J T

If you know a MAC address on a LAN, how do you find out what IP address the MAC address to resolved to.

Cheers

dsmith

RARP

If you're on a host on the same subnet

"arp -a" on a Win2K/NT/Linux box will give the IP to MAC table - search the MACs for the one you want

(n.b. the host must have talked IP to the device for the MAC address to show up - best therefore to use a router or server tha you knwo talks to it)

There's probably a unix tool to actually do the RARP query directly but I dont know it

Deano

[Edited by dsmith - 5/21/2002 5:44:18 PM]

dsmith

On some hosts you can force it to query all IP addresses for the MAC by pinging the subnet broadcast address.

J T

Thanks for that If you have a lot of MAC addresses it can take a while going through the ARP table.

Is their an app that will allow you to put in one MAC address and return its IP.

dsmith

grep

(or "find" on windows)
e.g.
Linux : "arp -a | grep 000:B7:46:E5:8D"
Windows : "arp -a | find "00-D0-B7-46-E5-8D"
Cisco Rtr : "sh arp | inc 00d0.b746.e58d"

[Edited by dsmith - 5/21/2002 5:59:44 PM]

dowser

Or jump on the subnet's gateway router/s and issue a 'sh ip arp' (if it's blue). Still need to search the output though.

Richard

dowser

Doh..must read posts b4 posting

J T

Tried typing in

arp -a | find 00-D0-B7-46-E5-8D

In to windows command and got the reply: FIND: Parameter format not correct.

Any ideas?

dsmith

mac address needs quotes
arp -a | find "MAC HERE"

Dr Hu

How do you get the straight line after the -a It looks like the pipe key ¦ - but it doesnt like this?

This command would be very useful!

J T

It is the pipe key, unsure why it appears as | when i type it in here.

dsmith

One of the "lesser" windows 95/98/Me ? doesn't like pipe I think. It should work just fine on NT/2K/XP I beleive

its defo pipe - above backslash