 The original Linux kernel implementation misunderstood this part of Bernstein's description and used a single global variable to switch on SYN cookies for all ports; this was pointed out by a research student and subsequently fixed in .The technique was created by Daniel J. Bernstein and Eric Schenk in September 1996.The first implementation (for SunOS) was released by Jeff Weisberg a month later, and Eric Schenk released his Linux implementation in February 1997.