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I have developed a set of python-based tools for network testing, and I am currently building a GUI around it and I am going to attempt to sell it. My issue is one part of my code relies on wireshark, or more specifically tshark. The code communicates with tshark exactly how wireshark suggests you use it in their FAQ, through subprocess pipes. So as I attempt to build an installer, for the sake of convenience to the user, can I have the installer check for the tshark path then if it does not exist install it for them?

TL;DR If my proprietary installer installs wireshark, will I be in legal trouble.

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The GPLv2 explains:

In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.

So you can distribute the GPLv2-covered software alongside your proprietary software. The GPL only applies to the covered software, not to the entirety of the software that you distribute – iff the two are separable. Your proprietary software will then not be a derived work in the sense of copyright law.

For the GPL-covered part, you must comply with the GPL. In particular:

  • You must provide the source code or a written offer for the source code of the GPL-covered software. Such an offer must be open to anyone, not just for your customers.
  • Your installer should announce that it contains or installs GPL-covered parts, and should give the user a summary of their rights and how to view the license. However, it is not necessary that the GPL is accepted before installation.
  • You must not add any restrictions to the GPL-covered parts. E.g. you must not prevent someone from copying these parts. You must not require acceptance of any EULA prior to offering access to the GPL-covered parts.
  • In the spirit of the GPL, you should not prevent modifications to the Wireshark software that you installed, e.g. by requiring an exact version or even by checksumming the installation.

It is important to get GPLv2 compliance right:

You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License.

As written, your right to distribute Wireshark is terminated if you violate the license for any reason, and fixing the violations will not necessarily reinstate the license. If your business depends on Wireshark, consider checking your compliance effort with an IP lawyer. On the other hand, many GPLv2 licensors have no interest in a strict enforcement of this clause and will not consider your license terminated if you show a good faith effort to comply and fix any violations.

See also: Kuhn, Williamson, Sandler (2008): A Practical Guide to GPL Compliance. Software Freedom Law Center.

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  • Thank you very much this was extremely helpful. I am curious though with your first bullet point, would providing a link to wireshark's documentation or just their website suffice, or would I have to release the source for the whole installer.
    – Fitz
    Oct 29, 2018 at 17:05
  • P.S. I cannot upvote because I do not have enough upvotes myself, but I appreciate your help!
    – Fitz
    Oct 29, 2018 at 17:06
  • @Fitz Wireshark is covered by the GPL, your installer is not. So you only need to supply the Wireshark source. Please read the Practical Guide I linked and/or section 3 of the GPLv2, these explain in more detail how to supply the source. Linking to the Wireshark website is not sufficient: you must either provide the source on the same medium or provide a written offer. Simply bundling the source code with the installer is the easiest way to comply.
    – amon
    Oct 29, 2018 at 17:25
  • Much appreciated, you've been very helpful.
    – Fitz
    Oct 29, 2018 at 17:59
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    @Fitz the thing to do if you're happy with an answer is accept it by clicking the tick outline next to it. This drives the reputation system for both you and author of the accepted answer, and stops the question floating around forever like a querulous albatross. My apologies if you already know this.
    – MadHatter ♦
    Oct 29, 2018 at 20:55

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