OpenBSD Copyright Policy


Copyright law is complex, OpenBSD policy is simple — OpenBSD strives to provide code that can be freely used, copied, modified, and distributed by anyone and for any purpose. This maintains the spirit of the original Berkeley Software Distribution. The preferred wording of a license to be applied to new code can be found in the license template.

OpenBSD can exist as it does today because of the example set by the Computer Systems Research Group at Berkeley and the battles which they and others fought to create a Unix source distribution un-encumbered by proprietary code and commercial licensing.

The ability of a freely redistributable "Berkeley" Unix to move forward on a competitive basis with other operating systems depends on the willingness of the various development groups to exchange code amongst themselves and with other projects. Understanding the legal issues surrounding copyright is fundamental to the ability to exchange and re-distribute code, while honoring the spirit of the copyright and concept of attribution is fundamental to promoting the cooperation of the people involved.

The Berkeley Copyright

The original Berkeley copyright poses no restrictions on private or commercial use of the software and imposes only simple and uniform requirements for maintaining copyright notices in redistributed versions and crediting the originator of the material only in advertising.

For instance:

 * Copyright (c) 1982, 1986, 1990, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.

Berkeley rescinded the 3rd term (the advertising term) on 22 July 1999. Verbatim copies of the Berkeley license in the OpenBSD tree have that term removed. In addition, many 3rd-party BSD-style licenses consist solely of the first two terms.

Because the OpenBSD copyright imposes no conditions beyond those imposed by the Berkeley copyright, OpenBSD can hope to share the same wide distribution and applicability as the Berkeley distributions. It follows however, that OpenBSD cannot include material which includes copyrights which are more restrictive than the Berkeley copyright, or must relegate this material to a secondary status, i.e. OpenBSD as a whole is freely redistributable, but some optional components may not be.

Copyright Law

While the overall subject of copyright law is far beyond the scope of this document, some basics are in order. Under the current copyright law, copyrights are implicit in the creation of a new work and reside with the creator. In general the copyright applies only to the new work, not the material the work was derived from, nor those portions of the derivative material included in the new work.

Copyright law admits to three general categories of works:

Original Work
A new work that is not derived from an existing work.
Derivative Work
Work that is derived from, includes or amends existing works.
A work that is a compilation of existing new and derivative works.

The fundamental concept is that there is primacy of the copyright, that is a copyright of a derivative work does not affect the rights held by the owner of the copyright of the original work, rather only the part added. Likewise the copyright of a compilation does not affect the rights of the owner of the included works, only the compilation as an entity.

It is vitally important to understand that copyrights are broad protections as defined by national and international copyright law. The "copyright notices" usually included in source files are not copyrights, but rather notices that a party asserts that they hold copyright to the material or to part of the material. Typically these notices are associated with license terms which grant permissions subject to copyright law and with disclaimers that state the position of the copyright holder/distributor with respect to liability surrounding use of the material.

By international law, specifically the Berne Convention for the Protection of Literary and Artistic Works, part of the author's copyright, the so-called moral rights, are inalienable. This includes the author's right "to claim authorship of the work and to object to any distortion, mutilation or other modification of, or other derogatory action in relation to, the said work, which would be prejudicial to his honor or reputation". In some countries, the law reserves additional inalienable moral rights to the author. On the other hand, the author is free to transfer other parts of his copyright, the so-called economic rights, in particular the rights to use, copy, modify, distribute, and license the work.

Permissions — the flip side

Because copyrights arise from the creation of a work, rather than through a registration process, there needs to be a practical way to extend permission to use a work beyond what might be allowed by "fair use" provisions of the copyright laws.

This permission typically takes the form of a "release" or "license" included in the work, which grants the additional uses beyond those granted by copyright law, usually subject to a variety of conditions. At one extreme sits "public domain" where the originator asserts that he imposes no restrictions on use of the material, at the other restrictive clauses that actually grant no additional rights or impose restrictive, discriminatory or impractical conditions on use of the work.

Note that a license is not to be confused with a copyright transfer. While a transfer would give the new copyright holder exclusive rights to use the code and take these rights away from the author, a license typically grants additional people non-exclusive rights to use the code, while the authors retain all their rights.

The above observations regarding moral rights imply that putting code under an ISC or two-clause BSD license essentially makes the code as free as it can possibly get. Modifying the wording of these licenses can only result in one of the three following effects:

Again, an important point to note is that the release and conditions can only apply to the portion of the work that was originated by the copyright holder—the holder of a copyright on a derivative work can neither grant additional permissions for use of the original work, nor impose more restrictive conditions for use of that work.

Because copyright arises from the creation of a work and not the text or a registration process, removing or altering a copyright notice or associated release terms has no bearing on the existence of the copyright, rather all that is accomplished is to cast doubt upon whatever rights the person making the modifications had to use the material in the first place. Likewise, adding terms and conditions in conflict with the original terms and conditions does not supersede them, rather it casts doubts on the rights of the person making the amendments to use the material and creates confusion as to whether anyone can use the amended version or derivatives thereof.

Finally, releases are generally binding on the material that they are distributed with. This means that if the originator of a work distributes that work with a release granting certain permissions, those permissions apply as stated, without discrimination, to all persons legitimately possessing a copy of the work. That means that having granted a permission, the copyright holder can not retroactively say that an individual or class of individuals are no longer granted those permissions. Likewise should the copyright holder decide to "go commercial" he can not revoke permissions already granted for the use of the work as distributed, though he may impose more restrictive permissions in his future distributions of that work.

Specific Cases

This section attempts to summarize the position of OpenBSD relative to some commonly encountered copyrights.


