Usefull links

As I just stumbled on this very nice link about iptables and string-matching filter, I decided to start my personal link collection.

• Using iptables string-matching filter to block vulnerability scanners
• The entire Pro Git book, written by Scott Chacon and published by Apress, is available here 
• Howto: Fixing unstable clocksource in virtualised CentOS 

How to create a LVM testbed

Every once in a while I want to review/relearn a certain lvm feature. In order to do no harm, I want to create a testbed for lvm. Since I have done this a few times bevor, I now put all the commands in a little script, so that I don't have to type them again. Please note that this script does not do much checking, so please understand what it does bevor you use it, and use at your own risk :)

Migrating calendars from horde to zarafa

Recently I had to migrate a bunch of calendars from horde to zarafa. At the time of this writing (spring 2013) caldav access to horde is still just on the roadmap of horde. So basically, I had to log in for every users and export their calendars to ical files by hand. I named them username.ical.
Fortunatly, importing into zarafa can be automated. After importing a file, I realized that recurring events where off by 2 hours. In the ical files, the times were correct, but after importing them, recurring events startet and ended two hours later. So I had to modify the ical files. I did that with the following python script: Note that I used python icalendar 3.3, which exposed this issue. I made a temporary fix (see link), but with icalendar 3.4 and later this should be resolved.
So after the recurrence timing had been corrected, I imported all ical files with