I would like to modify an existing IETF RFC (Request for Comments) Standard and I was wondering what license they would fall under. I assume they are under something similar to the Unlicense but I want to be 100% sure.

If not, how would I properly attribute the RFC?

  • 1
    Have you already looked at RFC 5377 and RFC 5378? May 2, 2022 at 7:32
  • The problem with "modifying a standard" is that the modified thing no longer is a standard. If you use the result it for your own code ("we implement RFC $X except for provisions a,b & c") then the RFC license doesn't really matter. The license matters for the distribution of your not-a-standard, but why would you do that?
    – MSalters
    May 2, 2022 at 10:25
  • @MSalters Standards are modified all the time, this is how protocols evolve. RFC 733 was replaced with RFC 822 and later RFC 2822.
    – Barmar
    May 2, 2022 at 14:40

1 Answer 1


I assume they are under something similar to the Unlicense but I want to be 100% sure.

Sorry, but you are 100% wrong if nothing else because RFC 1 was published in 1969, 41 years before the Unilicense was published.

For RFCs published after 2008 or so (I can't find the exact date), RFCs are licensed with the IETF Trust Legal Provisions which is definitively not an open source license - it allows unmodified distribution and quoting but not modification. This is often preferred for standards documents as you don't want randoms publishing "Version 2" of your standards document and labelling it "Official". More details on the reasoning behind the license are in RFC 5377 and RFC 5378.

RFCs published before 2008 are under an ambiguous license.

  • This is likely a separate question entirely (on a separate SE) - but do you know whether the example you give (phony standards docs) has a legal defence besides copyright? It feels like a sort of fraud. But I wonder if there is anything (in, say, US law) that codifies that. May 3, 2022 at 19:04
  • This is the same reason why open source licenses are usually not themselves open source licensed. You don't want someone to be able to modify the GPL, because the whole point of having a well-known license is that the term "GPL" has a fixed meaning, and I don't have to read the GPL license of every GPL-licensed project because I know they are all the same. May 4, 2022 at 11:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.