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 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 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 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 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 at 11:08

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