[nycbug-talk] Finding a device's IP address

[Charles Sprickman]

On Thu, 19 Mar 2009, Pete Wright wrote:

> On 19-Mar-09, at 3:52 PM, Charles Sprickman wrote:
>
>> Perhaps a bit OT, but a general question...
>> 
>> You have a device on a network that you do not have physical access to.
>> It has an IP address which may or may not be on the subnet it's actually
>> attached to.
>> 
>> How do you find what IP is configured?  What magic ARP stuff can you spew
>> in it's direction that would perhaps make it respond with something that
>> would give away it's IP?
>
> in the past when i've been in this pickle i logged into a switch i suspected 
> was close to the host in question.  found its entry in the arp cache (which 
> was associated w/another switch).  connected to that switch, washed hands 
> repeated until i found the subnet that the box was on (in this case our IBM 
> nodes all had a similar range of mac addy's which was sufficiently different 
> than our foundry switches which made things easier).

That's near where I started.  I'm thinking that perhaps the switch is a 
bit wonky, because I've looked at the "port address table" on this HP 
switch and it just comes up empty, which is annoying:

===========================- TELNET - MANAGER MODE
                Status and Counters - Port Address Table - Port 11

    MAC Address
   -------------

Nice, huh?

> there's even a fun diagram i found online:
> http://www.networkblueprints.com/troubleshooting/using-mac-address-table-and-arp-cache-lan

Thanks for the pointers...

Charles

> HTH
> -p