Thanks to everyone for the explanations.
Let me give you some more details.

Multiple clients programs (written in Delphi) are connecting to the FB server, some of them through LAN some of them through the Internet.
I'd like to secure communication between the clients and the server

I'm looking for a very cheap (possibly free) solution.

To be honest I don't have much knowledge about network security yet, so I'm also looking for something that can be easily setup and that is safe enough by default.

Currently, both the clients and the server are running on Windows, but we might move to Linux servers later in the future.

What do you guys suggest?

Any good sources to read up on these things?

Thanks!
Zd

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