On Monday 4.3.2013. From 08:30 to 09:00 we faced extensive distributed DoS attacks against our customers ' websites. This led to the overloading of the main firewall and due to this there was an unavailability of part of the services and our customer support. We have immediately taken appropriate countermeasures against attacks. At the moment, the situation is stabilized and the services provided are again available in the usual quality.