The release of reference licenses for Windows CIFS and SMB protocols - designed to increase competition in the file-sharing marketplace and also satisfy regulators' antitrust concerns - could actually kill competition, thanks to some Microsoft Corp fine print. Redmond, Washington-based Microsoft agreed to license its Common Internet File System (CIFS) protocol on a royalty-free basis, to enable other companies to implement the protocol on non-Windows operating systems.

This was done to appease the concerns of both the US Department of Justice and the European Commission about Microsoft's anti-competitive behavior. ComputerWire predicted the release of CIFS and SMB could squash open source when news first broke of its decision to open the technology in March. As details of the CIFS license have emerged since then, it has become clear Microsoft has effectively banned open source companies from distributing implementations of CIFS, if the software is distributed under the General Public License (GPL).

This caveat is not entirely unexpected as it enables Microsoft to ensure that its CIFS patents cannot be converted to the GPL, and protects the company's intellectual property. However, by specifically targeting the GPL, Microsoft could effectively kill off the open-source Samba project's implementation of SMB (Server Message Block the forerunner to CIFS).

Samba is an open source software suite that allows non-Windows computer to work in Windows file and print sharing environments. While Samba is a reverse-engineered implementation of SMB, and was originally written without reference to the SMB protocol itself, the Samba team has had to keep up with Microsoft's SMB and CIFS enhancements over the years to ensure that Samba provides adequate file and print-sharing capabilities between Unix/Linux servers and Windows clients.

The main problem for the Samba team is that while the open source version has been specifically designed to be interoperable with the Microsoft's SMB implementation without copying Microsoft's code, the new license references software patents implemented in CIFS, which some observers speculate Samba may inadvertently infringe upon.

In a posting on the geek community site slashdot.org, Samba team member Jeremy Allison states: "We don't think Samba infringes on these patents. We've looked at them. The problem is it doesn't matter what we think, it matters what lawyers think of this. We're currently getting a legal opinion on this and will post a more complete statement once we've done so."

Even if Samba does not currently infringe on the patents, the Samba team is likely to struggle to keep up with closed-source vendors that have been granted royalty-free access to the patents. The CIFS technical reference license grants licensees the right to develop technologies based on the CIFS protocol, and a royalty-free license to Microsoft's specified patents, as long as the licensee does "not distribute any company implementation in any manner that would subject such company implementation to the terms of an IPR impairing license."

IPR impairing licenses are defined by Microsoft as: "the GNU General Public License, the GNU Lesser/Library General Public License, and any license that requires in any instance that other software distributed with software subject to such license (a) be disclosed and distributed in source code form; (b) be licensed for purposes of making derivative works; or (c) be redistributable at no charge".

The Free Software Foundation, developer and keeper of the GPL, has responded in typically outraged manner and has accused Microsoft of using software patents as a method of stifling the growth of free software alternatives.

"Microsoft's new assault follows a year's worth of rhetoric aimed at slandering the GPL and those who, in the name of software freedom, advocate the use of GPL. Now, that war of words has been followed up with a legal attack," states Bradley Kuhn, executive director of the FSF.

"In copylefted Free Software, Microsoft now faces a rival that they cannot buy nor run out of business. As expected, they've turned to their patent pool as their last resort to assail us."