I'm trying to find the IP address of a device on my network using only its MAC address. The network can be quite large (like /16 or even /8), so just pinging the broadcast and checking the ARP table can be really slow. I wrote a simple C program that sends ARP requests and waits for a response, which works fine on a /16 network, but takes about a minute.
I've also considered sending a DHCP discovery packet while spoofing the MAC address to see if the server will return the IP address. This could be faster, but I haven't had any luck with it yet. I've tried using arping, but it just times out without giving me an IP.
Has anyone faced a similar issue and found an easier way to get the IP from the MAC? Any tips or ready solutions would be greatly appreciated! Also, sorry if my English isn't perfect!
6 Answers
I recommend using Fing; it’s a handy tool for scanning the network and can help you find that device quickly. It’s user-friendly if you’re looking for something simple.
Nmap is another solid option for scanning your network. It can give detailed information about devices connected to the network, which might help you find what you're looking for.
If those devices are DHCP clients, check the DHCP server’s lease records. You might find the IP address listed there. Alternatively, you can look at the router's ARP table or the switch if you’re doing layer 3 switching. Also, if you're connecting to services on those devices, maybe set static IPs or DHCP reservations to make things easier down the road.
If you’ve got no access to switches or routers, consider using something like Angry IP Scanner. It might take a little while, but you should be able to locate the device on a /16 with it.
Checking the router's ARP table is a great way to find the IP address too. If you can get into the router, look there first. Some switches also let you look up MAC addresses if you have access to them.
If you can access the ARP table on the switch, that might be your best bet. Most switches allow you to see the MAC addresses and their corresponding IPs, which could save you a lot of time.
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