a colleague brought me a machine (metal detector) that has a small linux in a card and the only way to connect that machine is via Network card. The thing is that He (and me) don't know anything about this machine, we don't have a way to guess its IP address (so we could scan ports or guess, at least, wich operating system version it has).
What I am thinking, and not tested yet, is to run a linux notebook, and try to use some auditing tool like nmap or an sniffer, then wait for the software to receive anything that may come from the machine.
What it is strange to me is what would happen if the machine does not send any packets... so my question would be... is there someway I can connect a linux notebook with this machine (or network card) through a network cable, and force this machine to answer to my linux notebook? so I can finally get the IP of this machine??