The initiative has included speeches and statements in recent weeks by Microsoft officials, and reached a crescendo of sorts in a recent Chicago Sun-Times interview with Microsoft Chief Executive Steve Ballmer, in which he called Linux "a cancer that attaches itself in an intellectual-property sense to everything it touches."
"Open source" software involves freely available programs in which the underlying source code, or blueprints, can be viewed and modified by programmers. Microsoft maintains that open-source poses a hidden threat because of licensing provisions that accompany the software.
The Redmond, Wash., company appears to be fighting an uphill battle, since open-source code has become important for a growing number of companies.
One of them, in fact, has been Microsoft itself. The company's Hotmail free e-mail service for years used the FreeBSD operating system and the Apache Web server, both leading open-source programs. After buying Hotmail in 1997, Microsoft tried to replace FreeBSD with its own Windows software. Hotmail insiders said the company found Windows couldn't handle the heavy load, something Microsoft at the time declined to discuss. Wednesday, Microsoft said that since last summer, Hotmail has been running on both Windows 2000 and the Solaris operating system from Sun Microsystems Inc.
Craig Mundie, a Microsoft senior vice president, said the company's main objection is with the General Public License, or GPL, under which Linux is distributed. That license requires companies that incorporate GPL software in their own programs to, in turn, make those programs freely available. The GPL is usually considered the most restrictive of the several open-source licenses now in use; Microsoft says it threatens all intellectual property at companies using it.
But in its statements, Microsoft tends not to draw attention to the fact that the GPL also allows companies to write their own proprietary programs that work in connection with a GPL program, as long as those programs don't themselves contain any GPL code. "You can write a proprietary word-processing program that runs on Linux -- that's fine," said Jorge L. Contreras, who deals with open-source issues at Hale and Dorr, Boston's largest law firm. "Microsoft is spinning this the way they feel they need to."
Indeed, many large software companies, including Oracle Corp., sell proprietary programs that work with Linux, and Tivo Inc. uses Linux in its proprietary digital-video recorder product. Other companies, like International Business Machines Corp., have massive in-house Linux projects underway.
What's more, other open-source software, such as FreeBSD, is distributed under licenses that contain virtually no restrictions at all. For example, Apple Computer's new proprietary Macintosh operating system uses FreeBSD.
Mundie said he didn't have any concrete examples of companies actually being harmed by open source. He conceded that some companies might indeed be able to use Linux and not risk their other intellectual property, but said doing so would require "an army of lawyers" because of the complexity of the GPL. He also said it was too early to conclude that using Linux was entirely safe for companies, since many of the issues haven't been tried in a courtroom.
Brian Youmans, who handles copyright issues for the Free Software Foundation, the Boston-based group that developed the GPL, said violations of the license sometimes occur, usually inadvertently, and his group usually works quietly with the company to resolve the matters. "We are not interested in ruining companies by forcing them to reveal their intellectual property," he said. "Microsoft is using scare tactics."
Microsoft's campaign has helped unify open-source leaders who often spend much of their time arguing over philosophical issues but who all signed a statement criticizing Microsoft. Brian Behlendorf, who works with Apache, said Microsoft is running the campaign because it views open-source software as the main competition to its ".Net" Internet initiative.