NetBSD Licensing and Redistribution

This page exists to give you a bit of background information about copyright, to explain the licensing terms that most of the NetBSD operating system is distributed under, and to explain why we chose those licensing terms.

NetBSD's copyright and licensing terms

The traditional Berkeley license
Default license for all code assigned to The NetBSD Foundation

NetBSD's choice of license

Why the NetBSD Project uses a Berkeley-style license
Why NetBSD switched from using a 4-clause to a 2-clause license

NetBSD's copyright and licensing terms

The traditional Berkeley license

For the most part, the software constituting the NetBSD operating system is not in the public domain; its authors retain their copyright. However, because the people working on the NetBSD Project are committed to providing a free operating system, the license terms that cover most of the Project's source code are relatively lenient. In general, developers pattern their license terms after what's known as the “Berkeley license”. This license was used in the University of California, Berkeley's second Berkeley Networking Release and the 4.4BSD Lite software release, and looks like this:

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

  1. Redistributions of source code must retain the above copyright
     notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.
  3. Neither the name of the University nor the names of its contributors
     may be used to endorse or promote products derived from this software
     without specific prior written permission.

The license is preceded by the copyright statement itself, and is followed by some disclaimer information, so that if someone has problems with the software the authors can't be held liable.

The Berkeley license is a rather liberal license. All it requires is that the author of the work be given due credit for their creation, and that their name not be used to promote products based on their work. It allows free distribution, as long as the terms are followed, and also allows people to modify the work and not distribute it, if they so choose. Some contributors also omit the third clause.

Though the Berkeley license is generally used as the template for the license terms of works that are part of the NetBSD source tree, it does not apply to all works in the source tree, and you should check the individual source files to see what license applies to them. In particular, certain parts of the source tree are covered by the GNU General Public License (also known as the GPL), which is very different from the Berkeley license. Though we would like all of the software that we distribute to be covered by a Berkeley-style license, we can't make other people change their license terms, and we don't have an infinite amount of time to rewrite all of the software that we need.

Default license for all code assigned to The NetBSD Foundation

The NetBSD Foundation's (TNF) license is a “2 clause” Berkeley-style license, which is used for all code contributed to TNF. If you write code and assign the copyright to TNF, this is the license that will be used:

/*-
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by 
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

NetBSD's choice of license

Why the NetBSD Project uses a Berkeley-style license

The people working on the NetBSD Project want to provide a high-quality system that anyone can use for whatever they want. We are not in it for the money (we are volunteers!), so we have no desire to keep people from distributing our work. However, neither do we want to place our work into the public domain, and thereby give up our claim to even having our names on the software we wrote!

One thing that some people don't realize about Berkeley-style licenses is that they allow licensees (the users of the licensed work) to sell the code, in any form, with or without modification, and that they make no requirement that licensees give away the source code, even if they're selling binaries. This provides a striking contrast to the license terms granted by the GNU General Public License, because the GPL requires that, if you're distributing binaries, you must be willing to give away the sources to build those binaries.

Those of us working on the NetBSD Project are aware of this distinction, and some even value it. As stated above, we want anyone to be able to use the NetBSD operating system for whatever they want, just as long as they follow the few restrictions made by our license terms. Additionally, we don't think it's right to require people who add to our work and want to distribute the results (for profit or otherwise) to give away the source to their additions; they made the additions, and they should be free to do with them as they wish.

In summary, the people involved in the NetBSD Project use a Berkeley-style license where possible because it closely matches our goal of allowing users to do whatever they'd like with our software, while still retaining the copyright and getting credit for the work we have done. We are pragmatic, however, and will include software with different license terms in the NetBSD operating system if it significantly improves the quality of the system.

Why NetBSD switched from using a 4-clause to a 2-clause license

In 2008, following on from a vote amongst the membership of the NetBSD Foundation, and in recognition of the changing face of software licensing, the NetBSD Foundation has changed its recommended license to be a 2 clause BSD license. This recommended license is the one that the NetBSD Foundation strongly encourages its contributors to use when assigning copyright to the NetBSD Foundation.

At the same time, all the code which was contributed to the NetBSD Foundation has been modified to use the new 2-clause NetBSD license.

The change in license has come about because of a number of factors:

We have seen organisations and people concerned about the old clause 3 (the advertising clause) in the license, to the extent where NetBSD code could not be used in commercial products; the new license means that these concerns are no longer valid.
UCB moved some time ago to remove clause 3 from the code contributed to UCB; this change mirrors that one.
Some of our developers work for companies in Open Source or research departments where they are allowed to contribute back daytime work to the open source project, but only if the project's license is acceptable to their legal department, and the 4 clause BSD license has been rejected in some cases.
The members of the NetBSD Foundation (i.e. its developers) no longer considered clause 4 (the "endorsement" clause) to be useful in today's software world.

Third parties are encouraged to change the license on any files which have a 4-clause license contributed to the NetBSD Foundation to a 2-clause license. We would also encourage you to inform us about these files, so that we can continue to track the many places in which NetBSD is used.

Copyright information

What is copyright, anyway?

This information is for educational purposes only and we do not claim to provide legal advice. If you need legal advice, you should talk to a lawyer licensed to practice in your area. If you would like more information about copyright than we provide here, you may want to look at the Copyright FAQ, but you should note that it doesn't provide legal advice, either.

Copyright is the mechanism that allows creators to obtain certain exclusive rights to their creations. For instance, it allows a poem's author the right of exclusive reproduction of his or her poem; only the creator of a work, or those given permission by the creator, may reproduce that work. Copyright protects original expression. It does not protect the ideas or facts that underlie a work, nor does it protect any pre-existing work that the creator of a work has incorporated into their work. In the United States and in other countries that are signatories to the Berne Convention, a work's creator does not need to mark the work in any way to retain copyright.

The various protected rights to a work can be granted by means of a license, a set of terms and conditions that define the situations in which a third party may reproduce a creator's work. The terms of a license can vary greatly: some licenses demand a fee, while others make no such requirement; some licenses restrict further redistribution of a work, while others may require it in certain conditions.

There are many ways that the terms of a license can come into effect. For instance, a license agreement may be signed before access to a work is given, or a prominent statement of the license terms may be made along with a statement that use of the work implies acceptance of the license terms (known as a shrink-wrap agreement).

Note that there is a significant difference between works for which a creator retains copyright and works that are placed into the public domain by their creator. When a creator places a work into the public domain, he or she gives up all rights to the work in question. An author of a piece of software cannot say something such as, "This work is in the public domain. You may redistribute it freely as long as you do not charge for it." This is self-contradictory, because by placing the work in the public domain, they gave up their right to control its reproduction.