PRET VS Metasploit

So i decided to tinker a bit before spending a shitload of money into toners or new printers, i'm using this tool to try access and issuing commands to the printer, the connection gets succesfully enstablished. After that i can issue commands in three different languages: PS and PJL doesn't seem to do anything, with PCL at least i see a Device: Unknown printer but all the commands i issue seem to simply not be taken in consideration from the printer, in any of the 3 languages, giving a Command execution failed (timed out) error.

my friend that owns a coffee shop asked me to poke around on his network to look for vulnerabilities in exchange for some free coffees and i saw that they had 9100 open, wasn't familiar with it so played around and found out about PRET which gave me access to his HP printer, with transversal you can gain access to the file system etc and from what i read you can open a root shell on another port, would the scope be limited to the printer, or can the printer be used as a vector to gain access to other systems connecting to said printer?

Preferable you don't want it accessible from the internet at all. Using stuff like the Printer Exploitation Toolkit (PRET), people can get up to some nasty stuff on a public accessible (insecure) printer : https://github.com/RUB-NDS/PRET

You'll love PRET then. It can also brick printers and do all kinds of other fun stuff with them.

Printer exploit framework: https://github.com/RUB-NDS/PRET

Printer Exploitation Toolkit (PRET) - Tool for printer security testing capable of IP and USB connectivity, fuzzing, and exploitation of PostScript, PJL, and PCL printer language features.

Metasploit

Metasploit: https://github.com/rapid7/metasploit-framework

1-) Learn Hacking on a debian based distro like Kali Linux - I personally started with tools like nikto, camhacker... and then moved to more complex frameworks like metasploit.

I once had to give a presentation about Metasploit, and whether it was ethically correct for the creator to make it free and open-source, available to everyone. And in researching this I realized that there were a lot of parallels between the arguments for or against hacking tools being readily available and the arguments for or against gun control. I'll just list a few quickly:

Metasploit Framework (mentioned earlier)

This phase is where the pen testers practically prove that there exist potential vulnerabilities in the target system. The pen testers do the hacking using an array of technical approaches and social engineering methods to exploit the vulnerabilities. The ethical hackers commonly use Metasploit framework to automatically execute exploitation against the target systems. Moreover, they may install malwares such as rootkit to persistently maintain their foothold and further compromise the target system.