[mettamage]

Excellent tip and really true for both the theory and the practice indeed. This almost never comes up in the CRUD apps that I had to make. But when it did come up, you better know stuff like ping, traceroute, netstat, netcat, tcpdump/wireshark and also nmap. I've learned about these tools from my networking classes.

But where I got to master them a lot more was playing hackthebox.eu with a friend! Also, the hacking skills obtained there are useful. Your employer might not always appreciate that you're hacking his/her company though. Not because you're hacking it, but because you're going "outside of your role" and not actually producing any features. So be careful with that one, I've burned myself twice on that front (it depends on company culture, I suppose).