How would you define a production server? Do you mean in the context of a home server or a server used by a large company? The guide is intended for a server for home use. I hope anyone securing a large corporate server is not using information on GitHub. If they are then the company has far bigger problems than security.

I think for home use, ufw is probably good enough. I've been using it for 3+ years and it's worked out okay for me okay.

I have not heard of ferm but I will check it out. Thanks!