Information
SYN flooding is a well-known denial-of-service attack on TCP-based services. TCP requires a three-way
handshake before actual communications begin between two hosts. A server must allocate resources to
process new connection requests that are received. A potential intruder is capable of transmitting large
amounts of service requests (in a very short period of time), causing servers to allocate all resources to
process the phony incoming requests. Using the 'ip firewall check syn-flood' command configures the
AOS stateful inspection firewall to filter out phony service requests and allow only legitimate requests to pass through.
Solution
Run the following command to enable syn-flood detection :
ip firewall check syn-flood