[prosody]

As I understand it, Cisco licenses the relevant patents and sublicenses them gratis to every user who uses Cisco’s binaries obtained from Cisco directly and not redistributed (thus also the difficulties in the article with working with Cisco’s unmaintained web server). The sublicense doesn’t apply to binaries built independently from source. I suppose this was imposed by the patent holders.

[boricj]

Can that library be rebuilt in a reproducible manner? If so, what's the difference between the library hosted by Cisco and a locally built one that is identical bit-for-bit? Is there any mechanism to ensure that the library was genuinely downloaded from Cisco rather than procured through alternative channels? If the Cisco server is turned off tomorrow, how can one tell if a copy of the library wasn't downloaded from the Cisco server while it was available?

I'm most likely missing a lot of crucial context, but it appears to me that this peculiar licensing scheme was a compromise made between lawyers that makes little practical sense on a technical level. That, or I'm far too chaotic for such nonsense.

[mod50ack]

The difference is legal, not technical. You don't have the right to redistribute copyrighted material with permission, except according to exceptions to copyright law (which are narrow enough to not apply here). Cisco gives permission for users to use the software only if downloaded directly from Cisco, and doesn't grant anybody permission to mirror and redistribute it.

Can you tell if a copy was downloaded from Cisco directly? No. Does it make a technical difference? No. But those are the rules Cisco chose, and so there it is.

One potential reason I can think of for this happening is Cisco being required to count the number of downloads of the software (or something like that). But, in the end, there's no requirement that there be logical sense to a rule like this.