The knowledge about how to write a program comes naturally when you know, in fine enough detail, both the problem which the program should solve, how to solve it, and the environment in which the program should run. In this case, writing a Python server program to respond to requests was relatively simple; Python provides built-in modules which makes writing servers easy. And when you know what the client program (i.e. the program running on the currently locked host) should do, and you know what environment the program has to operate in, the program more or less writes itself.
The first version of the program used a simple UDP broadcasting method to a hard-coded port to find servers, which required some rudimentary networking knowledge, but only basic TCP/IP stuff.
Later, both the server and client parts have gone through numerous refactorings which brought in many features (like a plugin system on the client side, and a D-Bus interface on the server side), but those were manageable chunks to add to an already mature and working system.
But sure, in addition to the knowledge one could acquire from LFS, I also had some high-level knowledge of how TLS and its handshake worked, I knew that there was some way to use OpenPGP keys instead of X.509 certificates in TLS, and I knew a little about how DNS-SD worked. The rest I needed I read up on as I wrote the code.
The first version of the program used a simple UDP broadcasting method to a hard-coded port to find servers, which required some rudimentary networking knowledge, but only basic TCP/IP stuff.
Later, both the server and client parts have gone through numerous refactorings which brought in many features (like a plugin system on the client side, and a D-Bus interface on the server side), but those were manageable chunks to add to an already mature and working system.
But sure, in addition to the knowledge one could acquire from LFS, I also had some high-level knowledge of how TLS and its handshake worked, I knew that there was some way to use OpenPGP keys instead of X.509 certificates in TLS, and I knew a little about how DNS-SD worked. The rest I needed I read up on as I wrote the code.