The OpenSSL exception is a clause added to the GNU General Public License (GPL) by free software developers who want to use OpenSSL with their software.

=License incompatibilities=

==Redistribution==

The GPL contains the following text in section 6 (emphasis added):

:Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License.

The OpenSSL license, on the other hand, contains two sections which seem to conflict with it:

:3. All advertising materials mentioning features or use of this software must display the following acknowledgment: : This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. (http://www.openssl.org/)

:6. Redistributions of any form whatsoever must retain the following acknowledgment: : This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/)

==Bundling==

The GPL contains the following text in section 3 (emphasis added):

: 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:

:: a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,

:: [subsections b and c deleted for brevity]

: The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.

This is taken by some to mean that if you use OpenSSL (whose license is incompatible with the GPL) in a GPL program, they cannot be distributed together with an operating system.

=The exception=

Some programs that are licensed under the GPL have included an exception in order to use OpenSSL. GNU Wget uses the following:

:In addition, as a special exception, the Free Software Foundation gives permission to link the code of its release of Wget with the OpenSSL project s OpenSSL library (or with modified versions of it that use the same license as the OpenSSL library) , and distribute the linked executables. You must obey the GNU General Public License in all respects for all of the code used other than OpenSSL . If you modify this file, you may extend this exception to your version of the file, but you are not obliged to do so. If you do not wish to do so, delete this exception statement from your version.

MICQ uses a slightly different exception:

:Beginning with 0.4.12, as a special exception permission is granted to link the code of this release of mICQ with the OpenSSL project s OpenSSL library, and distribute the linked executables. You must obey the GNU General Public License, version 2 , in all respects for all of the code used other than OpenSSL . If you modify this file, you may extend this exception to your version of the file, but you are not obliged to do so. If you do not wish to do so, delete this exception statement from your version of this file.

=Alternatives=

An alternative workaround, suggested by the OpenSSL Project in their FAQ, is to provide a dual license: allow users to choose to use your program under either the GPL (without OpenSSL) or a license that is compatible with the OpenSSL license. OpenSSL itself is dual-licensed, but neither license is the GPL.

=See also=

=External links=