Red Hat has slammed the new alliance between rivals Microsoft and Novell as "unthinkable", while at the same time claiming it is a victory for open-source software.

Following on the heels of its "unfakeable" response to last week's incursion by Oracle into the company's core Linux support business, Red Hat attacked the alliance by the two long-time enemies, but also claimed that "the best technology has been acknowledged - Linux has won."

A long-time foe of open source, Microsoft announced yesterday that it would work with Linux distributor Novell to make Windows inter-operate with Suse Linux in the data centre in areas such as virtualisation and Web services. Microsoft will also help market Suse to its customers.

Both Microsoft CEO Steve Ballmer and Novell CEO Ron Hovsepian said the two companies will continue to compete, but will also aid each other with support for the increasing number of companies running mixed Windows-Linux environments.

The tie-up is widely perceived as the second blow to Red Hat in two weeks. Oracle said last week that it would clone Red Hat's market-leading version of Linux in order to offer discounted support to enterprise customers.

In its statement, Red Hat decried Microsoft and Novell's technical alliance. "Openly defined standards create inter-operability everyone can implement. That's the real solution. It doesn't require a deal between two companies."

Red Hat also criticised Microsoft and Novell's patent cross-licensing deal. Microsoft vowed not to sue non-commercial Linux developers nor Suse Linux users for any possible patent violations, but declined to rule out suing other Linux companies or users.

In its statement, Red Hat also called that threat a looming "innovation tax". It said its Open Source Assurance program would allow customers to continue using Red Hat and JBoss software in case of a legal challenge and indemnify them against intellectual property infringement claims.

Red Hat's head of support also defiantly said last week that the company hasn't seen any of its 200,000-plus customers defect to Oracle yet. "I've asked my support engineers to give me feedback. Honestly, it's been business as usual," said Iain Gray.