nubae's Habari | Linux and Education

The Asus eeePC has become an extremely popular linux based laptop, and it works great with the preinstalled OS Xandros. It is, however, a desirable thin terminal in that its small, already has a monitor and is cheap. The smaller model's screen might be a bit too small, but one can always add an external monitor, keyboard and mouse and make it a full thin terminal. In order to do that, one must fix the atl2 kernel panic bug. The instructions that follow are not mine, I found them elsewhere on the net and adapted a little:

sudo chroot /opt/ltsp/i386
nano /etc/initramfs-tools/modules

add atl2 to the modules list.
Next update your initramfs with (where kernel-version is version number of your kernel [ie. 2.6.27-6-386):

update-initramfs -k kernel-version-number -c 
exit

This will update the kernel and create the initramfs that is in /boot/ under a name something like initrd.img-2.6.27-6-386. The file must now be copied from /opt/ltsp/i386/boot to /var/lib/tftpboot/ltsp/i386 after having renamed the existing one, for backup :

mv /var/lib/tftpboot/ltsp/i386/kernel-version-number /var/lib/tftpboot/ltsp/i386/kernel-version-number.bak
cp /opt/ltsp/i386/boot/kernel-version-number /var/lib/tftpboot/ltsp/i386/

You should now restart the asus eeePC and it should just work.

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With the announcement that the Sugar packages were finally up to date in Ubuntu, it was time to try something I've been wanting to do for a while, run a sugar environment on Ubuntu LTSP terminals with collaboration. With the help of some sugar devs I managed to get it all working quite nicely:

Installing Sugar

The base sugar and activities all seem to work wonderfully, although at the time of writing some of the other sugar activties are not working yet. By the time Intrepid is released this will probably be fixed.

sudo apt-get install sugar sugar-activities

You can search for what other sugar activites you can install like this:

sudo apt-cache search sugar

Then change the default session to sugar like this:

sudo nano /home/$username/.xsession

(where $username is the user for whom you want sugar to be the default shell.)

And add the following to the .xsession file:

export SUGAR_LOGGER_LEVEL=debug
export GABBLE_DEBUG=all
export GABBLE_LOGFILE=/home/$user/.sugar/default/logs/telepathy-gabble.log
export PRESENCESERVICE_DEBUG=1
export LM_DEBUG=net
exec ck-launch-session dbus-launch --exit-with-session sugar-shell

A quick explanation of the file is in order. The export lines are actually for debugging, and aren't needed if you don't intend to look at the log files. Remember $user should be the user home folder. The ck-launch-session is for making sugar exit properly when exiting from the menu. The --exit-with-session is for making sure there are no lingering sessions on ctrl-alt-backspace, currently the only way to exit, as ck-launch-session doesn't seem to work.

Finally, make sure you have your server hostname in place of olpc.collabora.co.uk:

sudo sed -ie "s/olpc.collabora.co.uk/hostname/" /home/username/.sugar/default/config

There are now 2 ways to install ejabberd, as the ejabberd packages in debian are up to date so installing ejabberd from scratch only really helps for non debian distros.

Installing Ejabberd from the repositories

sudo apt-get install ejabberd
sudo dpkg-reconfigure ejabberd

You need to add the user (usually admin) and the fully qualified domain name where ejabberd will be running. You can find what this is by doing hostname -f.

Patch /etc/ejabberd.cfg by downloading the olpc based patch and applying it:

wget http://dev.laptop.org/~morgan/ejabberd/ejabberd.cfg.patch
sudo patch /etc/ejabberd/ejabberd.cfg  ejabberd.cfg.patch
sudo /etc/init.d/ejabberd restart

skip the installing ejabberd from source and continue where it says installing the SSL certificate

Installing Ejabberd from source

The first step involves downloading the source package like this:

mkdir ejabberd
cd ejabberd
wget http://www.process-one.net/downloads/ejabberd/2.0.0/ejabberd-2.0.0.tar.gz
tar xfz ejabberd-2.0.0.tar.gz

