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Forgotten IPs


If this doesn't work, most devices have a Manufacturer specific method. Check your documentation or google for it.



So, if what you're trying to do is crack into a device whose IP address you have forgotten, try this (windows)


  1. Directly connect the Ethernet port of your computer to the device's Ethernet port (or switched/hubbed to it, but not routed.)

  2. Pick an address on the subnet of your network that isn't being used (example- you are 192.168.1.44/24 ... so pick 192.168.1.99 for the device.)

  3. At the CLI enter the ARP command with '-s' and the device MAC and the selected network IP address
    Ex) 'arp -s 192.168.1.99 01-13-46-af-1d-32'

  4. Telnet/ssh/web to the device using the selected IP address (192.168.1.99 in the example.)

  5. Once in device, read it's real IP or change it.



The arp description in windows says the -s switch makes the entry permanent... but an 'arp -d' should clear ARP entries, even permanent ones.



The idea is that within a directly connected IP domain, devices really speak to each other via MAC address, so the IP address assigned to it can really be anything.



This great FAQ taken from a post by Dan Farrell on an isp-wireless mailing list.