Nice post, but 2020 and still using an unauthenticated connection (plain netcat) to transfer data including executables (if I understood correctly) is not something you can justify when there are plenty of safe alternatives (e.g. wormhole, syncthing).
Maybe the recipient and the sender just compare hashes via a secure channel, but there's no mention of this.
The files were transferred via yggdrasil. In any case, it would have to be an unusually clever attacker to identify executables in a tarball being transmitted unwrapped via TCP on a port chosen out of a hat, and intercept it to do something malicious.
Malice is not the only concern. There was a post on here a couple days ago where AT&T was corrupting certain packets, and due to either luck of the TCP checksums being recalculated on the faulty equipment itself the bad packets were actually considered valid by the recipient.
I wish you would have at least mentioned it in your post that you were indeed relying on the security of the network and that nc by itself is not secure.
I'm not saying it would have been a real risk in your particular case, but giving these examples on a public website is basically saying "see, you can do it like this". I'm not saying you don't know better, but some of your readers might not, and may replicate your unsafe (without the underlying assumptions) code where the risk is higher.
This is especially bad given that there are safe alternatives with equal or better ergonomics.
Maybe the recipient and the sender just compare hashes via a secure channel, but there's no mention of this.