The SYN flood attack is a common attack strategy as part of Distributed Denial-of-Service, which steadily becomes more frequent and of higher volume. To defend against SYN floods, preventing valuable service downtime, malicious traffic has to be separated from legitimate TCP requests. For this challenge, sophisticated filtering mechanisms operating at high bandwidths are needed. Modern programmable data plane devices can handle traffic in the 10 Gbit/s range without overloading. We discuss how we can harness their performance to defend entire networks against SYN flood attacks. Therefore, we analyze different defense strategies, SYN authentication and SYN cookie, and discuss implementation difficulties when ported to different target data planes: software, network processors, and FPGAs. We provide prototype implementations and performance figures for all three platforms.