Spanish authorities have arrested a 35-year-old Dutchman they say is "suspected of unprecedented heavy attacks" on Spamhaus, the international group that helps network owners around the world block spam.
A press release (English translation here) issued by the Dutch Public Prosecutor Service identified the suspect only by the initials SK and said he was living in Barcelona. A variety of circumstantial evidence, mostly taken from this Facebook profile, strongly suggests the suspect is one Sven Olaf Kamphuis. He's the man quoted in a March 26 New York Times article saying a Dutch hosting company called CyberBunker, which Kamphuis is affiliated with, was behind distributed denial-of-service attacks aimed at Spamhaus. Kamphuis later denied he or CyberBunker had anything to do with the attacks.
With peaks of 300 gigabits per second, the March attacks were among the biggest ever recorded. Besides their size, they were also notable because they attacked the London Internet Exchange, a regional hub where multiple networks from different service providers connect. As Ars writer Peter Bright explained, the size and technique threatened to clog up the Internet's core infrastructure and make access to the rest of the Internet slow or impossible. While some critics said that assessment was overblown, Bright provided this follow-up explaining why the attacks had the potential to break key parts of the Internet.