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<h1>Software components</h1>

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an Edubuntu lab includes both Chapter 11 as well as office tools and

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web browsers (see Section 7.3). At its core, however, it

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consists of the server software that runs the classroom server

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and the Wizzy internet proxy server.

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7.1. K12LTSP classroom server

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7.1.1. About the K12LTSP distribution

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an Edubuntu lab classroom server is based on the K12LTSP

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distribution, with some configuration changes and additional

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software packages.

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K12LTSP is based on RedHat Fedora Linux and the work of the

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LTSP. It's easy to install and configure. It's distributed

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under the GNU General Public License. That means it's free and

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it's based on Open Source software.

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This is quite a mouthful, so I'll unpack the terms one by one.

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* The LTSP is the Linux Terminal Server Project. This

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project assembles all the software components that are

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necessary for a computer to act as a fat server for a

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network of thin clients, and provides the configuration

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necessary for the server to function as such.

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* RedHat Fedora Linux is the free distribution packaged by

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RedHat, Inc. The K12LTSP team has added an option to the

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RedHat installation menu, so that installing a classroom

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server is as simple as choosing the first installation

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option and answering some questions.

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The K12LTSP distribution tries to make it as easy as possible

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for you. It is a regular Fedora distro with an option to

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install LTSP right there in the setup screen. When installing,

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the LTSP option is the first item on the menu, added above the

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default Workstation, Server and Custom options. This means

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that you don't have to mess around with the configuration

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files until you've had a chance to see what it is they do, and

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by then you'll probably only need to tweak them a little.

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The LTSP server defaults to an IP gateway and firewall when

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two Ethernet cards are present. This will only be the case in

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Edubuntu labs that are permanently online, which will usually not be

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the case. Normally, the Wizzy server will be the gateway, as

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all Edubuntu labs with internet access use a Wizzy server.

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_________________________________________________________

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7.2. Wizzy server

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A Wizzy server can be used to provide a managed internet

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access solution for an Edubuntu lab. Currently, a Wizzy server is an

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extra to an Edubuntu lab install. The Shuttleworth Foundation may

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award a Wizzy server to a school with an Edubuntu lab if the school

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demonstrates that it is making good use of the lab. Wizzy is a

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project of Andy Rabagliati, a techno-philanthropist who has

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been wiring rural schools for cheap internet connectivity for

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many years now.

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The software (like K12LTSP) is based on RedHat Linux,

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currently version 8.0. Whereas K12LTSP is based on RedHat

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Fedora, Wizzy is an adapted version of Whitebox Linux, itself

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a straight recompile from source RPMs of RedHat Enterprise

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Linux. Many extra packages have been added, all under the GPL

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license.

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It performs the duties of dialup manager, firewall, mailserver

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(IMAP mailserver XXX), web cache, and authentication server

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(LDAP authentication server XXX). The Wizzy server does normal

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dialup via a telephone line, but it can also do ADSL and

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wireless. It would be possible to do all these things on the

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classroom LTSP server as well, but a custom mail arrangement

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would still be necessary: while the Edubuntu lab is not connected to

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the internet, mail needs to be delivered to an remote server.

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Another reason to separate the internet gateway from the

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classroom server, is that it might not be such a good idea for

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the classroom server to have a public-facing IP address. All

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machines exposed to the internet are vulnerable to compromise,

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and the classroom server contains all the user data.

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The way in which the Wizzy server sends and receives email is

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customised to work with an intermittent internet connection.

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It utilises a protocol that was more commonly used in the days

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before permanent internet connections became common, namely

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UUCP (the Unix-to-Unix Copy Protocol). UUCP is suited to

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queueing data to be copied to remote hosts for delivery when a

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network connection is established.

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Wizzy has the goal of providing all its services via UUCP, in

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order to accommodate high latency connections where there may

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be long disconnected periods. This type of connection includes

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situations where a connection is established by dialling up at

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night when phone rates are low, as well as situations without

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any dialup access at all.

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In cases without dialup access, the connection is made by

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carrying the data across by hand! [10] The transfer medium may

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be, for example, a USB memory stick, a mobile wireless-enabled

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laptop, or a USB hard drive. The transfer medium will contain

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newly fetched data and the queued requests for new web pages,

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as well as mail waiting to be sent. This is not a stated goal

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of the Edubuntu labs project, so if your school wishes to pursue

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this route, you may have to contact Wizzy to work out the

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details.

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A wireless antenna that plugs into a USB plug on a laptop or a

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PC.

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If you do have access to a telephone line for the Edubuntu lab, the

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internet is dialled up only at night when the rates are low

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(Telkom South Africa provides a particular phone account that

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allows a single 12 hour phone call for R7). In this period,

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approximately 250MB of email and web material can be

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downloaded onto the Wizzy server in the classroom. In the

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morning, after the phone has been hung up, the learners can

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access the downloaded material as though they had a direct web

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connection. Their experience of email and web during the

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school day is almost identical to a very fast online web

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experience, with the exception that newly requested pages will

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only be available by the next morning. [11]

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Normally, if you want to connect to the internet, you need a

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telephone line and a modem, a satellite uplink, or some other

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means of tapping into 'the Net'. Unfortunately, in South

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Africa, the necessary telecommunications infrastructure is not

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always there to tap into. Around a third of South Africans

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don't have a phone line, and roughly 88% of schools in the

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Northern Province lack an internet connection. [12]

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7.2.1. Benefits of a Wizzy server

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Every student can have email and web access without the cost

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of being online. This is true even for schools that don't have

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a telephone.

