The myth persists that the Net was built to withstand the blast of an atomic bomb. But that was the military-run Arpanet of the 1970s, not the corporate-run Internet of today. "What's basically wrong is we are centralized," explains Dr. Peter Salus, Internet historian and author of Casting the Net. "We have violated the constraints that the Department of Defense had in 1967."

Indeed, one of the most significant results of commercializing the Internet has been to create more single points of failure, rather than a more redundant and reliable network. That's because companies are busy finding ways to make themselves indispensable: User self-sufficiency is incompatible with sustained corporate profits.

In December 1995, Internet pioneer Bob Metcalfe predicted a global Internet meltdown. Since then, he has eaten his words. Nevertheless, real problems with the Internet remain. What's more, it's increasingly likely that these lurking problems will be deliberately exploited or tickled by accident, and result in another global Internet collapse.

How might it be done? The following 50 ways to crash the Net are based on conversations I had with Gene Spafford at Purdue University, Alan Wexelblat at the MIT Media Lab, Eugene Kashpureff at AlterNIC, and Fred Cohen at Sandia Laboratory's Computer Security Group. Most of these attacks work by targeting a single point of failure within today's Internet. Others rely on creating storms of activity that overwhelm legitimate network traffic.

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