The Berkeley copyright is the model for the OpenBSD copyright. It retains the rights of the copyright holder, while imposing minimal conditions on the use of the copyrighted material. Material with Berkeley copyrights, or copyrights closely adhering to the Berkeley model can generally be included in OpenBSD.


As part of its settlement with AT&T, Berkeley included an AT&T copyright notice on some of the files in 4.4BSD lite and lite2. The terms of this license are identical to the standard Berkeley license.

Additionally, OpenBSD includes some other AT&T code with non-restrictive copyrights, such as the reference implementation of awk.


The original Unix code (AT&T versions 1 through 7 UNIX, including 32V) was freed by Caldera, Inc. on 23 January 2002 and is now available under a 4-term BSD-style license. As a result, it would theoretically be possible to incorporate original Unix code into OpenBSD. However, that code is now so old that it does not satisfy today's interface and quality standards.

DEC, Sun, other manufacturers/software houses.

In general OpenBSD does not include material copyrighted by manufacturers or software houses. Material may be included where the copyright owner has granted general permission for reuse without conditions, with terms similar to the Berkeley copyright, or where the material is the product of an employee and the employer's copyright notice effectively releases any rights they might have to the work.

Carnegie-Mellon (CMU, Mach)

The Carnegie-Mellon copyright is similar to the Berkeley copyright, except that it requests that derivative works be made available to Carnegie-Mellon. Because this is only a request and not a condition, such material can still be included in OpenBSD. It should be noted that existing versions of Mach are still subject to AT&T copyrights, which prevents the general distribution of Mach sources.


The original Apache license was similar to the Berkeley license, but source code published under version 2 of the Apache license is subject to additional restrictions and cannot be included into OpenBSD. In particular, if you use code under the Apache 2 license, some of your rights will terminate if you claim in court that the code violates a patent.

A license can only be considered fully permissive if it allows use by anyone for all the future without giving up any of their rights. If there are conditions that might terminate any rights in the future, or if you have to give up a right that you would otherwise have, even if exercising that right could reasonably be regarded as morally objectionable, the code is not free.

In addition, the clause about the patent license is problematic because a patent license cannot be granted under Copyright law, but only under contract law, which drags the whole license into the domain of contract law. But while Copyright law is somewhat standardized by international agreements, contract law differs wildly among jurisdictions. So what the license means in different jurisdictions may vary and is hard to predict.


The ISC copyright is functionally equivalent to a two-term BSD copyright with language removed that is made unnecessary by the Berne convention. This is the preferred license for new code incorporated into OpenBSD. A sample license is available in the file /usr/share/misc/license.template.

GNU General Public License, GPL, LGPL, copyleft, etc.

The GNU Public License and licenses modeled on it impose the restriction that source code must be distributed or made available for all works that are derivatives of the GNU copyrighted code.

While this may superficially look like a noble strategy, it is a condition that is typically unacceptable for commercial use of software. So in practice, it usually ends up hindering free sharing and reuse of code and ideas rather than encouraging it. As a consequence, no additional software bound by the GPL terms will be considered for inclusion into the OpenBSD base system.

For historical reasons, the OpenBSD base system still includes the following GPL-licensed components: the GNU compiler collection (GCC) with supporting binutils and libraries, GNU CVS, GNU texinfo, the mkhybrid file system creation tool, and the readline library. Replacement by equivalent, more freely licensed tools is a long-term desideratum.


Much of OpenBSD is originally based on and evolved from NetBSD, since some of the OpenBSD developers were involved in the NetBSD project. The general NetBSD license terms are compatible with the Berkeley license and permit such use. Material subject only to the general NetBSD license can generally be included in OpenBSD.

In the past, NetBSD has included material copyrighted by individuals who have imposed license conditions beyond that of the general NetBSD license, but granted the NetBSD Foundation license to distribute the material. Such material can not be included in OpenBSD as long as the conditions imposed are at odds with the OpenBSD license terms or releases from those terms are offered on a discriminatory basis.


Most of FreeBSD is also based on Berkeley licensed material or includes copyright notices based on the Berkeley model. Such material can be included in OpenBSD, while those parts that are subject to GPL or various individual copyright terms that are at odds with the OpenBSD license can not be included in OpenBSD.


Most of Linux is subject to GPL style licensing terms and therefore can not be included in OpenBSD. Individual components may be eligible, subject to the terms of the originator's copyright notices. Note that Linux "distributions" may also be subject to additional copyright claims of the distributing organization, either as a compilation or on material included that is not part of the Linux core.


The X.Org Foundation maintains and distributes the X Window System under a modified MIT license, which is quite similar to the BSD license and additionally allows sublicensing. Under the name of Xenocara, the OpenBSD base system includes an improved and actively maintained version of the X.Org code.

Shareware, Charityware, Freeware, etc.

Most "shareware" copyright notices impose conditions for redistribution, use or visibility that are at conflict with the OpenBSD project goals. Review on a case-by-case basis is required as to whether the wording of the conditions is acceptable in terms of conditions being requested vs. demanded and whether the spirit of the conditions is compatible with goals of the OpenBSD project.

Public Domain

While material that is truly entered into the "public domain" can be included in OpenBSD, review is required on a case by case basis. Frequently the "public domain" assertion is made by someone who does not really hold all rights under copyright law to grant that status or there are a variety of conditions imposed on use. For a work to be truly in the "public domain" all rights are abandoned and the material is offered without restrictions.

In some jurisdictions, it is doubtful whether voluntarily placing one's own work into the public domain is legally possible. For that reason, to make any substantial body of code free, it is preferable to state the copyright and put it under an ISC or BSD license instead of attempting to release it into the public domain.