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While the delay in retrieving web pages is a necessary

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consequence of the Wizzy solution, it has a desirable side

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effect in that it helps educators to manage web access. Since

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anybody with an internet connection can publish on the Web,

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there is an absolute ocean of complete trash that threatens to

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engulf the unwary browser. Groping through this mess just

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wastes school resources. Automated solutions to this issue

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have been proposed, often by companies that market filtering

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products. Apart from the fact that these products suffer from

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both false positives and negatives, blocking material

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unnecessarily and letting undesirable material through, it

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shifts responsibility from the teacher to a software product.

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The Wizzy solution believes that it's better to let the

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teacher decide what is appropriate. This also allows the

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teacher to stay in touch with the material accessed by the

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learners he or she is teaching. Teachers can explicitly choose

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the web material that learners can access and definitively

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reject web material that is not appropriate. They can also set

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the Wizzy server to monitor websites, retrieving new versions

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as they become available.

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Because the school is never in direct connection with the

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internet, but rather has its web content delivered upon

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request, students cannot "surf" the internet. However, since

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all the web sites that have been requested by the IT

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administrator of the school are delivered and stored on the

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school's server, the students can "surf" this local web cache

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as though it were a miniature internet.

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These specially chosen web sites can easily number in the

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hundreds. They can be updated daily; and should a new site be

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desired on a regular basis, the school would have to wait only

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one day for the delivery to begin. The "surfing" of this

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miniature internet within the Edubuntu lab costs nothing, and is

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fast enough to give you whiplash, since all communication

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takes place within the Edubuntu lab, between the server and the

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client computers. [13]

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Edubuntu labs aims to give educators the tools to help learners

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explore computers and the Wizzy server allows them to put

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reasonable limits on learners' access, guiding them towards

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independent use of the computer as they mature. Edubuntu labs does

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not make any judgement regarding what content is regarded as

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appropriate, but is there to help provide the tools and

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documentation to help educators with these decisions. The

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focus is more on the "guidance" aspect, rather than

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restriction, as the former is a positive activity while the

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latter is negative.

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The Wizzy solution integrates seamlessly with existing labs.

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Normally, no additional equipment is required to have this

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kind of internet lab.

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7.2.2. Batch mail delivery solutions

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First, a recap of the basics. [14] How does mail from far away

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get to your account, say: somebody@myschool.wizzy.org.za?

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* The remote mail client probably punts the mail to a

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smarter host --- the SMTP (Simple Mail Transfer Protocol)

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server of their ISP (Internet Service Provider). This will

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have been configured by the sender when first setting up

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their mail client.

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* Their ISP mail server will ask a local nameserver (i.e.

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DNS server) for the MX (Mail Exchange) records of

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myschool.wizzy.org.za. These are the IP addresses of

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machines listed as handling mail for this domain. The ISP

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will try to deliver directly to the lowest-numbered MX

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record in the list, via SMTP. If it cannot connect, it

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will try other MX hosts, usually in ascending order.

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The DNS service for the Edubuntu lab and Wizzy networks is

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provided by SchoolNet

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* With this step, or via intermediate MX hosts, the mail

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will eventually land on the target host --- the

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lowest-numbered MX, often your local ISP. Most of the

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time, your ISP will deliver all the mail for that domain

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into a single mailbox, and leave you to figure out the

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rest.

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* The reason why the ISP can't easily do more, is due to the

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fact that SMTP is not authenticated to specific users, and

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therefore relies on name services --- fixed IP addresses

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--- to route messages to their destination. This makes it

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impractical for intermittently connected machines, that

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dial up nightly and are dynamically assigned an IP address

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by the ISP, to function as mail exchangers.

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One way to preserve the SMTP protocol across dynamic IP

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addresses is to batch SMTP commands in a file, and pass

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the file over a separate transport. [15] Batched SMTP is

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similar to normal SMTP, but, because it is being written

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to a file, all responses are ignored. (Normally, an SMTP

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connection is a conversation of commands and responses

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between the sending and the receiving servers, so that the

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sender may probe for the capabilities of the receiver,

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confirm successful delivery, etc.) Fortunately, this is

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not critical: as long as all the responses are known to be

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OK, everything works.

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The Wizzy solution is to write messages to a file, use

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UUCP over TCP/IP as an authenticated transport from the

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SMTP server of the ISP (in this situation, Andy's Cape

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Town Wizzy server will be the SMTP), and unpack the batch

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at the final destination (the Edubuntu lab). The batched SMTP

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format is described in RFC 2442 --- The Batch SMTP Media

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Type

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Wizzy uses exim as the SMTP agent at both ends, and Taylor

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(GNU) UUCP as the middle transport.

