KEA-Dhcp comes with Netconf support and a number of Yang modules. The KEA-Dhcp package is distributed under Mozilla Public License v2.0, my question is how does the license apply to modifications or changes in the Yang files? If I decide to extend or modify the models, am I supposed to return the changes in the open source domain?

The models are in https://gitlab.isc.org/isc-projects/kea/-/tree/master/src/share/yang/modules kea-*.yang files don't seem to contain any license/copying information.

Since those files are not really source code and not compiled with gcc, I'm not sure if normal licensing terms apply to it.

I would appreciate any advice and comments, thanks.

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    Please provide a link to these Yang modules. Do they have license information inside, or the website where you take them? At the first glance they seem to be independent config files and not directly linked to the source code of Kea DHCP. Jan 7, 2022 at 13:29
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    @Martin_in_AUT thanks for comment. I updated the question.
    – Mark
    Jan 7, 2022 at 14:11

1 Answer 1


The Yang files (as per your link in the question) are in a directory structure, where (a few levels up in https://gitlab.isc.org/isc-projects/kea/-/tree/master/) there is a license file, which covers the entire tree with sub-folders.

You can therefore assume that the files in the sub-folders, including these Yang files, are also covered by the MPL v2 license.

As far as I can see, these Yang files perfectly fit the definition of 'Source Code Form' in the MPL v2 license language, therefore you should treat them accordingly.

In case you find other suitable Yang models/modules elsewhere on the web (try GitHub!) then you will need to comply with the license terms of those files, which might not necessarily be MPL v2.

If you modify a file under MPLv2 license, then the modification needs to be under the same license. You don't need to give your modifications to the KEA project, but you need to give the source code to all the recipients of your software. However, if you add your own Yang files you are not bound by the license of other (KEA) files, you can decide the license terms on your own.

  • thanks for comment. Does this mean that if I modify one of the Yang files or add my own, I'm not be obliged to return the changes to the KEA project?
    – Mark
    Jan 7, 2022 at 18:39
  • Thanks @Martin_in_AUT, your comments are very helpful. When I add my own Yang files under different license, will the new license not conflict with MPLv2 in some ways? Also, it is possible that my new Yang file will include the existing one (under MPLv2), how does this work together?
    – Mark
    Jan 10, 2022 at 14:43
  • @Mark You should either check this site for answers related to 'aggregate' vs. 'derivative work', or you should ask a new question. Jan 10, 2022 at 16:28
  • Thank you. May be you could merge your first comment with the answer, so that I can accept it as complete answer.
    – Mark
    Jan 11, 2022 at 15:07

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