What are SYN flood attacks?
A SYN flood is a type of denial of service attack which works by exploiting a weakness in the TCP/IP stacks running on machines connected to the Internet. These stacks can typically hold thousands of on-going SYN requests which is more than sufficient for daily use. In normal circumstances an SYN request will prompt an acknowledgment message (ACK) inviting more information from the client. In the event of an SYN flood attack the attacker will send thousands of SYN requests but not respond to the resultant ACK requests. Eventually the SYN buffer zone of your server will fill up and be unable to accept requests from genuine clients.
