Detecting a device’s IP

Alright, so I got this mini print server from a friend and he couldn’t remember the IP he had assigned to it. So I couldn’t get to its admin interface to set any configuration options, and to make matters worse, there was no factory reset button. So my problem became, how do I find the IP of a device. My first idea was to do an nmap sweep of the devices’ last know IP range, but after two hours of scanning 65 thousand hosts this wasn’t turning anything up. I suspected that my friend had given it a class A private IP, but I wasn’t sure and I wasn’t about to try and scann 65 million possible hosts 😛

Then I got a second idea. First I downloaded Wireshark (formerly Ethereal) for packet capturing. Then I went into my vat-o-patches where approximately 72 million feet of cat5 patch cable call their semi-permanent home and found a crossover cable. I connected the two devices by the crossover cable then plugged in the power for the mini print server. The first packet that came across gave me what I needed, the source IP of the packet ( Then I changed my computer to be on the same subnet as the print server ( and fired up a browser and pointed it at I was greeted by the web admin interface, and from there I set the IP to my subnet and to the configuration I wanted.

Of course this all would have been for not if there had been a password on the print server, I still have no idea how I would have reset that should I have needed to.. :-/

For those of you that are wondering, the mini print sever it is a Netgear PS101, but this could work for any device really. Have fun!

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