British teen Seth Nolan Mcdonagh, aka "narko" has been sentenced for his role in a 2013 attack which slowed the internet around the world.

Mcdonagh was sentenced at Southwark crown court to 240 hours of community service for the attack, thought to be the "biggest cyber attack in history".

The massive DDoS attack targeted junk mail tracker Spamhaus on 15 March 2013, knocking it offline. The company requested help from anti-DDoS specialist Cloudflare, which escalated the attacks. At its peak the attack was channeling 300 gigabits of traffic every second to Spamhaus servers, and the sheer scale of it began to impact on LINX - the London Internet Exchange. This in turn began to slow international internet traffic due to the volume of requests.

The court heard the impact on the internet had been "substantial", according to the BBC. Mcdonagh was also described as a "gun for hire" who took down sites on demand, although other individuals may also have been involved, the court heard.

The BBC also reports that the court heard more than £72,000 had been found in Mcdonagh's bank account after his arrest, and that source code used in the attacks was also found on machines at his home.

Judge Pegden described the crimes committed as “serious” and “sophisticated and unprecedented in scope”, according to a report by Team Cymru.

However, the judge accepted that Mcdonagh had shown "complete and genuine remorse" after his arrest, and said there was virtually no risk of re-offending, so a custodial sentence was not necessary.

Richard Cox, chief information officer at Spamhaus, told the BBC: "We fully appreciate the difficult predicament with which the sentencing judge was faced, and hope that anyone considering similar attacks will take heed of his remarks, that in any other circumstances such criminality would have resulted in a custodial sentence," he said.