I have a 'simple share nas' that I am unable to discover on my network. It will not show up on the client list of my router, but I believe it is statically set to an adress for the auto discover application that will not run. Is there a way to plug it directly into the lan port of a computer/notebook running a pfsense live boot and discover the address the device is using and capture packets?
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This is one of those tasks, which is easier on IPv6 than on IPv4. If the device supports IPv6, you can simply ping ff02::1 to find its IP address. If you have a Linux machine on the same network, this command should work ping6 -c2 -n ff02::1%eth0. You should be able to do the same from other operating systems, but I can't tell you what the ping command need to look like on other operating systems.
If the device whose IP address you want to find is IPv4 only, things get more difficult. You could try sniffing network traffic. ARP packets are the most interesting to be looking for. If the device is trying to send any IPv4 packets, it will first need to broadcast an ARP request. That ARP request will show you the IPv4 address of the device. Using tcpdump or wireshark you should be able to see those ARP requests being broadcast and reach machines, even if they do not have an IPv4 address in the same segment as the device you are interested in.
If the device does duplicate-address-detection on IPv4, things may look slightly different. In that case, when the device boots, it will send an ARP request for the statically configured IPv4 address of the device itself. If that IPv4 address happens to be used by another device on the LAN, that ARP request may be the only packet the device ever sends.
kasperd
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