I have for a few decades worked in networking and security, and everything seems to have grown.
I will try to lay out a path for people who wants to get into networking and security, with some references to pentesting, software security, and related areas. Where to start and which skills you should start learning.
I will use my existing courses as a guide. These are taught as part of the of the Diploma in IT Security at KEA Kompetence https://kompetence.kea.dk/uddannelser/it/diplom-i-it-sikkerhed
Note: I will reference book resources, but if you are on a tight budget lots of other resources may be used instead.
Related links: https://zencurity.gitbook.io/kea-it-sikkerhed/ lecture plans and book references https://github.com/kramse/security-courses all my training and educational materials, including exercises booklets with small exercises that you can do with virtual machines like Debian and Kali Linux using lots of open source tools.