We then need to download the patches from olpc that allow ejabberd to perform proper collaboration, and install the patches:

wget http://people.collabora.co.uk/~robot101/olpc-ejabberd/shared_roster_push2.diff
wget http://people.collabora.co.uk/~robot101/olpc-ejabberd/shared_roster_recent.diff
wget http://people.collabora.co.uk/~robot101/olpc-ejabberd/shared_roster_online.diff
wget http://people.collabora.co.uk/~robot101/olpc-ejabberd/mod_ctlextra.diff
wget http://people.collabora.co.uk/~robot101/olpc-ejabberd/ejabberd.cfg
cd ejabberd-2.0.0/
patch -p1  ../shared_roster_push2.diff
patch -p1  ../shared_roster_recent.diff
patch -p1  ../shared_roster_online.diff
patch -p1  ../mod_ctlextra.diff

cd src
./configure
make
sudo make install

We also edit /etc/ejabberd/ejabberd.cfg and replace jabber.laptop.org with the actual server hostname and the user "jtest" with "admin" (although u can use a different user if you like):

cd ../..
sudo cp ejabberd.cfg /etc/ejabberd/
sudo sed -ie "s/{hosts, ["jabber.laptop.org"]}./{hosts, ["hostname"]}./" /etc/ejabberd/ejabberd.cfg
sudo sed -ie "s/{acl, admin, {user, "jtest","jabber.laptop.org"}}./{acl, admin, {user, "admin","hostname"}}./" /etc/ejabberd/ejabberd.cfg

Remember to change hostname for the actual server hostname.

Installing the SSL certificate

You must also install an SSL certificate, which is required for collaboration to work (this is an important step.)

openssl req -newkey rsa:1024 -keyout ejabberd.pem -nodes -x509 -days 3650 -out ejabberd.cer
echo "" >> ejabberd.pem
cat ejabberd.cer >> ejabberd.pem
sudo cp ejabberd.pem /etc/ejabberd/ejabberd.pem
sudo chown ejabberd:ejabberd /etc/ejabberd/ejabberd.pem
sudo chmod 400 /etc/ejabberd/ejabberd.pem

Finally we add the user@hostname to /etc/ejabberd/ejabberdctl.cfg remembering to change hostname for your real server hostname:

echo "ejabberd@hostname" | sudo tee -a /etc/ejabberdctl.cfg /dev/null

Then you can turn ejabberd on with

sudo ejabberdctl start

See if ejabberd is running properly:

sudo ejabberdctl status

which should produce the following output:

Node ejabberd@hostname is started. Status: started
ejabberd is running

Then add the admin user:

sudo ejabberdctl register admin hostname xx

This should now allow you to login to the web ejabberd control panel:

Go to http://yourserver:5280/admin/
Log in as your ejabberd's administrative user. Your username is a Jabber address e.g. "admin@yourserver".
Select Virtual Hosts, then your server hostname, then Shared Roster
Add a group called Online with the following settings:
o Name: Online
o Members: @online@
o Displayed Groups: Online

It is recommended you register a user via your favorite jabber program and as the sugar users log in, you'll be able to see them in the Online group.

If you run into problems you can check the logs in /var/log/ejabberd/ to see what could be wrong. And for Sugar logs, you can look at /home/$user/.sugar/default/logs/

Enjoy your terminal session sugar experience!

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For more detailed instructions please look here: http://www.nubae.com/ltsp-linux-terminal-server-project-netbooted-fat-client-for-ubuntu-hardy-and-intrepid

LTSP stands for the Linux Terminal Server Project and is about the coolest and most cost effective technology out there. I've been fortunate and privileged enough to be working with this technology in schools and businesses. Generally LTSP reuses older hardware that runs as a terminal connected to a powerful server. In this way, older penitum and pentium 2 machines can run at practically the same speed as the server feeding them. This is because the processor and ram of the server are actually being used, with only the screen, keyboard and mouse being used on the terminal end. This is great for older machines and dedicated thin clients (which can cost as little as 50 euros), but for newer intel core 2 duo machines, running them as thin clients would be a waste. That said, the benefits of having a centralised location for the computer image and management of users is extremely helpful to an Administrator. This is where a low fat netbooted client comes in. Instead of running the programs on the server, the entire environment is run in the client, hence the term fat. This also relieves the server cpu and ram, as well as the bandwidth of the network slightly, and is ideal for multimedia systems that require Flash, Video, and Audio streaming. Installing the fat client is very easy and requires you downloading the script from here for Ubuntu Intrepid Ibex.

/usr/share/ltsp/plugins/ltsp-build-client/Ubuntu/030-fatclient

You then build your fat client by doing:

ltsp-build-client --chroot (name-of-chroot) --fatclient Ubuntu --highfat

Not the capital U in Ubuntu. The usage of --highfat is an extra option that builds a full multimedia sytstem and is quite resource intensive. A normal fat client has only the base educational games and programs, along with a basic internet suite. The --chroot (name-of-chroot) option is not required, it is only used if you already have a thin client environment under the default i386, which is under /opt/ltsp/i386, so name-of-chroot here would be something like fati386, which would correspond to the location /opt/ltsp/fati386/.

You can see an image here of the thin client in action:

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