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7.3. Applications

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7.3.1. OpenOffice.org

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OpenOffice is a full office suite, intended to measure up to

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and surpass Microsoft Office. This is what its original

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author, Marco Börries, intended when he started StarDivision

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to create the software that would eventually become OpenOffice

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in 1984, when he was just sixteen. He called it StarOffice. By

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the time Sun Microsystems bought Marco's company in 1999, over

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25 million copies of Star Office had been sold to customers

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who needed platform independence (see Section 16.4) and an

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alternative to Microsoft.

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In July 2000, Sun released most of the Star Office source code

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(about 7.5 million lines of C++) to the stewardship of the

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open source community, under the Free Software Foundation's

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LGPL license. The community project has as its goal: "To

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create, as a community, the leading international office suite

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that will run on all major platforms and provide access to all

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functionality and data through open-component based APIs and

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an XML-based file format." The open APIs (see Section 16.4)

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and file formats are turning OpenOffice into a platform in its

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own right, supporting projects such as OpenGroupware, which

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aims to provide an open alternative to Microsoft's Exchange

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and SharePoint products.

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This is in direct contrast to Microsoft's approach, who have

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always used the fact that only their own software could easily

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use their document formats to keep customers locked in, in

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effect reserving the Office platform to Windows applications.

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OpenOffice includes a word processor, spreadsheet, interfaces

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to many databases, a presentation builder, and a diagramming

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tool. It is now able to decode most variants of Microsoft

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Office document formats, but although its StarBasic macro

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language is syntactically identical to Visual Basic,

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OpenOffice cannot execute Visual Basic scripts. Although these

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are preserved upon conversion, the scripts need to be adjusted

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to use the OpenOffice API before they can be used.

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OpenOffice can be used to teach all the basic computer skills

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required to enter the job market, and as the design paradigms

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of the software is very close to Microsoft Office, the skills

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learnt are readily transferable.

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7.3.2. Mozilla

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In 1998, Netscape Communications released the source code of

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its Navigator web browser software as open source, and the

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Mozilla project was born. Netscape released their software as

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open source in order to compete with Microsoft, who were

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bundling Internet Explorer with every copy of Windows sold.

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Netscape hoped that the cooperation of thousands of developers

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around the world would create a better product than Internet

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Explorer. It did, but it took years, and Netscape fell by the

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wayside. The code lived on, though.

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In 2004, six years after the start of the project, the

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non-profit Mozilla Foundation that was created to coordinate

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the project finally released version 1.0 of the Firefox

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browser. Earlier versions of the software had been in use for

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years, but at last it was deemed ready for a high-profile

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release to the general public.

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The full Mozilla suite includes far more than the web browser.

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It includes Thunderbird, a mail client with address books and

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calendaring support, and Composer, a web page editor. For

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developers, it includes Venkman, a Javascript debugger, and

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the DOM Inspector, a wonderful tool for interactively

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exploring the enormous, intricate internal structure of

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complicated web pages.

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The code base has been painstakingly restructured to get as

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much use out of it as possible. So, for instance, all the

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Mozilla applications use the same rendering engine, called

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Gecko, to layout and display HTML pages on screen. This is

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critical, since it is extremely hard work to implement the

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standards that govern web page structure and display

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correctly. Mozilla has the best support for the HTML and CSS

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standards of any browser out there. In the past, Microsoft has

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used Internet Explorer's idiosyncratic and incomplete

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implementation of web standards to coerce people to craft

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their web pages to look good in Internet Explorer at the

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expense of other browsers. For the web to become a dependable

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platform, however, developers have to be able to build on

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solid public standards that don't leave them at the mercy of

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any company's prosperity.

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As with OpenOffice, the Mozilla project is becoming a platform

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for extensions from the community.

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7.3.2.1. Security

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As the internet has become more popular, viruses, spam,

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spyware and trojans have grown to be an enormous problem.

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These are all caused by programs that are received and

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executed on computers without the knowledge or consent of

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their users. How can this happen?

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In general, there are two ways for this to happen:

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* You may have given implicit permission without intending

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to do so;

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* The unwanted program may be exploiting errors or bugs in

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some program in order to insinuate themselves into it, so

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that it can execute with the permissions of the original

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program.

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Firefox and Thunderbird try to protect you as far as possible

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by setting up reasonable defaults. Nothing in an email message

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is executed unless you explicitly run it yourself. And

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execution of Javascript in web pages can be switched off at

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any point. Firefox also allows you to grant or revoke specific

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permissions (e.g. opening popups, hiding the status bar, or

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changing images) to Javascript.

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The Mozilla suite also affords you a measure of protection

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from the second case. While Internet Explorer has access to

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practically the entire running system of a Windows PC via a

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powerful integration technology called ActiveX, Firefox and

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Thunderbird are far more restricted. It also helps to be

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running on Linux, where the user of the web browser will

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generally not be able to damage the operating system, and the

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system administration account is never used to run user

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applications.

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