Archive for the ‘ Hints and Tricks ’ Category

NX- Connection to Ubuntu with Unity-Desktop

If you want to connect with an NX-client to an Ubuntu with Unity-Desktop, you have to set the window manager manually.

The command to start unity as window manager:

 gnome-session --session=ubuntu-2d 


Other available gnome-sessions are listed on the server in the directory



We provide a full featured internal Debian and Ubuntu mirror

From now on, we provide an internal Debian and Ubuntu repository mirror based on apt-cacher-ng.

This allows you to get your updates and applications with up to 1 Gigabit/s from our servers,
saving time and bandwidth for you and all the other users in our labs.

There is no limitation on what Repositories you use since apt-cacher-ng is not the classic “prefetched”
– it caches your packages on demand and allows you to use 3rd party repositories as you like –
there is no special server side configuration required.

You can use it for fresh installs, upgrades, dist-upgrades, software installation … you name it!


We provide further information and configuration guides for your clients


All the best,




Austria starts with 6 months of data retention on the 1st of April 2012!

No, there’s no joke inside, the data retention (also known as “Vorratsdatenspeicherung”
or – in Newspeak – “Mindestdatenspeicherung”) starts on the 1st of April 2012.

Although national media covers the topic – now that there are just a few days left –
they refused to cover the topic for the last few months to keep the people calm.

Several independent groups tried to inform our citizens but the vast majority is
still unsure about the effect of data retention and that austrian providers have
to start collecting data in a few days.

You may be disappointed, shocked or frustrated, you may feel indifferent
about the whole topic or just resign …


… or you can respond with proper action!

Links, Tools and Information to protect your privacy after the break…

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Using Puppet to configure OpenStack Instances

About Puppet

Puppet is a configuration management tool which can be used to configure servers / instances on runtime. For further information visit:

Our Approach

Install and configure the puppet client directly on the image which will be used to launch instances. After the instance has booted, the puppet client connects to its configured puppet server and retrieves its associated specification of configuration (puppet calls that manifests).

We installed puppet server on our cloud controller c2n2. The puppet client runs inside an virtual instance. Further information about our test environment can be found: here.

Client and Server Installation and configuration after the break…

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Differential block-based backup using rdiff-backup

Time has come for us to stop worrying about a safe, reliable and efficient (aka. cheap) backup strategy. After weeks of comparing lots of backup solutions we found the one we’re going to use from now on (for our *x infrastructure).

If you are looking for a solid and easy way to backup your data (from single files to full machines) rdiff-backup may be your weapon of choice. While backing up your data from a given source directory (or set of directories) it preserves all meta-information and in the end provides a full copy of the source directory with extra reverse diffs that are stored in a special subdirectory of that target directory. This way you can recover your files easily by copying them back to their original location with cp, but you may also go back in time and recover files you deleted (or modified) a specified period of time ago. It fully resembles the features of Apples “TimeMachine” while being introduced in mid 2001.

rdiff-backup is available for all major platforms (yes – even Windows) and is licensed under GPL.

For more information, visit the rdiff-backup website.