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IP Sniffer

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IP Sniffer
Is there a software product that would look out the RJ45 Ethernet port on my laptop and give me the IP address of what I have connected?

There are times where I am working on either my own equipment or someone else' and it would be nice to find the units IP address without going to factory defaults.

Vance - KC8RGO
k1ky's picture
IP Sniffer

I use 2 programs: 1. Netgear Genie  2. Advanced IP Scanner
Both are free. 
1. Genie will give you a graphical representation of your network and you can assign custom name tags and Icons to the discovered devices.  I find that sometimes it doesn't "find" everything, but pretty close.  It can show connections to multiple Ethernet Ports as well as Wi-Fi.  It runs interactively and will discover devices as they are connected and will alert when they drop off the network.

2. Advanced IP scanner is a "one pass at a time" scanner that can give more detail about the devices discovered, including a drill-down representation of the "other stuff" that is connected to those devices.  It's great at reporting manufacturer of the connected devices as well.

Enjoy!  T.D.

Open cmd.exe in windows and
Open cmd.exe in windows and type arp -a. 
Gentlemen, thanks for the
Gentlemen, thanks for the responses.  There are some neat and useful features in your recommendations.  It tried all three. 
My problem still needs a solution:    I have an IP device (Linksys/Cisco 5 port smart switch).  I can always factory reset it and set IPV4 to and reprogram the unit. I have worked on units where I would like to go in find what needs fixing.   None of the suggestions find my unit on the RJ45 Ethernet port.  Tried also plugging into  both LAN and DtD ports on my ARHP hoping it would be found on a subnet etc.  No joy.

Thanks again
Wireshark. Reboot the device and it will likely send a "gratuitous ARP" broadcast on the wire which will contain the IP address the device wants to use. It may or may not show up in arp -a since that will only show if your computer happens to be set to the same subnet.
Loaded Wireshark - saw the
Loaded Wireshark - saw the arp for the etherbet port, but not the device - will have to read and experiment.

Honestly there is no real
Honestly there is no real easy way for this.

You can use an IP scanner but most require the IP to be reached by normal routing which wouldn’t work in this case.

Wireshark and arp only will work if it sends out packets to announce itself. Subnote: Make sure you did a promiscuous mode capture.

Bonjour(avahai) *might* work but it’s probably a long shot, some devices self announce themselves but that’s less so switches and more so routers and tv’s etc. But these would also probably show up in Wireshark too.

Ultimately there is no real good method for this.

Network equipment relies on the fact that the network manager knows what is set in the gear.

DHCP would be my option choice or leave it at stock up or write an IP on it, but that doesn’t work for ear your coming into after the fact so I can’t call any of those a solution to your request.

Appreciate the responses - it
Appreciate the responses - it seemed like there would be a solution, but that I had just not found it.  The recommendations have given me more tools for my toolbox, so the question was worth asking on my part.

Thanks for the help!

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