"Mastering Linux Security and Hardening, 2nd Edition" is a great read, my Live Raizo install was very soft when I started reading it and thankfully it is absolutely turgid after applying the knowledge found within.

Highly recommend the Linux Programming Interface by Michael Kerrisk. Other books I've read will maybe give a sentence or to into a kernel feature, or maybe "here's how you use it," but this one goes further into "here's how it works."

https://www.humblebundle.com/books/become-linux-master-packt-books?hmb_source=&hmb_medium=product_tile&hmb_campaign=mosaic_section_1_layout_index_1_layout_type_threes_tile_index_2_c_becomelinuxmasterpackt_bookbundle

tap the price-buttons, until you get the subset you want,

then "adjust the donation" to give more to charity,

then proceed to payment.

All sorts of highly-rated security stuff, in that set.

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You might research academic books aimed at networking and security certification tests.

You don't necessarily have to take the tests, but they tend to be aimed at what is considered industry-standard knowledge.

Like I've got an old copy of CompTIA Security+ Guide to Network Security Fundamentals by Mark Campia aimed at passing the CompTIA Security+ certification test.

There's plenty of other books like that, that's just an example. Research which industry certification tests sound like what you'd like to know and then find a book aimed at passing one of those tests. They tend to be pretty competently structured.

You could always turn to libgen or anna's archive for copies, as well.

Kurose / Ross, Computer Networking