find IP from MAC

mcirsta · 04-19-2005, 07:00 PM

OK so here's my problem . I have a linux server running Debian and a custom compiled kernel in a network . I have the MAC
of a certain computer in the LAN and I need to find its IP .
How can I do this ?

homey · 04-19-2005, 08:00 PM

I'm sure there are other ways to do this but since it is on your network, you could ping a range of ip addresses and arp the same range. Then match up the mac to ip.
You may also have success using nmap on the range of ip addresses....
nmap -sP 192.168.1/24

For example: I setup a loop to ping 10 addresses on a range of 192.168.1/24

Code:

#!/bin/bash

for ((i=1; i<=10; i++));do
ping -c 1 192.168.1.$i 2>&1 >/dev/null
arp -a 192.168.1.$i
done

angrybeaver · 04-19-2005, 09:19 PM

fping is pretty handy to :

fping -g 192.168.1.0/24 | arp -a | grep aa:bb:cc:dd:ee:ff

mcirsta · 04-20-2005, 05:04 PM

Thanks ! Yeah this stuff could work . I think I'll use arping though to make sure I can ping even if some machines have a firewall .

epayen · 04-16-2007, 02:40 PM

Dear friends thank you for your help... that were very usefull,
I wish to leave a batch, in the same way of the original:

vi a file and write this code:

for ((i=$4; i<=$5; i++));do
/bin/ping -c 1 12.5.$3.$i 2>&1 >/dev/null
/sbin/arp -a 12.5.$3.$i
done

Then save the file as findmac.sh (or as you want).
Change permissions: #chmode 777 findmac.sh

and run the batch:

#./findmac.sh 12 5 80 0 62

And with this you will get the MACs of the IPs from 12.5.80.0 to 12.5.80.62

With a more work you can enhance this batch so you can find all octets.

nobler1050 · 06-16-2009, 03:06 PM

I know this topic is old, but I ran into the same issue and found that running nmap as root instead of a general user gives you the MAC address from a standard scan. Example 'nmap 192.168.0.0/24' has the following output:

Interesting ports on 192.168.0.10:
Not shown: 1712 closed ports
PORT STATE SERVICE
443/tcp open https
1720/tcp open H.323/Q.931
MAC Address: 00:1A:E8:05:A6:01 (Siemens Enterprise Communications GmbH & Co. KG)