[matfil]

While I wouldn't necessarily say that problems in this style are the right way to recruit in 2019, something equivalent to:

Please do not use an existing networking framework (e.g., Twisted or asyncore for Python, ACE for C++, etc.) to implement the server.

...would be a massively positive signal to me as a candidate. Places that truly value "full stack" abilities like this seem to be hard to track down.

[closeparen]

Same. I had to do this in first-year CS, and got pretty surprised to find out I'd be working with senior backend engineers who've never heard of sockets. Concerns at this layer don't come up much, but when they do, the set of people available to help gets a lot smaller.