Cybersecurity in general:
- https://www.packtpub.com/eu/networking-and-servers/hands-cybersecurity-architects
- https://www.packtpub.com/eu/networking-and-servers/information-security-handbook
- https://www.owasp.org/index.php/Main_Page
- https://www.packtpub.com/eu/networking-and-servers/practical-security-automation-and-testing
Concurrency:
- https://www.packtpub.com/eu/application-development/concurrent-patterns-and-best-practices
- https://www.packtpub.com/eu/application-development/mastering-c-multithreading
Operating system hardening: