All current versions of BIND 9, versions 9.11.0b and greater, Kea DHCP versions 1.0.0 and greater, ISC DHCP versions 4.4.0 and greater, and Stork are available for free under the Mozilla Public License 2.0. Some Kea Hooks are licensed under the MPL 2.0, others are commercially licensed. The Kea Administrative Reference Manual clearly states which hooks are open source.
Mozilla publishes a helpful FAQ about the MPL 2.0 license.
The MPL 2.0 license is approved by the Open Source Initiative.
BIND 9 versions prior to BIND 9.11.0b, ISC DHCP versions prior to ISC DHCP 4.4.0, and Kea versions prior to Kea 1.0.0 were released under the ISC License, the text of which is shown below. The ISC License is registered with and approved by the Open Source Initiative. Permission to use, copy, modify, and/or distribute this License text for any purpose with or without fee is hereby granted. (like SPDX: 0BSD)
Text of the ISC License:
Copyright © 2004-2013 by Internet Systems Consortium, Inc. (“ISC”)
Copyright © 1995-2003 by Internet Software Consortium
Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED “AS IS” AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.