Spamhaus, a group based in both London and Geneva, is a non-profit organisation which aims to help email providers filter out spam and other unwanted content.
To do this, the group maintains a number of blocklists - a database of servers known to be being used for malicious purposes.
Recently, Spamhaus blocked servers maintained by Cyberbunker, a Dutch web host which states it will host anything with the exception of child pornography or terrorism-related material.
Sven Olaf Kamphuis, who claims to be a spokesman for Cyberbunker, said, in a message, that Spamhaus was abusing its position, and should not be allowed to decide "what goes and does not go on the internet".
Spamhaus has alleged that Cyberbunker, in cooperation with "criminal gangs" from Eastern Europe and Russia, is behind the attack.
But, the good guys seem better armed than even their governments;
Spamhaus's Domain Name System (DNS) servers were targeted - the infrastructure that joins domain names, such as bbc.co.uk, the website's numerical internet protocol address.
Mr [Steve] Linford [chief executive of Spamhaus] said the attack's power would be strong enough to take down government internet infrastructure.
"If you aimed this at Downing Street they would be down instantly," he said. "They would be completely off the internet."
Also in the fray; Google.