The TrustedBSD extensions are intended for use with the open source FreeBSD operating systems, as well as related open and closed source operating systems such as Mac OS X, NetBSD, OpenBSD, and Linux. Almost all TrustedBSD code is under a two-clause Berkeley or substantially similar open source license:

Copyright (c) [year] [name]
All rights reserved.

This software was developed by the TrustedBSD Project.

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 AUTHOR 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 AUTHOR 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.

This license is intended to encourage commercial, research, and personal use of this software without limitation, providing that the copyright notice is observed and documented, and that authors and contributors are not held liable for any damages that may result from use of the code. With the exception of a small amount of GPL code associated with SEBSD, all TrustedBSD code may be incorporated into close source products without fee. Please make sure to observe all licenses included with distributed source code.

Organizations and individuals who extend TrustedBSD are encouraged to contribute bug reports, bug fixes, functional enhancements, and documentation to the project under similar licenses. While not obligatory, financial contributions via the FreeBSD Foundation are most welcome, and support developer travel, test hardware, etc.

The copyright on the BSD Daemon is held by Kirk McKusick; the copyright for the TrustedBSD Daemon, Trusty, is held by Leigh Denault. For more information on using the BSD Daemon, see our BSD Daemon Copyright page.