SCO's main website, www.sco.com, was offline at 4am, according to UK-based internet monitoring company Netcraft. It remained unavailable at 9am today, 27 August.
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The site had just recovered from a crippling denial of service (DOS) attack that lasted throughout the weekend and for much of the business day on 25 August.
The outage prompted Netcraft to declare that SCO was again the target of a DOS attack. However, SCO said the site was inaccessible as a result of preventive measures being taken minimise the effects of future attacks.
The software company has been the target of animosity within the open-source community after it sued IBM for, among other things, alleged misappropriation of SCO's Unix source code for the Linux operating system.
In May, SCO went a step further, announcing that it was dropping its Linux software business. At the same time, the company warned commercial Linux suppliers that they might be liable for misuse of SCO's intellectual property.
The suit has angered the open-source software community because it threatens to undermine the growing popularity of Linux, casting doubt on the legal status of the operating system.
The weekend DOS attack followed a similar attack in May and was probably launched by individuals within the open-source community, according to Eric Raymond, president of Open Source Initiative.
Following the attacks last weekend, Raymond and other open-source advocates condemned the actions and appealed to those within the community to stop attacking SCO's website.
"It was surprising to me that it happened and don't think it will happen again," he said. "We're ethical people."
Paul Roberts writes for IDG News Service