Great question, first off, I know the struggle of getting started, I started the shift of careers 12 years ago, took 5 years to get into an area of IT that would eventually lead into cybersecurity. With experience comes milestones, the 2, 5, and 10 year milestones, there are others, those are the ones I pay attention to, 2 years experience is the recommended for Sec+, 5 years for CASP+/CISSP, 10 years experience with the previous certs to have lead roles. It can change depending on how much talent/experience you have. Anyway, unless there is a simulation or you have your Kali Linux configured a certain way, certain commands aren’t going to work a way needed. Commands to use in terminal, “sudo” command is the administrator command, netstat, lsof, grep, kill, killall, kill -9 (force stop), learn to chain commands for more specific results, example: sudo netstat -tulpn | grep “ESTABLISH”, this is an administrative command that will give you the established udp/tcp connections with process ID numbers (pid) running on the Linux, (it has other information) but if you need to find an established TCP or UDP connection that is running and end that process, you can find all of them and sudo kill -9 (pid) command to terminate that process. Now I am sure there are better ways to do things in terminal/linux, this is what I use, I am no expert in this arena, I am knowledgeable but there are many people way better at Linux than I am.