Commands/tools I have been using frequently
Nmap UDP scan nmap <IP> -sU
Output the nmap scan in 3 major formats nmap <IP> -oA filename
nmap scan to do service and OS detection and scan all ports nmap -p- -SV -A <IP>
[https://www.stationx.net/nmap-cheat-sheet/]
[https://highon.coffee/blog/nmap-cheat-sheet/]
nikto -h <IP>
Digital ocean has become my favorite resource for learning about Linux, straight to the point and easy to understand.
/etc/
/etc/passwd
/etc/fstab
/etc/hosts
/etc/init.d
/usr/sbin
display the first few lines of a file head file.txt
display the last few lines of a file tail file.txt