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Got a weird one here.

I've got an IP address in my subnet that is alive and responds to ping requests, but I can't figure out what device actually live at that address. I've tried a couple of IP scanners that usually list hostnames and open ports / services, I've tried connecting to that address via http, https, telnet, SSH, but nothing responds and I don't have anything in DNS at that address.

We have no records or documentation of any device existing at this address and I'm at a bit of a loss because I need to expand my DHCP range, and this address is in the way.

Anyone know of a better way to interrogate that address to figure out what it is?

Thanks!

EDIT: I don't really see how this is a duplicate since that other question is from a completely different case [He has data from Advanced IP Scanner and I don't, he's using VMs, and I'm not] and that thread also has no answer. But it doesn't really matter because I found the offending device due to some great advice and good utilities in this thread. Thanks everyone!

Catatonic27
  • 921

2 Answers2

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Your objective is to find the device which is running in the specific IP address. For this I would recommend you to use nmap. Let's take for an example that the ipaddress is 192.168.1.7 in your network.

  • If you want to know the OS information
    nmap -A 192.168.1.7
  • Search for open port
    • nmap 192.168.1.7

    When you scan for the open port, if any port is open then try to connect with that port (if the port is connectable). Or you can even use the port to get the information through that open port, like:
    nmap -p 80 192.168.1.7
    Here I am using port 80 to scan for the information. You can download nmap from here. There's ports for most of the popular desktop OSes (You've not mentioned what you use), so chances are you can run this on most PCs
    Journeyman Geek
    • 133,878
    Prashant Dey
    • 209
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    [...] my network has like 25 different switches and poor documentation.

    If your network doesn't need to be up 24/24: Unplug stuff from switches until you cannot longer ping the device in question. Follow the cable you just unplugged, rinse and repeat. While you are at it, make some notes so documentation gradually improves.

    dirkt
    • 17,461