D. J. Bernstein TCP/IP SYN cookies Mail service for Panix, an ISP in New York, was shut down by a SYN flood starting on 6 September 1996. A week later the story was covered by the RISKS Digest, the Wall Street Journal, the Washington Post, and many other newspapers. SYN flooding had been considered by security experts before. It was generally considered insoluble. See, for example, ``Practical UNI