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Online iPython Notebook Viewer


We recently started using the slide function of iPython notebooks. Basically it allows you to partition your notebook onto different slides, slide fragments and subslides. Those can be exported to reveal.js

There is already a great viewer for notebooks on To save some steps in exporting, converting and adding reveal.js, I took the idea and added a slide viewer. Anyone can use it to link to their slides on Github, Gist or any other place. We even support Basic Auth. Check it out at:


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Beware of header filtering, when sending to iCloud


It’s well documented that Apple/iCloud has a very obscure filtering policy. Emails are delivered to the server and then disappear. Read the rest of this post »

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New nameservers


About a year ago EditDNS was bought by Dyn Inc. They have in fact ruined the old site and tried to lure as many customers as possible to their site. They didn’t honor lifetime memberships at EditDNS and even charged money for migration. Their prices are absolutely unrealistic as well. Hosting your DNS with them costs more than hosting a whole server. Fortunately there are some alternatives left.

Currently the site’s nameservers are mirrored in four locations, which should provide plenty of redundancy.

Additionally the most popular nameservers run by ISP are monitored hourly to detect any anomalies.

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Email Arrival Times


I was interested in arrival times of emails this morning. This should reflect the world’s work- and communication patterns. Sample size is around 80,000. Here are the results. Most messages arrive in the late morning and from Mon to Thu. Sat is rather quiet. Times normalized to UTC+1

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Upgrade to Debian 6.0 “Squeeze”


This Sunday, the new stable version of Debian was launched. I just upgraded the server. All the essential stuff seems to work. Apart from a minor problem with MySQL.

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Email-Privacy and the Law


After having sent and received as many as 13,196 emails in 2010, I started thinking about how well this kind of communication is actually protected. The problem has a technical and legal perspective. I’ve long focused on the technical side. SSL, good passwords and some hard drive encryption should offer reasonable protection. The legal perspective is also not too bad. At least in Austria.

As opposed to Germany, Austrian law gives emails a similar protection as letters, as long as they are in transit and haven’t been downloaded to a user’s personal computer (=letter is still closed).

Abschließend kann also gesagt werden, dass die passwortgesicherten e-Mails in Österreich dem Schutz nach § 118 StGB (Briefgeheimnis) unterliegen. In Deutschland scheitert man beim Briefgeheimnis (§ 202 dStGB) für e-Mails am Erfordernis der Körperlichkeit. Nach § 202a dStGB sind nur passwortgesicherte bzw auf dem Übertragungsweg verschlüsselte  e-Mails geschützt.
by Prof Dr. Thomas Hoeren, Briefgeheimnis im Strafrecht

This general protection has been substantially weakened by a variety of “anti-terror laws” that have been imposed in the US and Europe. In fact most big providers who want to display advertising already weaken your privacy in their terms of service. Moreover, once they surpass a certain number of users, they are usually obliged to install a backdoor for government bodies.

For that reason, I strongly encourage everyone to run a private email-server. If you share it with your friend, the costs won’t be more than a few EURs per year and it’s a good learning opportunity. Moreover, if your admin lives in Austria you can hold him accountable, as if he was opening up your love letters.

If you can somehow emphasize the educational point of view, Amazon might even give you a free server for some time.

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