We had sporadic website outages throughout yesterday due to a large and extremely distributed denial of service attack largely originating from China Telecom.
Starting at 9:51 AM CT we started receiving spoofed TCP connection requests. During the attack we were receiving 99.87% invalid connections requests. The attack was aimed at our web server firewall and load balancer chains. The high volume of invalid connections prevented services from responding to many valid requests. While we have equipment to mitigate these types of attacks the sheer volume of connections being established overwhelmed the hardware designed to prevent this type of attack and which are critical in providing web services. We eventually mitigated this attack and greatly increased our capacity for this path through our network. We are working with our vendors further increase our capacity for this type of attack.
We apologize for any inconvenience this may have caused our users.