Security is essential.

Security needs to convince: https://utcc.utoronto.ca/~cks/space/blog/tech/SecurityNeedsToConvince

Network recon without being detected.

OSINT → tool hierarchy for information gathering
Spiderfoot → CLI/webUI automated OSINT scanner
crt.sh → subdomain finder based on SSL certs

Search engine specifiers that sometimes reveal useful info.

https://www.exploit-db.com/google-hacking-database

https://www.exploit-db.com/ → Practical CVEs

https://primer.picoctf.org → CTF introduction

https://book.hacktricks.wiki/en/index.html → CTF resources for different attacks
https://trailofbits.github.io/ctf/ → CTF field guide

https://hacktricks.boitatech.com.br/misc/basic-python/bypass-python-sandboxes → break python sandbox

https://play.picoctf.org/practice/ → CTF practice

Feeds for security updates one should follow.