R
ymdport is a cross-platform tool that can be used to share files, directories or even plain text between different devices. It requires users to enter a secret code between the two machines and the intended file, directory or text message is shared only when the correct code is entered.
You’ll obviously have to install Rymdport on all the target machines. Unfortunately, the project isn’t available in the software repos of many distros and there are no official binary packages. If you don’t want to go through the trouble of chasing after dependencies, you can take advantage of the official Flatpak package.