Thin client - what it is and what it is eaten with (on the example of WTWare)

A thin client (English thin client) in computer technologies is a diskless client computer in networks with a client-server or terminal architecture that transfers all or most of the information processing tasks to a server (Wikipedia).

If it is simpler, then the thin client is a non-computer that loads a lightweight operating system (usually Linux is used, in the review we take it as a priori) and connects to the terminal server.

Thin clients are usually created to save on hardware and software, in rare cases for other reasons.
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In this article I will try to make a brief overview of WTWare , which is a Linux distribution designed specifically for creating thin clients.

First about the thin client.

A thin client is a system unit, which usually does not have a hard disk, and there is only a minimum set of hardware needed to run the operating system of a ton client (hereinafter referred to as just a thin client). Power, mouse, keyboard, monitor, network cable are connected to the system unit. In addition to the standard set, other devices can be connected to the thin client, provided that it can recognize and transmit them to the terminal server.
The network diagram with thin clients looks like this:


How it works:

1. A thin client is being downloaded from one of the sources on the computer. The main options for boot sources are LAN, CD, HDD.
2. During the boot process of a thin client (or before it, when using the LAN version), the network card of the computer is given an IP address.
3. After the download is complete, the thin client via rdesktop raises a terminal session with the specified terminal server in the settings.

Why does it work:

1. Significantly reduced the cost of "iron". An enterprise can buy old junk for pennies, and all that is needed for its operation is a terminal server with a sufficient amount of resources and customized thin clients.
2. Reduced software costs - no need to buy software for desktops, you just need to license the terminal server (but you need to buy terminal licenses).
3. Reduced administration costs. You only need to administer the terminal server. As practice has shown, thin clients are practically not killed (if you do not make targeted efforts), and practically do not give failures. But you need to understand that when you change the sysadmin, he must understand the whole thing, for example by simulating the work of thin clients in virtual machines, because any failure will lead to a general collapse.

Types of downloads:

1. Network download. Works as follows: in the local network, DHCP and TFTP servers should be raised. The computer must have either a network card with a BootROM or drivers for a network card emulating a BootROM. The network card looks for a DHCP server on the network, gets all the necessary network settings + TFTP server address. Next, the TFTP server is accessed and the operating system is loaded.
2. Booting from CD / DVD / Flash / IDE is standard here, like any other operating system.

What is WTWare?

WTWare is a GNU / Linux distribution designed specifically for creating thin clients. It is based on a popular client called Thinstation. The main difference is the focus on Russian users (in the Thinstation itself there are problems with the Cyrillic alphabet), plus all sorts of minor fixes.

Configure WTWare.

I will not talk about setting up DHCP and TFTP servers, everything is quite standard. I will only remind you that in the DHCP server you need to specify the address of the TFTP server, and in the TFTP server the path to the download file and the name of this file itself.

Also, I will not delve into fine-tuning WTWare, because The information on the official website of WTWare is quite accessible, there are lots of it and all of it is in Russian. I will point out only the main aspects.

So. First of all, download the image of Thinstation from the WTWare site. Unpack.
The boot file is called pxelinux.0 when booting via PXE (if the BootROM is built into your network or motherboard) or wtshell.nbi for the Etherboot bootloader (when using the BootROM emulator).

By the way, Etherboot is a source project that releases firmware for almost all existing network cards. Etherboot firmware can be written to a BootROM chip or flash-card of a network card, it can be run from a floppy or hard disk as a boot sector or as a program from DOS.

Further, if you boot via LAN and you have DHCP and TFTP servers configured correctly, everything should work “as is”. The only thing - the terminal server will not be found, because you have not yet configured your thin clients.

If you are loading in a different way, then it is worth reading here , choosing the way of loading that interests you.

Configuration

Again, I will not delve into the jungle of configuration files, because there are hundreds of parameters. Here you can see their full list. I will tell only about the main ones.

WTWare has the following types of configuration files:

1. all.wtc is a system-wide configuration file.
2. list.wtc - include configuration files according to the list.
3. Individual configuration files.

Individual configuration files can be of the following types:

1. Terminal_name.wtc. The name of the terminal, respectively, is issued by a DHCP server.
2. ma.ka.dr.es.te.rm.wtc. The binding goes to the MAC address of the plug-in terminal.

Configuration files have the following priorities:

1. all.wtc
2. Files listed in list.wtc
3. Files connected via include
4. Individual config

System-wide file configuration variables:
win2kIP = 10.100.50.1 // address of the terminal server 1.
win2kIP2 = 10.100.50.2 // address of the terminal server 2.
video = VESA (S) // universal driver, works on almost all video cards
mouse_wheel = on // enable mouse wheel
resolution = 1024x768 // screen resolution
bpp = 32 // Color Depth

Configuration files for individual files:
user = username // username
password = user_password // user password
domain = enterprise_domain // enterprise domain

If in an individual file to write a variable that is present in the general file - it will receive a higher priority.

Also in the individual files are additionally connected devices, such as printers, scanners, etc.

And in the end I wanted to mention another interesting possibility - connecting local resources (Floppy, DVD, Flash, HDD, Sound). The config looks like this:
floppy = on
cdrom = on
usb1 = on
sound = on
The disk will be available in the session of the current user from Windows Explorer at: \\ tsclient \ {floppy | cdrom | usbN}.

Disadvantages:

1. There may be problems with connecting the equipment if there are no drivers for it in the system. I know that through certain crutches you can disassemble the image, push the driver in there, assemble the image back. I have not tried it myself.
2. If the card does not have a BootROM, problems may arise with the selection of the Etherboot firmware (there is not for all cards).

Licensing:

It is worth noting that the system itself is free, but you can purchase a license with a very interesting purpose - to remove the WTWare logo from the boot splash screen. As I understand it, this is done for enterprises that are massively implementing this product under the auspices of outsourcing.

Thin client creation equipment:

On the WTWare website you can also purchase equipment for creating thin clients (so as not to collect them from the trash). I must say that it (the equipment) meets all the requirements of glamor. Several screenshots:


Well, that's probably all. With the correct setting of the terminal, DHCP and TFTP server, everything should work out. There are a lot of Russian-language literature on the Internet, so there should not be any problems with the settings. And in general, in terms of documentation, I really liked the system, the manufacturer’s website has almost everything.

PS I personally installed this product on two companies, on one 34 PCs, on the second 16 PCs.
PPS It should be understood that this product is not an alternative to the same Linux, and perhaps the name on each PC on the installed OS, the overall picture will be much nicer. Perhaps not. This is exactly a thin client, and nothing else.