks they are performing are not hugely CPU intensive, so a thin client system is perfectly suited to this type of application. You will also find LTSP solutions very commonly used in information systems (e.g., in airports) and in point-of-sale systems.
LTSP Availability in Ubuntu
The LTSP system isn't limited to just Edubuntu. Ubuntu is perfectly capable of installing and running an LTSP setup. However, performing an Ubuntu installation and then installing LTSP requires you to do a lot of the work yourself. The LTSP package comes with several scripts to assist you in easily creating an LTSP system.
Edubuntu installs and configures the LTSP system for you. However, if you require the addition of an LTSP system to an already installed Ubuntu server, you should follow the instructions provided later in this chapter.